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Articles 31 - 60 of 521
Full-Text Articles in Earth Sciences
A Brief Early History Of The Unlv Department Of Geoscience, Matthew S. Lachniet
A Brief Early History Of The Unlv Department Of Geoscience, Matthew S. Lachniet
Geoscience Faculty Research
This project represents four years of part-time research and investigation. It started as something simple, a need for a spreadsheet for me, as a new Department Chair in January of 2020, to assemble the tenure and promotion timelines of existing faculty based on their employment starting dates. It then expanded to document every Geoscience faculty member, which revealed so many interesting stories along the way. Once it began it was hard to stop, with the research taking on a mind of its own as it meandered down the historical archive of the Department. And why stop with people? Buildings? Fair …
The Behemoth Of The Last Ice Age: The Evolutionary Saga Of The Columbian Mammoth In North America, Nathaniel Valentine
The Behemoth Of The Last Ice Age: The Evolutionary Saga Of The Columbian Mammoth In North America, Nathaniel Valentine
Calvert Undergraduate Research Awards
The Columbian’s mammoth evolutionary history can be traced back to the origin of life and its evolutionary lineage can be tracked down by examining select species over geologic time. I conducted a literature review with multiple scientific journals to identify key transitional species that trace their lineage to the Columbian mammoth. Transitional species were selected from the Precambrian and the various periods of the Phanerozoic which exhibited vertebrate-like body structures and behaviors. Evidence suggests that early vertebrate-like animals were present by the Cambrian period. Mammal evolution would continue in the Mesozoic era and radiate in the Cenozoic era. The Columbian …
Unlv Title Iii Aanapisi & Mcnair Scholars Institute Research Journal 2024, Jesica Godinez-Paredes, Kian Hassankhan, Apia Hickman, Robin Ruth Kee, Kevin Ayala Pineda, Briana Melendez, Kalli Ramos, Saturn L. Reyes, Fabian Leija, Selena Pepe, Silva Topchyan, Celeste Ainsley, Mayra Arzate, Jessica Balistreri, Zantana Ephrem, Mirella Jasso, Karl Panou, Nichole Pelaez, Miklo Alcala, Akshay Dave, Mey Mey Heng, Michael Finkle, Janessa Montenegro, Reynafe Naol Aniga, Victor Mejia, Angelica G. Diaz, Anayeli Flores-Garibay, Kari Lee Joe Goold, Samantha Hernandez, Lianelys Cabrera Martinez, Caitlin Reynolds, Kimberly N. Usbeck, Abdulrahman Alahdal, Angelica Diaz, Willaine Mae Kahano, Raquel Jackson, Cecia Ruiz-Hernandez, Kers Ung-Watson, Yessenia Henriquez, Vanessa Marie Booth, Alexia Brown, Darlyn Magana, Bianca Navarro, Nicholas Pereira, Gia Renemae Calip, Lucky Heng, Ralph Sagun, Lucas Abreu, Alexandra Maria Acosta, Tristan Benally, Cosset Hernandez Pena, Adrian Montenegro, Cierra Paaaina-Daquioag, Nicole Torosian, Tracy Fuentes, Julissa Martinez, Medina Mcallister, Michal Newhouse-Van Vlerin, Tiria Carr, Nima Abkenar, Isabella Aceituno, Yuhan Bi, Victoria Campos, Melika Cummings, Zachary J. Johnigan, Alexis Sotolongo-Marin
Unlv Title Iii Aanapisi & Mcnair Scholars Institute Research Journal 2024, Jesica Godinez-Paredes, Kian Hassankhan, Apia Hickman, Robin Ruth Kee, Kevin Ayala Pineda, Briana Melendez, Kalli Ramos, Saturn L. Reyes, Fabian Leija, Selena Pepe, Silva Topchyan, Celeste Ainsley, Mayra Arzate, Jessica Balistreri, Zantana Ephrem, Mirella Jasso, Karl Panou, Nichole Pelaez, Miklo Alcala, Akshay Dave, Mey Mey Heng, Michael Finkle, Janessa Montenegro, Reynafe Naol Aniga, Victor Mejia, Angelica G. Diaz, Anayeli Flores-Garibay, Kari Lee Joe Goold, Samantha Hernandez, Lianelys Cabrera Martinez, Caitlin Reynolds, Kimberly N. Usbeck, Abdulrahman Alahdal, Angelica Diaz, Willaine Mae Kahano, Raquel Jackson, Cecia Ruiz-Hernandez, Kers Ung-Watson, Yessenia Henriquez, Vanessa Marie Booth, Alexia Brown, Darlyn Magana, Bianca Navarro, Nicholas Pereira, Gia Renemae Calip, Lucky Heng, Ralph Sagun, Lucas Abreu, Alexandra Maria Acosta, Tristan Benally, Cosset Hernandez Pena, Adrian Montenegro, Cierra Paaaina-Daquioag, Nicole Torosian, Tracy Fuentes, Julissa Martinez, Medina Mcallister, Michal Newhouse-Van Vlerin, Tiria Carr, Nima Abkenar, Isabella Aceituno, Yuhan Bi, Victoria Campos, Melika Cummings, Zachary J. Johnigan, Alexis Sotolongo-Marin
McNair Journal
Journal articles based on research conducted by undergraduate students in the AANAPISI, LSAMP, and McNair Scholars Program.
Table of Contents
About AANAPISI
Dr. Chris Heavey, Interim President
Dr. Keith Rogers, Vice President for Student Affairs
Ms. Zhanna Aronov, Associate Vice President for Retention & Outreach
Zagamiite, Caal2si3.5o11, The Hexagonal High-Pressure Cas Phase With Dominant Si, As A Mineral From Mars, Chi Ma, Oliver Tschauner, John R. Beckett, Eran Greenberg, Vitali B. Prakapenka
Zagamiite, Caal2si3.5o11, The Hexagonal High-Pressure Cas Phase With Dominant Si, As A Mineral From Mars, Chi Ma, Oliver Tschauner, John R. Beckett, Eran Greenberg, Vitali B. Prakapenka
Geoscience Faculty Research
Within the Ca-Al-silicate system, dense, layered hexagonal phases occur at high temperatures and pressures between 20 and 23 GPa. They have been observed both in nature and in experiments. In this study, we describe the endmember with a dominant sixfold coordinated Si as a mineral zagamiite (IMA 2015-022a). This new mineral identified in Martian meteorites has a general formula of (Ca,Na)(Al,Fe,Mg)2(Si,Al,□)4O11, thus defining CaAl2Si3.5O11 as a previously unknown endmember of the hexagonal CAS phases. Zagamiite assumes space group P63/mmc with a unit cell of a = 5.403(2) Å, c = 12.77(3) Å, V = 322.9(11) Å3, and Z = 2. …
New Observations On The Age And Origin Of The Geologist Seamounts, South Hawaiian Seamount Province, Brandon Chester Scott
New Observations On The Age And Origin Of The Geologist Seamounts, South Hawaiian Seamount Province, Brandon Chester Scott
UNLV Theses, Dissertations, Professional Papers, and Capstones
Investigation into seamounts that stem from intraplate volcanism—that is volcanism occurring far from plate boundaries—presents an opportunity to deconvolve processes associated with mantle compositional heterogeneities and melting dynamics. Upwelling and decompression of thermochemically anomalous mantle plumes is the primary mechanism for significant intraplate volcanism; however, many seamounts dotted across the Pacific Plate do not correlate spatially, temporally, or geochemically with mantle plume volcanism. One region of enigmatic volcanism in the ocean basins that is not clearly attributable to plume-derived magmatism are the Geologist Seamounts and the wider South Hawaiian Seamount Province (∼19°N, 157°W). Here we present merged multibeam (<100 m) and satellite altimetry bathymetric maps of the Geologist Seamounts region, new 40 …100>
Examining The Spatial Periodicity Of Force Chains And Strain Localization In Polycrystal Models, Richard D. Panduro-Allanson
Examining The Spatial Periodicity Of Force Chains And Strain Localization In Polycrystal Models, Richard D. Panduro-Allanson
UNLV Theses, Dissertations, Professional Papers, and Capstones
Shear strain localization is typical in deforming rocks and is vital for developing faults and tectonic boundaries. There are various proposed drivers of shear localization (temperature, fluid, phase transformation, and microstructure); we will explore the effects of elastic heterogeneity (a microstructural influence) on shear localization in polycrystal models. Elastic heterogeneity can lead to varied stress states in material and drive shear localization. Previous simulations of elastically heterogeneous polycrystal models have shown that the stress distribution can be described as forming an anastomosing pattern of high-stress streams parallel to the compression direction. This anastomosing patterning resembles force chains; linear, high-stress features …
Water Efficiency & Sustainability In The Mountain West, 2022, Zachary Billot, Caitlin J. Saladino, William E. Brown Jr.
Water Efficiency & Sustainability In The Mountain West, 2022, Zachary Billot, Caitlin J. Saladino, William E. Brown Jr.
Environment
This fact sheet analyzes the effectiveness of state-level policies related to water usage, conservation, and sustainability for the Mountain West states of Arizona, Colorado, Nevada, New Mexico, and Utah in 2022. The original data are published in the “2022 State Policy Scorecard for Water Efficiency and Sustainability” report written by the Alliance for Water Efficiency.
Climatic Influences On Incipient Alteration In Mars-Relevant Ultramafic Soils, Anthony Feldman
Climatic Influences On Incipient Alteration In Mars-Relevant Ultramafic Soils, Anthony Feldman
UNLV Theses, Dissertations, Professional Papers, and Capstones
An ongoing debate exists around the nature of the climatic conditions present during the Noachian and early Hesperian periods (~4.1 to 3 Gyr ago) of Mars’ ancient history. The various theories put forward can reasonably be grouped into “warm and wet” vs “cold and icy” camps. Warm and wet approximates an Earth-like system with a relatively clement climate with significant liquid water present including potentially long-lived oceans. Cold and icy theories generally postulate thick ice sheets at high elevations with periodic warming events driving precipitation and the formation of river channels and leading to the formation of chemical alteration products. …
Magmatic Processes Leading To Compositional Diversity In The Mars Crust, Amanda Marie Ostwald
Magmatic Processes Leading To Compositional Diversity In The Mars Crust, Amanda Marie Ostwald
UNLV Theses, Dissertations, Professional Papers, and Capstones
The ancient Mars crust can yield insights into planet formation and evolution that Earth cannot. Direct investigation of the martian surface is limited to studies on meteorites and rover-obtained analyses. The nakhlites and chassignites, two classes of martian meteorites, are together the largest suite of martian meteorites derived from a single location on the surface. As such, they present a rare opportunity to study the Mars crust in detail using samples bearing a contextual relationship. Rover studies have found a surprising amount of compositional diversity in surface materials, the formation mechanisms of which are not well-constrained. This dissertation leverages meteorites …
Critical Metals: From Granitic Pegmatites To The Anthropogenic Cycle, Dalton Mccaffrey
Critical Metals: From Granitic Pegmatites To The Anthropogenic Cycle, Dalton Mccaffrey
UNLV Theses, Dissertations, Professional Papers, and Capstones
Critical metals are vital to the functionality of the modern world. The increased diversity and usage intensity of these commodities in defense-related and strategic technologies (e.g., jet engines, rocket assemblies), modern infrastructure and products (e.g., high-strength steel, cellular phones, laptop computers), and energy-related, low-emissions technologies (e.g., nuclear reactors, solar panels, wind turbines, hybrid and electric vehicles) has drastically increased our reliance on critical metals and, thus, the United States (and global) exposure to supply restrictions. Granitic pegmatites are unique mineral deposits that represent a past, present and future resource for many (approximately half) of these critical resources. Even with the …
Study Of Trace Elements In Southern Nevada Spring Waters And Lakes, Hyejeong Lee
Study Of Trace Elements In Southern Nevada Spring Waters And Lakes, Hyejeong Lee
UNLV Theses, Dissertations, Professional Papers, and Capstones
Comprehending the natural water resource is imperative for the entire state of Nevada and of particular significance for Southern Nevada, where rapid population growth and climate change are placing significant strain on supplies. This research underscores the significance of water chemistry in identifying potential water source areas through trace elements. For the first time, the study proposed measuring the compositions of the entire suite of metal elements, ranging from Li to U, in over 40 springs in the Moapa Valley and its upper gradient valleys, utilizing the iCAP Qc ICP-MS (Inductively Coupled Plasma Mass Spectrometer) at UNLV. The research evaluated …
Characterization Of Hematite Coated Bedrock Fault Scarps In The Northern Colorado River Extensional Corridor Near Lake Mead, Nevada, Molly E. Pickerel
Characterization Of Hematite Coated Bedrock Fault Scarps In The Northern Colorado River Extensional Corridor Near Lake Mead, Nevada, Molly E. Pickerel
UNLV Theses, Dissertations, Professional Papers, and Capstones
Fault mirrors are reflective, thin, typically <1 mm thick, fault slip surfaces in exhumed fault zones that can provide a record of thermal, chemical, and rheological changes to fault materials during deformation. This study investigates a series of hematite coated fault mirrors along bedrock fault scarps in Miocene volcanic rocks near Lake Mead, Nevada. The studied faults are located in a structurally complex area that includes NE-SW trending left-lateral strike-slip faults of the Lake Mead fault system, NW-SE right-lateral strike-slip faults of the Las Vegas Shear Zone, and N-S striking extensional faults of the Northern Colorado River Extensional Corridor.New zircon U-Pb ages from fault scarp host rocks 21-BC-03 and 21-BC-05 are and 13.86 ± 0.27 Ma and 12.90 ± 0.31 Ma (2σ standard error), respectively. New apatite (U-Th)/He dates range from 5.64 ± 0.46 Ma to 12.4 ± 0.36 Ma (2σ standard error) and are interpreted to be partially reset after eruption due to reheating. Inverse thermal history modeling in HeFTy of apatite He dates indicates a thermal history of reheating to ~65 °C which is interpreted as shallow burial around ~11 - 5 Ma followed by cooling to the surface, interpreted as exhumation between ~4.5 - 2 Ma. The zircon U-Pb ages, apatite He dates, and inverse thermal history models indicate the fault host rocks were erupted to the surface and stayed within the upper ~2 km of the crust since the Miocene. Nearly vertical fault scarps that host the fault mirror surfaces exhibit two sets of slickenlines, indicating oblique and strike-slip motion, with different orientations indicating that there have been multiple episodes of deformation along the surfaces. Three of the five studied fault scarps have E-W orientations, and one scarp is NW-SE, and one is NE-SW striking. The studied faults are interpreted to have been active during deformation associated with the Lake Mead Fault System and the Las Vegas Valley Shear Zone at 13 – 9 Ma and record both strike slip and oblique slip events in the complex strain field during this time. Micro-nano scale texture and grain morphology analysis of the hematite fault mirror volumes shows extreme strain localization along the fault mirror surface. Some fault mirrors exhibit multiple domains separated by discrete slip surfaces. Comminution and cataclasis appear to be the dominant deformation mechanisms in the fault mirror volume. Hematite textures and morphologies are consistent with observations from other fault systems that are interpreted to record aseismic to sub-seismic slip rates, and relatively low coseismic temperature rise. Fluid injection veins and post-deformation FeO mineralization in fractures are interpreted as evidence of high fluid pressures during slip and fluid circulation postdeformation. The new geochronologic and microstructural data inform on the processes operating along discrete fault surfaces in the shallow crust since the Miocene in the Lake Mead region.
Morphologic Comparisons Of Recrystallized And Neocrystallized Fibrous Amphibole Asbestos: Implications For Corresponding Health Risk Potential, Natalie G. Renkes
Morphologic Comparisons Of Recrystallized And Neocrystallized Fibrous Amphibole Asbestos: Implications For Corresponding Health Risk Potential, Natalie G. Renkes
UNLV Theses, Dissertations, Professional Papers, and Capstones
The presence of naturally-occurring asbestos (NOA) is increasingly concerning for scientists, health and regulatory agencies, and citizens living in impacted areas. It is commonly believed that fibrous amphibole asbestos can only form through neocrystallization. In southern Nevada, NOA occurs as a result of hydrothermal alteration of granitic rock producing fibrous amphibole both as cross-cutting neocrystallized veins and via recrystallization of original magmatic hornblende crystals. Fibers with a greater aspect ratio are known to have increased toxicity. This study measured the maximum length and average width of both neocrystallized and recrystallized fibers to see if the morphologies were similar. Neocrystallized and …
Trace Element Behaviors During Igneous Evolution And Hydrothermal Alteration Of An Evolved Rhyolite, The Blawn Formation, Wah Wah Mountains, Utah: Implications For Critical Metal Abundances In Highly Evolved Rhyolites, Drew William Barkoff
UNLV Theses, Dissertations, Professional Papers, and Capstones
A-type rhyolites and granites often contain elevated concentrations of the rare earth elements (REE) and many other critical trace elements relative to I- and S-type rhyolites and granites. Their trace element-enriched nature makes them potentially prospective bulk tonnage, low-grade resources of the REE and many other critical trace elements, including Li, Be, Mo, Sn, and W, but little work has been performed to delineate their economic potential. The 22.1 Ma Red Beryl Rhyolite (RBR) and the 18.3 Ma Tetons Rhyolite (TR) units of the Blawn Formation represent two A-type rhyolite domes located in the southern Wah Wah Mountains of Utah. …
Age And Genesis Of W-Mo-Cu Mineralization, Gold Hill, Utah, Nathan J. Carey
Age And Genesis Of W-Mo-Cu Mineralization, Gold Hill, Utah, Nathan J. Carey
UNLV Theses, Dissertations, Professional Papers, and Capstones
Utah's Gold Hill mining district hosts a Jurassic felsic pluton (~80 km^2) that was emplaced into a Mississippian to Pennsylvanian carbonate-dominated sedimentary sequence and is spatially associated with numerous polymetallic mineral deposits. This study focuses on W-Mo-Cu mineralization at the Lucy L., Doctor, Yellow Hammer, Reaper, and Rustler deposits within the district. The new, detailed petrographic observations, mineral chemistry (on scheelite, molybdenite, chalcopyrite, magnetite, garnet, and pyroxene), and Re-Os molybdenite geochronological data presented here allows for the determination of key mineral associations and paragenesis, the characterization of deposit types and their evolution, and the constraining of the relative and absolute …
Calcite Spherulite Formations And Their Controls In Halophilic Bacterial Cultures, Zakaria Jibrin
Calcite Spherulite Formations And Their Controls In Halophilic Bacterial Cultures, Zakaria Jibrin
UNLV Theses, Dissertations, Professional Papers, and Capstones
This study arose from an accidental discovery of calcite spherulites forming on colonies of various halophilic bacteria grown on solid Luria-Bertani medium made containing water from a brine pool in Death Valley, their natural habitat. Further studies with a large spherulite forming bacteria, Pseudoalteromonas haloplanktis, showed that calcite precipitation conditions were the consequence of bacteria using amino acids as a source of carbon and energy, a metabolism that produces NH3 and CO2 waste products. NH3 raises the pH of the medium, turning CO2 into CO32-. Calcium in the natural brine combines with CO32-. The resulting spherulitic calcite precipitation is nano-acicular …
Hydrogeologic Heterogeneity Identification: Using Inverse Modeling Of Synthetic Borehole Temperatures To Predict Groundwater Flux, Kevin Heintz
UNLV Theses, Dissertations, Professional Papers, and Capstones
Heat has been effectively used as a groundwater tracer for decades, and high-resolution temperature data can better identify and quantify discrete flow zones. Refinements to the numerical modeling of advective heat transfer in borehole temperature sensing deployments can improve understanding of dynamic hydrogeologic systems. In my thesis, I develop a novel two-dimensional coupled radial groundwater flow and heat transfer numerical model that considers intra-borehole vertical flow. To test the performance of this model, I used finite element analysis to generate synthetic data sets consisting of prescribed variable flow fields and resulting borehole temperatures. I input synthetic temperatures into the two-dimensional …
Along Strike Tectonic Evolution Of The Neogene Bermejo Foreland Basin And Eastern Precordillera Thrust Front, Argentina (30-32ºs), Zoey Catherine Plonka
Along Strike Tectonic Evolution Of The Neogene Bermejo Foreland Basin And Eastern Precordillera Thrust Front, Argentina (30-32ºs), Zoey Catherine Plonka
UNLV Theses, Dissertations, Professional Papers, and Capstones
The Bermejo retroarc foreland basin system formed in flexural response to Miocene crustal thickening in the Andean orogenic system, specifically, the eastward propagation of the Precordillera fold-thrust belt and the basement-involved uplift of the Sierras Pampeanas. Previous work in the area has mainly focused on the mechanisms and expression of flat slab subduction and the structural geometry of the basement-involved Sierras Pampeanas and east-vergent Precordillera fold-thrust belt at depth. Much of this work has furthered the understanding of Bermejo basin evolution north of 31ºS, however debate still exists whether the N-S trending Bermejo basin evolved synchronously or asynchronously through time. …
Mesozoic Sevier Thrusts Overprinted By Miocene-Quaternary Left-Lateral Deformation: Structures And Tectonism Of The Kane Springs Wash Region, Nevada, Andrew Reid
UNLV Theses, Dissertations, Professional Papers, and Capstones
Recognizing how rifts develop through space and time is vital to enrich our understanding of continental breakup. Rifts are commonly segmented by transfer or accommodations zones that form as the rift develops due to differences in the onset, direction, magnitude, or rates of extension on either side of the transfer or accommodation zone. The Basin and Range province is a wide rift where Cenozoic extension overprints and exposes earlier Mesozoic Sevier fold-thrust belt shortening structures. This exposure allows Sevier thrust correlations between individual mountain ranges and use of these shortening structures to study rift segmentation by strike-slip transfer faults. The …
Paleoenvironmental Changes Across The Devonian-Carboniferous Transition, Audrey M. Warren
Paleoenvironmental Changes Across The Devonian-Carboniferous Transition, Audrey M. Warren
UNLV Theses, Dissertations, Professional Papers, and Capstones
The Devonian-Carboniferous (D-C) transition was a critical interval in earth history, witnessing profound environmental changes associated with plant and animal evolution and extinction. Two first-order mass extinctions occurred leading up to the D-C boundary: the Kellwasser Event at the Frasnian-Famennian (F-F) boundary (~371 Ma) and the D-C boundary Hangenberg Event (~359 Ma). Both events were associated with significant sea level changes and major carbon cycle perturbations, evidenced by widespread deposition of black shale and positive carbon isotope (δ13C) excursions, all of which have been used to correlate these events across the globe. Because preservation of black shale requires anoxic conditions, …
Beyond Functional Diversity: The Importance Of Trophic Position To Understanding Functional Processes In Community Evolution, Roxanne M. W. Banker, Ashley A. Dineen, Melanie G. Sorman, Carrie L. Tyler, Peter D. Roopnarine
Beyond Functional Diversity: The Importance Of Trophic Position To Understanding Functional Processes In Community Evolution, Roxanne M. W. Banker, Ashley A. Dineen, Melanie G. Sorman, Carrie L. Tyler, Peter D. Roopnarine
Geoscience Faculty Research
Ecosystem structure—that is the species present, the functions they represent, and how those functions interact—is an important determinant of community stability. This in turn aects how ecosystems respond to natural and anthropogenic crises, and whether species or the ecological functions that they represent are able to persist. Here we use fossil data from museum collections, literature, and the Paleobiology Database to reconstruct trophic networks of Tethyan paleocommunities fromthe Anisian and Carnian (Triassic), Bathonian (Jurassic), and Aptian (Cretaceous) stages, and compare these to a previously reconstructed trophic network from a modern Jamaican reef community. We generated model food webs consistent with …
Groundwater Quality: Global Challenges, Emerging Threats And Novel Approaches, Dan Lapworth, Thomas Boving, Bentje Brauns, Jane Dottridge, Paul Hynds, Seifu Kebede, David Kreamer, Bruce Misstear, Abhijit Mukherjee, Viviana Re, James Sorensen, Claudia Ruz Vargas
Groundwater Quality: Global Challenges, Emerging Threats And Novel Approaches, Dan Lapworth, Thomas Boving, Bentje Brauns, Jane Dottridge, Paul Hynds, Seifu Kebede, David Kreamer, Bruce Misstear, Abhijit Mukherjee, Viviana Re, James Sorensen, Claudia Ruz Vargas
Geoscience Faculty Research
Improving our understanding of groundwater quality threats to human health and the environment is essential to protect and manage groundwater resources effectively. This essay highlights some global groundwater quality challenges, describes key contaminant groups and threats of emerging concern, including antimicrobial resistance, and discusses novel approaches to assessing groundwater quality. Groundwater quality monitoring needs to improve significantly in order to effectively identify and mitigate threats to groundwater from historical, current and future pollution.
Combining Freestanding Ferroelectric Perovskite Oxides With Two-Dimensional Semiconductors For High Performance Transistors, Sergio Puebla, Thomas Pucher, Victor Rouco, Gabriel Sanchez-Santolino, Yong Xie, Victor Zamora, Fabian A. Cuellar, Federico J. Mompean, Carlos Leon, Carlos O. Island, Mar Garcia-Hernandez, Jacobo Santamaria, Carmen Munuera, Andres Castellanos-Gomez
Combining Freestanding Ferroelectric Perovskite Oxides With Two-Dimensional Semiconductors For High Performance Transistors, Sergio Puebla, Thomas Pucher, Victor Rouco, Gabriel Sanchez-Santolino, Yong Xie, Victor Zamora, Fabian A. Cuellar, Federico J. Mompean, Carlos Leon, Carlos O. Island, Mar Garcia-Hernandez, Jacobo Santamaria, Carmen Munuera, Andres Castellanos-Gomez
Physics & Astronomy Faculty Research
We demonstrate the fabrication of field-effect transistors based on single-layer MoS2 and a thin layer of BaTiO3 (BTO) dielectric, isolated from its parent epitaxial template substrate. Thin BTO provides an ultrahigh-κ gate dielectric effectively screening Coulomb scattering centers. These devices show mobilities substantially larger than those obtained with standard SiO2 dielectrics and comparable with values obtained with hexagonal boron nitride, a dielectric employed for fabrication of high-performance two-dimensional (2D) based devices. Moreover, the ferroelectric character of BTO induces a robust hysteresis of the current vs gate voltage characteristics, attributed to its polarization switching. This hysteresis is strongly suppressed when the …
Compositionally And Density Stratified Igneous Terrain In Jezero Crater, Mars, Roger C. Wiens, Arya Udry, Olivier Beyssac, Cathy Quantin-Nataf, Nicolas Mangold, 80+ Authors Contributed To This Work
Compositionally And Density Stratified Igneous Terrain In Jezero Crater, Mars, Roger C. Wiens, Arya Udry, Olivier Beyssac, Cathy Quantin-Nataf, Nicolas Mangold, 80+ Authors Contributed To This Work
Geoscience Faculty Research
Before Perseverance, Jezero crater’s floor was variably hypothesized to have a lacustrine, lava, volcanic airfall, or aeolian origin. SuperCam observations in the first 286 Mars days on Mars revealed a volcanic and intrusive terrain with compositional and density stratification. The dominant lithology along the traverse is basaltic, with plagioclase enrichment in stratigraphically higher locations. Stratigraphically lower, layered rocks are richer in normative pyroxene. The lowest observed unit has the highest inferred density and is olivine-rich with coarse (1.5 millimeters) euhedral, relatively unweathered grains, suggesting a cumulate origin. This is the first martian cumulate and shows similarities to martian meteorites, which …
Antler Foreland Basin Evolution Recorded In Detrital Zircon U-Pb Geochronology, James Duncan
Antler Foreland Basin Evolution Recorded In Detrital Zircon U-Pb Geochronology, James Duncan
UNLV Theses, Dissertations, Professional Papers, and Capstones
The Antler orogeny was a Devonian-Mississippian (375-320 Ma) mountain building event that occurred along the western Laurentian margin. The initiation of the Antler orogeny is marked by the emplacement of the Roberts Mountain Allochthon (RMA) that thrust Cambrian-Devonian deep water marine siliciclastic rocks 100 km eastward onto the western Laurentian margin. Shortening related to the Antler orogeny deformed RMA strata and caused a flexural response in the continental crust that resulted in the formation of the adjacent Antler Foreland basin. The paleogeographic history of the RMA strata and tectonic drivers for the Antler orogeny are still debated. Proposed models suggest …
Source And Parental Melts Of Poikilitic Shergottites: Implications For Martian Magmatism, Evan W. O'Neal
Source And Parental Melts Of Poikilitic Shergottites: Implications For Martian Magmatism, Evan W. O'Neal
UNLV Theses, Dissertations, Professional Papers, and Capstones
Martian poikilitic shergottite meteorites are cumulate rocks that can be used to understand melt evolution on Mars from the bottom of the crust (~10 kbar) all the way up to near-surface shallow depths (~1 kbar). There is a general lack of knowledge regarding shergottites including, parental magma compositions, crystallization ages, and the location of the enriched geochemical source of the shergottites in the martian mantle. Through a comprehensive petrographic and geochemical study, we have attempted to better understand poikilitic shergottite formation and the evolution of the martian interior during the Amazonian period (~3 Ga – present day). We studied a …
The Application Of Detrital Zircon Geochronology, Pressure-Temperature Modeling, Monazite Petrochronology, And Quartz-In-Garnet Elastic Geobarometry To The Tectonic Evolution Of The Funeral Mountains And Related Metamorphic Core Complexes, Suzanne Renae Mulligan
UNLV Theses, Dissertations, Professional Papers, and Capstones
This dissertation investigates and applies different techniques for studying mid-crustal metamorphic rocks including detrital zircon geochronology, monazite petrochronology, thermodynamic pressure-temperature modeling, and elastic geobarometry. The first chapter reconstructs stratigraphy in deformed metamorphic rocks from the Funeral Mountains metamorphic core complex in Death Valley, California, and the Bullfrog Hills, Nevada, using U-Pb detrital zircon (DZ) geochronology. This study documents another successful application of stratigraphic techniques applied to metamorphic rocks and migmatites. DZ geochronology identified Pahrump Group metasediments in rocks that were previously interpreted to be Paleoproterozoic basement gneisses, providing insights into the distribution of Rodinia rift basins. This analysis has shown …
Coexistence Of Vitreous And Crystalline Phases Of H2o At Ambient Temperature, Ali K. Shargh, Aude Picard, Rostislav Hrubiak, Dongzhou Zhang, Russell J. Hemley, Shanti Deemyad, Niaz Abdolrahim, Saveez Saffarian
Coexistence Of Vitreous And Crystalline Phases Of H2o At Ambient Temperature, Ali K. Shargh, Aude Picard, Rostislav Hrubiak, Dongzhou Zhang, Russell J. Hemley, Shanti Deemyad, Niaz Abdolrahim, Saveez Saffarian
Life Sciences Faculty Research
Formation of vitreous ice during rapid compression of water at room temperature is important for biology and the study of biological systems. Here, we show that Raman spectra of rapidly compressed water at greater than 1 GPa at room temperature exhibits the signature of high-density amorphous ice, whereas the X-ray diffraction (XRD) pattern is dominated by crystalline ice VI. To resolve this apparent contradiction, we used molecular dynamics simulations to calculate full vibrational spectra and diffraction patterns of mixtures of vitreous ice and ice VI, including embedded interfaces between the two phases. We show quantitatively that Raman spectra, which probe …
Steel Module-To-Concrete Core Connection Methods In High Rise Modular Buildings: A Critical Review, Bishal Poudel, Seungtaek Lee, Jin Ouk Choi
Steel Module-To-Concrete Core Connection Methods In High Rise Modular Buildings: A Critical Review, Bishal Poudel, Seungtaek Lee, Jin Ouk Choi
Civil and Environmental Engineering and Construction Faculty Research
Modularization in a high-rise building is different from a small building, as it is exposed to more lateral forces like wind and earthquakes. The integrity, robustness, and overall stability of the modules and their performance is based on the joining techniques and strong structural systems. High lateral stiff construction structures like concrete shear walls and frames, braced steel frames, and steel moment frames are used for the stability of high-rise modular buildings. Similarly, high-rise stick-built buildings have concrete cores and perimeter frames for lateral load strength and stiffness. Methods for general steel-concrete connections are available in many works of literature. …
Preliminary Planning For Mars Sample Return (Msr) Curation Activities In A Sample Receiving Facility (Srf), Kimberly T. Tait, Francis M. Mccubbin, Caroline L. Smith, Carl B. Agee, Henner Busemann, Barbara Cavalazzi, Viciane Debaille, Aurore Hutzler, Tomohiro Usui, Gerhard Kminek, Michael A. Meyer, David W. Beaty, Brandi L. Carrier, Timothy Haltigin, Lindsay E. Hays, Charles S. Cockell, Daniel P. Glavin, Monica M. Grady, Ernst Hauber, Bernard Marty, Lisa M. Pratt, Aaron B. Regberg, Alvin L. Smith, Roger E. Summons, Timothy D. Swindle, Nicholas J, Tosca, Arya Urdry, Michael A. Velbel, Meenakshi Wadhwa, Frances Westall, Maria-Paz Zorzano
Preliminary Planning For Mars Sample Return (Msr) Curation Activities In A Sample Receiving Facility (Srf), Kimberly T. Tait, Francis M. Mccubbin, Caroline L. Smith, Carl B. Agee, Henner Busemann, Barbara Cavalazzi, Viciane Debaille, Aurore Hutzler, Tomohiro Usui, Gerhard Kminek, Michael A. Meyer, David W. Beaty, Brandi L. Carrier, Timothy Haltigin, Lindsay E. Hays, Charles S. Cockell, Daniel P. Glavin, Monica M. Grady, Ernst Hauber, Bernard Marty, Lisa M. Pratt, Aaron B. Regberg, Alvin L. Smith, Roger E. Summons, Timothy D. Swindle, Nicholas J, Tosca, Arya Urdry, Michael A. Velbel, Meenakshi Wadhwa, Frances Westall, Maria-Paz Zorzano
Geoscience Faculty Research
The Mars Sample Return Planning Group 2 (MSPG2) was tasked with identifying the steps that encompass all the curation activities that would happen within the MSR Sample Receiving Facility (SRF) and any anticipated curation-related requirements. An area of specific interest is the necessary analytical instrumentation. The SRF would be a Biosafety Level-4 facility where the returned MSR flight hardware would be opened, the sample tubes accessed, and the martian sample material extracted from the tubes. Characterization of the essential attributes of each sample would be required to provide enough information to prepare a sample catalog used in guiding the preparation …