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2017

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Articles 511 - 540 of 1124

Full-Text Articles in Earth Sciences

Paleoecological Analysis Of The Clayton Formation (Paleocene) Near Malvern, Arkansas, Brenna J. Hart May 2017

Paleoecological Analysis Of The Clayton Formation (Paleocene) Near Malvern, Arkansas, Brenna J. Hart

Honors Theses

The Clayton Formation is a section of the Midway Group immediately above the Cretaceous-Paleogene boundary that contains marine fossils from the Paleocene Epoch. The formation is composed of glauconitic sand, clay, marl, and limestone. Fossils within the formation commonly occur in clay or are concentrated in conglomeratic lag lenses. To assess paleoecology of the region during the Paleocene, the Clayton Formation was sampled for fossil content at a distinctly visible exposure along Interstate 30 near Malvern, Arkansas, that was excavated as part of a landslide mitigation project. Complimentary sites were sampled nearby along the Ouachita River and behind a shopping …


Converting Chemical Signatures In Vaterite Otoliths To Aragonite Otoliths In Steelhead Trout: Developing A Partition Coefficient, Jamie Justice May 2017

Converting Chemical Signatures In Vaterite Otoliths To Aragonite Otoliths In Steelhead Trout: Developing A Partition Coefficient, Jamie Justice

Honors Projects

Otoliths are small bones near the brain of teleost fish that aid in hearing and balance. Otoliths are typically composed of a polymorph of calcium carbonate called aragonite; however, when stressed, fish may transition to producing a less dense polymorph called vaterite. Otoliths are typically used in studies of fish natal origin or migration patterns because 1) otoliths grow concentrically around an origin (birth point), 2) the material in the otolith is not replaced over time, and 3) microelements (Sr and Ba) can be incorporated into the otoliths in proportion to elemental ratios in the water (i.e., when fish move …


Geochemical And Petrophysical Characteristics Of The Horn River Formation: British Columbia, Ca, Joseph Anthony Sortore May 2017

Geochemical And Petrophysical Characteristics Of The Horn River Formation: British Columbia, Ca, Joseph Anthony Sortore

Earth & Environmental Sciences Theses - Archive

The Devonian Horn River basin of northeastern British Columbia is the largest producing shale gas field in Canada. It has an estimated 500-600 TCF of light hydrocarbons in place stacked in multiple formations in an over-pressured setting conducive to, but too tight for natural flow. Not until the development of new drilling and production technologies were implemented a little over a decade ago were these massive resource plays able to be exploited. Shale development in British Columbia began in 2005 with the Triassic Montney Play, and shortly after that the Horn River Play in 2007. As of 2012, the Horn …


Paleoimagery: The Artistic Restoration Of Dinosaurs And Prehistoric Life, Colin Mcnulty May 2017

Paleoimagery: The Artistic Restoration Of Dinosaurs And Prehistoric Life, Colin Mcnulty

Honors Projects

My purpose in creating this paper is to research a holistic view of paleontological illustration (also called paleoimagery or paleoart). A thorough history of paleoimagery is outlined from its roots in biblical illustration in the 17th and 18th centuries approaching the modern day. A two-fold examination of the utility of art to communicate science and its use within the science of paleontology is also given. This includes discussions of the specific components of art pieces that help them to successfully communicate scientific ideas and examples of how paleoimagery contributes to paleontology. The author then outlines the conception and …


Assessing Landslide Susceptibility With Gis Using Qualitative And Quantitative Methods In Knox County, Nebraska, Christian J. Cruz May 2017

Assessing Landslide Susceptibility With Gis Using Qualitative And Quantitative Methods In Knox County, Nebraska, Christian J. Cruz

Department of Geography: Dissertations, Theses, and Student Research

This thesis assesses landslide susceptibility using data from LiDAR DEMs, land cover, and soil surveys. Data were assessed quantitatively through Bayesian logistic regression within a geographic information system (GIS) and statistical software to produce a landslide susceptibility map. The study area exhibits moderate relief where bluffs along the Missouri River valley gradually recede into rolling loess-mantled hills further to the south and southeast in Knox County. The six factors used to determine susceptibility to landslides are: land cover, parent material, slope aspect, slope curvature slope degree, and soil series. My findings show an increase in slope is the most significant …


The Relationship Among Suture Complexity, Shell Form, And Stratigraphic Formation In Ammonites Of The Western Interior Seaway, Darrah Jorgensen May 2017

The Relationship Among Suture Complexity, Shell Form, And Stratigraphic Formation In Ammonites Of The Western Interior Seaway, Darrah Jorgensen

Master's Theses or Doctor of Nursing Practice

Throughout ammonite evolution, shell suture patterns grew increasingly more complex, but the purpose of these sutures has long been debated. One hypothesis is that suture complexity is related to the structural integrity of the shell under pressure. To test this hypothesis, suture complexity was compared to shell form and stratigraphic formation to determine if there were significant differences in suture complexity, as a proxy for structural integrity, among shell forms or stratigraphic formations. Highly complex sutures might have allowed for the tightly coiled form of many ammonites, an advantage compared to less coiled forms because the pressure is distributed over …


Analysis Of Big Creek Aquifer Alluvial Facies And Associated Phreatic Surface Contour Maps Hays, Ellis County, Kansas, Krisopher John Neuhauser May 2017

Analysis Of Big Creek Aquifer Alluvial Facies And Associated Phreatic Surface Contour Maps Hays, Ellis County, Kansas, Krisopher John Neuhauser

Master's Theses or Doctor of Nursing Practice

Three contour maps of groundwater elevation levels below Hays, Kansas generated in 2016 show that the phreatic surface in eight monitoring wells declined 3.6 inches to 1 foot 9.6 inches over a three-month period of July, August, and September. They also indicate that groundwater flows in curvilinear directions toward Big Creek. Analyses of ten north-south oriented structural cross sections of the alluvial fill beneath the central region of Hays provide evidence of buried low-sinuosity and meandering streams, floodplains, and possibly adjoining tributaries and abandoned channels. Correlation of the more porous and permeable sand and gravel facies along a northwest to …


Uas-Collected Multispectral Imagery For The Identification Of Rangeland Vegetation In A Southern Mixed-Grass Prairie, Adam Rusk May 2017

Uas-Collected Multispectral Imagery For The Identification Of Rangeland Vegetation In A Southern Mixed-Grass Prairie, Adam Rusk

Master's Theses or Doctor of Nursing Practice

The interest in using unmanned aerial systems (UAS) for remote sensing of natural resources and ecology has grown rapidly in recent years and continues to develop. Recent improvements in the cost, size, and accessibility of consumer-grade UASs are now facilitating image collection on low-flying UAS platforms. Rangelands provide a unique opportunity to explore the uses of UAS remote sensing due to their large spatial extent and spatial and temporal heterogeneity. This study focuses on the use of UAS’s to identify rangeland vegetation in a southern mixed-grass prairie in Kansas. Two primary questions were asked: 1) Do small UASs with low-cost …


Stable Isotope Diet Analysis Of Teleoceras Fossiger From The High Plains Of Kansas, Patrick J. Wilson May 2017

Stable Isotope Diet Analysis Of Teleoceras Fossiger From The High Plains Of Kansas, Patrick J. Wilson

Master's Theses or Doctor of Nursing Practice

Stable isotope geochemistry provides a way of examining both modern and ancient ecosystems. One important use of stable carbon isotopes is to determine the amount of C3 versus C4 plant biomass in the diet of herbivorous mammals. C3 plants have a more negative stable carbon isotope ratio (δ13C) than C4 plants because of the different photosynthetic pathways each type uses. These different δ13C values are preserved in the hydroxyapatite of herbivores upon consumption of the different plant types. The purpose of this study it to use δ13C values from serial samples of tooth enamel from six isolated permanent molars of …


Hydrogeological Study Of A Municipal Groundwater Well Field In Central Kansas, Tyler Saryerwinnie May 2017

Hydrogeological Study Of A Municipal Groundwater Well Field In Central Kansas, Tyler Saryerwinnie

Master's Theses or Doctor of Nursing Practice

The City of Victoria is a small town of approximately 1,200 people situated in Central Kansas. Along with other communities in Kansas, recent drought has made the issue of water quality and availability a pressing concern with local officials. This city relies heavily on the use of ground-water wells located south of the town near the Big Creek channel. It is the purpose of this study to define the hydrogeological conditions effecting the City’s well field, and in turn apply this information to define an area of influence and outline potential hazards for the well field. Utilizing previous studies, along …


Impacts On The Stakeholders Of The Nexus Pipeline, Jessica A. Speweike May 2017

Impacts On The Stakeholders Of The Nexus Pipeline, Jessica A. Speweike

Honors Projects

This journalistic feature covers the different impacts on those individuals who are involved with or affected by the Nexus Gas Transmission pipeline. Testimony from Ohio landowners, activists, scientists and public officials cover a variety of opinions and concerns raised by the pipeline. Private property rights, environmental impact, and possible economic implications are detailed by those who have been involved with the Nexus pipeline since its early stages of implementation.


Integration Of Hydrogeophysical Datasets For Improved Water Resource Management In Irrigated Systems, Catherine E. Finkenbiner May 2017

Integration Of Hydrogeophysical Datasets For Improved Water Resource Management In Irrigated Systems, Catherine E. Finkenbiner

School of Natural Resources: Dissertations, Theses, and Student Research

Water scarcity is predicted to be the major limitation to increasing agronomic outputs to meet future food and fiber demands. With the agricultural sector accounting for 80 – 90% of all consumptive water use and an average water use efficiency (WUE) of less than 45%, major advances must be made in irrigation water management. Precision agriculture, specifically variable-rate irrigation (VRI) and variable-speed irrigation (VSI) systems, offers the technologies to address and manage for infield variability and incorporate that into management decisions. The major limitation to implementing this technology often lies in the management of spatial datasets and the development of …


Problematizing Socio-Scientific Issues: An Approach To Understanding Student Decision-Making Using Construal Level Theory, Ashley M. Peterson May 2017

Problematizing Socio-Scientific Issues: An Approach To Understanding Student Decision-Making Using Construal Level Theory, Ashley M. Peterson

School of Natural Resources: Dissertations, Theses, and Student Research

Socio-scientific issues (SSIs) are challenges at the intersection of science and everyday life that require use of scientific knowledge, argumentation skills, personal values, and morals to articulate science-informed decisions. While addressing SSIs, the ways in which individuals define a problem will influence the solution or decision reached. The problem definition can differ along many dimensions, including content and construal level. A construal is a mental construction of the past and future, other places and people, and unlikely events. Construal Level Theory (CLT) suggests pro-environmental intentions are associated with abstract situations. I explore the application of CLT to teaching and learning …


Improving Regional Hydrology Forecasting For The North Central Texas Region Utilizing Conditional Ensemble Streamflow And Hydrometeorological Condition Predictions With Artificial Neural Network Modeling, Tyler Fincannon May 2017

Improving Regional Hydrology Forecasting For The North Central Texas Region Utilizing Conditional Ensemble Streamflow And Hydrometeorological Condition Predictions With Artificial Neural Network Modeling, Tyler Fincannon

Earth & Environmental Sciences Theses - Archive

The predictive skill of hydrologic variables such as streamflow and soil moisture, in North Central Texas, has improved substantially in the recent decades. However, substantial model-data biases are still present during extreme climate events, such as droughts and flash floods. In this study, we have optimized the Hydraulic Ensemble Forecasting System (HEFS) through development of a conditional ensemble streamflow system, as well as forecast reservoir hydrometeorological conditions (e.g. drought indices) with an artificial neural network (ANN) model. Improving prediction of these reservoir conditions enables more effective reservoir management in terms of water resource and energy efficiency during regional weather and …


Tectonic Processes And Continental Hydroclimate During The Laramide Deformation In The Central Rocky Mountains, Min Gao May 2017

Tectonic Processes And Continental Hydroclimate During The Laramide Deformation In The Central Rocky Mountains, Min Gao

Earth & Environmental Sciences Dissertations - Archive

The central Rocky Mountains in western U.S.A. is a geologic province formed by the low-angle subduction of the Farallon oceanic plate under the North American continental plate during the latest Cretaceous–early Eocene Laramide orogeny. The tectonic processes and mechanism, the paleotopography and depositional environment, and the evolution of continental hydroclimate during the Laramide deformation remain controversial. This dissertation examines the tectonic processes of the Laramide orogeny throughout the entire central Rocky Mountains, and paleotopography, depositional processes, and paleoclimate in the Greater Green River Basin in southwestern Wyoming. The first project of this study uses a 2D flexural subsidence modeling method …


Investigations On The Mesozoic Geologic And Tectonic History Of The Jackson Mountains, Northwest Nevada, Thomas Anthony Colby May 2017

Investigations On The Mesozoic Geologic And Tectonic History Of The Jackson Mountains, Northwest Nevada, Thomas Anthony Colby

Boise State University Theses and Dissertations

New geologic mapping, high-precision U-Pb zircon geochronology, and isotope geochemistry provide insight into the early Mesozoic paleogeography and magmatic, stratigraphic, and structural evolution of the Jackson Mountains in the Black Rock Desert region of northwest Nevada. The magmatic history of the Jackson Mountains records Late Triassic to Early Jurassic (~215-195 Ma) marine deposition of the Boulder Creek Beds adjacent to the arc followed by the Early Jurassic (~193-189 Ma) eruption and emplacement of the Happy Creek Igneous Complex and associated plutons of the Early Mesozoic Intrusive Suite. Pb, Sr, and Nd isotopic data from Early Jurassic intrusive rocks of the …


Geochronology Of The Tectonic, Stratigraphic, And Magmatic Evolution Of Neoproterozoic To Early Paleozoic, North American Cordillera And Cryogenian Glaciation, Vincent H. Isakson May 2017

Geochronology Of The Tectonic, Stratigraphic, And Magmatic Evolution Of Neoproterozoic To Early Paleozoic, North American Cordillera And Cryogenian Glaciation, Vincent H. Isakson

Boise State University Theses and Dissertations

Neoproterozoic sedimentary successions contain evidence for some of the most extreme climate fluctuations, breakup of the paleo-supercontinent Rodina, multiple low-latitude global glaciations, and the resultant evolution and radiation of complex life. The stratigraphic record of these events are found on all major continents and have been associated with, in part, global ‘Snowball Earth’ events. However, the understanding and integration of these, and related phenomenon, are limited by disparate and imprecise age constraints that prohibit clear correlation between locations.

This research focused on high-precision geochronology within an integrated framework of sedimentology, stratigraphy, and geochemistry to resolve the timing and duration of …


Targeting Sav Restoration At Lake Mattamuskeet Using Gis And Landsat 8 Data, Lindsey Shanks May 2017

Targeting Sav Restoration At Lake Mattamuskeet Using Gis And Landsat 8 Data, Lindsey Shanks

Theses, Dissertations and Culminating Projects

Lake Mattamuskeet, a large, shallow lake on the coast of North Carolina, has undergone water quality degradation and submerged aquatic vegetation (SAV) decline over recent years. Water depth and water clarity have been established as key drivers of SAV loss. To target locations for the restoration of SAV in the lake, an analysis that focuses on water clarity, water depth, and current SAV presence was developed. Two separate methodologies were conducted and compared to analyze water clarity in the lake. The first applied four years (2013-2016) of Landsat 8 imagery to a previously developed model that predicts water clarity from …


A Floral Assemblage Of The Upper Cretaceous El Gallo Formation, El Rosario, Baja California, Mexico, Reilly F. Hayes, Marisol Montellano-Ballesteros, Gerardo Álvarez-Reyes, René Hernandez-Rivera, David E. Fastovsky May 2017

A Floral Assemblage Of The Upper Cretaceous El Gallo Formation, El Rosario, Baja California, Mexico, Reilly F. Hayes, Marisol Montellano-Ballesteros, Gerardo Álvarez-Reyes, René Hernandez-Rivera, David E. Fastovsky

Senior Honors Projects

Over the past eight months, I have collaborated with paleontologists from the Universidad Nactional Autónoma de México to formally describe plant fossils they uncovered in Baja California between their 2013 and 2016 field seasons. We report the first floral assemblage of the dinosaur-aged El Gallo Formation, Baja California, Mexico, a small (82-specimen) collection of plant fossils from fossil soils contained within the 75.84 +/- 0.05 to 74.55 +/- 0.09 million-year-old El Disecado Member of the unit. A compound fruit belonging to the genus Operculifructus, previously reported from the 3.40 to 1.08 million year younger Cerro del Pueblo Formation, Coahuila, …


Basement And Cover Structural Analysis Along The Eagle River Gorge, Sawatch Range, Colorado, Kaitlin Lee Askelson May 2017

Basement And Cover Structural Analysis Along The Eagle River Gorge, Sawatch Range, Colorado, Kaitlin Lee Askelson

Electronic Theses and Dissertations

The Sawatch Range within the Rocky Mountains of central Colorado exposes Paleoproterozoic basement and overlying Paleozoic sedimentary rocks with a complex history of ductile and brittle deformation.

The goal of this study is to conduct analyses of brittle structures that occur in the basement and cover units to determine geometric relationships between the structures, provide a detailed description of structures and refine a geologic history for structures along the basement-cover contact in the northeastern Sawatch Range along the Eagle River canyon and U.S. Highway 24 from Red Cliff to Gilman, Colorado. Paleoproterozoic basement rocks include the Cross Creek granite, diorites, …


Spatiotemporal Analyses Of Recycled Water Production, Jana E. Archer May 2017

Spatiotemporal Analyses Of Recycled Water Production, Jana E. Archer

Electronic Theses and Dissertations

Increased demands on water supplies caused by population expansion, saltwater intrusion, and drought have led to water shortages which may be addressed by use of recycled water as recycled water products. Study I investigated recycled water production in Florida and California during 2009 to detect gaps in distribution and identify areas for expansion. Gaps were detected along the panhandle and Miami, Florida, as well as the northern and southwestern regions in California. Study II examined gaps in distribution, identified temporal change, and located areas for expansion for Florida in 2009 and 2015. Production increased in the northern and southern regions …


Cranial Morphological Distinctiveness Between Ursus Arctos And U. Americanus, Benjamin James Hillesheim May 2017

Cranial Morphological Distinctiveness Between Ursus Arctos And U. Americanus, Benjamin James Hillesheim

Electronic Theses and Dissertations

Despite being separated by millions of years of evolution, black bears (Ursus americanus) and brown bears (Ursus arctos) can be difficult to distinguish based on skeletal and dental material alone. Complicating matters, some Late Pleistocene U. americanus are significantly larger in size than their modern relatives, obscuring the identification of the two bears. In the past, fossil bears have been identified based on differences in dental morphology or size. This study used geometric morphometrics to look at overall differences in cranial shape and used step-wise discriminant analysis to identify specific characters that distinguish cranial morphology between …


The 2016 North Atlantic Hurricane Season: A Season Of Extremes, Jennifer Collins, David R. Roache May 2017

The 2016 North Atlantic Hurricane Season: A Season Of Extremes, Jennifer Collins, David R. Roache

School of Geosciences Faculty and Staff Publications

The 2016 North Atlantic hurricane season had an early start with a rare and powerful storm for January impacting the Azores at hurricane force. Likewise, the end of season heralded Otto which was record breaking in location and intensity being a high‐end Category 2 storm at landfall over southern central America in late November. We show that high precipitable water, positive relative vorticity, and low sea level pressure allowed for conducive conditions. During the season, few storms occurred in the main development region. While some environmental conditions were conducive for formation there (such as precipitable water, relative vorticity, and shear), …


Strain Release At The Trench During Shallow Slow Slip: The Example Of Nicoya Peninsula, Costa Rica, Yan Jiang, Zhen Liu, Earl E. Davis, Susan Y. Schwartz, Timothy H. Dixon, Nicholas K. Voss, Rocco Malservisi, Marino Protti May 2017

Strain Release At The Trench During Shallow Slow Slip: The Example Of Nicoya Peninsula, Costa Rica, Yan Jiang, Zhen Liu, Earl E. Davis, Susan Y. Schwartz, Timothy H. Dixon, Nicholas K. Voss, Rocco Malservisi, Marino Protti

School of Geosciences Faculty and Staff Publications

The near‐trench behavior of subduction megathrust faults is critical for understanding earthquake hazard and tsunami generation. The shallow subduction interface is typically located in unconsolidated sediments that are considered too weak to accumulate elastic strain. However, the spectrum of shallow fault slip behavior is still elusive, due in large part to the lack of near‐field observations. Here we combine measurements from seafloor pressure sensors near the trench and an onshore GPS network in a time‐dependent inversion to image the initiation and migration of a well‐documented slow slip event (SSE) in 2007 at the Nicoya Peninsula, Costa Rica. Our results show …


Black Bears (Ursus Americanus) Versus Brown Bears (U. Arctos): Combining Morphometrics And Niche Modeling To Differentiate Species And Predict Distributions Through Time, Theron Michael Kantelis May 2017

Black Bears (Ursus Americanus) Versus Brown Bears (U. Arctos): Combining Morphometrics And Niche Modeling To Differentiate Species And Predict Distributions Through Time, Theron Michael Kantelis

Electronic Theses and Dissertations

Late Pleistocene American black bears (Ursus americanus) often overlap in size with Pleistocene brown bears (U. arctos), occasionally making them difficult to diagnose. Large U. americanus have previously been distinguished from U. arctos by the length of the upper second molar (M2). However, the teeth of fossil U. americanus sometimes overlap size with U. arctos. As such, there is need for a more accurate tool to distinguish the two species. Here, 2D geometric morphometrics is applied to the occlusal surface of the M2 to further assess the utility of this tooth for distinguishing U. americanus and …


An Analysis Of The Relationship Between Snowpack And Groundwater Across Utah Watersheds., Samuel Wright May 2017

An Analysis Of The Relationship Between Snowpack And Groundwater Across Utah Watersheds., Samuel Wright

Electronic Theses and Dissertations

This thesis examined what type of relationship existed between snow water equivalence (SWE) volume and groundwater elevation within six sub-watersheds in Utah. Data was gathered on SWE from seventeen SNOTEL sites and groundwater elevation data was gathered from six continuously monitored groundwater wells. This data was gathered for January through May for 2011, 2013, and 2014 in order to represent the water conditions that were above average, below average, and average respectively. Using MLR formulas the total SWE for each sub-watershed was determined for each year/month. Afterwards a correlation analysis was performed to determine if any association existed between SWE …


Comparison Of Flow Dynamics And Bifurcation Angles In Tributary And Distributary Channel Networks, Thomas Coffey May 2017

Comparison Of Flow Dynamics And Bifurcation Angles In Tributary And Distributary Channel Networks, Thomas Coffey

Graduate Theses and Dissertations

The dynamics of channel mouth bifurcations on river deltas can be understood using theory developed in tributary channel networks. Bifurcations in groundwater-fed tributary networks have been shown to evolve dependent on diffusive ground water flow patterns

directly adjacent to the channel network, producing a critical angle of 72°. We test the hypothesis that bifurcation angles in distributary channel networks are likewise dictated by a diffusive external flow field, in this case the shallow surface water surrounding the subaqueous portion of distributary channels in a deltaic setting. We measured 25 unique distributary bifurcations in an experimental delta and 197 bifurcations in …


Depositional Dynamics Of The Upper Eagle Ford (Upper Cretaceous): Karnes And Gonzales Counties, South Texas, Josie Brunick May 2017

Depositional Dynamics Of The Upper Eagle Ford (Upper Cretaceous): Karnes And Gonzales Counties, South Texas, Josie Brunick

Graduate Theses and Dissertations

The mixed siliciclastic/carbonate late Cretaceous Eagle Ford Formation is commonly divided into the lower Eagle Ford and the upper Eagle Ford. The lower Eagle Ford is arguably the most obvious organic rich interval highlighted with wireline log data; however, the upper Eagle Ford may have just as much potential for hydrocarbon production success as the lower Eagle Ford has had. A better understanding of the upper Eagle Ford will allow a more thorough and educated assessment into its full potential as an unconventional reservoir, and allow its sweet spots for oil or gas to be found and exploited.

This study …


Phosphate Release: The Effect Of Prebiotic Organic Compounds On Dissolution Of Merrillite, Whitlockite, Chlorapatite, And Fluorapatite, Courtney Lea Bartlett May 2017

Phosphate Release: The Effect Of Prebiotic Organic Compounds On Dissolution Of Merrillite, Whitlockite, Chlorapatite, And Fluorapatite, Courtney Lea Bartlett

UNLV Theses, Dissertations, Professional Papers, and Capstones

Phosphate is an essential nutrient on Earth, used by life for ATP, DNA, RNA, and phospholipid membranes. Therefore, if life is or ever was present on Mars, phosphorus may have played an important role in determining the habitability of an environment. Phosphorus does not have a significant volatile phase; its release from minerals is consequently critical to phosphorus availability and prebiotic chemistry. Phosphate release from Mars-relevant minerals such as merrillite and chlorapatite has been previously found to differ significantly from phosphate release from fluorapatite, the dominant phosphate phase on Earth. However, the environments in which phosphate release would have been …


Late Cretaceous Extensional Collapse Of The Southern Cordillera: Evidence From The Bristol And Granite Mountains, Se California, Lee Hess May 2017

Late Cretaceous Extensional Collapse Of The Southern Cordillera: Evidence From The Bristol And Granite Mountains, Se California, Lee Hess

UNLV Theses, Dissertations, Professional Papers, and Capstones

Demonstrating the regional extent of Late Cretaceous extensional collapse of western North America’s southern Cordillera is important to understanding the tectonic evolution of the Sevier-Laramide orogens, and the geodynamics of ancient and modern orogens and synconvergent extension. Documenting Late Cretaceous extension in the southern Cordillera requires looking through the extensive overprint by Cenozoic structures. Late Cretaceous extension in the eastern Mojave region has been inferred from geochronology and thermochronology studies, which document Late Cretaceous cooling of Mesozoic granitoid rocks, some of which were emplaced in the middle crust. Cooling histories from these rocks have also been interpreted to be a …