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1. Manganese-Iron Phosphate Nodules at the Groken Site, Gale Crater, Mars

Author

Allan H. Treiman, Nina L. Lanza, Scott VanBommel, Jeff Berger, Roger Wiens, Thomas Bristow, Jeffrey Johnson, Melissa Rice, Reginald Hart, Amy McAdam, Patrick Gasda, Pierre-Yves Meslin, Albert Yen, Amy J. Williams, Ashwin Vasavada, David Vaniman, Valerie Tu, Michael Thorpe, Elizabeth D. Swanner, Christina Seeger, Susanne P. Schwenzer, Susanne Schröder, Elizabeth Rampe, William Rapin, Silas J. Ralston, Tanya Peretyazhko, Horton Newsom, Richard V. Morris, Douglas Ming, Matteo Loche, Stéphane Le Mouélic, Christopher House, Robert Hazen, John P. Grotzinger, Ralf Gellert, Olivier Gasnault, Woodward W. Fischer, Ari Essunfeld, Robert T. Downs, Gordon W. Downs, Erwin Dehouck, Laura J. Crossey, Agnes Cousin, Jade M. Comellas, Joanna V. Clark, Benton Clark, Steve Chipera, Gwenaël Caravaca, John Bridges, David F. Blake, and Ryan Anderson

Subjects
Mars, Gale Crater, diagenesis, manganese, phosphate, laueite, Mineralogy, QE351-399.2
Abstract

The MSL Curiosity rover investigated dark, Mn-P-enriched nodules in shallow lacustrine/fluvial sediments at the Groken site in Glen Torridon, Gale Crater, Mars. Applying all relevant information from the rover, the nodules are interpreted as pseudomorphs after original crystals of vivianite, (Fe2+,Mn2+)3(PO4)2·8H2O, that cemented the sediment soon after deposition. The nodules appear to have flat faces and linear boundaries and stand above the surrounding siltstone. ChemCam LIBS (laser-induced breakdown spectrometry) shows that the nodules have MnO abundances approximately twenty times those of the surrounding siltstone matrix, contain little CaO, and have SiO2 and Al2O3 abundances similar to those of the siltstone. A deconvolution of APXS analyses of nodule-bearing targets, interpreted here as representing the nodules’ non-silicate components, shows high concentrations of MnO, P2O5, and FeO and a molar ratio P/Mn = 2. Visible to near-infrared reflectance of the nodules (by ChemCam passive and Mastcam multispectral) is dark and relatively flat, consistent with a mixture of host siltstone, hematite, and a dark spectrally bland material (like pyrolusite, MnO2). A drill sample at the site is shown to contain minimal nodule material, implying that analyses by the CheMin and SAM instruments do not constrain the nodules’ mineralogy or composition. The fact that the nodules contain P and Mn in a small molar integer ratio, P/Mn = 2, suggests that the nodules contained a stoichiometric Mn-phosphate mineral, in which Fe did (i.e., could) not substitute for Mn. The most likely such minerals are laueite and strunzite, Mn2+Fe3+2(PO4)2(OH)2·8H2O and –6H2O, respectively, which occur on Earth as alteration products of other Mn-bearing phosphates including vivianite. Vivianite is a common primary and diagenetic precipitate from low-oxygen, P-enriched waters. Calculated phase equilibria show Mn-bearing vivianite could be replaced by laueite or strunzite and then by hematite plus pyrolusite as the system became more oxidizing and acidic. These data suggest that the nodules originated as vivianite, forming as euhedral crystals in the sediment, enclosing sediment grains as they grew. After formation, the nodules were oxidized—first to laueite/strunzite yielding the diagnostic P/Mn ratio, and then to hematite plus an undefined Mn oxy-hydroxide (like pyrolusite). The limited occurrence of these Mn-Fe-P nodules, both in space and time (i.e., stratigraphic position), suggests a local control on their origin. By terrestrial analogies, it is possible that the nodules precipitated near a spring or seep of Mn-rich water, generated during alteration of olivine in the underlying sediments.

Published
2023
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2. Cerebral Small Vessel Disease: Cognition, Mood, Daily Functioning, and Imaging Findings from a Small Pilot Sample

Author

John G. Baker, Amy J. Williams, Catalina C. Ionita, Peterkin Lee-Kwen, Marilou Ching, and Robert S. Miletich

Subjects
Cerebrovascular disease, Cerebral small vessel disease, Stroke, SPECT, Neuropsychology, Subcortical vascular cognitive impairment, CogHealth, RBANS, SF-36, Neurology. Diseases of the nervous system, RC346-429, Geriatrics, RC952-954.6
Abstract

Cerebral small vessel disease, a leading cause of cognitive decline, is considered a relatively homogeneous disease process, and it can co-occur with Alzheimer’s disease. Clinical reports of magnetic resonance imaging (MRI)/computed tomography and single photon emission computed tomography (SPECT) imaging and neuropsychology testing for a small pilot sample of 14 patients are presented to illustrate disease characteristics through findings from structural and functional imaging and cognitive assessment. Participants showed some decreases in executive functioning, attention, processing speed, and memory retrieval, consistent with previous literature. An older subgroup showed lower age-corrected scores at a single time point compared to younger participants. Performance on a computer-administered cognitive measure showed a slight overall decline over a period of 8–28 months. For a case study with mild neuropsychology findings, the MRI report was normal while the SPECT report identified perfusion abnormalities. Future research can test whether advances in imaging analysis allow for identification of cerebral small vessel disease before changes are detected in cognition.

Published
2012
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3. Diverse Organic-Mineral Associations in Jezero Crater, Mars

Author

Sunanda Sharma, Ryan D. Roppel, Ashley E. Murphy, Luther W. Beegle, Rohit Bhartia, Andrew Steele, Joseph Razzell Hollis, Sandra Siljeström, Francis M. McCubbin, Sanford A. Asher, William J. Abbey, Abigail C. Allwood, Eve L. Berger, Benjamin L. Bleefeld, Aaron S. Burton, Sergei V. Bykov, Emily L. Cardarelli, Pamela G. Conrad, Andrea Corpolongo, Andrew D. Czaja, Lauren P. DeFlores, Kenneth Edgett, Kenneth A. Farley, Teresa Fornaro, Allison C. Fox, Marc D. Fries, David Harker, Keyron Hickman-Lewis, Joshua Huggett, Samara Imbeah, Ryan S. Jakubek, Linda C. Kah, Carina Lee, Yang Liu, Angela Magee, Michelle Minitti, Kelsey R. Moore, Alyssa Pascuzzo, Carolina Rodriguez Sanchez-Vahamonde, Eva L. Scheller, Svetlana Shkolyar, Kathryn M. Stack, Kim Steadman, Michael Tuite, Kyle Uckert, Alyssa Werynski, Roger C. Wiens, Amy J. Williams, Katherine Winchell, Megan R. Kennedy, and Anastasia Yanchilina

Subjects
Lunar and Planetary Science and Exploration, Geosciences (General)
Abstract

The presence and distribution of preserved organic matter on the surface of Mars can provide key information about the Martian carbon cycle and the potential of the planet to host life throughout its history. Several types of organic molecules have been previously detected in Martian meteorites1 and at Gale crater, Mars. Evaluating the diversity and detectability of organic matter elsewhere on Mars is important for understanding the extent and diversity of Martian surface processes and the potential availability of carbon sources1,5,6. Here we report the detection of Raman and fluorescence spectra consistent with several species of aromatic organic molecules in the Máaz and Séítah formations within the Crater Floor sequences of Jezero crater, Mars. We report specific fluorescence-mineral associations consistent with many classes of organic molecules occurring in different spatial patterns within these compositionally distinct formations, potentially indicating different fates of carbon across environments. Our findings suggest there may be a diversity of aromatic molecules prevalent on the Martian surface, and these materials persist despite exposure to surface conditions. These potential organic molecules are largely found within minerals linked to aqueous processes, indicating that these processes may have had a key role in organic synthesis, transport or preservation.

Published
2023
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4. Overview and Results From the Mars 2020 Perseverance Rover's First Science Campaign on the Jezero Crater Floor

Author

Vivian Z. Sun, Kevin P. Hand, Kathryn M. Stack, Ken A. Farley, Justin I. Simon, Claire Newman, Sunanda Sharma, Yang Liu, Roger C. Wiens, Amy J. Williams, Nicholas Tosca, Sanna Alwmark, Olivier Beyssac, Adrian Brown, Fred Calef, Emily L. Cardarelli, Elise Clavé, Barbara Cohen, Andrea Corpolongo, Andrew D. Czaja, Tyler Del Sesto, Alberto Fairen, Teresa Fornaro, Thierry Fouchet, Brad Garczynski, Sanjeev Gupta, Chris D. K. Herd, Keyron Hickman-Lewis, Briony Horgan, Jeffrey Johnson, Kjartan Kinch, Tanya Kizovski, Rachel Kronyak, Robert Lange, Lucia Mandon, Sarah Milkovich, Robert Moeller, Jorge Núñez, Gerhard Paar, Guy Pyrzak, Cathy Quantin-Nataf, David L. Shuster, Sandra Siljestroem, Andrew Steele, Michael Tice, Olivier Toupet, Arya Udry, Alicia Vaughan, and Brittan Wogsland

Subjects
Lunar And Planetary Science And Exploration
Abstract

The Mars 2020 Perseverance rover landed in Jezero crater on 18 February 2021. After a 100-sol period of commissioning and the Ingenuity Helicopter technology demonstration, Perseverance began its first science campaign to explore the enigmatic Jezero crater floor, whose igneous or sedimentary origins have been much debated in the scientific community. This paper describes the campaign plan developed to explore the crater floor's Máaz and Séítah formations and summarizes the results of the campaign between sols 100–379. By the end of the campaign, Perseverance had traversed more than 5 km, created seven abrasion patches, and sealed nine samples and a witness tube. Analysis of remote and proximity science observations show that the Máaz and Séítah formations are igneous in origin and composed of five and two geologic members, respectively. The Séítah formation represents the olivine-rich cumulate formed from differentiation of a slowly cooling melt or magma body, and the Máaz formation likely represents a separate series of lava flows emplaced after Séítah. The Máaz and Séítah rocks also preserve evidence of multiple episodes of aqueous alteration in secondary minerals like carbonate, Fe/Mg phyllosilicates, sulfates, and perchlorate, and surficial coatings. Post-emplacement processes tilted the rocks near the Máaz-Séítah contact and substantial erosion modified the crater floor rocks to their present-day expressions. Results from this crater floor campaign, including those obtained upon return of the collected samples, will help to build the geologic history of events that occurred in Jezero crater and provide time constraints on the formation of the Jezero delta.

Published
2023
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5. The Curiosity Rover’s Exploration of Glen Torridon, Gale Crater, Mars: An Overview of the Campaign and Scientific Results

Author

Kristen A Bennett, Valerie K Fox, Alex Bryk, William Dietrich, Christopher Fedo, Lauren Edgar, Michael T Thorpe, Amy J Williams, Gregory M Wong, Erwin Dehouck, Amy McAdam, Brad Sutter, Maëva Millan, Steven G Banham, Candice C Bedford, Thomas Bristow, Abigail Fraeman, Ashwin R Vasavada, John Grotzinger, Lucy Thompson, Catherine O’Connell-Cooper, Patrick Gasda, Amanda Rudolph, Robert Sullivan, Allan Treiman, Jennifer Eigenbrode, and Gwénaël Caravaca

Subjects
Lunar and Planetary Science and Exploration
Abstract

The Mars Science Laboratory rover, Curiosity, explored the clay mineral-bearing Glen Torridon region for 1 Martian year between January 2019 and January 2021, including a short campaign onto the Greenheugh pediment. The Glen Torridon campaign sought to characterize the geology of the area, seek evidence of habitable environments, and document the onset of a potentially global climatic transition during the Hesperian era. Curiosity roved 5 km in total throughout Glen Torridon, from the Vera Rubin ridge to the northern margin of the Greenheugh pediment. Curiosity acquired samples from 11 drill holes during this campaign and conducted the first Martian thermochemolytic-based organics detection experiment with the Sample Analysis at Mars instrument suite. The lowest elevations within Glen Torridon represent a continuation of lacustrine Murray formation deposits, but overlying widespread cross bedded sandstones indicate an interval of more energetic fluvial environments and prompted the definition of a new stratigraphic formation in the Mount Sharp group called the Carolyn Shoemaker formation. Glen Torridon hosts abundant phyllosilicates yet remains compositionally and mineralogically comparable to the rest of the Mount Sharp group. Glen Torridon samples have a great diversity and abundance of sulfur-bearing organic molecules, which are consistent with the presence of ancient refractory organic matter. The Glen Torridon region experienced heterogeneous diagenesis, with the most striking alteration occurring just below the Siccar Point unconformity at the Greenheugh pediment. Results from the pediment campaign show that the capping sandstone formed within the Stimson Hesperian aeolian sand sea that experienced seasonal variations in wind direction.

Published
2022
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6. Aqueous alteration processes in Jezero crater, Mars—implications for organic geochemistry

Author

Eva L. Scheller, Joseph Razzell Hollis, Emily L. Cardarelli, Andrew Steele, Luther W. Beegle, Rohit Bhartia, Pamela Conrad, Kyle Uckert, Sunanda Sharma, Bethany L. Ehlmann, William J. Abbey, Sanford A. Asher, Kathleen C. Benison, Eve L. Berger, Olivier Beyssac, Benjamin L. Bleefeld, Tanja Bosak, Adrian J. Brown, Aaron S. Burton, Sergei V. Bykov, Ed Cloutis, Alberto G. Fairén, Lauren DeFlores, Kenneth A. Farley, Deidra M. Fey, Teresa Fornaro, Allison C. Fox, Marc Fries, Keyron Hickman-Lewis, William F. Hug, Joshua E. Huggett, Samara Imbeah, Ryan S. Jakubek, Linda C. Kah, Peter Kelemen, Megan R. Kennedy, Tanya Kizovski, Carina Lee, Yang Liu, Lucia Mandon, Francis M. McCubbin, Kelsey R. Moore, Brian E. Nixon, Jorge I. Núñez, Carolina Rodriguez Sanchez-Vahamonde, Ryan D. Roppel, Mitchell Schulte, Mark A. Sephton, Shiv K. Sharma, Sandra Siljeström, Svetlana Shkolyar, David L. Shuster, Justin I. Simon, Rebecca J. Smith, Kathryn M. Stack, Kim Steadman, Benjamin P. Weiss, Alyssa Werynski, Amy J. Williams, Roger C. Wiens, Kenneth H. Williford, Kathrine Winchell, Brittan Wogsland, Anastasia Yanchilina, Rachel Yingling, and Maria-Paz Zorzano

Subjects
Multidisciplinary
Abstract

The Perseverance rover landed in Jezero crater, Mars, in February 2021. We used the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument to perform deep-ultraviolet Raman and fluorescence spectroscopy of three rocks within the crater. We identify evidence for two distinct ancient aqueous environments at different times. Reactions with liquid water formed carbonates in an olivine-rich igneous rock. A sulfate-perchlorate mixture is present in the rocks, which probably formed by later modifications of the rocks by brine. Fluorescence signatures consistent with aromatic organic compounds occur throughout these rocks and are preserved in minerals related to both aqueous environments.

Published
2022

7. Influence of Calcium Perchlorate on the Search for Organics on Mars with Tetramethylammonium Hydroxide Thermochemolysis

Author

Yuanyuan He, Pin Lu, Paul R. Mahaffy, Charles Malespin, Melissa Guzman, Cyril Szopa, Amy J. Williams, Samuel Teinturier, Maeva Millan, Sarah Stewart Johnson, Michel Cabane, Hervé Cottin, Jennifer C. Stern, Jennifer L. Eigenbrode, Rafael Navarro-González, Vincent Butin, Fabien Stalport, Naila Chaouche-Mechidal, Caroline Freissinet, Arnaud Buch, D. Coscia, Daniel P. Glavin, Jamila El Bekri, Jean-Yves Bonnet, Laboratoire de Génie des Procédés et Matériaux (LGPM), CentraleSupélec-Université Paris-Saclay, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), University of Florida [Gainesville] (UF), NASA Goddard Space Flight Center (GSFC), Georgetown University [Washington] (GU), GSFC Solar System Exploration Division, Telespazio France, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Instituto de Ciencias Nucleares [Mexico], Universidad Nacional Autónoma de México = National Autonomous University of Mexico (UNAM), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Paris (UP)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12), and Universidad Nacional Autónoma de México (UNAM)

Subjects
chemistry.chemical_classification, Tetramethylammonium hydroxide, Perchlorates, Extraterrestrial Environment, Inorganic chemistry, Pyrolysis gc ms, Mars, Calcium perchlorate, Mars Exploration Program, 010402 general chemistry, 01 natural sciences, Agricultural and Biological Sciences (miscellaneous), Gas Chromatography-Mass Spectrometry, 0104 chemical sciences, Quaternary Ammonium Compounds, chemistry.chemical_compound, chemistry, [SDU]Sciences of the Universe [physics], 13. Climate action, Space and Planetary Science, 0103 physical sciences, Sample Analysis at Mars, Calcium, Organic matter, 010303 astronomy & astrophysics
Abstract

International audience; The Mars Organic Molecule Analyzer (MOMA) and Sample Analysis at Mars (SAM) instruments onboard the Exomars 2022 and Mars Science Laboratory rovers, respectively, are capable of organic matter detection and differentiating potentially biogenic from abiotic organics in martian samples. To identify organics, both these instruments utilize pyrolysis–gas chromatography coupled to mass spectrometry, and the thermochemolysis agent tetramethylammonium hydroxide (TMAH) is also used to increase organic volatility. However, the reactivity and efficiency of TMAH thermochemolysis are affected by the presence of calcium perchlorate on the martian surface. In this study, we determined the products of TMAH pyrolysis in the presence and absence of calcium perchlorate at different heating rates (flash pyrolysis and SAM-like ramp pyrolysis with a 35°C·min−1 heating rate). The decomposition mechanism of TMAH pyrolysis in the presence of calcium perchlorate was studied by using stepped pyrolysis. Moreover, the effect of calcium perchlorate (at Mars-relevant concentrations) on the recovery rate of fatty acids with TMAH thermochemolysis was studied. Results demonstrate that flash pyrolysis yields more diversity and greater abundances of TMAH thermochemolysis products than does the SAM-like ramp pyrolysis method. There is no obvious effect of calcium perchlorate on TMAH degradation when the [ClO4−] is lower than 10 weight percent (wt %). Most importantly, the presence of calcium perchlorate does not significantly impact the recovery rate of fatty acids with TMAH thermochemolysis under laboratory conditions, which is promising for the detection of fatty acids via TMAH thermochemolysis with the SAM and MOMA instruments on Mars.

Published
2021

8. Mars Extant Life: What's Next? Conference Report

Author

Z. E. Gallegos, Rachel Mackelprang, Diana E. Northup, David Beaty, M. A. Nellessen, Vlada Stamenkovic, Paul R. Mahaffy, M. Hoffman, Nina Lanza, Shiladitya DasSarma, J. G. Blank, Patrick J. Gasda, Jie Xu, M. A. Meyer, B. R. W. O'Connor, Brian D. Wade, H. H. Bolivar Torres, C. J. Walker, Priya DasSarma, Aaron E. Engelhart, D. Viola, Zachary Garvin, Corien Bakermans, Larry Matthies, M. S. Bell, J. A. Torres Celis, Carol R. Stoker, Scott Perl, Kennda Lynch, Mark A. Schneegurt, Richard C. Quinn, Boris Sauterey, Laura Rowe, H. D. Smith, A. H. D. Koeppel, Amy J. Williams, Kevin D. Webster, J. L. Eigenbrode, L. A. Scuderi, Luoth Chou, Roger C. Wiens, P. Boston, Petra Schwendner, B. C. Clark, J. M. Williams, Dirk Schulze-Makuch, Rachel L. Harris, Thomas L. Kieft, J. H. Green, Andrew C. Schuerger, R. Bruner, P. A. Lee, J. D. Tarnas, Bonnie K. Baxter, Xiang Li, David J. Des Marais, Natalie Grefenstette, S. A. Benner, Horton E. Newsom, and Michael N. Spilde

Subjects
History, Life in extreme environments, 010504 meteorology & atmospheric sciences, business.industry, Library science, Mars Exploration Program, Mars extant life, Astrobiology, 01 natural sciences, Agricultural and Biological Sciences (miscellaneous), Extant taxon, Space and Planetary Science, Publishing, Life detection, 0103 physical sciences, Biosignatures, News & Views, business, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

On November 5–8, 2019, the “Mars Extant Life: What's Next?” conference was convened in Carlsbad, New Mexico. The conference gathered a community of actively publishing experts in disciplines related to habitability and astrobiology. Primary conclusions are as follows: A significant subset of conference attendees concluded that there is a realistic possibility that Mars hosts indigenous microbial life. A powerful theme that permeated the conference is that the key to the search for martian extant life lies in identifying and exploring refugia (“oases”), where conditions are either permanently or episodically significantly more hospitable than average. Based on our existing knowledge of Mars, conference participants highlighted four potential martian refugium (not listed in priority order): Caves, Deep Subsurface, Ices, and Salts. The conference group did not attempt to reach a consensus prioritization of these candidate environments, but instead felt that a defensible prioritization would require a future competitive process. Within the context of these candidate environments, we identified a variety of geological search strategies that could narrow the search space. Additionally, we summarized a number of measurement techniques that could be used to detect evidence of extant life (if present). Again, it was not within the scope of the conference to prioritize these measurement techniques—that is best left for the competitive process. We specifically note that the number and sensitivity of detection methods that could be implemented if samples were returned to Earth greatly exceed the methodologies that could be used at Mars. Finally, important lessons to guide extant life search processes can be derived both from experiments carried out in terrestrial laboratories and analog field sites and from theoretical modeling.

Published
2020

9. Lipid Biomarkers in Ephemeral Acid Salt Lake Mudflat/Sandflat Sediments: Implications for Mars

Author

Slavka Andrejkovičová, C. A. Knudson, Cherie N. Achilles, Sarah Stewart Johnson, Amy McAdam, Kathleen C. Benison, Heather Graham, Maeva Millan, and Amy J. Williams

Subjects
Geologic Sediments, 010504 meteorology & atmospheric sciences, Geochemistry, Mars, Ferric Compounds, 01 natural sciences, Exobiology, 0103 physical sciences, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, chemistry.chemical_classification, Minerals, Sulfates, Ephemeral key, Western Australia, Mars Exploration Program, Lipids, Agricultural and Biological Sciences (miscellaneous), Lakes, Brine, chemistry, Space and Planetary Science, Acid salt, Sedimentary rock, Lipid biomarkers, Biomarkers, Geology
Abstract

Sedimentary strata on Mars often contain a mix of sulfates, iron oxides, chlorides, and phyllosilicates, a mineral assemblage that is unique on Earth to acid brine environments. To help characterize the astrobiological potential of depositional environments with similar minerals present, samples from four naturally occurring acidic salt lakes and adjacent mudflats/sandflats in the vicinity of Norseman, Western Australia, were collected and analyzed. Lipid biomarkers were extracted and quantified, revealing biomarkers from vascular plants alongside trace microbial lipids. The resilience of lipids from dead organic material in these acid saline sediments through the pervasive stages of early diagenesis lends support to the idea that sulfates, in tandem with phyllosilicates and iron oxides, could be a viable target for biomarkers on Mars. To fully understand the astrobiological potential of these depositional environments, additional investigations of organic preservation in ancient acidic saline sedimentary environments are needed.

Published
2020

11. Flexible fieldwork

Author

Anita M. S. Marshall, Jennifer L. Piatek, David A. Williams, Elisabeth Gallant, Sean Thatcher, Stephen Elardo, Amy J. Williams, Trevor Collins, and Yesenia Arroyo

Subjects
Atmospheric Science, Pollution, Nature and Landscape Conservation, Earth-Surface Processes
Published
2022

12. Perseverance rover reveals an ancient delta-lake system and flood deposits at Jezero crater, Mars

Author

C. Quantin-Nataf, Keyron Hickman-Lewis, Adrian J. Brown, Tanja Bosak, Scott M. McLennan, David L. Shuster, Kenneth H. Williford, R. A. Yingst, Kenneth A. Farley, Benjamin P. Weiss, James F. Bell, Sylvestre Maurice, Amy J. Williams, Linda C. Kah, S. F. Sholes, Gilles Dromart, Vivian Z. Sun, Justin I. Simon, S. Holm-Alwmark, Jorge I. Nunez, Olivier Gasnault, Sunetra Gupta, Ann Ollila, Melissa S. Rice, Allan H. Treiman, K. M. Stack, John P. Grotzinger, N. Mangold, J. Martinez-Frias, Bethany L. Ehlmann, Roger C. Wiens, J. W. Rice, Olivier Beyssac, P. Pilleri, Fred Calef, Briony Horgan, J. D. Tarnas, Nathan R. Williams, S. Le Mouélic, Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
Delta, Hydrology Geomorphology fluvial 1625, 010504 meteorology & atmospheric sciences, Geochemistry, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Mars, 01 natural sciences, Jezero crater, [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology, Impact crater, Margin (machine learning), 0103 physical sciences, 010303 astronomy & astrophysics, CORINTH, 0105 earth and related environmental sciences, ARCHITECTURE, Multidisciplinary, Flood myth, ORIGIN, Mars Exploration Program, SCIENCE, Sedimentology, 13. Climate action, RIFT, Sedimentary rock, Geology
Abstract

Perseverance images of a delta on Mars The Perseverance rover landed in Jezero crater, Mars, in February 2021. Earlier orbital images showed that the crater contains an ancient river delta that was deposited by water flowing into a lake billions of years ago. Mangold et al . analyzed rover images taken shortly after landing that show distant cliff faces at the edge of the delta. The exposed stratigraphy and sizes of boulders allowed them to determine the past lake level and water discharge rates. An initially steady flow transitioned into intermittent floods as the planet dried out. This history of the delta’s geology provides context for the rest of the mission and improves our understanding of Mars’ ancient climate. —KTS

Published
2021

13. Influence of Calcium Perchlorate on the Search for Martian Organic Compounds with MTBSTFA/DMF Derivatization

Author

Sarah Stewart Johnson, Amy J. Williams, Daniel P. Glavin, Jean-Yves Bonnet, Melissa Guzman, Charles Malespin, Caroline Freissinet, Rafael Navarro-González, Michel Cabane, Arnaud Buch, Yuanyuan He, D. Coscia, Cyril Szopa, Maeva Millan, Jennifer L. Eigenbrode, Samuel Teinturier, Pin Lu, Paul R. Mahaffy, Laboratoire de Génie des Procédés et Matériaux (LGPM), CentraleSupélec-Université Paris-Saclay, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Department of Biology [Washington], Georgetown University [Washington] (GU), NASA Goddard Space Flight Center (GSFC), Instituto de Ciencias Nucleares [Mexico], Universidad Nacional Autónoma de México (UNAM), Department of Geological Sciences [Gainesville] (UF|Geological), University of Florida [Gainesville] (UF), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), and Telespazio France

Subjects
Extraterrestrial Environment, 010504 meteorology & atmospheric sciences, Inorganic chemistry, Mars, 01 natural sciences, Gas Chromatography-Mass Spectrometry, Perchlorate, chemistry.chemical_compound, 0103 physical sciences, Derivatization, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Perchlorates, Chemistry, Chloromethane, Dimethylformamide, Calcium perchlorate, Agricultural and Biological Sciences (miscellaneous), 13. Climate action, Space and Planetary Science, Chlorobenzene, [SDU]Sciences of the Universe [physics], Reagent, Sample Analysis at Mars, Calcium, Pyrolysis
Abstract

International audience; N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA), mixed with the solvent N,N-dimethylformamide (DMF), is used as a derivatizing reagent by the Sample Analysis at Mars (SAM) experiment onboard NASA's Curiosity rover and will soon be utilized by the Mars Organic Molecule Analyzer experiment onboard the ESA/Roscosmos Rosalind Franklin rover. The pyrolysis products of MTBSTFA, DMF, and the MTBSTFA/DMF mixtures, obtained at different temperatures, were analyzed. Two different pyrolysis modes were studied, flash pyrolysis and ramp pyrolysis (35°C/min), to evaluate the potential influence of the sample heating speed on the production of products in space chromatographs. The effect of the presence of calcium perchlorate on the pyrolysis products of MTBSTFA/DMF was also studied to ascertain the potential effect of perchlorate species known to be present at the martian surface. The results show that MTBSTFA/DMF derivatization should be applied below 300°C when using flash pyrolysis, as numerous products of MTBSTFA/DMF were formed at high pyrolysis temperatures. However, when an SAM-like ramp pyrolysis was applied, the final pyrolysis temperature did not appear to influence the degradation products of MTBSTFA/DMF. All products of MTBSTFA/DMF pyrolysis are listed in this article, providing a major database of products for the analysis of martian analog samples, meteorites, and the in situ analysis of martian rocks and soils. In addition, the presence of calcium perchlorate does not show any obvious effects on the pyrolysis of MTBSTFA/DMF: Only chloromethane and TBDMS-Cl (chloro-tertbutyldimethylsilane) were detected, whereas chlorobenzene and other chlorine-bearing compounds were not detected. However, other chlorine-bearing compounds were detected after pyrolysis of the Murchison meteorite in the presence of calcium perchlorate. This result reinforces previous suggestions that chloride-bearing compounds could be reaction products of martian samples and perchlorate.

Published
2021

14. Using ChemCam LIBS data to constrain grain size in rocks on Mars: Proof of concept and application to rocks at Yellowknife Bay and Pahrump Hills, Gale crater

Author

Olivier Forni, Sylvestre Maurice, Amy J. Williams, Nicolas Mangold, Kathryn M. Stack, Horton E. Newsom, Marion Nachon, Jonas L'Haridon, Dawn Y. Sumner, Olivier Gasnault, Roger C. Wiens, Frances Rivera-Hernandez, University of California [Davis] (UC Davis), University of California, Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Department of Computer Science [Davis] (UC Davis), University of California-University of California, Los Alamos National Laboratory (LANL), Department of Earth and Planetary Sciences [Davis], Université d'Angers (UA)-Université de Nantes - Faculté des Sciences et des Techniques, Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Météo France-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Météo France-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS), Institute of Meteoritics [Albuquerque] (IOM), The University of New Mexico [Albuquerque], Department of Physics, Astronomy, and Geosciences [Towson], Towson University [Towson, MD, United States], University of Maryland System-University of Maryland System, University of California (UC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Department of Computer Science [Univ California Davis] (CS - UC Davis), and University of California (UC)-University of California (UC)

Subjects
Martian, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Bedrock, Mineralogy, Astronomy and Astrophysics, Mars Exploration Program, Exploration of Mars, 01 natural sciences, Grain size, Sedimentary depositional environment, [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology, [SDU]Sciences of the Universe [physics], 13. Climate action, Space and Planetary Science, 0103 physical sciences, Sedimentary rock, Laser-induced breakdown spectroscopy, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Geology, 0105 earth and related environmental sciences
Abstract

Grain size in martian sedimentary rocks can be constrained using point-to-point chemical variabilities in Laser Induced Breakdown Spectroscopy (LIBS) data from the ChemCam instrument on the Mars Science Laboratory (MSL) Curiosity rover. The diameter of each point ablated by the ChemCam laser is in the range of medium to coarse sand in size. Thus, rocks with grains significantly smaller than the laser spot size produce bulk rock compositions at each LIBS point and low point-to-point chemical variability among LIBS points. In contrast, analyses of rocks with grains about the size of the spot or larger contain contributions from individual grains at each point and often have high point-to-point chemical variability. The Gini index, a statistical parameter, was used to calculate the point-to-point chemical variability in major-element oxide compositions derived from the ChemCam LIBS data. First, the total range of each LIBS major-element oxide composition was normalized from 0 to 1 across all LIBS observations. Then the Gini index was calculated for each oxide in each LIBS observation. Finally, the Gini indices of each oxide were averaged to derive a Gini index mean score, G MEAN , for each LIBS observation. A correlation between G MEAN and grain size was validated using sedimentary rocks of various grain sizes from the Yellowknife Bay formation and the Pahrump Hills member of the Murray formation in Gale crater. Overall, finer-grained rocks had smaller G MEAN than coarser-grained rocks. To calibrate G MEAN to grain size, grain size estimates based on visual assessment of high-resolution images were compared to G MEAN values for the same targets to create a calibrated scale. This calibrated scale was used to infer the grain size of rocks with unknown grain size. Overall, the grain sizes predicted for rocks with unknown grain size overlapped with those of known grain size from the same units and/or bedrock targets. The grain sizes inferred using the G MEAN based on ChemCam LIBS data are complimentary to those determined from images and both techniques can be used to improve interpretations of the depositional environments of rocks analyzed by Curiosity and future Mars missions with LIBS, such as the Mars 2020 rover.

Published
2019

15. Metabolic Processes Preserved as Biosignatures in Iron-Oxidizing Microorganisms: Implications for Biosignature Detection on Mars

Author

David R. Emerson, Amy J. Williams, Andrej Grubisic, and Melissa Floyd

Subjects
Chemoautotrophic Growth, 010504 meteorology & atmospheric sciences, Microorganism, chemistry.chemical_element, Mars, Life on Mars, 01 natural sciences, Oxygen, Astrobiology, Pterin cofactor, Iron bacteria, 0103 physical sciences, Biosignature, Exobiology, Environmental Microbiology, 010303 astronomy & astrophysics, Research Articles, 0105 earth and related environmental sciences, biology, Iron-oxidizing bacteria, Bacteria, Geomicrobiology, Mars Exploration Program, biology.organism_classification, Agricultural and Biological Sciences (miscellaneous), TMSH, chemistry, Space and Planetary Science
Abstract

Iron-oxidizing bacteria occupy a distinct environmental niche. These chemolithoautotrophic organisms require very little oxygen (when neutrophilic) or outcompete oxygen for access to Fe(II) (when acidophilic). The utilization of Fe(II) as an electron donor makes them strong analog organisms for any potential life that could be found on Mars. Despite their importance to the elucidation of early life on, and potentially beyond, Earth, many details of their metabolism remain unknown. By using on-line thermochemolysis and gas chromatography–mass spectrometry (GC-MS), a distinct signal for a low-molecular-weight molecule was discovered in multiple iron-oxidizing isolates as well as several iron-dominated environmental samples, from freshwater and marine environments and in both modern and older iron rock samples. This GC-MS signal was neither detected in organisms that did not use Fe(II) as an electron donor nor present in iron mats in which organic carbon was destroyed by heating. Mass spectral analysis indicates that the molecule bears the hallmarks of a pterin-bearing molecule. Genomic analysis has previously identified a molybdopterin that could be part of the electron transport chain in a number of lithotrophic iron-oxidizing bacteria, suggesting one possible source for this signal is the pterin component of this protein. The rock samples indicate the possibility that the molecule can be preserved within lithified sedimentary rocks. The specificity of the signal to organisms requiring iron in their metabolism makes this a novel biosignature with which to investigate both the evolution of life on ancient Earth and potential life on Mars.

Published
2018

16. Diagenesis Revealed by Fine‐Scale Features at Vera Rubin Ridge, Gale Crater, Mars

Author

Marie J. Henderson, Erwin Dehouck, Connor R. Tinker, Frances Rivera-Hernandez, Lauren A. Edgar, Nathan Stein, Briony Horgan, Abigail A. Fraeman, Linda C. Kah, Kenneth S. Edgett, Kristen A. Bennett, Amy J. Williams, Christopher S. Edwards, R. E. Kronyak, Deirdra M. Fey, Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Geophysics, Scale (ratio), [SDU]Sciences of the Universe [physics], Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Ridge (meteorology), Gale crater, Mars Exploration Program, Geomorphology, Geology, Diagenesis
Abstract

International audience; Fine scale (submillimeter to centimeter) depositional and diagenetic features encountered during the Curiosity rover's traverse in Gale crater provide a means to understand the geologic history of Vera Rubin ridge (VRR). VRR is a topographically high feature on the lower north slope of Aeolis Mons, a 5 km high stratified mound within Gale crater. We use high spatial resolution images from the Mars Hand Lens Imager (MAHLI) as well as grain sizes estimated with the Gini index mean score technique that uses ChemCam Laser Induced Breakdown Spectroscopy (LIBS) chemical data to constrain the postdepositional history of the strata exposed on this ridge. MAHLI images were used to examine the color, grain size, and style of lamination of the host rocks, as well as to explore the occurrence of nodules, diagenetic crystals, pits, and a variety of dark gray iron rich features. This survey revealed abundant and widespread diagenetic features within the rocks exposed on VRR and demonstrated that rock targets estimated to be coarser generally contain more diagenetic features than those estimated to have finer grains, which indicate that grain size may have influenced the degree and type of diagenesis. A subset of rocks within VRR are gray in color and exhibit the highest proportion of diagenetic features. We suggest that these targets experienced a different diagenetic history than the other rocks on VRR and hypothesize that redistribution and recrystallization of iron within specific intervals may have resulted in both the gray color and the abundance of dark gray iron rich diagenetic features.

Published
2021

17. Constraints on the Mineralogy and Geochemistry of Vera Rubin Ridge, Gale Crater, Mars, From Mars Science Laboratory Sample Analysis at Mars Evolved Gas Analyses

Author

Heather B. Franz, Amy McAdam, J. M. T. Lewis, G. M. Wong, Christopher H. House, Slavka Andrejkovičová, Douglas W. Ming, Sarah Stewart Johnson, Brad Sutter, Jennifer C. Stern, Jennifer L. Eigenbrode, J. V. Clark, Cherie N. Achilles, C. A. Knudson, Lucy M. Thompson, Richard V. Morris, Amy J. Williams, Elizabeth B. Rampe, Paul R. Mahaffy, Rafael Navarro-González, Thomas F. Bristow, Ralf Gellert, and P. Douglas Archer

Subjects
Geophysics, Space and Planetary Science, Geochemistry and Petrology, Sample Analysis at Mars, Earth and Planetary Sciences (miscellaneous), Ridge (meteorology), Geochemistry, Gale crater, Mars Exploration Program, Geology
Published
2020

18. Evidence for a diagenetic origin of vera rubin ridge, gale crater, Mars: summary and synthesis of curiosity's exploration campaign

Author

Craig Hardgrove, Kirsten L. Siebach, John P. Grotzinger, Christopher S. Edwards, Alexander B. Bryk, Susanne P. Schwenzer, Sarah Stewart Johnson, William E. Dietrich, Lauren A. Edgar, Sunetra Gupta, Steven G. Banham, Jeffrey G. Catalano, S. Czarnecki, K. M. Stack, Ashwin R. Vasavada, R. V. Morris, Danika Wellington, John Bridges, Christopher H. House, Kristen A. Bennett, S. M. R. Turner, David M. Rubin, Jonas L'Haridon, Jeffrey R. Johnson, Roger C. Wiens, Valerie Fox, S. Jacob, Raymond E. Arvidson, Amy J. Williams, Vivian Z. Sun, Christopher M. Fedo, Jens Frydenvang, Travis Gabriel, Briony Horgan, Woodward W. Fischer, E. B. Rampe, Abigail A. Fraeman, Lucy M. Thompson, N. Mangold, G. M. Wong, Mark R. Salvatore, Nathaniel Stein, G. David, Science and Technology Facilities Council (STFC), UK Space Agency, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Geochemistry & Geophysics, 010504 meteorology & atmospheric sciences, Outcrop, Lacustrine, Geochemistry, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Mars, Hematite, FLUID-FLOW, Geologic record, 01 natural sciences, Diagenesis, Geochemistry and Petrology, 0201 Astronomical and Space Sciences, Earth and Planetary Sciences (miscellaneous), 0402 Geochemistry, CHEMCAM INSTRUMENT SUITE, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Spectral signature, Science & Technology, SEDIMENTARY-ROCKS, MOUNT SHARP, Bedrock, DYNAMIC ALBEDO, Gale crater, Mars Exploration Program, MURRAY FORMATION, 15. Life on land, ATOM EXCHANGE, Geophysics, Curiosity, 0403 Geology, Space and Planetary Science, visual_art, Physical Sciences, visual_art.visual_art_medium, PAHRUMP HILLS, (U-TH)/HE DATES, Geology
Abstract

This paper provides an overview of the Curiosity rover's exploration at Vera Rubin ridge and summarizes the science results. Vera Rubin ridge (VRR) is a distinct geomorphic feature on lower Aeolis Mons (informally known as Mt. Sharp) that was identified in orbital data based on its distinct texture, topographic expression, and association with a hematite spectral signature. Curiosity conducted extensive remote sensing observations, acquired data on dozens of contact science targets, and drilled three outcrop samples from the ridge, as well as one outcrop sample immediately below the ridge. Our observations indicate that strata composing VRR were deposited in a predominantly lacustrine setting and are part of the Murray formation. The rocks within the ridge are chemically in family with underlying Murray formation strata. Red hematite is dispersed throughout much of the VRR bedrock, and this is the source of the orbital spectral detection. Gray hematite is also present in isolated, gray‐colored patches concentrated towards the upper elevations of VRR, and these gray patches also contain small, dark Fe‐rich nodules. We propose that VRR formed when diagenetic event(s) preferentially hardened rocks, which were subsequently eroded into a ridge by wind. Diagenesis also led to enhanced crystallization and/or cementation that deepened the ferric‐related spectral absorptions on the ridge, which helped make them readily distinguishable from orbit. Results add to existing evidence of protracted aqueous environments at Gale crater and give new insight into how diagenesis shaped Mars’ rock record.

Published
2020

19. The search for organic compounds with TMAH thermochemolysis: From Earth analyses to space exploration experiments

Author

Arnaud Buch, D. Coscia, Daniel P. Glavin, Michel Cabane, Caroline Freissinet, Melissa Guzman, Charles Malespin, Jennifer L. Eigenbrode, Maeva Millan, Cyril Szopa, Yuanyuan He, Samuel Teinturier, Amy J. Williams, Paul R. Mahaffy, Pin Lu, Laboratoire de Génie des Procédés et Matériaux (LGPM), CentraleSupélec-Université Paris-Saclay, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), University of Florida [Gainesville] (UF), Georgetown University [Washington] (GU), NASA Goddard Space Flight Center (GSFC), and GSFC Solar System Exploration Division

Subjects
Tetramethylammonium hydroxide, Internal standard, Tetramethylammonium hydroxide (TMAH), SAM and MOMA, 010401 analytical chemistry, Pyrolysis gc ms, Space experiment, 01 natural sciences, Derivatization, 0104 chemical sciences, Analytical Chemistry, Thermally assisted hydrolysis and methylation (THM), chemistry.chemical_compound, TMAH degradation, chemistry, Pyrolysis-GC/MS, [SDU]Sciences of the Universe [physics], In situ analysis, Environmental chemistry, Thermochemolysis, Quantitative analysis, Spectroscopy, Earth (classical element)
Abstract

International audience; Tetramethylammonium hydroxide (TMAH) is one of the most popular methylation reagents that have been increasingly used for the detection of organic compounds within a wide range of samples, such as soil, coal, lacquer, lignin, polymers and for in situ analysis of solid samples by space experiments. The analytical methods and instruments, experimental conditions, and the qualitative and quantitative analysis of organic compounds using TMAH thermochemolysis for the last 10 years were reviewed; additionally, the mechanism of TMAH thermochemolysis and TMAH degradation are overviewed herein. The objective of this paper is to give a broad view of the TMAH thermochemolysis analysis, to demonstrate how the technique can be used for the detection of organics on Mars and other planets, and to promote cooperation between different disciplines which may use thermochemolysis.

Published
2020

21. Encyclopedia of Biophysics

Author

Amy J. Williams and Nia Thomas

Subjects
Electrophysiology, Membrane, biology, Chemistry, Biophysics, biology.organism_classification, Ion channel, Bacteria, Intracellular
Published
2020

24. Contrasting Regional Soil Alteration Across the Topographic Dichotomy of Mars

Author

Kyeong Ja Kim, C. Fralick, D. R. Hood, Suniti Karunatillake, Lujendra Ojha, Jennifer L. Heldmann, Olivier Gasnault, B. Dutrow, Amy J. Williams, S. Kobs, Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Habitability, Earth science, Martian soil, Mars Exploration Program, 01 natural sciences, Geophysics, [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology, 0103 physical sciences, General Earth and Planetary Sciences, 010303 astronomy & astrophysics, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

International audience

Published
2019

25. Biosignature Preservation and Detection in Mars Analog Environments

Author

Heather Graham, Thomas M. McCollom, Kennda Lynch, Elisabeth M. Hausrath, M Niki Parenteau, Briony Horgan, Amy J. Williams, Sally L. Potter-McIntyre, Lindsay Hays, and David J. Des Marais

Subjects
Sample selection, 010504 meteorology & atmospheric sciences, Extraterrestrial Environment, Habitability, Earth, Planet, Iron, Mars, Water, Context (language use), Mars Exploration Program, Review Article, 01 natural sciences, Agricultural and Biological Sciences (miscellaneous), Astrobiology, Space and Planetary Science, 0103 physical sciences, Biosignature, Exobiology, Source material, Water chemistry, Environmental science, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

This review of material relevant to the Conference on Biosignature Preservation and Detection in Mars Analog Environments summarizes the meeting materials and discussions and is further expanded upon by detailed references to the published literature. From this diverse source material, there is a detailed discussion on the habitability and biosignature preservation potential of five primary analog environments: hydrothermal spring systems, subaqueous environments, subaerial environments, subsurface environments, and iron-rich systems. Within the context of exploring past habitable environments on Mars, challenges common to all of these key environments are laid out, followed by a focused discussion for each environment regarding challenges to orbital and ground-based observations and sample selection. This leads into a short section on how these challenges could influence our strategies and priorities for the astrobiological exploration of Mars. Finally, a listing of urgent needs and future research highlights key elements such as development of instrumentation as well as continued exploration into how Mars may have evolved differently from Earth and what that might mean for biosignature preservation and detection. Key Words: Biosignature preservation—Biosignature detection—Mars analog environments—Conference report—Astrobiological exploration. Astrobiology 17, 363–400., Table of Contents Abstract 1. Executive Summary 2. Introduction 2.1. Habitable environments, biosignatures, preservation 3. Mars Analog Environments on Earth 3.1. Hydrothermal spring systems 3.1.1. Definition of hydrothermal spring systems3.1.2. Habitability of hydrothermal spring systems 3.1.2.1. Habitability pros3.1.2.2. Habitability cons3.1.3. Biosignature preservation in hydrothermal spring systems 3.1.3.1. Biosignature preservation pros3.1.3.2. Biosignature preservation cons3.2. Subaqueous environments 3.2.1. Definition of subaqueous environments3.2.2. Habitability of subaqueous environments 3.2.2.1. Habitability pros3.2.2.2. Habitability cons3.2.3. Biosignature preservation in subaqueous environments 3.2.3.1. Biosignature preservation pros3.2.3.2. Biosignature preservation cons3.3. Subaerial environments 3.3.1. Definition of subaerial environments3.3.2. Habitability of subaerial environments 3.3.2.1. Habitability pros3.3.2.2. Habitability cons3.3.3. Biosignature preservation in subaerial environments 3.3.3.1. Biosignature preservation pros3.3.3.2. Biosignature preservation cons3.4. Subsurface environments 3.4.1. Definition of subsurface environments3.4.2. Habitability of subsurface environments 3.4.2.1. Habitability pros3.4.2.2. Habitability cons3.4.3. Biosignature preservation in subsurface environments 3.4.3.1. Biosignature preservation pros3.4.3.2. Biosignature preservation cons3.5. Iron-rich environments 3.5.1. Definition of iron-rich environments3.5.2. Habitability of iron-rich environments 3.5.2.1. Habitability pros3.5.2.2. Habitability cons3.5.3. Biosignature preservation in iron-rich environments 3.5.3.1. Biosignature preservation pros3.5.3.2. Biosignature preservation cons 4. Exploring Past Habitable Environments on Mars 4.1. Common challenges 4.1.1. Identification of sites 4.1.1.1. Orbital observations for site selection4.1.1.2. Surface observations4.1.1.3. Sample collection4.1.1.4. Mars 2020 rover instrument suite4.1.2. Preservation4.2. Orbital observations 4.2.1. Hydrothermal spring systems4.2.2. Subaqueous environments4.2.3. Subaerial environments4.2.4. Subsurface environments4.2.5. Iron-rich environments4.3. Observations and sample selection on the ground 4.3.1. Hydrothermal spring systems 4.3.1.1. Observations4.3.1.2. Sample selection4.3.2. Subaqueous systems 4.3.2.1. Observations4.3.2.2. Sample selection4.3.3. Subaerial environments 4.3.3.1. Observations4.3.3.2. Sample selection4.3.4. Subsurface environments 4.3.4.1. Observations4.3.4.2. Sample selection4.3.5. Iron-rich environments 4.3.5.1. Observations4.3.5.2. Sample selection4.4. Strategies and priorities 5. Urgent Needs and Future Research Acknowledgments Author Disclosure Statement References Abbreviations Used

Published
2017

26. Application of TMAH thermochemolysis to the detection of nucleobases: Application to the MOMA and SAM space experiment

Author

Pin Lu, Paul R. Mahaffy, M. Morisson, Cyril Szopa, Melissa Guzman, Jason P. Dworkin, Maeva Millan, J. L. Eigenbrode, Jean-Yves Bonnet, Caroline Freissinet, Sarah Stewart Johnson, Amy J. Williams, Yuanyuan He, D. Coscia, Arnaud Buch, Daniel P. Glavin, Charles Malespin, Rafael Navarro-González, Laboratoire de Génie des Procédés et Matériaux - EA 4038 (LGPM), CentraleSupélec, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), University of Florida [Gainesville] (UF), Georgetown University [Washington] (GU), NASA Goddard Space Flight Center (GSFC), Laboratorio de Química de Plasmas y Estudios Planetarios [Mexico], Instituto de Ciencias Nucleares [Mexico], Universidad Nacional Autónoma de México (UNAM)-Universidad Nacional Autónoma de México (UNAM), Telespazio France, and Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
Hot Temperature, Guanine, Mars, MOMA, 02 engineering and technology, Pyrimidinones, 01 natural sciences, Gas Chromatography-Mass Spectrometry, Analytical Chemistry, Nucleobase, chemistry.chemical_compound, Limit of Detection, Hypoxanthine, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Tetramethylammonium hydroxide, Nucleobases, Chromatography, Tetramethylammonium hydroxide (TMAH)SAM, 010401 analytical chemistry, Uracil, Space Flight, 021001 nanoscience & nanotechnology, Derivatization, 0104 chemical sciences, Thymine, chemistry, 13. Climate action, Purines, Sample Analysis at Mars, Thermochemolysis, GC-MS, 0210 nano-technology, Cytosine, Pyrolysis
Abstract

International audience; Thermochemolysis of seven nucleobases—adenine, thymine, uracil, cytosine, guanine, xanthine, and hypoxanthine—in tetramethylammonium hydroxide (TMAH) was studied individually by pyrolysis gas chromatography mass spectrometry in the frame of the Mars surface exploration. The analyses were performed under conditions relevant to the Sample Analysis at Mars (SAM) instrument of the Mars Curiosity Rover and the Mars Organic Molecule Analyzer (MOMA) instrument of the ExoMars Rover. The thermochemolysis products of each nucleobase were identified and the reaction mechanisms studied. The thermochemolysis temperature was optimized and the limit of detection and quantification of each nucleobase were also investigated. Results indicate that 600°C is the optimal thermochemolysis temperature for all seven nucleobases. The methylated products trimethyl-adenine, 1, 3-dimethyl-thymine, 1, 3-dimethyl-uracil, trimethyl-cytosine, 1, 3, 7-trimethyl-xanthine (caffeine), and dimethyl-hypoxanthine, respectively, are the most stable forms of adenine, thymine, uracil, cytosine, guanine, and xanthine, and hypoxanthine in TMAH solutions. The limits of detection for adenine, thymine, and uracil were 0.075 nmol; the limits of detection for guanine, cytosine, and hypoxanthine were higher, at 0.40, 0.55, and 0.75 nmol, respectively. These experiments allowed to well constrain the analytical capabilities of the thermochemolysis experiments that will be performed on Mars to detect nucleobases.

Published
2019

27. Late-Stage Diagenetic Concretions in the Murray Formation, Gale Crater, Mars

Author

Christopher H. House, Lucy M. Thompson, K. Stack, Woodward W. Fischer, Roger C. Wiens, Amy J. Williams, Marion Nachon, Vivian Z. Sun, Sarah Stewart Johnson, Linda C. Kah, Scott VanBommel, and R. E. Kronyak

Subjects
010504 meteorology & atmospheric sciences, Geochemistry, Late stage, Gale crater, Astronomy and Astrophysics, Mars Exploration Program, Sediment compaction, engineering.material, Cementation (geology), 01 natural sciences, Diagenesis, Space and Planetary Science, Concretion, 0103 physical sciences, engineering, 010303 astronomy & astrophysics, Lithification, 0105 earth and related environmental sciences
Abstract

Concretions are prevalent features in the generally lacustrine deposits of the Murray formation in Gale crater. In this work, we document the morphologic, textural, and chemical properties of these concretions throughout 300 m of Murray formation stratigraphy from Mars Science Laboratory observations between Sols 750–1900. We interpret these observations to constrain the timing and composition of post-depositional fluid events at Gale crater. We determine that the overall diversity of concretion morphology, size, texture, and chemistry throughout the Murray formation indicates that concretions formed in multiple, likely late diagenetic, episodes with varying fluid chemistries. Four major concretion assemblages are observed at distinct stratigraphic intervals and approximately correlate with major distinct chemical enrichments in Mg-S-Ni-Cl, Mn-P, and Ca-S, among other local enrichments. Different concretion size populations and complex relationships between concretions and veins also suggest multiple precipitation events at Gale crater. Many concretions likely formed during late diagenesis after sediment compaction and lithification, based on observations of concretions preserving primary host rock laminations without differential compaction. An upsection decrease in overall concretion size corresponds to an inferred upsection decrease in porosity and permeability, thus constraining concretion formation as postdating fluid events that produced initial cementation and porosity loss. The combined observations of late diagenetic concretions and distinct chemical enrichments related to concretions allow constraints to be placed on the chemistry of late stage fluids at Gale crater. Collectively, concretion observations from this work and previous studies of other diagenetic features (veins, alteration halos) suggest at least six post-depositional events that occurred at Gale crater after the deposition of the Murray formation.

Published
2019

28. Recovery of Fatty Acids from Mineralogic Mars Analogs by TMAH Thermochemolysis for the Sample Analysis at Mars Wet Chemistry Experiment on the Curiosity Rover

Author

R. Williams, Rafael Navarro-González, Cyril Szopa, Paul R. Mahaffy, Amy J. Williams, Daniel P. Glavin, Jennifer L. Eigenbrode, Charles Malespin, Maeva Millan, Kathleen C. Benison, Roger E. Summons, Sarah Stewart Johnson, Arnaud Buch, Mary Beth Wilhelm, C. A. Knudson, Amy McAdam, J. M. T. Lewis, Kathleen L. Craft, Melissa Floyd, Shane S. O'Reilly, Caroline Freissinet, Slavka Andrejkovičová, Department of Physics, Astronomy, and Geosciences [Towson], Towson University [Towson, MD, United States], University of Maryland System-University of Maryland System, Center for Research and Exploration in Space Science and Technology [Baltimore] (CRESST), University of Maryland [Baltimore County] (UMBC), GSFC Solar System Exploration Division, NASA Goddard Space Flight Center (GSFC), NASA Ames Research Center (ARC), Department of Earth, Atmospheric and Planetary Sciences [MIT, Cambridge] (EAPS), Massachusetts Institute of Technology (MIT), UCD School od Earth Sciences, University College Dublin [Dublin] (UCD), Department of Biology [Washington], Georgetown University [Washington] (GU), Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Center for Research and Exploration in Space Science and Technology [College Park] (CRESST), University of Maryland [College Park], Universities Space Research Association (USRA), Laboratoire de Génie des Procédés et Matériaux - EA 4038 (LGPM), CentraleSupélec, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Department of Geology and Geography [Morgantown], West Virginia University [Morgantown], Instituto de Ciencias Nucleares [Mexico], and Universidad Nacional Autónoma de México (UNAM)

Subjects
Time Factors, Extraterrestrial Environment, 010504 meteorology & atmospheric sciences, Iron, Carboxylic acid, Sample Analysis at Mars (SAM) instrument, Inorganic chemistry, Carboxylic Acids, Mars, Iron sulfide, Mass spectrometry, 01 natural sciences, Gas Chromatography-Mass Spectrometry, TMAH, chemistry.chemical_compound, Exobiology, 0103 physical sciences, MSL, Spacecraft, 010303 astronomy & astrophysics, Research Articles, 0105 earth and related environmental sciences, chemistry.chemical_classification, Minerals, Tetramethylammonium hydroxide, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Methanol, Fatty Acids, Temperature, Esters, Mars Exploration Program, Silicon Dioxide, Agricultural and Biological Sciences (miscellaneous), FAME, Quaternary Ammonium Compounds, Pyrolysis–gas chromatography–mass spectrometry, chemistry, 13. Climate action, Space and Planetary Science, Molecular biosignatures, Sample Analysis at Mars, Clay, Gas chromatography–mass spectrometry
Abstract

The Mars Curiosity rover carries a diverse instrument payload to characterize habitable environments in the sedimentary layers of Aeolis Mons. One of these instruments is Sample Analysis at Mars (SAM), which contains a mass spectrometer that is capable of detecting organic compounds via pyrolysis gas chromatography mass spectrometry (py-GC-MS). To identify polar organic molecules, the SAM instrument carries the thermochemolysis reagent tetramethylammonium hydroxide (TMAH) in methanol (hereafter referred to as TMAH). TMAH can liberate fatty acids bound in macromolecules or chemically bound monomers associated with mineral phases and make these organics detectable via gas chromatography mass spectrometry (GC-MS) by methylation. Fatty acids, a type of carboxylic acid that contains a carboxyl functional group, are of particular interest given their presence in both biotic and abiotic materials. This work represents the first analyses of a suite of Mars-analog samples using the TMAH experiment under select SAM-like conditions. Samples analyzed include iron oxyhydroxides and iron oxyhydroxysulfates, a mixture of iron oxides/oxyhydroxides and clays, iron sulfide, siliceous sinter, carbonates, and shale. The TMAH experiments produced detectable signals under SAM-like pyrolysis conditions when organics were present either at high concentrations or in geologically modern systems. Although only a few analog samples exhibited a high abundance and variety of fatty acid methyl esters (FAMEs), FAMEs were detected in the majority of analog samples tested. When utilized, the TMAH thermochemolysis experiment on SAM could be an opportunity to detect organic molecules bound in macromolecules on Mars. The detection of a FAME profile is of great astrobiological interest, as it could provide information regarding the source of martian organic material detected by SAM.

Published
2019

29. Filamentous Hydrous Ferric Oxide Biosignatures in a Pipeline Carrying Acid Mine Drainage at Iron Mountain Mine, California

Author

Amy J. Williams, Kate M. Campbell, Dawn Y. Sumner, and Charles N. Alpers

Subjects
Mineral, 010504 meteorology & atmospheric sciences, Schwertmannite, Mineralogy, macromolecular substances, engineering.material, 010502 geochemistry & geophysics, Acid mine drainage, 01 natural sciences, Microbiology, Hydrous ferric oxides, Microbial population biology, Environmental chemistry, Biosignature, Earth and Planetary Sciences (miscellaneous), medicine, engineering, Environmental Chemistry, Ferric, Iron Mountain Mine, Geology, 0105 earth and related environmental sciences, General Environmental Science, medicine.drug
Abstract

A pipeline carrying acidic mine effluent at Iron Mountain, CA, developed Fe(III)-rich precipitate caused by oxidation of Fe(II)aq. The native microbial community in the pipe included filamentous microbes. The pipe scale consisted of microbial filaments, and schwertmannite (ferric oxyhydroxysulfate, FOHS) mineral spheres and filaments. FOHS filaments contained central lumina with diameters similar to those of microbial filaments. FOHS filament geometry, the geochemical environment, and the presence of filamentous microbes suggest that FOHS filaments are mineralized microbial filaments. This formation of textural biosignatures provides the basis for a conceptual model for the development and preservation of biosignatures in other environments.

Published
2016

36. Global Seasonal forecast system version 5 (GloSea5): a high-resolution seasonal forecast system

Author

A. Maidens, Michael Vellinga, Prince K. Xavier, K. A. Peterson, Amy J. Williams, Alberto Arribas, Joanne Camp, D. Fereday, Gurvan Madec, Margaret Gordon, Adam A. Scaife, Ruth E. Comer, and Craig MacLachlan

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, 0207 environmental engineering, Forecast skill, Madden–Julian oscillation, 02 engineering and technology, 01 natural sciences, Atmosphere, Arctic oscillation, 13. Climate action, North Atlantic oscillation, Climatology, Subtropical ridge, Environmental science, East Asia, Precipitation, 020701 environmental engineering, 0105 earth and related environmental sciences
Abstract

This article describes the UK Met Office Global Seasonal forecast system version 5 (GloSea5). GloSea5 upgrades include an increase in horizontal resolution in the atmosphere (N216–0.7°) and the ocean (0.25°), and implementation of a 3D-Var assimilation system for ocean and sea-ice conditions. GloSea5 shows improved year-to-year predictions of the major modes of variability. In the Tropics, predictions of the El Nino–Southern Oscillation are improved with reduced errors in the West Pacific. In the Extratropics, GloSea5 shows unprecedented levels of forecast skill and reliability for both the North Atlantic Oscillation and the Arctic Oscillation. We also find useful levels of skill for the western North Pacific Subtropical High which largely determines summer precipitation over East Asia.

Published
2014

37. Skillful long‐range prediction of European and North American winters

Author

Chris K. Folland, Leon Hermanson, Emily Wallace, Edward W. Blockley, Michael Vellinga, Matthew Martin, A. Maidens, Craig MacLachlan, D. J. Lea, Anca Brookshaw, Alberto Arribas, D. Fereday, Nick Dunstone, Rosie Eade, Adam A. Scaife, Robin T. Clark, Jennifer Waters, Amy J. Williams, Doug Smith, Jeff Knight, Margaret Gordon, and A. Peterson

Subjects
Geophysics, Work (electrical), Climatology, Political science, General Earth and Planetary Sciences, Library science, media_common.cataloged_instance, European union, Service research, media_common
Abstract

This work was supported by the Joint DECC/Defra Met Office Hadley Centre Climate Programme (GA01101), the UK Public Weather Service research program, and the European Union Framework 7 SPECS project. Leon Hermanson was funded as part of his Research Fellowship by Willis as part of Willis Research Network (WRN).

Published
2014

38. Evaluation of the Zurich Guidelines and Exercise Testing for Return to Play in Adolescents Following Concussion

Author

Anthony Surace, John J. Leddy, John G. Baker, Amy J. Williams, Scott R. Darling, Barry Willer, and Jeffrey C. Miecznikowski

Subjects
Male, medicine.medical_specialty, Adolescent, MEDLINE, Physical Therapy, Sports Therapy and Rehabilitation, Neuropsychological Tests, Young Adult, Physical medicine and rehabilitation, Concussion, medicine, Humans, Attention, Orthopedics and Sports Medicine, Young adult, Treadmill, Brain Concussion, Retrospective Studies, Schools, business.industry, Neuropsychology, Retrospective cohort study, Recovery of Function, medicine.disease, Return to play, Test (assessment), Athletic Injuries, Practice Guidelines as Topic, Exercise Test, Physical therapy, Female, business
Abstract

To evaluate return to play (RTP) and return to classroom outcomes when the Zurich guidelines are combined with a standardized exercise treadmill test [Buffalo Concussion Treadmill Test (BCTT)] and computerized neuropsychological (cNP) testing in adolescent athletes after concussion.Retrospective chart review and follow-up.University Sports Medicine Concussion Clinic.One hundred seventeen athletes (75% male) with sport concussion ages 13 to 19 years and telephone follow-up of 91 (77.8%) athletes and their parents.Concussed athletes who were asymptomatic at rest completed Automated Neuropsychological Assessment Metrics or Immediate Post-concussion Assessment and Cognitive Test cNP testing followed by the BCTT on the same day. Athletes then followed the Zurich consensus guidelines for RTP.The primary outcome measure was the degree of success in RTP, that is, RTP with or without return of concussive symptoms. Secondary outcome measure was return to school with or without symptoms.All athletes returned to sport without exacerbation of symptoms. Telephone follow-up revealed that 38.5% experienced new issues upon return to the classroom. Forty-eight percent of athletes had 1 or more cNP subtests below average (ninth percentile) when asymptomatic. Ultimately, performance on cNP was not predictive of return to school issues.The BCTT in combination with the Zurich consensus guidelines seems to be safe and successful for RTP. There is evidence to suggest that cNP testing performed in athletes who do not have a preinjury baseline test was not related to RTP or problems upon return to school.

Published
2014

40. Hydrogeochemistry of the Middle Rio Grande aquifer system — Fluid mixing and salinization of the Rio Grande due to fault inputs

Author

Mark Person, Dennis L. Newell, Laura J. Crossey, Amy J. Williams, Karl E. Karlstrom, and Emily Woolsey

Subjects
Hydrology, geography, geography.geographical_feature_category, Soil salinity, Rift, δ18O, Geology, Aquifer, Salinity, Geochemistry and Petrology, Water quality, Aqueous geochemistry, Groundwater
Abstract

Deeply-derived fluids influence river and groundwater hydrochemistry at the Socorro “constriction” in the central New Mexico Rio Grande rift. New hydrochemical transects in the Rio Grande rift provide three-dimensional perspectives on sources contributing to surface and groundwaters. In addition to abrupt salinity increases in the Rio Grande, major and trace ion chemistry, δ18O, δD, δ13C, 87Sr/86Sr, 3H and 3He/4He variations in springs and wells across the rift are best explained by mixing of deeply-derived endogenic fluids, containing both mantle and crustal inputs, with shallow groundwater. Endogenic fluids ascend along rift-bounding and intra-rift faults, and can cause increased salinity accompanied by an increase in metals and overall degradation of water quality. Our data reinforce models that attribute a downstream increase in salinity to geological, not agricultural, influences. Hydrochemical mixing of endogenic waters along faults in shallow aquifers has a major influence on groundwater and surface water quality and variability in arid tectonically active regions, with important ramifications for water management.

Published
2013

41. Contents Vol. 36, 2013

Author

Edward D. Huey, A. Donati, Maria Eriksdotter, Jean Paul G. Vonsattel, Alexander Wutzler, Nicole M. Armstrong, T. Rune Nielsen, Charlotte Niederländer, Robert S. Miletich, Vesna Jelic, S. Petrillo, Hanne Gottrup, Elisabeth Steinhagen-Thiessen, Lawrence S. Honig, David S. Wack, Peter L. Kolominsky-Rabas, Eva Baillés, Abel López-Bermejo, Geir Selbæk, Wilhelm Haverkamp, Regine Becker, Amy J. Williams, Jordan Grafman, Philip Wahlster, J. Studer, Birgitte Bo Andersen, Nicole Schupf, Janne Røsvik, Hiroshi Yoshizawa, Gernot Lämmler, Knut Engedal, Milica G. Kramberger, J. Popp, Øyvind Kirkevold, C. Pocnet, Sandra Schaller, John G. Baker, Christine Kriza, Anne Marie Mork Rokstad, Jan H. Lützhøft, Bengt Winblad, Peter Høgh, J. Rossier, Ingemar Kåreholt, Druck Reinhardt Druck Basel, Jurate Saltyte Benth, Gunhild Waldemar, Thomas Andersson, Carme Carrion, Marta Aymerich, and A. Von Gunten

Subjects
Psychiatry and Mental health, Cognitive Neuroscience, Geriatrics and Gerontology
Published
2013

42. Xeropreservation of functionalized lipid biomarkers in hyperarid soils in the Atacama Desert

Author

M. N. Parenteau, Mary Beth Wilhelm, Rogers E. Summons, Shane S. O'Reilly, Jennifer L. Eigenbrode, Alfonso F. Davila, Linda L. Jahnke, Brian N. Stamos, Amy J. Williams, James J. Wray, and Xiao-Lei Liu

Subjects
chemistry.chemical_classification, Taphonomy, 010504 meteorology & atmospheric sciences, Ecology, Aquatic ecosystem, 010502 geochemistry & geophysics, 01 natural sciences, Article, law.invention, Deposition (aerosol physics), chemistry, Geochemistry and Petrology, law, Environmental chemistry, Soil water, Soil horizon, Organic matter, Radiocarbon dating, Quaternary, Geology, 0105 earth and related environmental sciences
Abstract

Our understanding of long-term organic matter preservation comes mostly from studies in aquatic systems. In contrast, taphonomic processes in extremely dry environments are relatively understudied and are poorly understood. We investigated the accumulation and preservation of lipid biomarkers in hyperarid soils in the Yungay region of the Atacama Desert. Lipids from seven soil horizons in a 2.5 m vertical profile were extracted and analyzed using GC-MS and LC-MS. Diagnostic functionalized lipids and geolipids were detected and increased in abundance and diversity with depth. Deeper clay units contain fossil organic matter (radiocarbon dead) that has been protected from rainwater since the onset of hyperaridity. We show that these clay units contain lipids in an excellent state of structural preservation with functional groups and unsaturated bonds in carbon chains. This indicates that minimal degradation of lipids has occurred in these soils since the time of their deposition between >40,000 and 2 million years ago. The exceptional structural preservation of biomarkers is likely due to the long-term hyperaridity that has minimized microbial and enzymatic activity, a taphonomic process we term xeropreservation (i.e. preservation by drying). The degree of biomarker preservation allowed us to reconstruct major changes in ecology in the Yungay region that reflect a shift in hydrological regime from wet to dry since the early Quaternary. Our results suggest that hyperarid environments, which comprise 7.5% of the continental landmass, could represent a rich and relatively unexplored source of paleobiological information on Earth.

Published
2016

43. Composition of conglomerates analyzed by the Curiosity rover: Implications for Gale Crater crust and sediment sources

Author

Sylvestre Maurice, Cécile Fabre, Nicolas Mangold, Martin R. Fisk, Fred Calef, William Rapin, R. Gellert, Amy J. Williams, Olivier Gasnault, Gilles Dromart, Dawn Y. Sumner, Roger C. Wiens, Samuel M. Clegg, Rebecca M. E. Williams, P.-Y. Meslin, S. Le Mouélic, Marisa C. Palucis, Kirsten L. Siebach, Agnes Cousin, Lucy M. Thompson, K. M. Stack, Diana L. Blaney, William E. Dietrich, L. Le Deit, Ryan B. Anderson, Olivier Forni, John P. Grotzinger, A. Yingst, H. E. Newsom, Kenneth S. Edgett, Violaine Sautter, Linda C. Kah, Scott M. McLennan, Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), DLR Institute of Planetary Research, German Aerospace Center (DLR), Los Alamos National Laboratory (LANL), Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Oregon State University (OSU), Department of Physics [Guelph], University of Guelph, California Institute of Technology (CALTECH), Stony Brook University [SUNY] (SBU), State University of New York (SUNY), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Institute of Meteoritics [Albuquerque] (IOM), The University of New Mexico [Albuquerque], Department of Earth and Planetary Science [UC Berkeley] (EPS), University of California [Berkeley], University of California-University of California, Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Division of Geological and Planetary Sciences [Pasadena], University of California [Davis] (UC Davis), University of California, Planetary Science Institute [Tucson] (PSI), NASA-California Institute of Technology (CALTECH), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), University of California (UC), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Earth science, Geochemistry, sedimentary rocks, Mars, Igneous textures, 01 natural sciences, Conglomerate, Geochemistry and Petrology, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Felsic, fluvial, Crust, Gale Crater, Diagenesis, Igneous rock, Geophysics, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Clastic rock, Sedimentary rock, Geology
Abstract

International audience; The Curiosity rover has analyzed various detrital sedimentary rocks at Gale Crater, among which fluvial and lacustrine rocks are predominant. Conglomerates correspond both to the coarsest sediments analyzed and the least modified by chemical alteration, enabling us to link their chemistry to that of source rocks on the Gale Crater rims. In this study, we report the results of six conglomerate targets analyzed by Alpha-Particle X-ray Spectrometer and 40 analyzed by ChemCam. The bulk chemistry derived by both instruments suggests two distinct end-members for the conglomerate compositions. The first group (Darwin type) is typical of conglomerates analyzed before sol 540; it has a felsic alkali-rich composition, with a Na2O/K2O\textgreater5. The second group (Kimberley type) is typical of conglomerates analyzed between sols 540 and 670 in the vicinity of the Kimberley waypoint; it has an alkali-rich potassic composition with Na2O/K2O\textless2. The variety of chemistry and igneous textures (when identifiable) of individual clasts suggest that each conglomerate type is a mixture of multiple source rocks. Conglomerate compositions are in agreement with most of the felsic alkali-rich float rock compositions analyzed in the hummocky plains. The average composition of conglomerates can be taken as a proxy of the average igneous crust composition at Gale Crater. Differences between the composition of conglomerates and that of finer-grained detrital sediments analyzed by the rover suggest modifications by diagenetic processes (especially for Mg enrichments in fine-grained rocks), physical sorting, and mixing with finer-grained material of different composition.

Published
2016

44. Origin and significance of decameter-scale polygons in the lower Peace Vallis fan of Gale crater, Mars

Author

Laetitia Le Deit, Amy J. Williams, Nicolas Mangold, Dorothy Z. Oehler, Alberto G. Fairén, Ronald S. Sletten, Jesús Martínez-Frías, Bernard Hallet, Johnson Space Center, NASA Astrobiology Institute (US), Centre National D'Etudes Spatiales (France), California Institute of Technology, and European Research Council

Subjects
geography, Mars surface, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Landform, Lava, Mars, Astronomy and Astrophysics, Context (language use), Weathering, Mars Exploration Program, Mars climate, 01 natural sciences, Paleontology, Space and Planetary Science, 0103 physical sciences, Polygon, Hesperian, Sedimentary rock, 010303 astronomy & astrophysics, Geology, 0105 earth and related environmental sciences
Abstract

Decameter-scale polygons are extensively developed in the Bedded Fractured (BF) Unit of the lower Peace Vallis fan. The polygons occur in a likely extension of the Gillespie Lake Member, north of Yellowknife Bay, the section first drilled by the Mars Science Laboratory (MSL) mission. We examine hypotheses for the origin of these polygons to provide insight into the history of Gale crater. The polygons are ∼4–30 m across, square to rectangular, and defined by ∼0.5–4 m wide, generally straight troughs with orthogonal intersections. Polygon networks are typically oriented-orthogonal systems, with occasional nearly circular patterns, hundreds of meters across. Potential origins include cooling of lava, and for sedimentary units, syneresis, unloading, weathering, desiccation, impact processes, and cold-climate thermal contraction. Cold-climate thermal contraction is the hypothesis most consistent with the sedimentary nature of the BF Unit and the polygon morphology, geometry, networks, and apparent restriction to the coarse-grained Gillespie Lake Member. A periglacial setting further provides the best analogs for the circular networks and is consistent with geologic context and MSL data. Most of the decametric polygons appear to be ancient. They are confined to the Hesperian BF Unit, and only a few of their bounding fractures extend into younger or recently exposed units. In this regard, they differ from the majority of proposed thermal-contraction polygons on Mars, as those are generally thought to be young features, and, accordingly, the history of formation, preservation and reactivation of the decametric polygons is likely to be more complex than that of any proposed young polygons on Mars. The decametric polygons in the BF Unit may represent landforms developed in a cold but still comparatively wet interlude between a clement early Mars and the much drier and colder planet of today., DZO was supported by the Astromaterials Research and Exploration Science (ARES) Division at Johnson Space Center and the NASA Mars Science Laboratory (MSL) Participating Scientist Grant No. 10-MSLPSP10-0094. French authors (NM and LL) were supported by grants from the French National Agency for Space Studies, Centre National d'Etudes Spatiales (CNES). BH and RSS were supported by NASA Mars Science Laboratory via Malin Space Science Systems. AGF was supported by the Project “icyMARS”, funded by the European Research Council Starting Grant No. 307,496.

Published
2016

45. Cerebral Small Vessel Disease: Cognition, Mood, Daily Functioning, and Imaging Findings from a Small Pilot Sample

Author

Catalina C. Ionita, Amy J. Williams, Robert S. Miletich, Peterkin Lee-Kwen, John G. Baker, and Marilou Ching

Subjects
medicine.medical_specialty, Cognitive Neuroscience, Cerebral small vessel disease, Single-photon emission computed tomography, Audiology, lcsh:Geriatrics, lcsh:RC346-429, Neuropsychology, CogHealth, SF-36, medicine, Original Research Article, Cognitive decline, Psychiatry, Cerebrovascular disease, Stroke, lcsh:Neurology. Diseases of the nervous system, medicine.diagnostic_test, Subcortical vascular cognitive impairment, Magnetic resonance imaging, Cognition, medicine.disease, Functional imaging, Psychiatry and Mental health, lcsh:RC952-954.6, Mood, SPECT, Psychology, RBANS
Abstract

Cerebral small vessel disease, a leading cause of cognitive decline, is considered a relatively homogeneous disease process, and it can co-occur with Alzheimer’s disease. Clinical reports of magnetic resonance imaging (MRI)/computed tomography and single photon emission computed tomography (SPECT) imaging and neuropsychology testing for a small pilot sample of 14 patients are presented to illustrate disease characteristics through findings from structural and functional imaging and cognitive assessment. Participants showed some decreases in executive functioning, attention, processing speed, and memory retrieval, consistent with previous literature. An older subgroup showed lower age-corrected scores at a single time point compared to younger participants. Performance on a computer-administered cognitive measure showed a slight overall decline over a period of 8–28 months. For a case study with mild neuropsychology findings, the MRI report was normal while the SPECT report identified perfusion abnormalities. Future research can test whether advances in imaging analysis allow for identification of cerebral small vessel disease before changes are detected in cognition.

Published
2012

46. Evaluating the effects of sample processing treatments on alkalinity measurements

Author

C. Brannon Andersen, Amy J. Williams, and Gregory P. Lewis

Subjects
Hydrology, Biogeochemical cycle, Alkalinity, law.invention, Turbidite, chemistry.chemical_compound, chemistry, law, Environmental chemistry, Dissolved organic carbon, Environmental science, Carbonate, Turbidity, Surface water, Filtration, Water Science and Technology
Abstract

summary The concentration of bicarbonate, the dominant anion in river water, is typically calculated using measured alkalinity concentrations. Alkalinity concentrations also are necessary for analytical charge balance, carbonate speciation, and PCO2 calculations. Although the Gran titration is the standard method for measuring alkalinity, previous studies have varied in how water samples have been processed prior to analysis. The purpose of this study was to determine whether variation in filtering, refrigeration, and sample storage time leads to statistically significant differences in alkalinity concentrations in oxic, low-turbidity surface waters and groundwaters ranging from undersaturated to supersaturated with respect to calcite. Samples were collected from the Blue Ridge and Piedmont Provinces of northwestern South Carolina and the Valley and Ridge Province of eastern Tennessee. Each sample was analyzed using four processing treatments: filtered and refrigerated, filtered and unrefrigerated, unfiltered and refrigerated, and unfiltered and unrefrigerated (n = 3 analyses per treatment combination). All replicates were analyzed within 24 h using the Gran titration method. Samples then were reanalyzed after 17–194 days of storage to determine if storage time affects alkalinity measurements. Overall, alkalinity concentrations ranged from 0.8 to 107 mg/L CaCO3. Statistically significant differences among the treatments and significant interactions between filtration and refrigeration were limited. For samples in which treatment means differed significantly or in which interactions were significant, differences generally were less than 10% and probably of little biogeochemical importance. For all but one sample locality, storage time did not affect alkalinity. Our results show that for oxic waters that have low concentrations of DOC and reduced metals, filtration, refrigeration and storage time are unlikely to affect measured alkalinity concentrations. However, additional research is needed to determine the degree to which sample processing treatment is important to interpreting the alkalinity concentrations of DOC- and metal-rich samples.

Published
2009

47. Understanding the Ecology of Blue Elderberry to Inform Landscape Restoration in Semiarid River Corridors

Author

Marcel Holyoak, Steven E. Greco, Mehrey G. Vaghti, Amy J. Williams, Theresa Sinicrope Talley, and Alexander K. Fremier

Subjects
Conservation of Natural Resources, Global and Planetary Change, geography, geography.geographical_feature_category, Ecology, Floodplain, Plant community, Pollution, California, Coleoptera, Rivers, Sambucus, Habitat, Water Movements, Animals, Riparian forest, Floodplain restoration, Landscape ecology, Restoration ecology, Ecosystem, Riparian zone
Abstract

Societal constraints often limit full process restoration in large river systems, making local rehabilitation activities valuable for regeneration of riparian vegetation. A target of much mitigation and restoration is the federally threatened Valley elderberry longhorn beetle and its sole host plant, blue elderberry, in upper riparian floodplain environments. However, blue elderberry ecology is not well understood and restoration attempts typically have low success rates. We determined broad-scale habitat characteristics of elderberry in altered systems and examined associated plant species composition in remnant habitat. We quantified vegetation community composition in 139 remnant riparian forest patches along the Sacramento River and elderberry stem diameters along this and four adjacent rivers. The greatest proportion of plots containing elderberry was located on higher and older floodplain surfaces and in riparian woodlands dominated by black walnut. Blue elderberry saplings and shrubs with stems

Published
2008

48. ChemCam results from the Shaler outcrop in Gale crater, Mars

Author

Gilles Dromart, Kevin W. Lewis, S. Maurice, John Bridges, Susanne P. Schwenzer, Richard Leveille, Violaine Sautter, Jérémie Lasue, Ann Ollila, S. Le Mouélic, Martin R. Fisk, J. M. Williams, Marion Nachon, Ryan B. Anderson, Amy J. Williams, Juergen Schieber, Lauren A. Edgar, A. Mezzacappa, Olivier Forni, Roger C. Wiens, Samuel M. Clegg, Eric Lewin, Sanjeev Gupta, Olivier Gasnault, Nina Lanza, D. T. Vaniman, B. C. Clark, Diana L. Blaney, Nicolas Mangold, H. E. Newsom, Astrogeology Science Center [Flagstaff], United States Geological Survey [Reston] (USGS), Space Research Centre [Leicester], University of Leicester, Department of Earth and Planetary Sciences [Santa Cruz], University of California [Santa Cruz] (UCSC), University of California-University of California, ASU School of Earth and Space Exploration (SESE), Arizona State University [Tempe] (ASU), Department of Earth and Planetary Sciences [Albuquerque] (EPS), The University of New Mexico [Albuquerque], Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), College of Earth, Ocean and Atmospheric Sciences [Corvallis] (CEOAS), Oregon State University (OSU), Department of Geological Sciences [Bloomington], Indiana University [Bloomington], Indiana University System-Indiana University System, Department of Earth Science and Technology [Imperial College London], Imperial College London, Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Los Alamos National Laboratory (LANL), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Optical Science Center for Applied Research (OSCAR), Delaware State University (DSU), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Space Science Institute [Boulder] (SSI), Department of Natural Resource Sciences, McGill University = Université McGill [Montréal, Canada], Institut des Sciences de la Terre (ISTerre), Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Johns Hopkins University (JHU), Dept. of Physical Sciences, The Open University [Milton Keynes] (OU), Planetary Science Institute [Tucson] (PSI), University of California [Santa Cruz] (UC Santa Cruz), University of California (UC)-University of California (UC), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-PRES Université de Grenoble-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)

Subjects
Basalt, Outcrop, Geochemistry, Mars, Astronomy and Astrophysics, Pyroxene, surface Mineralogy, Feldspar, Astrobiology, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], visual_art, Stratigraphic section, Clastic dike, Facies, visual_art.visual_art_medium, Sedimentary rock, Geology, Spectroscopy
Abstract

International audience; The ChemCam campaign at the fluvial sedimentary outcrop ‘‘Shaler’’ resulted in observations of 28non-soil targets, 26 of which included active laser induced breakdown spectroscopy (LIBS), and all ofwhich included Remote Micro-Imager (RMI) images. The Shaler outcrop can be divided into seven faciesbased on grain size, texture, color, resistance to erosion, and sedimentary structures. The ChemCamobservations cover Facies 3 through 7. For all targets, the majority of the grains were below the limitof the RMI resolution, but many targets had a portion of resolvable grains coarser than 0.5 mm. The Shalerfacies show significant scatter in LIBS spectra and compositions from point to point, but several keycompositional trends are apparent, most notably in the average K2O content of the observed facies. Facies3 is lower in K2O than the other facies and is similar in composition to the ‘‘snake,’’ a clastic dike thatoccurs lower in the Yellowknife Bay stratigraphic section. Facies 7 is enriched in K2O relative to the otherfacies and shows some compositional and textural similarities to float rocks near Yellowknife Bay. Theremaining facies (4, 5, and 6) are similar in composition to the Sheepbed and Gillespie Lake members,although the Shaler facies have slightly elevated K2O and FeOT. Several analysis points within Shaler suggestthe presence of feldspars, though these points have excess FeOT which suggests the presence of Feoxide cement or inclusions. The majority of LIBS analyses have compositions which indicate that theyhttp://dx.doi.org/10.1016/j.icarus.2014.07.0250019-1035/Published by Elsevier Inc.⇑ Corresponding author.E-mail addresses: rbanderson@usgs.gov (R. Anderson), jcb36@leicester.ac.uk (J.C. Bridges), amywill@ucdavis.edu (A. Williams), ledgar1@asu.edu (L. Edgar), aollila@unm.edu (A. Ollila), josh505@unm.edu (J. Williams), marion.nach@gmail.com (M. Nachon), nicolas.mangold@univ-nantes.fr (N. Mangold), Martin.Fisk@oregonstate.edu (M. Fisk),jschiebe@indiana.edu (J. Schieber), s.gupta@imperial.ac.uk (S. Gupta), gilles.dromart@ens-lyon.fr (G. Dromart), rwiens@lanl.gov (R. Wiens), stephane.lemouelic@univ-nantes.fr (S. Le Mouélic), olivier.forni@irap.omp.eu (O. Forni), nlanza@lanl.gov (N. Lanza), amezzacappa09@students.desu.edu (A. Mezzacappa), vsautter@mnhn.fr (V. Sautter), diana.l.blaney@jpl.nasa.gov (D. Blaney), bclark@spacescience.org (B. Clark), sclegg@lanl.gov (S. Clegg), olivier.gasnault@irap.omp.eu (O. Gasnault), jeremie.lasue@irap.omp.eu (J.Lasue), rich.leveille@gmail.com (R. Léveillé), Eric.LEWIN@obs.ujf-grenoble.fr (E. Lewin), sylvestre.maurice@irap.omp.eu (S. Maurice), newsom@unm.edu (H. Newsom),dvaniman@psi.edu (D. Vaniman).Icarus 249 (2015) 2–21Contents lists available at ScienceDirectIcarusjournal homepage: www.elsevier.com/ locate/ icarusare mixtures of pyroxene and feldspar. The Shaler feldspathic compositions are more alkaline than typicalfeldspars from shergottites, suggesting an alkaline basaltic source region, particularly for the K2OenrichedFacies 7. Apart from possible iron-oxide cement, there is little evidence for chemical alterationat Shaler, although calcium-sulfate veins comparable to those observed lower in the stratigraphic sectionare present. The differing compositions, and inferred provenances at Shaler, suggest compositionally heterogeneousterrain in the Gale crater rim and surroundings, and intermittent periods of deposition

Published
2015

49. Volatile and Organic Compositions of Sedimentary Rocks in Yellowknife Bay, Gale Crater, Mars

Author

M. A. Meyer, Mark I. Richardson, Robert C. Anderson, Marisa C. Palucis, Sara Navarro Lopez, Rodney C. Ewing, Sanjeev Gupta, Caroline Freissinet, Edward M. Stolper, James F. Bell, M. A. Ravine, I. G. Mitrofanov, Thomas F. Bristow, Dawn Y. Sumner, Joel A. Hurowitz, Robert M. Haberle, Claire E. Newman, Andrew Steele, Muriel Saccoccio, Leslie Keely, E. Pallier, Jason P. Dworkin, Claude Geffroy, Mary A. Voytek, Michael Caplinger, Fred Goesmann, Yann Parot, Maria-Paz Zorzano Mier, A. B. Sanin, S. W. Squyres, Javier Caride Rodriguez, J. L. Griffes, Julio José Romeral-Planello, Jason Feldman, Katherine L. French, V. Sautter, Nicolas Mangold, David L. Bish, Vivian Lafaille, Michael D. Smith, François Raulin, V. Prokhorov, Gilles Berger, S. Slavney, Heather B. Franz, S. Johnstone, Susanne P. Schwenzer, Felipe Gómez, Harri Haukka, Francis A. Cucinotta, J. Hudgins, T. Cleghorn, Pascaline Francois, Alain Lepinette Malvitte, Shuai Li, Paul R. Mahaffy, K. M. Robertson, Bruce M. Jakosky, J. Guo, Juergen Schieber, Rafael Navarro-González, G. J. Flesch, Scott M. McLennan, Jennifer G. Blank, M. Carmosino, Kenneth A. Farley, Yves Langevin, P. D. Archer, A. E. Brunner, M. D. Dyar, S. Le Mouélic, V. Hipkin, Sara Alejandra Sans Fuentes, Kenneth S. Edgett, Sabrina Feldman, Gale Paulsen, Paul Herrera, Alberto G. Fairén, Kirsten L. Siebach, Jan-Peter Muller, M. J. Schoppers, Eldar Noe Dobrea, Nina Lanza, Marc Gailhanou, Genevieve Marchand, Sönke Burmeister, Craig Hardgrove, Justin N. Maki, Ari-Matti Harri, Michael C. Malin, M. J. Wolff, Roger E. Summons, H. Blau, Jacqueline Cameron, Jeff A. Berger, Didier Keymeulen, Agnes Cousin, Guillermo M. Muñoz Caro, Eric Lyness, Cedric Pilorget, Michael B. Baker, Christopher S. Edwards, M. L. Litvak, Brian M. Duston, Rebecca M. E. Williams, T. Nolan, Robert T. Downs, V. E. Hamilton, Walter Goetz, Pamela G. Conrad, J. Baroukh, Nathan T. Bridges, Meenakshi Wadhwa, Roger C. Wiens, Samuel M. Clegg, Philippe Sarrazin, L. Bleacher, Eric Lorigny, Mike Toplis, Michael H. Wong, Timothy H. McConnochie, Ian Mcewan, Kiran Patel, Mary Beth Wilhelm, John P. Grotzinger, Jeffrey E. Moersch, Michael A. Wilson, Mark Paton, I. Plante, Eric Lewin, Franck Poitrasson, Tori M. Hoehler, P. Guillemot, Mackenzie Day, David F. Blake, José Antonio Rodríguez Manfredi, G. W. Lugmair, Robert F. Wimmer-Schweingruber, Dorothy Z. Oehler, Samuel Teinturier, Bent Ehresmann, Jérémie Lasue, K. E. Herkenhoff, Daniel C. Berman, Scott VanBommel, Jeffrey R. Johnson, Emily M. McCullough, A. A. Fraeman, Ezat Heydari, Penelope L. King, K. M. Stack, Diana L. Blaney, A. Salamon, John G. Spray, L. Posiolova, Jeff Hollingsworth, David Choi, Kevin W. Lewis, B. D. Prats, Tonci Balic-Zunic, Mehdi Benna, H. M. Elliott, Jesús Martínez-Frías, R. Mueller-Mellin, William V. Boynton, Lance E. Christensen, Richard Leveille, John A. Grant, David E. Harker, J. M. Morookian, Caleb I. Fassett, S. Jacob, Donald Fay, R. Perez, Horton E. Newsom, Morten Madsen, M. G. Trainer, G. Israel, B. E. Nixon, Claude d’Uston, John E. Moores, Olivier Gasnault, Daniel J. Krysak, Vladislav Tretyakov, G. M. Perrett, Andrew D. Aubrey, L. E. Kirkland, F. Stalport, B. L. Barraclough, Alain Cros, Stephan Böttcher, Michel Cabane, William B. Brinckerhoff, Jack D. Farmer, James J. Wray, P. Y. Meslin, Arnaud Buch, Allan H. Treiman, S. C. R. Rafkin, B. C. Clark, Noureddine Melikechi, R. Jackson, Luther W. Beegle, Angela Lundberg, Bethany L. Ehlmann, William E. Dietrich, Karl Iagnemma, K. Supulver, Radu Popa, R. Zimdar, Melissa Floyd, Wesley T. Huntress, Paul B. Niles, D. M. Delapp, C. N.. Achilles, Darrell Drake, T. Nelson, Alain Gaboriaud, Verónica Peinado-Gonzalez, Edward P. Vicenzi, T. Boucher, Jennifer L. Eigenbrode, C. Tate, David J. Des Marais, F. Javier Martin-Torres, Antoine Charpentier, Chris Webster, Mildred P. Martin, Robert M. Sucharski, Lucy M. Thompson, Cyril Szopa, D. Halleaux, Antonio Molina Jurado, Richard V. Morris, Andrey Vostrukhin, Peter C. Thomas, Ara V. Nefian, Pablo Sobron Sanchez, Manuel de la Torre Juárez, B. Elliott, Hannu Savijärvi, J. Bentz, Sergey Nikiforov, S. Gordon, Shaunna M. Morrison, Jean-Luc Lacour, Günter Reitz, M. E. Newcombe, David E. Brinza, C. Yana, Gary Kocurek, L. J. Lipkaman, C. M. Garcia, Maria Genzer, Fred Calef, A. Godber, Stubbe F. Hviid, C. Donny, T. Van Beek, Ruslan O. Kuzmin, Alexander Hayes, T. S. Olson, George D. Cody, J. Martín-Soler, N. Karpushkina, John Bridges, Mercedes Jiménez, M. Lefavor, Sylvestre Maurice, H. L. K. Manning, Ralph E. Milliken, Susanne Schröder, N. Spanovich, L. J. Edwards, A. Koefoed, Roser Urqui-O'Callaghan, Eduardo Sebastian Martinez, Cary Zeitlin, Noël Stewart, David T. Vaniman, E. A. Breves, Laurent Favot, A. Varenikov, Gérard Manhès, R. B. Williams, David Martin, Steven J. Rowland, E. Boehm, Adrian P. Jones, Alexis Paillet, R. Francis, Sushil K. Atreya, Mariek E. Schmidt, David Baratoux, N. I. Boyd, Qiu-Mei Lee, I. L. ten Kate, Bernard Hallet, K. Stoiber, Vivian Z. Sun, M. R. Kennedy, Gillian M. Krezoski, Mark A. Bullock, T. Stein, Michelle E. Minitti, I. Pradler, Susan L. S. Stipp, Scott Davis, Robert O. Pepin, B. L. Ehlmann, Janne Kauhanen, Dmitry Golovin, Steve J. Chipera, Raymond E. Arvidson, Javier Gómez-Elvira, L. C. Kah, Melissa S. Rice, Isaias Carrasco Blazquez, Cécile Fabre, John J. Simmonds, Joy A. Crisp, Jens Frydenvang, Florence Tan, Julia DeMarines, S. P. Gorevan, Elizabeth B. Rampe, E. McCartney, Lauren DeFlores, K. Harshman, D. N. Harpold, J. Van Beek, Luis Mora-Sotomayor, Douglas W. Ming, Kristen E. Miller, John Campbell, Amy McAdam, L. Saper, Robert Sullivan, Lorenzo Fluckiger, Kjartan M. Kinch, Arik Posner, H. Bower, A. A. Pavlov, D. Scholes, Insoo Jun, Brigitte Gondet, Patrice Coll, Burt Baker, Donald M. Hassler, Ralf Gellert, Laurie A. Leshin, T. Siili, Gilles Dromart, Lauren A. Edgar, Ryan B. Anderson, Robert Dingler, Leon Radziemski, Jean-Baptiste Sirven, G. Weigle, Cynthia K. Little, A. Mezzacappa, Olivier Forni, A. S. Kozyrev, Edward A. Cloutis, Ashwin Vasavada, A. Behar, François Robert, D. M. Rubin, Alexey Malakhov, E. Jensen, T. C. Owen, Sebastien Hettrich, Miguel Ramos, B. Sutter, Melinda A. Kahre, Patrick Pinet, John H. Jones, Claude Brunet, B. Pavri, Nilton O. Renno, Evgeny Atlaskin, Laurent Peret, Maxim Mokrousov, David Lees, J. J. B. Avalos, Jennifer C. Stern, Ann Ollila, Josefina Torres Redondo, Miles J. Johnson, M. A. D. P. Hernandez, Daniel P. Glavin, Albert S. Yen, Christophe Agard, Jouni Polkko, Christopher P. McKay, J. Peterson, Oliver Botta, Mark T. Lemmon, Marion Nachon, K. M. Bean, Bruce A. Cantor, Jan Köhler, M. Fitzgibbon, Carlos Armiens-Aparicio, Jorge Pla-Garcia, Henrik Kahanpää, Frances Westall, Walter Schmidt, M.-H. Kim, Kenneth G. Miller, Sharon A. Wilson, S. McNair, O. Kortmann, David Grinspoon, E. M. Lee, S. Indyk, Osku Kemppinen, E. Raaen, Michael Mischna, R. S. Sletten, James B. Garvin, John M. Ward, R. L. Tokar, Paulo M. Vasconcelos, Charles Malespin, T. J. Parker, Aaron J. Sengstacken, S. Bender, Jean-Pierre Williams, F. Fedosov, Patrick Mauchien, Audrey Dupont, R. A. Yingst, David Coscia, David A. Cremers, Danika Wellington, Kenneth H. Nealson, J. K. Jensen, Martin R. Fisk, J. Joseph, Amy J. Williams, W. 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Lyon (ENS Lyon), Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN), and Kruch, Catherine

Subjects
Geologic Sediments, 010504 meteorology & atmospheric sciences, Extraterrestrial Environment, Curiosity rover, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Mineralogy, [SDU.ASTR.EP] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Mars, Sulfides, 01 natural sciences, organic compositions, Bassanite, 0103 physical sciences, Exobiology, [SDU.ASTR.SR] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Hydrocarbons, Chlorinated, MSL, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Total organic carbon, Martian, mudstone samples, Volatile Organic Compounds, Multidisciplinary, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Water, Mars Exploration Program, Carbon Dioxide, Oxygen, Bays, 13. Climate action, Rocknest, Sample Analysis at Mars, Sedimentary rock, Pyrolysis
Abstract

H 2 O, CO 2 , SO 2 , O 2 , H 2 , H 2 S, HCl, chlorinated hydrocarbons, NO, and other trace gases were evolved during pyrolysis of two mudstone samples acquired by the Curiosity rover at Yellowknife Bay within Gale crater, Mars. H 2 O/OH-bearing phases included 2:1 phyllosilicate(s), bassanite, akaganeite, and amorphous materials. Thermal decomposition of carbonates and combustion of organic materials are candidate sources for the CO 2 . Concurrent evolution of O 2 and chlorinated hydrocarbons suggests the presence of oxychlorine phase(s). Sulfides are likely sources for sulfur-bearing species. Higher abundances of chlorinated hydrocarbons in the mudstone compared with Rocknest windblown materials previously analyzed by Curiosity suggest that indigenous martian or meteoritic organic carbon sources may be preserved in the mudstone; however, the carbon source for the chlorinated hydrocarbons is not definitively of martian origin.

Published
2014

50. The Zinc Finger-Associated SCAN Box Is a Conserved Oligomerization Domain

Author

Amy J. Williams, Tucker Collins, and Stephen C. Blacklow

Subjects
Molecular Sequence Data, Kruppel-Like Transcription Factors, Gene Expression, Repressor, Plasma protein binding, Biology, DNA-binding protein, Conserved sequence, EVH1 domain, Animals, Humans, Amino Acid Sequence, Binding site, Molecular Biology, Peptide sequence, Conserved Sequence, Zinc finger, Genetics, Binding Sites, Sequence Homology, Amino Acid, Zinc Fingers, Cell Biology, Cell biology, DNA-Binding Proteins, Repressor Proteins, COS Cells, Protein Binding
Abstract

A number of Cys(2)His(2) zinc finger proteins contain a highly conserved amino-terminal motif termed the SCAN domain. This element is an 80-residue, leucine-rich region that contains three segments strongly predicted to be alpha-helices. In this report, we show that the SCAN motif functions as an oligomerization domain mediating self-association or association with other proteins bearing SCAN domains. These findings suggest that the SCAN domain plays an important role in the assembly and function of this newly defined subclass of transcriptional regulators.

Published
1999

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