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Full-Text Articles in Geology
Controls On Soft Tissue And Cellular Preservation In Late Eocene And Oligocene Vertebrate Fossils From The White River And Arikaree Groups Of Nebraska, South Dakota, And Wyoming, John E. Gallucci, Grace Woolslayer, Kelsey Barker, Brian Kibelstis, Allison R Tumarkin-Deratzian, Paul V. Ullmann, David E. Grandstaff, Dennis O. Terry
Controls On Soft Tissue And Cellular Preservation In Late Eocene And Oligocene Vertebrate Fossils From The White River And Arikaree Groups Of Nebraska, South Dakota, And Wyoming, John E. Gallucci, Grace Woolslayer, Kelsey Barker, Brian Kibelstis, Allison R Tumarkin-Deratzian, Paul V. Ullmann, David E. Grandstaff, Dennis O. Terry
School of Earth & Environment Faculty Scholarship
Previous studies on microtaphonomy have identified multiple types of organic microstructures in fossil vertebrates from a variety of time periods and past environmental settings. This study investigates potential taphonomic, paleoenvironmental, and paleoclimatic controls on soft tissue and cellular preservation in fossil bone. To this end, fifteen vertebrate fossils were studied: eight fossils collected from the Oligocene Sharps Formation of the Arikaree Group in Badlands National Park, South Dakota, and seven fossils from formations in the underlying White River Group, including the Oligocene Brule Formation of Badlands National Park, and the Eocene Chadron Formation of Flagstaff Rim, Wyoming; Toadstool Geologic Park, …
Dust And Loess As Archives And Agents Of Climate And Climate Change In The Late Paleozoic Earth System, Gerilyn S. Soreghan, Nicholas G. Heavens, Lily Pfeifer, Michael J. Soreghan
Dust And Loess As Archives And Agents Of Climate And Climate Change In The Late Paleozoic Earth System, Gerilyn S. Soreghan, Nicholas G. Heavens, Lily Pfeifer, Michael J. Soreghan
School of Earth & Environment Faculty Scholarship
Palaeo-loess and silty aeolian-marine strata are well recognized across the Carboniferous–Permian of equatorial Pangaea. Aeolian-transported dust and loess appear in the Late Devonian in the west, are common by the Late Carboniferous, and predominate across equatorial Pangaea by the Permian. The thickest loess deposits in Earth history – in excess of 1000 m – date from this time, and archive unusually dusty equatorial conditions, especially compared to the dearth of equatorial dust in the Cenozoic. Loess archives a confluence of silt generation, aeolian emission and transport, and ultimate accumulation in dust traps that included ephemerally wet surfaces and epeiric seas. …
An Eolian Dust Origin For Clastic Fines Of Devono-Mississippian Mudrocks Of The Greater North American Midcontinent, Austin J. Mcglannan, Alicia Bonar, Lily Pfeifer, Sebastian Steinig, Paul Valdes, Steven Adams, David Duarte, Benmadi Milad, Andrew Cullen, Gerilyn S. Soreghan
An Eolian Dust Origin For Clastic Fines Of Devono-Mississippian Mudrocks Of The Greater North American Midcontinent, Austin J. Mcglannan, Alicia Bonar, Lily Pfeifer, Sebastian Steinig, Paul Valdes, Steven Adams, David Duarte, Benmadi Milad, Andrew Cullen, Gerilyn S. Soreghan
School of Earth & Environment Faculty Scholarship
Upper Devonian and Lower–Middle Mississippian strata of the North American midcontinent are ubiquitously fine-grained and silt-rich, comprising both so-called shale as well as argillaceous limestone (or calcareous siltstone) that accumulated in the Laurentian epeiric sea. Although long recognized as recording marine deposition, the origin and transport of the fine-grained siliciclastic material in these units remains enigmatic because they do not connect to any proximal deltaic feeder systems. Here, we present new data on grain size, whole-rock geochemistry, mineralogy, and U-Pb detrital-zircon geochronology from units across Oklahoma; we then integrate these data with models of surface wind circulation, refined paleogeographic reconstructions, …
Detecting Upland Glaciation In Earth’S Pre-Pleistocene Record, Gerilyn S. Soreghan, Lily Pfeifer, Dustin E. Sweet, Nicholas G. Heavens
Detecting Upland Glaciation In Earth’S Pre-Pleistocene Record, Gerilyn S. Soreghan, Lily Pfeifer, Dustin E. Sweet, Nicholas G. Heavens
School of Earth & Environment Faculty Scholarship
Earth has sustained continental glaciation several times in its past. Because continental glaciers ground to low elevations, sedimentary records of ice contact can be preserved from regions that were below base level, or subject to subsidence. In such regions, glaciated pavements, ice-contact deposits such as glacial till with striated clasts, and glaciolacustrine or glaciomarine strata with dropstones reveal clear signs of former glaciation. But assessing upland (mountain) glaciation poses particular challenges because elevated regions typically erode, and thus have extraordinarily poor preservation potential. Here we propose approaches for detecting the former presence of glaciation in the absence or near-absence of …
Ice-Crystal Traces Imply Ephemeral Freezing In Early Permian Equatorial Pangea, Lily S. Pfeifer, Brooke A. Birkett, Jean Van Den Driessche, Stephane Pochat, Geriliyn S. Soreghan
Ice-Crystal Traces Imply Ephemeral Freezing In Early Permian Equatorial Pangea, Lily S. Pfeifer, Brooke A. Birkett, Jean Van Den Driessche, Stephane Pochat, Geriliyn S. Soreghan
School of Earth & Environment Faculty Scholarship
Delicate impressions in lacustrine strata of the lower Permian (lower Cisuralian) Usclas Formation record ephemeral freezing in equatorial Pangea. These sediments accumulated in the paleoequatorial and intramontane Lodève Basin (southern Massif Central, France) during peak icehouse conditions of the Late Paleozoic Ice Age. Experimental replication of these features supports the interpretation that they are ice-crystal molds. Evidence for films of ice in marginal-lacustrine sediment at such low latitudes and inferred low to moderate altitudes (1–2 km) calls for a reevaluation of climate conditions in eastern equatorial Pangea. Ephemeral freezing implies either cold tropical temperatures (~5 °C cooler than the Last …
The Role Of Hydrated Minerals And Space Weathering Products In The Bluing Of Carbonaceous Asteroids, David Trang, Michelle S. Thompson, Bet E. Clark, Hannah H. Kaplan, Xiao-Duan Zou, Jian-Yang Li, Salvatore M. Ferrone, Victoria E. Hamilton, Amy A. Simon, Dennis C. Reuter, Lindsay P. Keller, M. Antonietta Barucci, Humberto Campins, Cateline Lantz, Daniella N. Dellagiustina, Ronald-Louis Ballouz, Erica R. Jawin, Harold Connolly Jr., Kevin J. Walsh, Dante Lauretta
The Role Of Hydrated Minerals And Space Weathering Products In The Bluing Of Carbonaceous Asteroids, David Trang, Michelle S. Thompson, Bet E. Clark, Hannah H. Kaplan, Xiao-Duan Zou, Jian-Yang Li, Salvatore M. Ferrone, Victoria E. Hamilton, Amy A. Simon, Dennis C. Reuter, Lindsay P. Keller, M. Antonietta Barucci, Humberto Campins, Cateline Lantz, Daniella N. Dellagiustina, Ronald-Louis Ballouz, Erica R. Jawin, Harold Connolly Jr., Kevin J. Walsh, Dante Lauretta
School of Earth & Environment Faculty Scholarship
The surfaces of airless bodies such as lunar and S-type asteroids typically become spectrally redder in visible to near-infrared reflectance with longer exposures to space weathering. However, some carbonaceous asteroids instead become spectrally bluer. Space weathering experiments on carbonaceous meteorites have provided some clues as to the space weathering products that could produce spectral bluing. We applied these experimental results to our Hapke radiative transfer model, with which we modeled spectral data from the OSIRIS-REx mission in order to determine whether these space weathering products—specifically, nanophase and microphase metallic iron, troilite, and magnetite—could explain the globally blue spectrum of the …
Relationship Between Individual Chamber And Whole Shell Mg/Ca Ratios In Trilobatus Sacculifer And Implications For Individual Foraminifera Palaeoceanographic Reconstructions, Gerald T. Rustic, Pratigya J. Polissar, Ana Christina Ravelo, Peter Demenocal
Relationship Between Individual Chamber And Whole Shell Mg/Ca Ratios In Trilobatus Sacculifer And Implications For Individual Foraminifera Palaeoceanographic Reconstructions, Gerald T. Rustic, Pratigya J. Polissar, Ana Christina Ravelo, Peter Demenocal
School of Earth & Environment Faculty Scholarship
Precisely targeted measurements of trace elements using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) reveal inter-chamber heterogeneities in specimens of the planktic foraminifer Trilobatus (Globigerinoides) sacculifer. We find that Mg/Ca ratios in the final growth chamber are generally lower compared to previous growth chambers, but final chamber Mg/Ca is elevated in one of thirteen sample intervals. Differences in distributions of Mg/Ca values from separate growth chambers are observed, occurring most often at lower Mg/Ca values, suggesting that single-chamber measurements may not be reflective of the specimen’s integrated Mg/Ca. We compared LA-ICPMS Mg/Ca values to paired, same-individual Mg/Ca measured via …
Meteoritic Evidence For A Ceres-Sized Water-Rich Carbonaceous Chondrite Parent Asteroid, V E. Hamilton, C A. Goodrich, A H. Treiman, Harold Connolly Jr., M E. Zolensky, M H. Shaddad
Meteoritic Evidence For A Ceres-Sized Water-Rich Carbonaceous Chondrite Parent Asteroid, V E. Hamilton, C A. Goodrich, A H. Treiman, Harold Connolly Jr., M E. Zolensky, M H. Shaddad
School of Earth & Environment Faculty Scholarship
Carbonaceous chondrite meteorites record the earliest stages of Solar System geo-logical activities and provide insight into their parent bodies' histories. Some carbonaceous chondrites are volumetrically dominated by hydrated minerals, providing evidence for low temperature and pressure aqueous alteration1. Others are dominated by anhydrous minerals and textures that indicate high temperature metamorphism in the absence of aqueous fluids1. Evidence of hydrous metamorphism at intermediate pressures and temperatures in carbonaceous chondrite parent bodies has been virtually absent. Here we show that an ungrouped, aqueously altered carbonaceous chondrite fragment (numbered 202) from the Almahata Sitta (AhS) meteorite contains an assemblage of minerals, including …
Report On Icdp Deep Dust Workshops: Probing Continental Climate Of The Late Paleozoic Icehouse-Greenhouse Transition And Beyond, Gerilyn S. Soreghan, Laurent Beccaletto, Kathleen C. Benison, Sylvie Borquin, Georg Feulner, Natsuko Hamamura, Michael Hamilton, Nicholas G. Heavens, Linda Hinnov, Adam Huttenlocker, Cindy Looy, Lily Pfeifer, Stephane Pochat, Mehrdad Sarder Abadi, James Zambito
Report On Icdp Deep Dust Workshops: Probing Continental Climate Of The Late Paleozoic Icehouse-Greenhouse Transition And Beyond, Gerilyn S. Soreghan, Laurent Beccaletto, Kathleen C. Benison, Sylvie Borquin, Georg Feulner, Natsuko Hamamura, Michael Hamilton, Nicholas G. Heavens, Linda Hinnov, Adam Huttenlocker, Cindy Looy, Lily Pfeifer, Stephane Pochat, Mehrdad Sarder Abadi, James Zambito
School of Earth & Environment Faculty Scholarship
Chamberlin and Salisbury's assessment of the Permian a century ago captured the essence of the period: it is an interval of extremes yet one sufficiently recent to have affected a biosphere with near-modern complexity. The events of the Permian – the orogenic episodes, massive biospheric turnovers, both icehouse and greenhouse antitheses, and Mars-analog lithofacies – boggle the imagination and present us with great opportunities to explore Earth system behavior. The ICDP-funded workshops dubbed “Deep Dust,” held in Oklahoma (USA) in March 2019 (67 participants from nine countries) and Paris (France) in January 2020 (33 participants from eight countries), focused on …
Global Patterns Of Recent Mass Movement On Asteroid (101955) Bennu, E. R. Jawin, K. J. Walsh, O. S. Barnouin, T. J. Mccoy, R.-L. Ballouz, D. N. Dellagiustina, Harold Connolly Jr.
Global Patterns Of Recent Mass Movement On Asteroid (101955) Bennu, E. R. Jawin, K. J. Walsh, O. S. Barnouin, T. J. Mccoy, R.-L. Ballouz, D. N. Dellagiustina, Harold Connolly Jr.
School of Earth & Environment Faculty Scholarship
The exploration of near‐Earth asteroids has revealed dynamic surfaces characterized by mobile, unconsolidated material that responds to local geophysical gradients, resulting in distinct morphologies and boulder distributions. The OSIRIS‐REx (Origins, Spectral Interpretation, Resource Identification, and Security‐Regolith Explorer) mission confirmed that asteroid (101955) Bennu is a rubble pile with an unconsolidated surface dominated by boulders. In this work, we documented morphologies indicative of mass movement on Bennu and assessed the relationship to slope and other geologic features on the surface. We found globally distributed morphologic evidence of mass movement on Bennu up to ~70° latitude and on spatial scales ranging from …
Meteoroid Impacts As A Source Of Bennu's Particle Ejection Events, W. F. Bottke, A. V. Moorhead, Harold Connolly Jr., C. W. Hergenrother, J. L. Molaro, P. Michel
Meteoroid Impacts As A Source Of Bennu's Particle Ejection Events, W. F. Bottke, A. V. Moorhead, Harold Connolly Jr., C. W. Hergenrother, J. L. Molaro, P. Michel
School of Earth & Environment Faculty Scholarship
Asteroid (101955) Bennu, a near‐Earth object with a primitive carbonaceous chondrite‐like composition, was observed by the Origins, Spectral Interpretation, Resource Identification, and Security‐Regolith Explorer (OSIRIS‐REx) spacecraft to undergo multiple particle ejection events near perihelion between December 2018 and February 2019. The three largest events observed during this period, which all occurred 3.5 to 6 hr after local noon, placed numerous particles <10 cm on temporary orbits around Bennu. Here we examine whether these events could have been produced by sporadic meteoroid impacts using the National Aeronautics and Space Administration's (NASA) Meteoroid Engineering Model 3.0. Most projectiles that impact Bennu come from nearly isotropic or Jupiter‐family comets and have evolved toward the Sun by Poynting‐Robertson drag. We find that 7,000‐J impacts on Bennu occur with a biweekly cadence near perihelion, with a preference to strike in the late afternoon (~6 pm local time). This timing matches observations. Crater scaling laws also indicate that these impact energies can reproduce the sizes and masses of the largest observed particles, provided the surface has the cohesive properties of weak, porous materials. Bennu's ejection events could be caused by the same kinds of meteoroid impacts that created the Moon's asymmetric debris cloud observed by the Lunar Atmosphere and Dust Environment Explorer (LADEE). Our findings also suggest that fewer ejection events should take place as Bennu moves further away from the Sun, a result that can be tested with future observations.
Loess In Eastern Equatorial Pangea Archives A Dusty Atmosphere And Possible Upland Glaciation, Lily Pfeifer, Gerilyn S. Soreghan, Stephane Pochat, Jean Van Den Driessche
Loess In Eastern Equatorial Pangea Archives A Dusty Atmosphere And Possible Upland Glaciation, Lily Pfeifer, Gerilyn S. Soreghan, Stephane Pochat, Jean Van Den Driessche
School of Earth & Environment Faculty Scholarship
Carboniferous–Permian strata in basins within the Central Pangean Mountains in France archive regional paleoequatorial climate during a unique interval in geological history (Pangea assembly, ice-age collapse, megamonsoon inception). The voluminous (∼1.5 km) succession of exclusively fine-grained red beds that comprises the Permian Salagou Formation (Lodève Basin, France) has long been interpreted to record either lacustrine or fluvial deposition, primarily based on a local emphasis of subaqueous features in the upper ∼25% of the section. In contrast, data presented here indicate that the lower-middle Salagou Formation is dominated by up to 15-m-thick beds of internally massive red mudstone with abundant pedogenic …
Collisional Formation Of Top-Shaped Asteroids And Implications For The Origins Of Ryugu And Bennu, P. Michel, R.-L. Ballouz, O. S. Barnouin, M. Jutzi, K. J. Walsh, B. H. May, C. Manzoni, D. C. Richardson, S. R. Schwartz, S. Sugita, S. Watanabe, H. Miyamoto, M. Hirabayashi, W. F. Bottke, Harold Connolly Jr., M. Yoshikawa, D. S. Lauretta
Collisional Formation Of Top-Shaped Asteroids And Implications For The Origins Of Ryugu And Bennu, P. Michel, R.-L. Ballouz, O. S. Barnouin, M. Jutzi, K. J. Walsh, B. H. May, C. Manzoni, D. C. Richardson, S. R. Schwartz, S. Sugita, S. Watanabe, H. Miyamoto, M. Hirabayashi, W. F. Bottke, Harold Connolly Jr., M. Yoshikawa, D. S. Lauretta
School of Earth & Environment Faculty Scholarship
Asteroid shapes and hydration levels can serve as tracers of their history and origin. For instance, the asteroids (162173) Ryugu and (101955) Bennu have an oblate spheroidal shape with a pronounced equator, but contain different surface hydration levels. Here we show, through numerical simulations of large asteroid disruptions, that oblate spheroids, some of which have a pronounced equator defining a spinning top shape, can form directly through gravitational reaccumulation. We further show that rubble piles formed in a single disruption can have similar porosities but variable degrees of hydration. The direct formation of top shapes from single disruption alone can …
Increased Fluvial Runoff Terminated Inorganic Aragonite Precipitation On The Northwest Shelf Of Australia During The Early Holocene, Maximilian Hallenberger, Lars Reuning, Stephen J. Gallagher, Stefan Back, Takeshige Ishiwa, Beth A. Christensen, Kara Bogus
Increased Fluvial Runoff Terminated Inorganic Aragonite Precipitation On The Northwest Shelf Of Australia During The Early Holocene, Maximilian Hallenberger, Lars Reuning, Stephen J. Gallagher, Stefan Back, Takeshige Ishiwa, Beth A. Christensen, Kara Bogus
School of Earth & Environment Faculty Scholarship
Inorganic precipitation of aragonite is a common process within tropical carbonate environments. Across the Northwest Shelf of Australia (NWS) such precipitates were abundant in the late Pleistocene, whereas present-day sedimentation is dominated by calcitic bioclasts. This study presents sedimentological and geochemical analyses of core data retrieved from the upper 13 meters of IODP Site U1461 that provide a high-resolution sedimentary record of the last ~15 thousand years. Sediments that formed from 15 to 10.1 ka BP are aragonitic and characterised by small needles (<5 >µm) and ooids. XRF elemental proxy data indicate that these sediments developed under arid conditions in …
Climate Evolution Across The Mid-Brunhes Transition, Aaron M. Barth, Peter U. Clark, Nicholas S. Bill, Feng He, Nicklas G. Pisias
Climate Evolution Across The Mid-Brunhes Transition, Aaron M. Barth, Peter U. Clark, Nicholas S. Bill, Feng He, Nicklas G. Pisias
School of Earth & Environment Faculty Scholarship
The Mid-Brunhes Transition (MBT) began ∼ 430 ka with an increase in the amplitude of the 100 kyr climate cycles of the past 800 000 years. The MBT has been identified in ice-core records, which indicate interglaciations became warmer with higher atmospheric CO2 levels after the MBT, and benthic oxygen isotope (δ18O) records, which suggest that post-MBT interglaciations had higher sea levels and warmer temperatures than pre-MBT interglaciations. It remains unclear, however, whether the MBT was a globally synchronous phenomenon that included other components of the climate system. Here, we further characterize changes in the climate system across the MBT …
Towards Understanding The Dynamical Evolution Of Asteroid 25143 Itokawa: Constraints From Sample Analysis, Harold Connolly Jr., Dante S. Lauretta, Kevin J. Walsh, Shogo Tachibana, William F. Bottke Jr.
Towards Understanding The Dynamical Evolution Of Asteroid 25143 Itokawa: Constraints From Sample Analysis, Harold Connolly Jr., Dante S. Lauretta, Kevin J. Walsh, Shogo Tachibana, William F. Bottke Jr.
School of Earth & Environment Faculty Scholarship
The data from the analysis of samples returned by Hayabusa from asteroid 25143 Itokawa are used to constrain the preaccretion history, the geological activity that occurred after accretion, and the dynamical history of the asteroid from the main belt to near-Earth space. We synthesize existing data to pose hypotheses to be tested by dynamical modeling and the analyses of future samples returned by Hayabusa 2 and OSIRIS-REx. Specifically, we argue that the Yarkosky-O’Keefe-Radzievskii-Paddack (YORP) effect may be responsible for producing geologically high-energy environments on Itokawa and other asteroids that process regolith and essentially affect regolith gardening.
Petrography, Stable Isotope Compositions, Microraman Spectroscopy, And Presolar Components Of Roberts Massif 04133: A Reduced Cv3 Carbonaceous Chrondrite, Jemma Davidson, Devin L. Schrader, Conel M. Alexander, Dante S. Lauretta, Henner Busemann, Ian A. Franchi, Richard C. Greenwood, Harold Connolly Jr., Kenneth J. Domanik, Alexander Verchovsky
Petrography, Stable Isotope Compositions, Microraman Spectroscopy, And Presolar Components Of Roberts Massif 04133: A Reduced Cv3 Carbonaceous Chrondrite, Jemma Davidson, Devin L. Schrader, Conel M. Alexander, Dante S. Lauretta, Henner Busemann, Ian A. Franchi, Richard C. Greenwood, Harold Connolly Jr., Kenneth J. Domanik, Alexander Verchovsky
School of Earth & Environment Faculty Scholarship
Here, we report the mineralogy, petrography, C-N-O-stable isotope compositions, degree of disorder of organic matter, and abundances of presolar components of the chondrite Roberts Massif (RBT) 04133 using a coordinated, multitechnique approach. The results of this study are inconsistent with its initial classification as a Renazzo-like carbonaceous chondrite, and strongly support RBT 04133 being a brecciated, reduced petrologic type >3.3 Vigarano-like carbonaceous (CV) chondrite. RBT 04133 shows no evidence for aqueous alteration. However, it is mildly thermally altered (up to approximately 440 °C); which is apparent in its whole-rock C and N isotopic compositions, the degree of disorder of C …