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In the past year we have been witnessing several important missions to Mars, including Mars 2020 Perseverance rover that landed to Jezero Crater to search for signs of ancient life. Multiple lines of evidence indicate an active hydrogeological history of Mars and chemolithoautotrophy-suited environments within its Noachian terrains. As a result, one of the primary aims of Mars missions is to search for signs of ancient life and collect a suite of samples to be returned to Earth via a Mars Sample Return mission. Being a few steps away from retrieving and returning the first Mars samples, we need to gain extensive knowledge how to access their potential biogenicity. In this connection, a valuable source of information can be extracted from microbial fingerprints of chemolithotrophic life based on Martian materials. Chemolithoautotrophy is the most ancient microbial form of life, which enables the transition of energy from a stone to the energy of a living entity. In our project, we investigate interactions of a wide variety of chemolithoautotrophs with Martian mineral materials (Martian meteorites and regolith simulants). Our recent research on the genuine Noachian Martian breccia “Black Beauty” permitted visualization and nanometer-scale imaging of microbial life designed and cultivated on Martian materials(1). Here we report on laboratory-scaled microbially assisted chemolithoautotrophic biotransformation(1) of the Noachian Martian breccia Northwest Africa (NWA) 7034 composed of ancient (~4.5 Gyr old) crustal materials from Mars. Nanoanalytical hyperspectral analysis provides clues for the trafficking and distribution of meteorite inorganic constituents in the microbial cell(1). We decipher biomineralization patterns associated with the biotransformation and reveal microbial nanometer-sized lithologies located inside the cell and on its outer surface layer(1). These investigations provide an opportunity to trace the putative bioalteration processes of the Martian crust and to assess the potential biogenicity of Martian materials. Our study on the Noachian Martian breccia composed of ~4.5 Gyr old crustal materials from Mars, delivered a prototype of microbial life experimentally designed on a real Martian material(1). This life of a pure Martian design is a rich source of Mars relevant biosignatures. 1. Milojevic, T., Albu, M., Kölbl, D. et al. Chemolithotrophy on the Noachian Martian breccia NWA 7034 via experimental microbial biotransformation. Commun Earth Environ 2, 39 (2021). https://doi.org/10.1038/s43247-021-00105-x

Despite its subdued expression and isolated location within the Great Plains of southeastern Colorado, the 80 km long Cheraw fault may be one of the most active faults in North America east of the Rocky Mountains. We present geomorphic analyses, geochronology, and paleoseismic trenching data to (1) document the rupture history of the ∼45 km long southwestern section of the Cheraw fault over the past ∼19 ka, and (2) evaluate slip rate changes for the entire fault over the past ∼200 ka. Results from new trenches excavated at the Old Ranch site show evidence of four surface rupture events since ∼19 ka, each with an average vertical displacement of 0.75 ± 0.15 m. An additional event is likely only slightly older than ∼19 ka. Evidence for relatively small displacements at and near the Old Ranch site indicates that most of these earthquakes were magnitude (M) 7 or less and likely did not rupture the full length of the Cheraw fault. Since ∼19 ka, the average slip rate is ∼0.16 ± 0.3 mm/yr near the Old Ranch site with an average interevent time of 3–5 ka. New geochronologic data for mid- to late-Quaternary geomorphic surfaces cut by the Cheraw fault imply rapid incision by local Arkansas River tributaries from ∼145 to ∼100 ka. Maximum vertical offsets of 7–9 m for these surfaces indicate that from ∼19 to >200 ka the average slip rate was no greater than ∼0.03 mm/yr. The accelerated slip rate since ∼19 ka indicates a possible response to rapid erosional unloading and/or a limited late Cenozoic

On 25 May 2014, a rain-on-snow–induced rock avalanche occurred in the West Salt Creek valley on the northern flank of Grand Mesa in western Colorado (United States). The avalanche mobilized from a preexisting rock slide in the Green River Formation and traveled 4.6 km down the confined valley, killing three people. The avalanche was rare for the contiguous United States because of its large size (54.5 Mm 3 ) and high mobility (height/length = 0.14). To understand the avalanche failure sequence, mechanisms, and mobility, we conducted a forensic analysis using large-scale (1:1000) structural mapping and seismic data. We used high-resolution, unmanned aircraft system imagery as a base for field mapping, and analyzed seismic data from 22 broadband stations (distances

In the Colorado Piedmont, talus flatiron chronosequences are associated with buttes that consist of erodible arkosic sandstone and resistant caprock. Following the removal of the caprock, some buttes evolve into crater-like relict slope rings resulting from the differential erosion of the soft bedrock in the core of the hills. These unique landforms are only documented in the Colorado Piedmont. Their development is attributed to the unusually high erodibility contrast between the low-cohesion sandy bedrock and the bouldery colluvial armor. The talus flatiron sequences and relict slope rings mapped in the three studied areas record alternating periods of accumulation and incision in the slopes that are likely controlled by changes in moisture availability and vegetation cover density. The obtained OSL dates place slope accumulation phases at > 124 ka, and ca. 73 ka, 50–40 ka, 15 ka, and 10–6 ka. A comparison of these geochronological data with paleoclimatic records from the region suggests that colluvium deposition occurred during periods of denser vegetation cover, which are controlled by climate changes. Further investigations, including additional and more accurate geochrological data from the relict slopes, will help to better understand the paleoclimatic significance of these largely unknown morphostratigraphic features.

Prepared in conjunction with the 2016 GSA Annual Meeting in Denver, Colorado, this volume contains sixteen guides to field trips in this rich geologic region. The four “Great Surveys” of the late 1800s ventured west to explore and document the region’s unknown natural resources and collect valuable geologic information. Many of the field guides in this volume, aptly titled Unfolding the Geology of the West, will cover the same hallowed ground as the early geologic expeditions. Organized into four sections, this volume spans some of the major subdisciplines of geology: (1) stratigraphy, sedimentology, and paleontology; (2) structure and metamorphism; (3) Quaternary landscape evolution; and (4) engineering and environmental geology.

Internet mapping applications for geologic data allow simultaneous data delivery and collection, enabling quick data modification while efficiently supplying the end user with information. Utilizing Web-based technologies, the Colorado Geological Survey's Colorado Late Cenozoic Fault and Fold Database was transformed from a monothematic, nonspatial Microsoft Access database into a complex information set incorporating multiple data sources. The resulting user-friendly format supports easy analysis and browsing. The core of the application is the Microsoft Access database, which contains information compiled from available literature about faults and folds that are known or suspected to have moved during the late Cenozoic. The database contains nonspatial fields such as structure type, age, and rate of movement. Geographic locations of the fault and fold traces were compiled from previous studies at 1:250,000 scale to form a spatial database containing information such as length and strike. Integration of the two databases allowed both spatial and nonspatial information to be presented on the Internet as a single dataset ( ). The user-friendly interface enables users to view and query the data in an integrated manner, thus providing multiple ways to locate desired information. Retaining the digital data format also allows continuous data updating and quick delivery of newly acquired information. This dataset is a valuable resource to anyone interested in earthquake hazards and the activity of faults and folds in Colorado. Additional geologic hazard layers and imagery may aid in decision support and hazard evaluation. The up-to-date and customizable maps are invaluable tools for researchers or the public.

A possible mesosiderite meteorite was found in the area of the Putorana Plateau, Noril'sk district, Siberia, Russia. Although this rock resembles a mesosiderite in its hand-sample aspect and in having Ni-bearing iron metal, it is not a meteorite. This inference is based on the lack of a fusion crust, the lack of cosmogenic nuclides, oxygen with terrestrial isotope ratios, and several mineral chemical criteria. Most likely, the rock is from the iron-metal-bearing basalts of the Siberian Trap basalt sequence, which are mined for their base and platinum-group metals. Mesosiderite imposters like this may be recognized by: (1) the presence of Cu metal in hand sample or as microscopic blebs in the low-Ni metal (kamacite), (2) the absence of high-Ni metal (taenite), and (3) the presence of iron carbide (cohenite) enclosing the kamacite. Even if these macroscopic tests are inconclusive, isotopic and mineral chemical tests will also distinguish rocks like this from mesosiderites.

The Alamo Breccia is a Late Devonian sedimentary layer as much as 135 m in thickness that is widespread over southern Nevada, USA. Direct evidence for an impact origin of the Alamo Breccia includes shocked quartz grains within the Breccia matrix and broken fragments of distinctive carbonate lapilli beds within the heterolithic Breccia clast population. The Breccia was studied as a potential impactite because it was recognized as an anomalous stratigraphic unit compared to the contrasting and predictable carbonate platform strata of the Devonian platform. To date, only one possible crater locality has been identified within the complex geology of Nevada.

Carbonate accretionary lapilli occur in the Late Devonian Alamo Breccia of south-central Nevada. They provide evidence for the extraterrestrial impact origin of the breccia, and help unravel the complicated events that formed it. The accretionary lapilli (Alamo lapilli) are concentrated in lapilli beds, and portions of the latter occur as reworked clasts that are isolated within the upper half of the thick breccia. The Alamo lapilli resemble volcanic accretionary lapilli reported from both silicate and carbonatite volcanoes. They are variable in size and detail, but generally exhibit a nucleus interpreted to be altered target rock, an enveloping mantle of siltand sandsized particles, and a very fine grained peripheral crust. Spherule composition is entirely carbonate, except for sparse shocked quartz grains incorporated into the mantle and diagenetic iron oxides. Rare preservation of undeformed bed segments shows the stratigraphy of the accretionary lapilli; they were deposited in poorly sizesorted layers with varying proportions of matrix. Their preserved form is spherical, deformed, or broken, implying varying degrees of damage before or during deposition, before bed hardening, and during catastrophic reworking and dewatering of the Alamo Breccia. We propose that the carbonate accretionary lapilli were preserved when target carbonate formations were pulverized by impact pressure and calcinated by impact heat, creating quicklime. The lapilli evolved by adhesion of particles within the impact cloud; they were partially cemented in flight by hydration, and then precipitated as one or more beds over early ejectite, debris flows, and/or nearly contemporaneous tsunamites. The cementation process continued in the lapilli beds so that portions of them survived reworking and initial breccia settling and dewatering. Coherent, isolated fragments of lapilli beds and deformed bed masses are preserved as much as 25 m beneath the top of the breccia, indicating the thickness of rock reworked during the Alamo Event. Warme, J.E., Morgan, M., and Kuehner, H.-C., 2002, Impact-generated carbonate accretionary lapilli in the Late Devonian Alamo Breccia, in Koeberl, C., and MacLeod, K.G., eds., Catastrophic Events and Mass Extinctions: Impacts and Beyond: Boulder, Colorado, Geological Society of America Special Paper 356, p. 489–504. J.E. Warme, M. Morgan, and H.-C. Kuehner 490 Figure 1. Alamo carbonate accretionary lapilli exposed on weathered surface of lapilli bed showing sizes, proportions of nuclei, mantles, and crust, and grainy matrix in this sample. Lapilli are circular, flattened, and in various stages of breakage. INTRODUCTION Carbonate spheroidal particles (Fig. 1), interpreted as impact-generated carbonate accretionary lapilli, represent an important constituent of the Late Devonian Alamo impact breccia in Nevada. For brevity, and to distinguish them from other kinds of accretionary spherules and spherical impact products, we call them Alamo lapilli. Shocked quartz grains are dispersed in the Alamo Breccia, and are incorporated into the Alamo lapilli. The beautifully preserved lapilli and shocked quartz are the best observable physical evidence for the impact origin of the breccia, although they compose much less than 1% of the deposit. Probably within only minutes to a day, a series of impactrelated events (Alamo Event of Warme and Sandberg, 1995, 1996; Morrow et al., 1998) eroded and resedimented a thick interval of carbonate platform rock of the Guilmette Formation, which became the thick Alamo carbonate megabreccia. The Alamo lapilli occur in isolated clasts scattered within the Alamo Breccia, and provide a key to understanding the character and the timing of events that led to the Alamo Breccia formation. Alamo lapilli are interpreted to have accreted in a vapor-rich impact plume by adhesion of carbonate particles and other contemporaneous processes. Their structure resembles some kinds of armored accretionary volcanic lapilli, having a central nucleus interpreted as carbonate target rock, an enveloping mantle of sandand silt-sized carbonate fragments, and an outer crust of very fine siltand clay-sized carbonate particles. Alamo lapilli imply that the impact target was dominated by carbonate rock and was wet. Evidence suggests that they precipitated as one or more widespread beds. The beds were then dismembered, by tsunami erosion and/or other energetic impact processes, and redeposited as isolated clasts in the massive breccia. Preserved lapilli survived these events by rapid cementation processes that began in flight and continued in the precipitated bed(s). This early cementation caused segments of the beds to be durable enough to withstand subsequent catastrophic transportation and deposition. Other examples of ancient carbonate lapilli may have formed and been preserved by impact processes. Carbonate strata anywhere may contain unrecognized intervals of impact lapilli and lapillistone.