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1. Reversibility controls on extreme methane clumped isotope signatures from anaerobic oxidation of methane

Author

Liu, Jiarui, Harris, Rachel L, Ash, Jeanine L, Ferry, James G, Krause, Sebastian JE, Labidi, Jabrane, Prakash, Divya, Lollar, Barbara Sherwood, Treude, Tina, Warr, Oliver, and Young, Edward D

Subjects
Methane isotopologues, Methyl -coenzyme M reductase, Kinetic fractionation, Equilibrium fractionation, Isotopic bond re -ordering, Geochemistry, Geology, Physical Geography and Environmental Geoscience, Geochemistry & Geophysics
Published
2023

3. Mineralization kinetics of biosiliceous sediments in hot subseafloors

Author

Aiello, Ivano W., Höfig, Tobias W., Riboulleau, Armelle, Teske, Andreas P., Lizarralde, Daniel, Ash, Jeanine L., Bojanova, Diana P., Buatier, Martine D., Edgcomb, Virginia P., Galerne, Christophe Y., Gontharet, Swanne, Heuer, Verena B., Jiang, Shijun, Kars, Myriam A.C., Kim, Ji-Hoon, Koornneef, Louise M.T., Marsaglia, Kathleen M., Meyer, Nicolette R., Morono, Yuki, Negrete-Aranda, Raquel, Neumann, Florian, Pastor, Lucie C., Peña-Salinas, Manet E., Pérez-Cruz, Ligia L., Ran, Lihua, Sarao, John A., Schubert, Florian, Khogenkumar Singh, S., Stock, Joann M., Toffin, Laurent, Xie, Wei, Yamanaka, Toshiro, and Zhuang, Guangchao

Published
2024
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4. Nitrogen isotope homogenization of dissolved ammonium with depth and 15N enrichment of ammonium during incorporation into expandable layer silicates in organic-rich marine sediment from Guaymas Basin, Gulf of California

Author

Aiello, Ivano W., Ash, Jeanine L., Bojanova, Diana P., Buatier, Martine D., Edgcomb, Virginia P., Galerne, Christophe Y., Gontharet, Swanne, Heuer, Verena B., Jiang, Shijun, Kars, Myriam A.C., Koornneef, Louise M.T., Marsaglia, Kathleen M., Meyer, Nicolette R., Morono, Yuki, Negrete-Aranda, Raquel, Neumann, Florian, Peña-Salinas, Manet E., Pérez-Cruz, Ligia L., Ran, Lihua, Riboulleau, Armelle, Sarao, John A., Schubert, Florian, Singh, S. Khogenkumar, Stock, Joann M., Toffin, Laurent, Xie, Wei, Zhuang, Guangchao, Yamanaka, Toshiro, Sakamoto, Arisa, Kiyokawa, Kanon, Jo, Jaeguk, Onishi, Yuji, Kuwahara, Yoshihiro, Kim, Ji-Hoon, Pastor, Lucie C., Teske, Andreas, Lizarralde, Daniel, and Höfig, Tobias W.

Published
2024
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13. Climate-controlled submarine landslides on the Antarctic continental margin.

Author

Gales, Jenny A., McKay, Robert M., De Santis, Laura, Rebesco, Michele, Laberg, Jan Sverre, Shevenell, Amelia E, Harwood, David, Leckie, R. Mark, Kulhanek, Denise K., King, Maxine, Patterson, Molly, Lucchi, Renata G., Kim, Sookwan, Kim, Sunghan, Dodd, Justin, Seidenstein, Julia, Prunella, Catherine, Ferrante, Giulia M., IODP Expedition 374 Scientists, and Ash, Jeanine

Subjects
LANDSLIDES, CONTINENTAL margins, GLOBAL warming, SUBMARINES (Ships), OCEAN circulation, BIOLOGICAL productivity
Abstract

Antarctica's continental margins pose an unknown submarine landslide-generated tsunami risk to Southern Hemisphere populations and infrastructure. Understanding the factors driving slope failure is essential to assessing future geohazards. Here, we present a multidisciplinary study of a major submarine landslide complex along the eastern Ross Sea continental slope (Antarctica) that identifies preconditioning factors and failure mechanisms. Weak layers, identified beneath three submarine landslides, consist of distinct packages of interbedded Miocene- to Pliocene-age diatom oozes and glaciomarine diamicts. The observed lithological differences, which arise from glacial to interglacial variations in biological productivity, ice proximity, and ocean circulation, caused changes in sediment deposition that inherently preconditioned slope failure. These recurrent Antarctic submarine landslides were likely triggered by seismicity associated with glacioisostatic readjustment, leading to failure within the preconditioned weak layers. Ongoing climate warming and ice retreat may increase regional glacioisostatic seismicity, triggering Antarctic submarine landslides. Changes in climate preconditioned large-scale, recurrent Miocene to Pleistocene Antarctic submarine landslides through variations in biological productivity, ice proximity and ocean circulation, posing tsunami risk to Southern Hemisphere populations. [ABSTRACT FROM AUTHOR]

Published
2023
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14. Magma-sediment mingling processes, control and longevity of related hydrothermal systems – Implications for the Earth’s Carbon-, Plate-, Life-Cycles (IODP Exp 385, Guaymas Basin, Gulf of California)

Author

Galerne, Christophe, Bach, Wolfgang, Berndt, Christian, Schwark, Lorenz, Höfig, Tobias, Buatier, Martine, Cheviet, Alban, Kahl, Wolf-Achim, Hasenclever, Jörg, Lizarralde, Daniel, Stockhausen, Martin, Wiggers, Christin, Karstens, Jens, Monien, Patrick, Teske, Andreas, Aiello, Ivano W., Ash, Jeanine L., Bojanova, Diana P., Edgcomb, Virginia P., Gontharet, Swanne, Heuer, Verena B., Jiang, Shijun, Kars, Myriam A.C., Singh, S. Khogenkumar, Kim, Ji-Hoon, Koornneef, Louise M.T., Marsaglia, Kathleen M., Meyer, Nicolette R., Morono, Yuki, Negrete-Aranda, Raquel, Neumann, Florian, Pastor, Lucie C., Pena-Salinas, Manet E., Cruz, Ligia L. Perez, Ran, Lihua, Riboulleau, Armelle, Sarao, John A., Schubert, Florian, Stock, Joann M., Toffin, Laurent M.A.A., Xie, Wei, Yamanaka, Toshiro, Zhuang, Guangchao, Ortega, Rodrigo Perez, Geoscience Department and MARUM, University of Bremen, Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), Institute of Geosciences [Kiel], Christian-Albrechts-Universität zu Kiel (CAU), Curtin University [Perth], Planning and Transport Research Centre (PATREC), International Ocean Discovery Program, Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC), University of Bremen, University of Hamburg, Woods Hole Oceanographic Institution (WHOI), University of North Carolina [Chapel Hill] (UNC), University of North Carolina System (UNC), Cycles biogéochimiques marins : processus et perturbations (CYBIOM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Geological Sciences, Florida State University [Tallahassee] (FSU), Kyung Hee University (KHU), Kochi Institute for Core Sample Research, and Japan Agency for Marine-Earth Science and Technology (JAMSTEC)

Subjects
[SDE]Environmental Sciences
Abstract

Magma-sediment mingling occurring in shallow porous sediments is mainly investigated through field observations of old exhumed rift basins. During the IODP Expedition 385 we have drilled through the shallow sills emplaced in the active rift of the Guaymas Basin, Gulf of California. The results of this expedition enable a pioneer study of the impact of recent magma-sediment mingling processes leading to peperite formation. Furthermore, it provides a present-day geological context to investigate and quantify the impact of this mingling process on the element cycles in subsurface sediments, and temporal evolution of the microbial habitat associated with epithermal hydrothermal fluid circulation. Our approach of exploring magma-sediment mingling processes includes laboratory experiments, numerical modelling, and identification of specific field analogues in addition to petrological and geochemical constraints.Using these modern techniques, we review here the discoveries made during the IODP Expedition 385 and present preliminary results from our post-cruise research from the perspective of the peperite formation. We report here petrographic and geochemical evidence of magma sediment hybridization indicative of an intense mingling process inferred to occur during the emplacement phase. The rheology of the soft, unconsolidated sediment controls and explains the various intrusion shapes and dimensions. Numerical simulation results indicate that heat dissipation in this context is much less efficient, which in turn considerably decreases the amount of thermogenic gas mobilized through thermal cracking in the contact aureole of sills. Additionally, we observe that hydrothermal pipe systems established during the cooling phase of sill emplacement can remain active at moderate- to low-temperature state after the heat of the sill has vanished. Using 2D seismic information and IODP drilling results, we were able to reconstruct the 3D structure of the sill at depth. It is funnel-shaped and roots in a depth where geothermal fluids can ascend from. The temperature found at these depths is consistent with the background geothermal gradient, suggesting that the large heat flow anomaly found at Hole U1548C is the mere expression of the active hydrothermal circulation fuelled by deeply sourced geothermal fluids.These potentially long-lasting hydrothermal systems provide preferable temperature and energetic conditions for microbial activity to thrive, with mildly degraded petroleum components from below and water recharge from above. Moreover, evidence indicates that the sill at Site U1547 is non-unique at the scale of the Guaymas Basin. How many of these catabolic reactors form at the early rifting phase? Can this process perhaps trigger peaks in subsurface biomass production associated with new continental margin formation? Our research heralds the dawn of a new paradigm. We suggest that in the context of a nascent ocean, sill emplacement in the first 500 m of sediments may power life instead of suppressing it.

Published
2022

15. Early and middle Miocene ice sheet dynamics in the Ross Sea: Results from integrated core-log-seismic interpretation

Author

Marine palynology and palaeoceanography, Marine Palynology, Pérez, Lara F., De Santis, Laura, McKay, R., Larter, Robert D., Ash, Jeanine, Bart, Phil J., Böhm, Gualtiero, Brancatelli, Giuseppe, Browne, Imogen B., Colleoni, Florence, Dodd, J.P., Geletti, Riccardo, Harwood, D.M., Kuhn, G., Laberg, Jan Sverre, Leckie, R. Mark, Levy, R.H., Marschalek, James, Mateo, Zenon, Naish, Timothy, Sangiorgi, Francesca, Shevenell, Amelia, Sorlien, Christopher C., Van De Flierdt, Tina, IODP Expedition 374 Scientists, Marine palynology and palaeoceanography, Marine Palynology, Pérez, Lara F., De Santis, Laura, McKay, R., Larter, Robert D., Ash, Jeanine, Bart, Phil J., Böhm, Gualtiero, Brancatelli, Giuseppe, Browne, Imogen B., Colleoni, Florence, Dodd, J.P., Geletti, Riccardo, Harwood, D.M., Kuhn, G., Laberg, Jan Sverre, Leckie, R. Mark, Levy, R.H., Marschalek, James, Mateo, Zenon, Naish, Timothy, Sangiorgi, Francesca, Shevenell, Amelia, Sorlien, Christopher C., Van De Flierdt, Tina, and IODP Expedition 374 Scientists

Published
2022

16. Sensitivity of the West Antarctic Ice Sheet to +2 °C (SWAIS 2C)

Author

Patterson, Molly O., Levy, Richard H., Kulhanek, Denise K., van de Flierdt, Tina, Horgan, Huw, Dunbar, Gavin B., Naish, Timothy R., Ash, Jeanine, Pyne, Alex, Mandeno, Darcy, Winberry, Paul, Harwood, David M., Florindo, Fabio, Jimenez-Espejo, Francisco J., Läufer, Andreas, Yoo, Kyu-Cheul, Seki, Osamu, Stocchi, Paolo, Klages, Johann P., Lee, Jae Il, Colleoni, Florence, Suganuma, Yusuke, Gasson, Edward, Ohneiser, Christian, Flores, José-Abel, Try, David, Kirkman, Rachel, Koch, Daleen, Science Team, SWAIS 2C inc., Sime, Louise, Smith, James, Patterson, Molly O., Levy, Richard H., Kulhanek, Denise K., van de Flierdt, Tina, Horgan, Huw, Dunbar, Gavin B., Naish, Timothy R., Ash, Jeanine, Pyne, Alex, Mandeno, Darcy, Winberry, Paul, Harwood, David M., Florindo, Fabio, Jimenez-Espejo, Francisco J., Läufer, Andreas, Yoo, Kyu-Cheul, Seki, Osamu, Stocchi, Paolo, Klages, Johann P., Lee, Jae Il, Colleoni, Florence, Suganuma, Yusuke, Gasson, Edward, Ohneiser, Christian, Flores, José-Abel, Try, David, Kirkman, Rachel, Koch, Daleen, Science Team, SWAIS 2C inc., Sime, Louise, and Smith, James

Abstract

The West Antarctic Ice Sheet (WAIS) presently holds enough ice to raise global sea level by 4.3 m if completely melted. The unknown response of the WAIS to future warming remains a significant challenge for numerical models in quantifying predictions of future sea level rise. Sea level rise is one of the clearest planet-wide signals of human-induced climate change. The Sensitivity of the West Antarctic Ice Sheet to a Warming of 2 ∘C (SWAIS 2C) Project aims to understand past and current drivers and thresholds of WAIS dynamics to improve projections of the rate and size of ice sheet changes under a range of elevated greenhouse gas levels in the atmosphere as well as the associated average global temperature scenarios to and beyond the +2 ∘C target of the Paris Climate Agreement. Despite efforts through previous land and ship-based drilling on and along the Antarctic margin, unequivocal evidence of major WAIS retreat or collapse and its causes has remained elusive. To evaluate and plan for the interdisciplinary scientific opportunities and engineering challenges that an International Continental Drilling Program (ICDP) project along the Siple coast near the grounding zone of the WAIS could offer (Fig. 1), researchers, engineers, and logistics providers representing 10 countries held a virtual workshop in October 2020. This international partnership comprised of geologists, glaciologists, oceanographers, geophysicists, microbiologists, climate and ice sheet modelers, and engineers outlined specific research objectives and logistical challenges associated with the recovery of Neogene and Quaternary geological records from the West Antarctic interior adjacent to the Kamb Ice Stream and at Crary Ice Rise. New geophysical surveys at these locations have identified drilling targets in which new drilling technologies will allow for the recovery of up to 200 m of sediments beneath the ice sheet. Sub-ice-shelf records have so far proven difficult to obtain but are critical to

Published
2022

17. Early and middle Miocene ice sheet dynamics in the Ross Sea: Results from integrated core-log-seismic interpretation

Author

Pérez, Lara, De Santis, Laura, McKay, Robert M., Larter, Robert D., Ash, Jeanine, Bart, Phil J., Böhm, Gualtiero, Brancatelli, Giuseppe, Browne, Imogen, Colleoni, Florence, Dodd, Justin P., Geletti, Riccardo, Harwood, David M., Kuhn, Gerhard, Laberg, Jan Sverre, Leckie, R. Mark, Levy, Richard H., Marschalek, James, Mateo, Zenon, Naish, Timothy R., Sangiorgi, Francesca, Shevenell, Amelia E., Sorlien, Christopher C., van de Flierdt, Tina, International Ocean Discovery Program Expedition, 374 Scientists, Pérez, Lara, De Santis, Laura, McKay, Robert M., Larter, Robert D., Ash, Jeanine, Bart, Phil J., Böhm, Gualtiero, Brancatelli, Giuseppe, Browne, Imogen, Colleoni, Florence, Dodd, Justin P., Geletti, Riccardo, Harwood, David M., Kuhn, Gerhard, Laberg, Jan Sverre, Leckie, R. Mark, Levy, Richard H., Marschalek, James, Mateo, Zenon, Naish, Timothy R., Sangiorgi, Francesca, Shevenell, Amelia E., Sorlien, Christopher C., van de Flierdt, Tina, and International Ocean Discovery Program Expedition, 374 Scientists

Abstract

Oscillations in ice sheet extent during early and middle Miocene are intermittently preserved in the sedimentary record from the Antarctic continental shelf, with widespread erosion occurring during major ice sheet advances, and open marine deposition during times of ice sheet retreat. Data from seismic reflection surveys and drill sites from Deep Sea Drilling Project Leg 28 and International Ocean Discovery Program Expedition 374, located across the present-day middle continental shelf of the central Ross Sea (Antarctica), indicate the presence of expanded early to middle Miocene sedimentary sections. These include the Miocene climate optimum (MCO ca. 17−14.6 Ma) and the middle Miocene climate transition (MMCT ca. 14.6−13.9 Ma). Here, we correlate drill core records, wireline logs and reflection seismic data to elucidate the depositional architecture of the continental shelf and reconstruct the evolution and variability of dynamic ice sheets in the Ross Sea during the Miocene. Drill-site data are used to constrain seismic isopach maps that document the evolution of different ice sheets and ice caps which influenced sedimentary processes in the Ross Sea through the early to middle Miocene. In the early Miocene, periods of localized advance of the ice margin are revealed by the formation of thick sediment wedges prograding into the basins. At this time, morainal bank complexes are distinguished along the basin margins suggesting sediment supply derived from marine-terminating glaciers. During the MCO, biosiliceous-bearing sediments are regionally mapped within the depocenters of the major sedimentary basin across the Ross Sea, indicative of widespread open marine deposition with reduced glacimarine influence. At the MMCT, a distinct erosive surface is interpreted as representing large-scale marine-based ice sheet advance over most of the Ross Sea paleo-continental shelf. The regional mapping of the seismic stratigraphic architecture and its correlation to drilling da

Published
2022

18. Pleistocene depositional environments and links to cryosphere-ocean interactions on the eastern Ross Sea continental slope, Antarctica (IODP Hole U1525A)

Author

King, Maxine V., Gales, Jenny A., Laberg, Jan Sverre, McKay, Robert M., De Santis, Laura, Kulhanek, Denise K., Hosegood, Phil J., Morris, Antony, Ash, Jeanine, Beny, F., Browne, Imogen, Cortese, G., Dodd, Justin P., Esper, Oliver, Harwood, D. M., Ishino, Saki, Keisling, B., Kim, S., Leckie, R. Mark, Müller, Juliane, Patterson, Molly O., Romans, Brian W., Romero, Oscar E., Sangiorgi, Francesca, Seki, Osamu, Shevenell, Amelia E., Singh, S., Cordeiro de Sousa, Isabela M., Sugisaki, Saiko T., van de Flierdt, Tina, van Peer, T. E., Xiao, Wenshen, Xiong, Zhifang, King, Maxine V., Gales, Jenny A., Laberg, Jan Sverre, McKay, Robert M., De Santis, Laura, Kulhanek, Denise K., Hosegood, Phil J., Morris, Antony, Ash, Jeanine, Beny, F., Browne, Imogen, Cortese, G., Dodd, Justin P., Esper, Oliver, Harwood, D. M., Ishino, Saki, Keisling, B., Kim, S., Leckie, R. Mark, Müller, Juliane, Patterson, Molly O., Romans, Brian W., Romero, Oscar E., Sangiorgi, Francesca, Seki, Osamu, Shevenell, Amelia E., Singh, S., Cordeiro de Sousa, Isabela M., Sugisaki, Saiko T., van de Flierdt, Tina, van Peer, T. E., Xiao, Wenshen, and Xiong, Zhifang

Abstract

The repeated proximity of West Antarctic Ice Sheet (WAIS) ice to the eastern Ross Sea continental shelf break during past ice age cycles has been inferred to directly influence sedimentary processes occurring on the continental slope, such as turbidity current and debris flow activity; thus, the records of these processes can be used to study the past history of the WAIS. Ross Sea slope sediments may additionally provide an archive on the history and interplay of density-driven or geostrophic oceanic bottom currents with ice-sheet-driven depositional mechanisms. We investigate the upper 121 m of Hole U1525A, collected during International Ocean Discovery Program (IODP) Expedition 374 in 2018. Hole U1525A is located on the southwestern external levee of the Hillary Canyon (Ross Sea, Antarctica) and the depositional lobe of the nearby trough-mouth fan. Using core descriptions, grain size analysis, and physical properties datasets, we develop a lithofacies scheme that allows construction of a detailed depositional model and environmental history of past ice sheet-ocean interactions at the eastern Ross Sea continental shelf break/slope since ~2.4 Ma. The earliest Pleistocene interval (~2.4- ~ 1.4 Ma) represents a hemipelagic environment dominated by ice-rafting and reworking/deposition by relatively persistent bottom current activity. Finely interlaminated silty muds with ice-rafted debris (IRD) layers are interpreted as contourites. Between ~1.4 and ~0.8 Ma, geostrophic bottom current activity was weaker and turbiditic processes more common, likely related to the increased proximity of grounded ice at the shelf edge. Silty, normally-graded laminations with sharp bases may be the result of flow-stripped turbidity currents overbanking the canyon levee during periods when ice was grounded at or proximal to the shelf edge. A sandy, IRD- and foraminifera-bearing interval dated to ~1.18 Ma potentially reflects warmer oceanographic conditions and a period of stronger Antarcti

Published
2022

19. Sensitivity of the West Antarctic Ice Sheet to +2 °C (SWAIS 2C)

Author

Ministry of Business, Innovation, and Employment (New Zealand), Patterson, Molly O., Levy, Richard H., Kulhanek, Denise K., van de Flierdt, Tina, Horgan, Huw, Dunbar, Gavin B., Naish, Timothy R., Ash, Jeanine, Pyne, Alex, Mandeno, Darcy, Winberry, Paul, Harwood, David M., Florindo, Fabio, Jimenez Espejo, Francisco Jose, Läufer, Andreas, Yoo, Kyu-Cheul, Seki, Osamu, Stocchi, Paolo, Klages, Johann P., Lee, Jae Il, Colleoni, Florence, Suganuma, Yusuke, Gasson, Edward, Ohneiser, Christian, Flores, José-Abel, Try, David, Kirkman, Rachel, Koch, Daleen, Ministry of Business, Innovation, and Employment (New Zealand), Patterson, Molly O., Levy, Richard H., Kulhanek, Denise K., van de Flierdt, Tina, Horgan, Huw, Dunbar, Gavin B., Naish, Timothy R., Ash, Jeanine, Pyne, Alex, Mandeno, Darcy, Winberry, Paul, Harwood, David M., Florindo, Fabio, Jimenez Espejo, Francisco Jose, Läufer, Andreas, Yoo, Kyu-Cheul, Seki, Osamu, Stocchi, Paolo, Klages, Johann P., Lee, Jae Il, Colleoni, Florence, Suganuma, Yusuke, Gasson, Edward, Ohneiser, Christian, Flores, José-Abel, Try, David, Kirkman, Rachel, and Koch, Daleen

Abstract

The West Antarctic Ice Sheet (WAIS) presently holds enough ice to raise global sea level by 4.3 m if completely melted. The unknown response of the WAIS to future warming remains a significant challenge for numerical models in quantifying predictions of future sea level rise. Sea level rise is one of the clearest planet-wide signals of human-induced climate change. The Sensitivity of the West Antarctic Ice Sheet to a Warming of 2 °C (SWAIS 2C) Project aims to understand past and current drivers and thresholds of WAIS dynamics to improve projections of the rate and size of ice sheet changes under a range of elevated greenhouse gas levels in the atmosphere as well as the associated average global temperature scenarios to and beyond the +2 °C target of the Paris Climate Agreement. Despite efforts through previous land and ship-based drilling on and along the Antarctic margin, unequivocal evidence of major WAIS retreat or collapse and its causes has remained elusive. To evaluate and plan for the interdisciplinary scientific opportunities and engineering challenges that an International Continental Drilling Program (ICDP) project along the Siple coast near the grounding zone of the WAIS could offer (Fig. 1), researchers, engineers, and logistics providers representing 10 countries held a virtual workshop in October 2020. This international partnership comprised of geologists, glaciologists, oceanographers, geophysicists, microbiologists, climate and ice sheet modelers, and engineers outlined specific research objectives and logistical challenges associated with the recovery of Neogene and Quaternary geological records from the West Antarctic interior adjacent to the Kamb Ice Stream and at Crary Ice Rise. New geophysical surveys at these locations have identified drilling targets in which new drilling technologies will allow for the recovery of up to 200 m of sediments beneath the ice sheet. Sub-ice-shelf records have so far proven difficult to obtain but are critical to

Published
2022

20. Clumped Isotopes as Tracers from Enzymes to Global Biogeochemical Cycles

Author

Ash, Jeanine L.

Subjects
Geochemistry, anaeobic methanotrophy, biosignatures, clumped isotopes, photosynthesis, respiration
Abstract

Reactions occurring at enzymes drive all of Earth’s biogeochemical cycles from the oxygen in the atmosphere to methane below the seafloor. Although these gases are critical for life on our planet, they have a multitude of sources and sinks that can be difficult to distinguish from one another, complicating our ability to understand their budgets both in the present and the past. Here, I explore new tracers of the oxygen and methane cycles with a focus on the biologic production and consumption of these gases: photosynthesis/respiration and methanogenesis/methanotrophy, respectively. Isotopes have been used as tracers of these processes since the inception of the field of stable isotope geochemistry, but only the measurement of singly-substituted molecules (i.e., 18O16O and 13CH4) has been possible. Within, I report measurements of the relative abundances of 18O18O and 18O17O for oxygen that has been biologically cycled in a terrarium experiment and respired in lake water as well as 13CH3D and 12CH2D2 of biologically produced and consumed subseafloor methane. These multiply-substituted isotopologues provide a new dimension of information by illuminating the enzyme level chemistry in making and breaking bonds. I find that photosynthesis and methanogenesis produce oxygen and methane respectively that is out of equilibrium with environmental temperatures and the resulting gases have fewer multiply-substituted isotopologues than predicted by chance alone. Respiration of oxygen leaves behind a residue enriched in these rare isotopologues; this unexpected result merits further exploration. However, anaerobic methanotrophy seems to be capable of reordering isotopes by enzymatic back reaction, driving a pool of methane to intra-species equilibrium at low temperature. These findings have consequences both for ongoing work in measuring marine primary productivity as well as exploring the extent of life in the deep biosphere and throughout the solar system.

Published
2017

21. Biological Sulfate Reduction in Deep Subseafloor Sediment of Guaymas Basin

Author

Nagakura, Toshiki, Schubert, Florian, Wagner, Dirk, Kallmeyer, Jens, Teske, Andreas, Lizarralde, Daniel, W., Tobias, Aiello, Ivano W., Ash, Jeanine L., Bojanova, Diana P., Buatier, Martine D., Edgcomb, Virginia P., Galerne, Christophe Y., Gontharet, Swanne, Heuer, Verena B., Jiang, Shijun, Kars, Myriam A.C., Singh, S. Khogenkumar, Kim, Ji-Hoon, Koornneef, Louise M.T., Marsaglia, Kathleen M., Meyer, Nicolette R., Morono, Yuki, Negrete-Aranda, Raquel, Neumann, Florian, Pastor, Lucie C., Pena-Salinas, Manet E., Cruz, Ligia L. Perez, Ran, Lihua, Riboulleau, Armelle, Sarao, John A., Stock, Joann M., Toffin, Laurent M.A.A., Xie, Wei, Zhuang, Guangchao, Ortega, Rodrigo Perez, Institute of Molecular Medicine and Cell Research (ZBMZ), University of Freiburg [Freiburg], GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ), Institute of Earth and Environmental Science [Potsdam], University of Potsdam = Universität Potsdam, University of North Carolina [Chapel Hill] (UNC), University of North Carolina System (UNC), Woods Hole Oceanographic Institution (WHOI), Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord]), Geological Sciences, Florida State University [Tallahassee] (FSU), and Kyung Hee University (KHU)

Subjects
Microbiology (medical), sulfate reduction subsurface life deep biosphere thermophiles Guaymas Basin, sulfate reduction, [SDE]Environmental Sciences, deep biosphere, Guaymas Basin, subsurface life, Microbiology, thermophiles
Abstract

Sulfate reduction is the quantitatively most important process to degrade organic matter in anoxic marine sediment and has been studied intensively in a variety of settings. Guaymas Basin, a young marginal ocean basin, offers the unique opportunity to study sulfate reduction in an environment characterized by organic-rich sediment, high sedimentation rates, and high geothermal gradients (100–958°C km−1). We measured sulfate reduction rates (SRR) in samples taken during the International Ocean Discovery Program (IODP) Expedition 385 using incubation experiments with radiolabeled 35SO42− carried out at in situ pressure and temperature. The highest SRR (387 nmol cm−3 d−1) was recorded in near-surface sediments from Site U1548C, which had the steepest geothermal gradient (958°C km−1). At this site, SRR were generally over an order of magnitude higher than at similar depths at other sites (e.g., 387–157 nmol cm−3 d−1 at 1.9 mbsf from Site U1548C vs. 46–1.0 nmol cm−3 d−1 at 2.1 mbsf from Site U1552B). Site U1546D is characterized by a sill intrusion, but it had already reached thermal equilibrium and SRR were in the same range as nearby Site U1545C, which is minimally affected by sills. The wide temperature range observed at each drill site suggests major shifts in microbial community composition with very different temperature optima but awaits confirmation by molecular biological analyses. At the transition between the mesophilic and thermophilic range around 40°C–60°C, sulfate-reducing activity appears to be decreased, particularly in more oligotrophic settings, but shows a slight recovery at higher temperatures.

Published
2022

22. Investigating microbial constraints on hydrocarbon processing in Guaymas Basin subseafloor sediments with sill intrusions

Author

Teske, Andreas, Mara, Paraskevi, Vázquez, Mirna, Baker, Brett, Morono, Yuki, Edgcomb, Virginia, Lizarralde, Daniel, Höfig, Tobias W., Aiello, Ivano W., Ash, Jeanine L., Bojanova, Diana P., Buatier, Martine, Galerne, Christophe Y., Gontharet, Swanne, Heuer, Verena B., Jiang, Shijun, Kars, Myriam A.C., Kim, Ji-Hoon, Koornneef, Louise M.T., Marsaglia, Kathleen M., Meyer, Nicolette R., Negrete-Aranda, Raquel, Neumann, Florian, Pastor, Lucie C., Peña-Salinas, Manet, Cruz, Ligia L. Pérez, Ran, Lihua, Riboulleau, Armelle, Sarao, John A., Schubert, Florian, Singh, S. Khogenkumar, Stock, Joann M., Toffin, Laurent M.A.A., Xie, Wei, Yamanaka, Toshiro, Zhuang, Guangchao, Department of Chemistry [Heraklion], University of Crete [Heraklion] (UOC), University of Texas at Austin [Austin], Woods Hole Oceanographic Institution (WHOI), Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord]), Geological Sciences, Florida State University [Tallahassee] (FSU), Kyung Hee University (KHU), Key Laboratory of Marine Ecosystem Dynamics, Institute of Molecular Medicine and Cell Research (ZBMZ), and University of Freiburg [Freiburg]

Subjects
[SDE]Environmental Sciences
Abstract

Guaymas Basin is a young marginal rift basin in the Gulf of California characterized by active seafloor spreading and rapid deposition of organic-rich sediments derived from highly productive overlying waters and terrigenous sediments from nearby continental margins. Catalyzed by the steep geothermal gradient, sedimentary organic material of photosynthetic origin turns into a diverse spectrum of hydrocarbons that accumulate especially in deep, hot sediments, and might supply substrates for hydrocarbon-degrading microorganisms. The “from magma to microbe” perspective on these processes motivated International Ocean Discovery Program Expedition 385“Guaymas Basin Tectonics and Biosphere.”Hydrocarbon concentrations were determined in sediment samples selected from eight drilling sites on the flanking regions and in the northern axial graben of Guaymas Basin. Total petroleum hydrocarbon (C9-C44) concentrations increased from ca. 50-250 mg/kg towards >2000 mg/kg at in-situ temperatures above 80°C. A similar increase from ca. 10 mg/kg towards >100 mg/kg was observed for total saturated hydrocarbons. These gradients are shaped by abiotic hydrocarbon generation above 80°C at depth, and possibly by microbial hydrocarbon degradation at cooler temperatures in the upper sediment column. In a two-pronged approach, we are currently investigating the activity of bacterial/fungal consortia, isolated from Guaymas Basin surficial sediments, in the oxidation of selected alkanes and polyaromatics that occur at Guaymas Basin. In parallel, we explore the diversity, depth range and in-situ temperature range of bacteria, archaea and fungi in the Guaymas Basin subsurface sediments using PCR and metagenomic sequencing, to constrain microbial hydrocarbon cycling in the deep subsurface. Updates on these ongoing investigations will be presented.

Published
2022

23. Methane clumped isotope signature of anaerobic oxidation of methane

Author

Liu, Jiarui, primary, Harris, Rachel L., additional, Ash, Jeanine L., additional, Ferry, James G., additional, Labidi, Jabrane, additional, Krause, Sebastian J.E., additional, Prakash, Divya, additional, Sherwood Lollar, Barbara, additional, Treude, Tina, additional, Warr, Oliver, additional, and Young, Edward D., additional

Published
2022
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25. Isotopic Ordering in Atmospheric O2 as a Tracer of Ozone Photochemistry and the Tropical Atmosphere

Author

Yeung, Laurence Y, Murray, Lee T, Ash, Jeanine L, Young, Edward D, Boering, Kristie A, Atlas, Elliot L, Schauffler, Sue M, Lueb, Richard A, Langenfelds, Ray L, Krummel, Paul B, Steele, L. Paul, and Eastham, Sebastian D

Subjects
Meteorology And Climatology, Geophysics
Abstract

The distribution of isotopes within O2 molecules can be rapidly altered when they react with atomic oxygen. This mechanism is globally important: while other contributions to the global budget of O2 impart isotopic signatures, the O(3P) + O2 reaction resets all such signatures in the atmosphere on subdecadal timescales. Consequently, the isotopic distribution within O2 is determined by O3 photochemistry and the circulation patterns that control where that photochemistry occurs. The variability of isotopic ordering in O2 has not been established, however. We present new measurements of 18O18O in air (reported as delta36 values) from the surface to 33 km altitude. They confirm the basic features of the clumped-isotope budget of O2: Stratospheric air has higher delta36 values than tropospheric air (i.e., more 18O18O), reflecting colder temperatures and fast photochemical cycling of O3. Lower delta36 values in the troposphere arise from photochemistry at warmer temperatures balanced by the influx of high-delta36 air from the stratosphere. These observations agree with predictions derived from the GEOS-Chem chemical transport model, which provides additional insight. We find a link between tropical circulation patterns and regions where delta36 values are reset in the troposphere. The dynamics of these regions influences lapse rates, vertical and horizontal patterns of O2 reordering, and thus the isotopic distribution toward which O2 is driven in the troposphere. Temporal variations in delta36 values at the surface should therefore reflect changes in tropospheric temperatures, photochemistry, and circulation. Our results suggest that the tropospheric O3 burden has remained within a +/-10 percent range since 1978.

Published
2016
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26. Guaymas Basin Tectonics and Biosphere

Author

Teske, A., Lizarralde, D., Höfig, T.W., Aiello, Ivano W., Ash, Jeanine L., Bojanova, Diana P., Buatier, Martine D., Edgcomb, Virginia P., Galerne, Christophe Y., Gontharet, Swanne, Heuer, Verena B., Jiang, Shijun, Kars, Myriam A.C., Singh, S. Khogenkumar, Kim, Ji-Hoon, Koornneef, Louise M.T., Marsaglia, Kathleen M., Meyer, Nicolette R., Morono, Yuki, Negrete-Aranda, Raquel, Neumann, Florian, Pastor, Lucie C., Pena-Salinas, Manet E., Perez-Cruz, Ligia L., Ran, Lihua, Riboulleau, Armelle, Sarao, John A., Schubert, Florian, Stock, Joann M., Toffin, Laurent M.A.A., Xie, Wei, Yamanaka, Toshiro, Zhuang, Guangchao, Ortega, Rodrigo Perez, European Infective Endocarditis Registry (Euro-Endo), Woods Hole Oceanographic Institution (WHOI), International Ocean Discovery Program, Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Cycles biogéochimiques marins : processus et perturbations (CYBIOM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Geological Sciences, Florida State University [Tallahassee] (FSU), Kyung Hee University (KHU), Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Key Laboratory of Marine Ecosystem Dynamics, Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord]), Institute of Molecular Medicine and Cell Research (ZBMZ), University of Freiburg [Freiburg], Seismological Laboratory, California Institute of Technology (CALTECH), and Tokyo University of Marine Science and Technology (TUMSAT)

Subjects
Tectonics, Guaymas Basin, [SDE]Environmental Sciences, Geochemistry, Biosphere, Geology
Abstract

A complete set of the logging data collected during the expedition is available at http://mlp.ldeo.columbia.edu/logdb/scientific_ocean_drilling. If you have problems downloading the data, wish to receive additional logging data, or have questions regarding the data, please contact Database Administrator, Bore

Published
2021

27. Magma plumbing system and associated hydrothermal vents in the Guaymas Basin - geometry and implications

Author

Galerne, Christophe, Lizarralde, Daniel, Berndt, Christian, Neumann, Florian, Höfig, Tobias, Stock, Joann, Peña-Salinas, Manet, Negrete-Aranda, Raquel, Teske, Andreas, Aiello, Ivano W., Ash, Jeanine L., Bojanova, Diana P., Buatier, Martine D., Edgcomb, Virginia P., Gontharet, Swanne, Heuer, Verena B., Jiang, Shijun, Kars, Myriam A.C., Singh, S. Khogenkumar, Kim, Ji-Hoon, Koornneef, Louise M.T., Marsaglia, Kathleen M., Meyer, Nicolette R., Morono, Yuki, Pastor, Lucie C., Cruz, Ligia L. Perez, Ran, Lihua, Riboulleau, Armelle, Sarao, John, Schubert, Florian, Toffin, Laurent M.A.A., Xie, Wei, Yamanaka, Toshiro, Zhuang, Guangchao, Ortega, Rodrigo Perez, Woods Hole Oceanographic Institution (WHOI), Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), International Ocean Discovery Program, Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Cycles biogéochimiques marins : processus et perturbations (CYBIOM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Geological Sciences, Florida State University [Tallahassee] (FSU), Kyung Hee University (KHU), Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Key Laboratory of Marine Ecosystem Dynamics, Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), and Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord])

Subjects
Guaymas Basin, Magma, [SDE]Environmental Sciences, Geochemistry, 14. Life underwater, Geology, Hydrothermal vent
Abstract

We document the geometry of a massive sill at the root of an approximately 20-m high and 800 m-wide ring of hydrothermal formations, termed Ringvent, located 28.5 km off-axis on the northwestern flanking regions of the actively rifting Guaymas Basin (Gulf of California). Using petrophysical data collected during the IODP Expedition 385 and processed 2D seismic profiles, we present evidence on the mechanics of sill emplacement and how the related hydrothermal vent conduits were constructed. The currently active moderate-temperature hydrothermal vent field indicates that, despite being cold and crystallized, the magma plumbing system, is tapping into a deeper geothermal source of the basin. The vent system roots at the vertical end of the magma plumbing system with the top of the sill located at a depth range of 80 to 150 m below the seafloor. Our research aims at constraining how far deep the geothermal fluids are coming from, and identifying how close the hydrothermal system is from a steady-state condition, to draw implications for how frequently such a system may arise in nascent ocean basins.

Published
2021

29. A large West Antarctic Ice Sheet explains early Neogene sea-level amplitude

Author

Marschalek, J. W., Zurli, L., Talarico, F., van de Flierdt, T., Vermeesch, P., Carter, A., Beny, F., Bout-Roumazeilles, V., Sangiorgi, F., Hemming, S. R., Pérez, L. F., Colleoni, F., Prebble, J. G., van Peer, T. E., Perotti, M., Shevenell, A. E., Browne, I., Kulhanek, D. K., Levy, R., Harwood, D., Sullivan, N. B., Meyers, S. R., Griffith, E. M., Hillenbrand, C.-D., Gasson, E., Siegert, M. J., Keisling, B., Licht, K. J., Kuhn, G., Dodd, J. P., Boshuis, C., De Santis, L., McKay, R. M., Ash, Jeanine, Beny, François, Browne, Imogen M., Cortese, Giuseppe, De Santis, Laura, Dodd, Justin P., Esper, Oliver M., Gales, Jenny A., Harwood, David M., Ishino, Saki, Keisling, Benjamin A., Kim, Sookwan, Kim, Sunghan, Kulhanek, Denise K., Laberg, Jan Sverre, Leckie, R. Mark, McKay, Robert M., Müller, Juliane, Patterson, Molly O., Romans, Brian W., Romero, Oscar E., Sangiorgi, Francesca, Seki, Osamu, Shevenell, Amelia E., Singh, Shiv M., Cordeiro de Sousa, Isabela M., Sugisaki, Saiko T., van de Flierdt, Tina, van Peer, Tim E., Xiao, Whenshen, Xiong, Zhifang, Marschalek, J. W., Zurli, L., Talarico, F., van de Flierdt, T., Vermeesch, P., Carter, A., Beny, F., Bout-Roumazeilles, V., Sangiorgi, F., Hemming, S. R., Pérez, L. F., Colleoni, F., Prebble, J. G., van Peer, T. E., Perotti, M., Shevenell, A. E., Browne, I., Kulhanek, D. K., Levy, R., Harwood, D., Sullivan, N. B., Meyers, S. R., Griffith, E. M., Hillenbrand, C.-D., Gasson, E., Siegert, M. J., Keisling, B., Licht, K. J., Kuhn, G., Dodd, J. P., Boshuis, C., De Santis, L., McKay, R. M., Ash, Jeanine, Beny, François, Browne, Imogen M., Cortese, Giuseppe, De Santis, Laura, Dodd, Justin P., Esper, Oliver M., Gales, Jenny A., Harwood, David M., Ishino, Saki, Keisling, Benjamin A., Kim, Sookwan, Kim, Sunghan, Kulhanek, Denise K., Laberg, Jan Sverre, Leckie, R. Mark, McKay, Robert M., Müller, Juliane, Patterson, Molly O., Romans, Brian W., Romero, Oscar E., Sangiorgi, Francesca, Seki, Osamu, Shevenell, Amelia E., Singh, Shiv M., Cordeiro de Sousa, Isabela M., Sugisaki, Saiko T., van de Flierdt, Tina, van Peer, Tim E., Xiao, Whenshen, and Xiong, Zhifang

Abstract

Early to Middle Miocene sea-level oscillations of approximately 40–60 m estimated from far-field records1–3 are interpreted to reflect the loss of virtually all East Antarctic ice during peak warmth2. This contrasts with ice-sheet model experiments suggesting most terrestrial ice in East Antarctica was retained even during the warmest intervals of the Middle Miocene4,5. Data and model outputs can be reconciled if a large West Antarctic Ice Sheet (WAIS) existed and expanded across most of the outer continental shelf during the Early Miocene, accounting for maximum ice-sheet volumes. Here we provide the earliest geological evidence proving large WAIS expansions occurred during the Early Miocene (~17.72–17.40 Ma). Geochemical and petrographic data show glacimarine sediments recovered at International Ocean Discovery Program (IODP) Site U1521 in the central Ross Sea derive from West Antarctica, requiring the presence of a WAIS covering most of the Ross Sea continental shelf. Seismic, lithological and palynological data reveal the intermittent proximity of grounded ice to Site U1521. The erosion rate calculated from this sediment package greatly exceeds the long-term mean, implying rapid erosion of West Antarctica. This interval therefore captures a key step in the genesis of a marine-based WAIS and a tipping point in Antarctic ice-sheet evolution.

Published
2021

30. Early and middle Miocene ice sheet dynamics in the Ross Sea: Results from integrated core-log-seismic interpretation

Author

Pérez, Lara F., De Santis, Laura, McKay, Robert M., Larter, Robert D., Ash, Jeanine, Bart, Phil J., Böhm, Gualtiero, Brancatelli, Giuseppe, Browne, Imogen, Colleoni, Florence, Dodd, Justin P., Geletti, Riccardo, Harwood, David M., Kuhn, Gerhard, Sverre Laberg, Jan, Leckie, R. Mark, Levy, Richard H., Marschalek, James, Mateo, Zenon, Naish, Timothy R., Sangiorgi, Francesca, Shevenell, Amelia E., Sorlien, Christopher C., van de Flierdt, Tina, 374 Scientists, International Ocean Discovery Program Expedition, Pérez, Lara F., De Santis, Laura, McKay, Robert M., Larter, Robert D., Ash, Jeanine, Bart, Phil J., Böhm, Gualtiero, Brancatelli, Giuseppe, Browne, Imogen, Colleoni, Florence, Dodd, Justin P., Geletti, Riccardo, Harwood, David M., Kuhn, Gerhard, Sverre Laberg, Jan, Leckie, R. Mark, Levy, Richard H., Marschalek, James, Mateo, Zenon, Naish, Timothy R., Sangiorgi, Francesca, Shevenell, Amelia E., Sorlien, Christopher C., van de Flierdt, Tina, and 374 Scientists, International Ocean Discovery Program Expedition

Abstract

Oscillations in ice sheet extent during early and middle Miocene are intermittently preserved in the sedimentary record from the Antarctic continental shelf, with widespread erosion occurring during major ice sheet advances, and open marine deposition during times of ice sheet retreat. Data from seismic reflection surveys and drill sites from Deep Sea Drilling Project Leg 28 and International Ocean Discovery Program Expedition 374, located across the present-day middle continental shelf of the central Ross Sea (Antarctica), indicate the presence of expanded early to middle Miocene sedimentary sections. These include the Miocene climate optimum (MCO ca. 17−14.6 Ma) and the middle Miocene climate transition (MMCT ca. 14.6−13.9 Ma). Here, we correlate drill core records, wireline logs and reflection seismic data to elucidate the depositional architecture of the continental shelf and reconstruct the evolution and variability of dynamic ice sheets in the Ross Sea during the Miocene. Drill-site data are used to constrain seismic isopach maps that document the evolution of different ice sheets and ice caps which influenced sedimentary processes in the Ross Sea through the early to middle Miocene. In the early Miocene, periods of localized advance of the ice margin are revealed by the formation of thick sediment wedges prograding into the basins. At this time, morainal bank complexes are distinguished along the basin margins suggesting sediment supply derived from marine-terminating glaciers. During the MCO, biosiliceous-bearing sediments are regionally mapped within the depocenters of the major sedimentary basin across the Ross Sea, indicative of widespread open marine deposition with reduced glacimarine influence. At the MMCT, a distinct erosive surface is interpreted as representing large-scale marine-based ice sheet advance over most of the Ross Sea paleo-continental shelf. The regional mapping of the seismic stratigraphic architecture and its correlation to drilling da

Published
2021

31. Bottom current control on sediment deposition between the Iselin Bank and the Hillary Canyon (Antarctica) since the late Miocene: An integrated seismic-oceanographic approach

Author

Conte, R., Rebesco, M., De Santis, L., Colleoni, F., Bensi, M., Bergamasco, A., Kovacevic, V., Gales, J., Zgur, F., Accettella, D., De Steur, L., Ursella, L., McKay, R., Kim, S., Lucchi, R.G., Ash, Jeanine, Beny, F., Browne, Imogen, Cortese, Giuseppe, Dodd, Justin P., Esper, Oliver, Harwood, D. M., Ishino, Saki, Keisling, B., Kulhanek, D. K., Laberg, Jan Sverre, Leckie, R. Mark, Müller, Juliane, Patterson, Molly O., Romans, Brian W., Romero, Oscar E., Sangiorgi, Francesca, Seki, Osamu, Shevenell, Amelia E., Singh, Shiv M., Cordeiro de Sousa, Isabela M., Sugisaki, Saiko T., Van De Flierdt, T., van Peer, T. E., Xiao, Whenshen, Xiong, Zhifang, Conte, R., Rebesco, M., De Santis, L., Colleoni, F., Bensi, M., Bergamasco, A., Kovacevic, V., Gales, J., Zgur, F., Accettella, D., De Steur, L., Ursella, L., McKay, R., Kim, S., Lucchi, R.G., Ash, Jeanine, Beny, F., Browne, Imogen, Cortese, Giuseppe, Dodd, Justin P., Esper, Oliver, Harwood, D. M., Ishino, Saki, Keisling, B., Kulhanek, D. K., Laberg, Jan Sverre, Leckie, R. Mark, Müller, Juliane, Patterson, Molly O., Romans, Brian W., Romero, Oscar E., Sangiorgi, Francesca, Seki, Osamu, Shevenell, Amelia E., Singh, Shiv M., Cordeiro de Sousa, Isabela M., Sugisaki, Saiko T., Van De Flierdt, T., van Peer, T. E., Xiao, Whenshen, and Xiong, Zhifang

Abstract

In this paper we analyze how oceanic circulation affects sediment deposition along a sector of the Ross Sea continental margin, between the Iselin Bank and the Hillary Canyon, and how these processes evolved since the Late Miocene. The Hillary Canyon is one of the few places around the Antarctic continental margin where the dense waters produced onto the continental shelf, mainly through brine rejection related to sea ice production, flow down the continental slope and reach the deep oceanic bottom layer. At the same time the Hillary Canyon represents a pathway for relatively warm waters, normally flowing along the continental slope within the Antarctic Slope Current, to reach the continental shelf. The intrusion of warm waters onto the continental shelf produces basal melting of the ice shelves, reduces their buttressing effect and triggers instabilities of the ice sheet that represent one of the main uncertainties in future sea level projections. For this study we use seismic, morpho-bathymetric and oceanographic data acquired in 2017 by the R/V OGS Explora. Seismic profiles and multibeam bathymetry are interpreted together with age models from two drilling sites (U1523 and U1524) of the International Ocean Discovery Program (IODP) Expedition 374. Oceanographic data, together with a regional oceanographic model, are used to support our reconstruction by showing the present-day oceanographic influence on sediment deposition. Regional correlation of the main seismic unconformities allows us to identify eight seismic sequences. Seismic profiles and multibeam bathymetry show a strong influence of bottom current activity on sediment deposition since the Early Miocene and a reduction in their intensity during the mid-Pliocene Warm Period. Oceanographic data and modelling provide evidence that the bottom currents are related to the dense waters produced on the Ross Sea continental shelf and flowing out through the Hillary Canyon. The presence of extensive mass transport

Published
2021

32. Magnetic mineral diagenesis and associated biogeochemical processes in cold seepage and gas hydrate sites of the Guaymas Basin

Author

Kars, Myriam, primary, Pastor, Lucie, additional, Burin, Céline, additional, Morono, Yuki, additional, Koornneef, Louise, additional, Höfig, Tobias, additional, Teske, Andreas, additional, Lizarralde, Daniel, additional, Aiello, Ivano, additional, Ash, Jeanine, additional, Bojanova, Diana, additional, Buatier, Martine, additional, Edgcomb, Virginia, additional, Galerne, Christophe, additional, Gontharet, Swanne, additional, Heuer, Verena, additional, Jiang, Shijun, additional, Kim, Ji-Hoon, additional, Marsaglia, Kathie, additional, Meyer, Nicolette, additional, Neumann, Florian, additional, Negrete, Raquel, additional, Peña-Salinas, Manet, additional, Perez Cruz, Ligia, additional, Ran, Lihua, additional, Riboulleau, Armelle, additional, Sarao, John, additional, Schubert, Florian, additional, Singh, S. Khogenkumar, additional, Stock, Joann, additional, Toffin, Laurent, additional, Xie, Wei, additional, Xu, Shumei, additional, Yamanaka, Toshiro, additional, and Zhuang, Guangchao, additional

Published
2021
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33. Sensitivity of the West Antarctic Ice Sheet to+2 ∘C (SWAIS 2C).

Author

Patterson, Molly O., Levy, Richard H., Kulhanek, Denise K., van de Flierdt, Tina, Horgan, Huw, Dunbar, Gavin B., Naish, Timothy R., Ash, Jeanine, Pyne, Alex, Mandeno, Darcy, Winberry, Paul, Harwood, David M., Florindo, Fabio, Jimenez-Espejo, Francisco J., Läufer, Andreas, Yoo, Kyu-Cheul, Seki, Osamu, Stocchi, Paolo, Klages, Johann P., and Lee, Jae Il

Subjects
ANTARCTIC ice, ICE sheets, ICE streams, PARIS Agreement (2016), GEOPHYSICAL surveys, ATMOSPHERE
Abstract

The West Antarctic Ice Sheet (WAIS) presently holds enough ice to raise global sea level by 4.3 m if completely melted. The unknown response of the WAIS to future warming remains a significant challenge for numerical models in quantifying predictions of future sea level rise. Sea level rise is one of the clearest planet-wide signals of human-induced climate change. The Sensitivity of the West Antarctic Ice Sheet to a Warming of 2 ∘ C (SWAIS 2C) Project aims to understand past and current drivers and thresholds of WAIS dynamics to improve projections of the rate and size of ice sheet changes under a range of elevated greenhouse gas levels in the atmosphere as well as the associated average global temperature scenarios to and beyond the + 2 ∘ C target of the Paris Climate Agreement. Despite efforts through previous land and ship-based drilling on and along the Antarctic margin, unequivocal evidence of major WAIS retreat or collapse and its causes has remained elusive. To evaluate and plan for the interdisciplinary scientific opportunities and engineering challenges that an International Continental Drilling Program (ICDP) project along the Siple coast near the grounding zone of the WAIS could offer (Fig. 1), researchers, engineers, and logistics providers representing 10 countries held a virtual workshop in October 2020. This international partnership comprised of geologists, glaciologists, oceanographers, geophysicists, microbiologists, climate and ice sheet modelers, and engineers outlined specific research objectives and logistical challenges associated with the recovery of Neogene and Quaternary geological records from the West Antarctic interior adjacent to the Kamb Ice Stream and at Crary Ice Rise. New geophysical surveys at these locations have identified drilling targets in which new drilling technologies will allow for the recovery of up to 200 m of sediments beneath the ice sheet. Sub-ice-shelf records have so far proven difficult to obtain but are critical to better constrain marine ice sheet sensitivity to past and future increases in global mean surface temperature up to 2 ∘ C above pre-industrial levels. Thus, the scientific and technological advances developed through this program will enable us to test whether WAIS collapsed during past intervals of warmth and determine its sensitivity to a + 2 ∘ C global warming threshold (UNFCCC, 2015). [ABSTRACT FROM AUTHOR]

Published
2022
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35. What Fractionates Oxygen Isotopes During Respiration? Insights from Multiple Isotopologues and Theory

Author

Yeung, Laurence, Ash, Jeanine, and Hu, Huanting

Subjects
bepress|Physical Sciences and Mathematics, EarthArXiv|Physical Sciences and Mathematics|Earth Sciences|Biogeochemistry, bepress|Physical Sciences and Mathematics|Earth Sciences, EarthArXiv|Physical Sciences and Mathematics|Earth Sciences, bepress|Physical Sciences and Mathematics|Earth Sciences|Biogeochemistry, EarthArXiv|Physical Sciences and Mathematics
Abstract

The precise mass dependence of respiratory O2 consumption underpins the “oxygen triple-isotope” approach to quantifying gross primary productivity in modern and ancient environments. Yet, the physical-chemical origins of the key 18O/16O and 17O/16O covariations observed during respiration have not been tied to theory; thus the approach remains empirical. First-principles calculations on enzyme active-site models suggest that changes in the O-O bond strength upon electron transfer strongly influence respiratory isotopic fractionation. However, molecular diffusion may also be important. Here, we use measurements of the relative abundances of rare isotopologues 17O18O and 18O18O as additional tracers of mass dependence during dark respiration experiments of lacustrine water. We then compare the experimental results to first-principles calculations of O2 interacting with heme-oxidase analogues. We find a significantly steeper mass dependence, supported by theory, than has been previously observed. Enrichments of 17O18O and 18O18O in the O2 residue suggest that theta values are strongly influenced by chemical processes, rather than being dominated by physical processes (i.e. by bond alteration rather than diffusion). In contrast, earlier data are inconsistent with theory, implying that analytical artifacts may have biased those results. Implications for quantifying primary productivity are discussed.

Published
2019

36. Exchange catalysis during anaerobic methanotrophy revealed by 12CH2D2 and 13CH3D in methane

Author

Geochemistry, Bio-, hydro-, and environmental geochemistry, Ash, Jeanine, Egger, Matthias, Treude, T., Kohl, I., Cragg, B., Parkes, R.J., Slomp, Caroline, Sherwood Lollar, B., Young, E.D., Geochemistry, Bio-, hydro-, and environmental geochemistry, Ash, Jeanine, Egger, Matthias, Treude, T., Kohl, I., Cragg, B., Parkes, R.J., Slomp, Caroline, Sherwood Lollar, B., and Young, E.D.

Published
2019

37. International ocean discovery program expedition 374 preliminary report: Ross sea west antarctic ice sheet history: ocean-ice sheet interactions and west antarctic ice sheet vulnerability: Clues from the neogene and quaternary record of the outer ross sea continental margin

Author

McKay, Robert M., De Santis, Laura, Kulhanek, Denise K., Ash, Jeanine A., Beny, François, Browne, Imogen B., Cortese, Giuseppe, De Sousa, Isabela M.Cordeiro, Dodd, Justin D., Esper, Oliver E., Gales, Jenny G., Harwood, David H., Ishino, Saki, Keisling, Benjamin K., Kim, Sookwan, Kim, Sunghan, Laberg, Jan Sverre, Leckie, R. Mark, Müller, Juliane, Patterson, Molly P., Romans, Brian R., Romero, Oscar R., Sangiorgi, Francesca, Seki, Osamu, Powell, John P., Shevenell, Amelia, Singh, Shiv S., Sugisaki, Saiko, Van De Flierdt, Tina, Van Peer, Tim E., Xiao, Wenshen, and Xiong, Zhifang

Abstract

The marine-based West Antarctic Ice Sheet (WAIS) is currently retreating due to shifting wind-driven oceanic currents that transport warm waters toward the ice margin, resulting in ice shelf thinning and accelerated mass loss of the WAIS. Previous results from geologic drilling on Antarctica's continental margins show significant variability in marine-based ice sheet extent during the late Neogene and Quaternary. Numerical models indicate a fundamental role for oceanic heat in controlling this variability over at least the past 20 My. Although evidence for past ice sheet variability has been collected in marginal settings, sedimentologic sequences from the outer continental shelf are required to evaluate the extent of past ice sheet variability and the associated oceanic forcings and feedbacks. International Ocean Discovery Program Expedition 374 drilled a latitudinal and depth transect of five drill sites from the outer continental shelf to rise in the eastern Ross Sea to resolve the relationship between climatic and oceanic change and WAIS evolution through the Neogene and Quaternary. This location was selected because numerical ice sheet models indicate that this sector of Antarctica is highly sensitive to changes in ocean heat flux. The expedition was designed for optimal data-model integration and will enable an improved understanding of the sensitivity of Antarctic Ice Sheet (AIS) mass balance during warmer-than-present climates (e.g., the Pleistocene "super interglacials," the mid-Pliocene, and the late early to middle Miocene). The principal goals of Expedition 374 were to • Evaluate the contribution of West Antarctica to far-field ice volume and sea level estimates; • Reconstruct ice-proximal atmospheric and oceanic temperatures to identify past polar amplification and assess its forcings and feedbacks; • Assess the role of oceanic forcing (e.g., sea level and temperature) on AIS stability/instability; • Identify the sensitivity of the AIS to Earth's orbital configuration under a variety of climate boundary conditions; and • Reconstruct eastern Ross Sea paleobathymetry to examine relationships between seafloor geometry, ice sheet stability/instability, and global climate. To achieve these objectives, we will • Use data and models to reconcile intervals of maximum Neogene and Quaternary Antarctic ice advance with far-field records of eustatic sea level change; • Reconstruct past changes in oceanic and atmospheric temperatures using a multiproxy approach; • Reconstruct Neogene and Quaternary sea ice margin fluctuations in datable marine continental slope and rise records and correlate these records to existing inner continental shelf records; • Examine relationships among WAIS stability/instability, Earth's orbital configuration, oceanic temperature and circulation, and atmospheric pCO2; and • Constrain the timing of Ross Sea continental shelf overdeepening and assess its impact on Neogene and Quaternary ice dynamics. Expedition 374 was carried out from January to March 2018, departing from Lyttelton, New Zealand. We recovered 1292.70 m of high-quality cores from five sites spanning the early Miocene to late Quaternary. Three sites were cored on the continental shelf (Sites U1521, U1522, and U1523). At Site U1521, we cored a 650 m thick sequence of interbedded diamictite, mudstone, and diatomite, penetrating the Ross Sea seismic Unconformity RSU4. The depositional reconstructions of past glacial and open-marine conditions at this site will provide unprecedented insight into environmental change on the Antarctic continental shelf during the early and middle Miocene. At Site U1522, we cored a discontinuous upper Miocene to Pleistocene sequence of glacial and glaciomarine strata from the outer shelf, with the primary objective to penetrate and date seismic Unconformity RSU3, which is interpreted to represent the first major continental shelf-wide expansion and coalescing of marine-based ice streams from both East and West Antarctica. At Site U1523, we cored a sediment drift located beneath the westerly flowing Antarctic Slope Current (ASC). Cores from this site will provide a record of the changing vigor of the ASC through time. Such a reconstruction will enable testing of the hypothesis that changes in the vigor of the ASC represent a key control on regulating heat flux onto the continental shelf, resulting in the ASC playing a fundamental role in ice sheet mass balance. We also cored two sites on the continental slope and rise. At Sit e U1524, we cored a Plio-Pleistocene sedimentary sequence on the continental rise on the levee of the Hillary Canyon, which is one of the largest conduits of Antarctic Bottom Water delivery from the Antarctic continental shelf into the abyssal ocean. Drilling at Site U1524 was intended to penetrate into middle Miocene and older strata but was initially interrupted by drifting sea ice that forced us to abandon coring in Hole U1524A at 399.5 m drilling depth below seafloor (DSF). We moved to a nearby alternate site on the continental slope (U1525) to core a single hole with a record complementary to the upper part of the section recovered at Site U1524. We returned to Site U1524 3 days later, after the sea ice cleared. W e then cored Hole U1524C with the rotary core barrel with the intention of reaching the target depth of 1000 m DSF. However, we were forced to terminate Hole U1524C at 441.9 m DSF due to a mechanical failure with the vessel that resulted in termination of all drilling operations and a return to Lyttelton 16 days earlier than scheduled. The loss of 39% of our operational days significantly impacted our ability to achieve all Expedition 374 objectives as originally planned. In particular, we were not able to obtain the deeper time record of the middle Miocene on the continental rise or abyssal sequences that would have provided a continuous and contemporaneous archive to the high-quality (but discontinuous) record from Site U1521 on the continental shelf. The mechanical failure also meant we could not recover sediment cores from proposed Site RSCR-19A, which was targeted to obtain a high-fidelity, continuous record of upper Neogene and Quaternary pelagic/hemipelagic sedimentation. Despite our failure to recover a shelf-to-rise transect for the Miocene, a continental shelf-to-rise transect for the Pliocene to Pleistocene interval is possible through comparison of the high-quality records from Site U1522 with those from Site U1525 an d legacy cores from the Antarctic Geological Drilling Project (ANDRILL).

Published
2018

39. Reconstructing Holocene temperature and salinity variations in the western Baltic Sea region: a multi-proxy comparison from the Little Belt (IODP Expedition 347, Site M0059)

Author

Kotthoff, Ulrich, Groeneveld, Jeroen, Ash, Jeanine, Fanget, Anne-Sophie, Krupinski, Nadine Quintana, Peyron, Odile, Stepanova, Anna, Warnock, Jonathan, van Helmond, N.A.G.M., Passey, Benjamin H., Clausen, Ole Rono, Bennike, O., Andrén, Elinor, Granoszewski, Wojciech, Andrén, Thomas, Filipsson, Helena L., Solveig-Seidenkrantz, M., Slomp, C.P., Bauersachs, Thorsten, Geochemistry, General geochemistry, University of Hamburg, Center for Marine Environmental Sciences [Bremen] (MARUM), Universität Bremen, Earth, Planetary and Space Sciences, University of California, Los Angeles, CA, USA, Aarhus University [Aarhus], Université de Perpignan Via Domitia (UPVD), Lund University [Lund], Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS), Texas A&M University [College Station], Indiana University of Pennsylvania, Pennsylvania State System of Higher Education (PASSHE), Utrecht University [Utrecht], University of Michigan [Ann Arbor], University of Michigan System, Geological Survey of Denmark and Greenland (GEUS), Södertörn University College, Christian-Albrechts-Universität zu Kiel (CAU), École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre National de la Recherche Scientifique (CNRS)-Institut de recherche pour le développement [IRD] : UR226, Geochemistry, and General geochemistry

Subjects
0106 biological sciences, Water mass, 010504 meteorology & atmospheric sciences, lcsh:Life, Temperature salinity diagrams, Climate change, 010502 geochemistry & geophysics, 01 natural sciences, lcsh:QH540-549.5, 14. Life underwater, Ecology, Evolution, Behavior and Systematics, Holocene, 0105 earth and related environmental sciences, Earth-Surface Processes, geography, geography.geographical_feature_category, Continental shelf, 010604 marine biology & hydrobiology, lcsh:QE1-996.5, Pelagic zone, lcsh:Geology, Salinity, lcsh:QH501-531, Oceanography, 13. Climate action, [SDE]Environmental Sciences, Paleosalinity, lcsh:Ecology, Geology
Abstract

Sediment records recovered from the Baltic Sea during Integrated Ocean Drilling Program Expedition 347 provide a unique opportunity to study paleoenvironmental and climate change in central and northern Europe. Such studies contribute to a better understanding of how environmental parameters change in continental shelf seas and enclosed basins. Here we present a multi-proxy-based reconstruction of paleotemperature (both marine and terrestrial), paleosalinity, and paleoecosystem changes from the Little Belt (Site M0059) over the past ∼ 8000 years and evaluate the applicability of inorganic- and organic-based proxies in this particular setting. All salinity proxies (diatoms, aquatic palynomorphs, ostracods, diol index) show that lacustrine conditions occurred in the Little Belt until ∼ 7400 cal yr BP. A connection to the Kattegat at this time can thus be excluded, but a direct connection to the Baltic Proper may have existed. The transition to the brackish–marine conditions of the Littorina Sea stage (more saline and warmer) occurred within ∼ 200 years when the connection to the Kattegat became established after ∼ 7400 cal yr BP. The different salinity proxies used here generally show similar trends in relative changes in salinity, but often do not allow quantitative estimates of salinity. The reconstruction of water temperatures is associated with particularly large uncertainties and variations in absolute values by up to 8 °C for bottom waters and up to 16 °C for surface waters. Concerning the reconstruction of temperature using foraminiferal Mg  /  Ca ratios, contamination by authigenic coatings in the deeper intervals may have led to an overestimation of temperatures. Differences in results based on the lipid paleothermometers (long chain diol index and TEXL86) can partly be explained by the application of modern-day proxy calibrations to intervals that experienced significant changes in depositional settings: in the case of our study, the change from freshwater to marine conditions. Our study shows that particular caution has to be taken when applying and interpreting proxies in coastal environments and marginal seas, where water mass conditions can experience more rapid and larger changes than in open ocean settings. Approaches using a multitude of independent proxies may thus allow a more robust paleoenvironmental assessment.

Published
2017

43. Reconstructing Holocene temperature and salinity variations in the western Baltic Sea region: A multi-proxy comparison from the Little Belt (IODP Expedition 347, Site M0059)

Author

Geochemistry, General geochemistry, Kotthoff, Ulrich, Groeneveld, Jeroen, Ash, Jeanine, Fanget, Anne-Sophie, Krupinski, Nadine Quintana, Peyron, Odile, Stepanova, Anna, Warnock, Jonathan, van Helmond, N.A.G.M., Passey, Benjamin H., Clausen, Ole Rono, Bennike, O., Andrén, Elinor, Granoszewski, Wojciech, Andrén, Thomas, Filipsson, Helena L., Solveig-Seidenkrantz, M., Slomp, C.P., Bauersachs, Thorsten, Geochemistry, General geochemistry, Kotthoff, Ulrich, Groeneveld, Jeroen, Ash, Jeanine, Fanget, Anne-Sophie, Krupinski, Nadine Quintana, Peyron, Odile, Stepanova, Anna, Warnock, Jonathan, van Helmond, N.A.G.M., Passey, Benjamin H., Clausen, Ole Rono, Bennike, O., Andrén, Elinor, Granoszewski, Wojciech, Andrén, Thomas, Filipsson, Helena L., Solveig-Seidenkrantz, M., Slomp, C.P., and Bauersachs, Thorsten

Published
2017

44. Supplementary material to "Reconstructing Holocene temperature and salinity variations in the western Baltic Sea region: A multi-proxy comparison from the Little Belt (IODP Expedition 347, Site M0059)"

Author

Kotthoff, Ulrich, primary, Groeneveld, Jeroen, additional, Ash, Jeanine L., additional, Fanget, Anne-Sophie, additional, Quintana Krupinski, Nadine, additional, Peyron, Odile, additional, Stepanova, Anna, additional, Warnock, Jonathan, additional, Van Helmond, Niels A. G. M., additional, Passey, Benjamin H., additional, Clausen, Ole Rønø, additional, Bennike, Ole, additional, Andrén, Elinor, additional, Granoszewski, Wojciech, additional, Andrén, Thomas, additional, Filipsson, Helena L., additional, Seidenkrantz, Marit-Solveig, additional, Slomp, Caroline P., additional, and Bauersachs, Thorsten, additional

Published
2017
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45. Reconstructing Holocene temperature and salinity variations in the western Baltic Sea region: A multi-proxy comparison from the Little Belt (IODP Expedition 347, Site M0059)

Author

Kotthoff, Ulrich, primary, Groeneveld, Jeroen, additional, Ash, Jeanine L., additional, Fanget, Anne-Sophie, additional, Quintana Krupinski, Nadine, additional, Peyron, Odile, additional, Stepanova, Anna, additional, Warnock, Jonathan, additional, Van Helmond, Niels A. G. M., additional, Passey, Benjamin H., additional, Clausen, Ole Rønø, additional, Bennike, Ole, additional, Andrén, Elinor, additional, Granoszewski, Wojciech, additional, Andrén, Thomas, additional, Filipsson, Helena L., additional, Seidenkrantz, Marit-Solveig, additional, Slomp, Caroline P., additional, and Bauersachs, Thorsten, additional

Published
2017
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49. Biological signatures in clumped isotopes of O2.

Author

Yeung, Laurence Y., Ash, Jeanine L., and Young, Edward D.

Subjects
*ISOTOPES, *HEAT of formation, *OXYGEN isotopes, *OXYGEN, *ISOTOPIC abundance, *NATURAL isotopic abundance
Abstract

The abundances of molecules containing more than one rare isotope have been applied broadly to determine formation temperatures of natural materials. These applications of "clumped" isotopes rely on the assumption that isotope-exchange equilibrium is reached, or at least approached, during the formation of those materials. In a closed-system terrarium experiment, we demonstrate that biological oxygen (O2) cycling drives the clumped-isotope composition of O2 away from isotopic equilibrium. Our model of the system suggests that unique biological signatures are present in clumped isotopes of O2--and not formation temperatures. Photosynthetic O2 is depleted in 18O18O and 17O18O relative to a stochastic distribution of isotopes, unlike at equilibrium, where heavy-isotope pairs are enriched. Similar signatures may be widespread in nature, offering new tracers of biological and geochemical cycling. [ABSTRACT FROM AUTHOR]

Published
2015
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