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Full-Text Articles in Geology

Newgeochemical Evidence For The Origin Of North America's Largest Dune Field, The Nebraska Sand Hills, Central Great Plains, Usa, Daniel R. Muhs, James R. Budahn Feb 2019

Newgeochemical Evidence For The Origin Of North America's Largest Dune Field, The Nebraska Sand Hills, Central Great Plains, Usa, Daniel R. Muhs, James R. Budahn

United States Geological Survey: Staff Publications

The Nebraska SandHills region is the largest dune field inNorthAmerica and has diverse aeolian landforms. It has been active during both the late Pleistocene and late Holocene. Despite decades of study, the source of sediment for this large sand sea is still controversial. Here we report new trace element compositions of aeolian sand that are compared to four hypothesized sediment sources, Tertiary rocks of the Arikaree Group and Ogallala Group, unconsolidated sands of Pliocene age, and Platte River systemsands. All four potential sources have amineralogy that is similar to the Nebraska Sand Hills. K/Rb, K/Ba, Sc-Th-La, Eu/Eu*, LaN/YbN, As/Sb, and …


Pace And Process Of Active Folding And Fluvial Incision Across The Kantishna Hills Anticline, Central Alaska, A. M. Bender, R. O. Lease, P. J. Haeussler, Tammy M. Rittenour, L. B. Corbett, P. R. Bierman, M. W. Caffee Feb 2019

Pace And Process Of Active Folding And Fluvial Incision Across The Kantishna Hills Anticline, Central Alaska, A. M. Bender, R. O. Lease, P. J. Haeussler, Tammy M. Rittenour, L. B. Corbett, P. R. Bierman, M. W. Caffee

Geosciences Faculty Publications

Rates of northern Alaska Range thrust system deformation are poorly constrained. Shortening at the system's west end is focused on the Kantishna Hills anticline. Where the McKinley River cuts across the anticline, the landscape records both Late Pleistocene deformation and climatic change. New optically stimulated luminescence and cosmogenic 10Be depth profile dates of three McKinley River terrace levels (~22, ~18, and ~14–9 ka) match independently determined ages of local glacial maxima, consistent with climate‐driven terrace formation. Terrace ages quantify rates of differential bedrock incision, uplift, and shortening based on fault depth inferred from microseismicity. Differential rock uplift and incision (≤1.4 …


Melt Inclusions And Their Application - New Perspective On The Subsurface Architecture Of Cerro Negro Volcano, Nicaragua, John M. Hamilton Feb 2019

Melt Inclusions And Their Application - New Perspective On The Subsurface Architecture Of Cerro Negro Volcano, Nicaragua, John M. Hamilton

Earth and Planetary Sciences ETDs

Volatiles are the drivers of volcanic eruptions and monitoring and measurement in quiescent times are the key in determining when unrest within a volcanic system is beginning leading to possible cataclysms. Previous studies have focused on direct measurements from volcanic plumes or fumaroles, however, this study proposes the use of melt inclusions from tephra to determine volatile contents from the 1992 eruption of Cerro Negro Volcano, Nicaragua. The analysis of melt inclusions adds a new technique to the volatile analytical toolbox and can help to determine volatile contents from past eruptions and their subsequent evolution within a volcanic system.

Though …


Informing Water Use Decision-Making For Waterfowl And Agricultural Production On A Ranch Along The North Platte River, Nebraska, Douglas R. Hallum P.G. Feb 2019

Informing Water Use Decision-Making For Waterfowl And Agricultural Production On A Ranch Along The North Platte River, Nebraska, Douglas R. Hallum P.G.

Conservation and Survey Division: Faculty and Staff Publications

In 2014, operators of a ranch along the North Platte River approached Conservation and Survey Division seeking expertise to interpret data collected on their ranch. The interpretations inform ranch decisions to accomplish operators’ goals. This publication documents the work by: 1) characterizing the ranch, 2) summarizing data collected, 3) characterizing hydrogeology of the site and the adjacent reach, and 4) conceptualizing groundwater/surface water interaction.

The ranch is a recreation property and a migratory waterfowl refuge with a few general goals: 1) develop and maintain high-quality wet meadow habitat, 2) maximize the extent and duration of surface water on the property …


Seismic Tremor Reveals Spatial Organization And Temporal Changes Of Subglacial Water System, Margot E. Vore, Timothy C. Bartholomaus, J. Paul Winberry, Jacob I. Walter, Jason M. Amundson Feb 2019

Seismic Tremor Reveals Spatial Organization And Temporal Changes Of Subglacial Water System, Margot E. Vore, Timothy C. Bartholomaus, J. Paul Winberry, Jacob I. Walter, Jason M. Amundson

All Faculty Scholarship for the College of the Sciences

Subglacial water flow impacts glacier dynamics and shapes the subglacial environment. However, due to the challenges of observing glacier beds, the spatial organization of subglacial water systems and the time scales of conduit evolution and migration are largely unknown. To address these questions, we analyze 1.5‐ to 10‐Hz seismic tremor that we associate with subglacial water flow, hat is, glaciohydraulic tremor, at Taku Glacier, Alaska, throughout the 2016 melt season. We use frequency‐dependent polarization analysis to estimate glaciohydraulic tremor propagation direction (related to the subglacial conduit location) and a degree day melt model to monitor variations in melt‐water input. We …


Investigations Of The Potential For Irrigated Agriculture On The Bonaparte Plains: Bore Completion Report, 2nd Edition, D L. Bennett Feb 2019

Investigations Of The Potential For Irrigated Agriculture On The Bonaparte Plains: Bore Completion Report, 2nd Edition, D L. Bennett

Resource management technical reports

Drilling programs were undertaken in 2013 and 2016 by the former Department of Agriculture and Food, Western Australia and in 2017 by DPIRD, at 10 sites in the Bonaparte Plains area, north of Kununurra in the East Kimberley region of Western Australia (WA).

These drilling programs were a component of resource availability and risk investigations conducted to determine the potential for developing irrigated agriculture on 30 000 hectares of Cockatoo Sands — free-draining loamy soils that have the potential to support crops in the wet and dry seasons. There was limited hydrogeological information available at a suitable scale for the …


In Situ Geochemistry Of Middle Ordovician Dolomites Of The Upper Mississippi Valley, Achim D. Herrmann Feb 2019

In Situ Geochemistry Of Middle Ordovician Dolomites Of The Upper Mississippi Valley, Achim D. Herrmann

Faculty Publications

The dolomitization and diagenetic history of Ordovician carbonates of southern Wisconsin is complex. Previous studies attributed dolomitization to various diagenetic factors and environments. In this study, high-resolution, in situ laser ablation inductively coupled mass spectrometry analysis of rare earth element patterns of dolomite was used to assess the diagenetic fluids responsible for dolomitization of the Ordovician Decorah Formation. Integrated geochemical data and petrographic evidence suggest that the dolostones are formed in two different diagenetic realms: shallow burial and hydrothermal. Shallow burial dolomites exhibit three distinct rare earth element patterns. Dolomite from the middle portion of the Guttenberg Member exhibits light …


Cache Valley: Liquefaction, Out-Of-Sync Earthquakes, Lake Bonneville, And Linking Up The West Cache Fault Zone, Susanne U. Jänecke, Robert Q. Oaks Jr., Nathan Ellis, James P. Evans, A. J. Knight, Justin Oakeson Feb 2019

Cache Valley: Liquefaction, Out-Of-Sync Earthquakes, Lake Bonneville, And Linking Up The West Cache Fault Zone, Susanne U. Jänecke, Robert Q. Oaks Jr., Nathan Ellis, James P. Evans, A. J. Knight, Justin Oakeson

Geosciences Faculty Publications

No abstract provided.


Comparison Of Microbial Communities In The Sediments And Water Columns Of Frozen Cryoconite Holes In The Mcmurdo Dry Valleys, Antarctica, Pacifica Sommers, John L. Darcy, Dorota L. Porazinska, Eli M. S. Gendron, Andrew G. Fountain, Felix Jacob Zamora, Kim Vincent, Kaelin M. Cawley, Adam J. Solon, Lara Vimercati, Jenna Ryder, Steven K. Schmidt Feb 2019

Comparison Of Microbial Communities In The Sediments And Water Columns Of Frozen Cryoconite Holes In The Mcmurdo Dry Valleys, Antarctica, Pacifica Sommers, John L. Darcy, Dorota L. Porazinska, Eli M. S. Gendron, Andrew G. Fountain, Felix Jacob Zamora, Kim Vincent, Kaelin M. Cawley, Adam J. Solon, Lara Vimercati, Jenna Ryder, Steven K. Schmidt

Geology Faculty Publications and Presentations

Although cryoconite holes, sediment-filled melt holes on glacier surfaces, appear small and homogenous, their microbial inhabitants may be spatially partitioned. This partitioning could be particularly important for maintaining biodiversity in holes that remain isolated for many years, such as in Antarctica. We hypothesized that cryoconite holes with greater species richness and biomass should exhibit greater partitioning between the sediments and water, promoting greater biodiversity through spatial niche partitioning. We tested this hypothesis by sampling frozen cryoconite holes along a gradient of biomass and biodiversity in the Taylor Valley, Antarctica, where ice-lidded cryoconite holes are a ubiquitous feature of glaciers. We …


First Description Of Subglacial Megalineations From The Late Paleozoic Ice Age In Southern Africa., Graham Dm Andrews, Andrew T. Mcgrady, Shannon M. Maynard Jan 2019

First Description Of Subglacial Megalineations From The Late Paleozoic Ice Age In Southern Africa., Graham Dm Andrews, Andrew T. Mcgrady, Shannon M. Maynard

Faculty & Staff Scholarship

We identify late Paleozoic ice age (LPIA) subglacial megalineations from field and geospatial imagery of the Twyfelfontein area of northern Namibia, and present the results of a geomorphometric analysis of those data. Asymmetric 0.1–1.5 km-long megawhalebacks indicate a paleo-ice flow to the northwest. We infer that an ice stream draining the LPIA Kaokoveld ice sheet existed within the proto-Huab River valley and that was comparable to ice streams in modern Antarctica. Recognition of a paleo-ice stream in northern Namibia supports interpretations of glaciogenic sedimentary successions (Itararé Group) in southern Brazil that suggest the presence of major, terrestrial glacial outlet systems …


Evaluation Of An Educational Campaign To Improve The Conscious Consumption Of Recreationally Caught Fish, Corey A. Krabbenhoft, Susan Manente, Donna R. Kashian Jan 2019

Evaluation Of An Educational Campaign To Improve The Conscious Consumption Of Recreationally Caught Fish, Corey A. Krabbenhoft, Susan Manente, Donna R. Kashian

Environmental Science and Geology Faculty Research Publications

Consumption guidelines are a common way of improving conscious consumption behaviors in areas where game fish are known to contain contaminants. However, guideline information can be difficult to distribute, and effectiveness difficult to measure. To increase the distribution and effectiveness of guideline information for the Detroit River, an educational campaign was launched in 2010, which included distribution of pamphlets with consumption information, posting of permanent signs at popular fishing locations, and hiring River Walkers to personally communicate with anglers. In 2013 and 2015, we conducted in-person surveys of active shoreline anglers to determine the effectiveness of education and outreach efforts. …


Speleothem Paleoclimatology For The Caribbean, Central America, And North America, Jessica L. Oster, Sophie F. Warken, Natasha Sekhon, Monica M. Arienzo, Matthew Lachniet Jan 2019

Speleothem Paleoclimatology For The Caribbean, Central America, And North America, Jessica L. Oster, Sophie F. Warken, Natasha Sekhon, Monica M. Arienzo, Matthew Lachniet

Geoscience Faculty Research

Speleothem oxygen isotope records from the Caribbean, Central, and North America reveal climatic controls that include orbital variation, deglacial forcing related to ocean circulation and ice sheet retreat, and the influence of local and remote sea surface temperature variations. Here, we review these records and the global climate teleconnections they suggest following the recent publication of the Speleothem Isotopes Synthesis and Analysis (SISAL) database. We find that low-latitude records generally reflect changes in precipitation, whereas higher latitude records are sensitive to temperature and moisture source variability. Tropical records suggest precipitation variability is forced by orbital precession and North Atlantic Ocean …


Iron Fertilization With Enhanced Phytoplankton Productivity Under Minimal Sulfur Compounds And Grazing Control Analysis In Hnlc Region, Tai-Jin Kim, G. H. Hong, D. G. Kim Kim, Mark Baskaran Jan 2019

Iron Fertilization With Enhanced Phytoplankton Productivity Under Minimal Sulfur Compounds And Grazing Control Analysis In Hnlc Region, Tai-Jin Kim, G. H. Hong, D. G. Kim Kim, Mark Baskaran

Environmental Science and Geology Faculty Research Publications

The present study investigated quantitatively the significance of HNLC (high-nutrient low-chlorophyll) regions and its grazing control with the im- proved iron fertilization for climate change. The limitation of iron (Fe) for phytoplankton growth in HNLC regions was confirmed by sulfur compounds (S) such as volcanic ash and hydrogen sulfide (H2S) in batch cultures, whose chemical sediment of Fe3S4 showed 4.06 wt%. The technologies developed for iron fertilization since 1993 till now were not practical to provide sufficient amounts of bioavailable iron due to sedimentary iron sulfides induced by undersea volcanic sulfur compounds. The proposed technology for iron fertilization was improved …


Geoarchaeological Evidence Of Middle-Age Tsunamis At Stromboli And Consequences For The Tsunami Hazard In The Southern Tyrrhenian Sea, M. Rosi, S. T. Levi, M. Pistolesi, A. Bertagnini, D. Brunelli, V. Cannavo, A. Di Renzoni, F. Ferranti, A. Renzulli, D. Yoon Jan 2019

Geoarchaeological Evidence Of Middle-Age Tsunamis At Stromboli And Consequences For The Tsunami Hazard In The Southern Tyrrhenian Sea, M. Rosi, S. T. Levi, M. Pistolesi, A. Bertagnini, D. Brunelli, V. Cannavo, A. Di Renzoni, F. Ferranti, A. Renzulli, D. Yoon

Publications and Research

Large-scale landslides at volcanic islands are one of the most dangerous geological phenomena, able to generate tsunamis whose effects can propagate far from the source. However, related deposits are scarcely preserved on-land in the geologic records, and are often difficult to be interpreted. Here we show the discovery of three unprecedented well-preserved tsunami deposits related to repeated flank collapses of the volcanic island of Stromboli (Southern Italy) occurred during the Late Middle Ages. Based on carbon datings, on stratigraphic, volcanological and archaeological evidence, we link the oldest, highest-magnitude investigated tsunami to the following rapid abandonment of the island which was …


Elastic Plastic Self-Consistent (Epsc) Modeling Of San Carlos Olivine Deformed In A D-Dia Apparatus, Pamela C. Burnley, Shirin Kaboli Jan 2019

Elastic Plastic Self-Consistent (Epsc) Modeling Of San Carlos Olivine Deformed In A D-Dia Apparatus, Pamela C. Burnley, Shirin Kaboli

Geoscience Faculty Research

We present a suite of low strain deformation experiments conducted on polycrystalline San Carlos olivine in a deformation DIA apparatus at temperatures ranging from 440 to 1106 °C at pressures between 3.8 and 4.6 GPa. The deformation behavior was monitored using in situ diffraction of white synchrotron X‑rays. The experiments were conducted at a slow strain rate of ~5 × 10–6/s so as to allow the initial elastic behavior to be closely monitored. For each experiment, we fit the diffraction data using elastic plastic self-consistent (EPSC) models. We find that to model the experiments we must incorporate an isotropic deformation …


Short Communication: The Topographic Analysis Kit (Tak) For Topotoolbox, Adam M. Fortes Jan 2019

Short Communication: The Topographic Analysis Kit (Tak) For Topotoolbox, Adam M. Fortes

Faculty Publications

Quantitative analysis of digital topographic data is an increasingly important part of many studies in the geosciences. Initially, performing these analyses was a niche endeavor, requiring detailed domain knowledge and programming skills, but increasingly broad, flexible, open-source code bases have been developed to increasingly democratize topographic analysis. However, many of these analyses still require specific computing environments and/or moderate levels of knowledge of both the relevant programming language and the correct way to take these fundamental building blocks and conduct an efficient and effective topographic analysis. To partially address this, we have written the Topographic Analysis Kit (TAK), which leverages …


Landslides Near Enguri Dam (Caucasus, Georgia) And Possible Seismotectonic Effects, Alessandro Tibaldi, Paolo Oppizzi, John S. Gierke, Thomas Oommen, Nino Tsereteli, Zurab Gogoladze Jan 2019

Landslides Near Enguri Dam (Caucasus, Georgia) And Possible Seismotectonic Effects, Alessandro Tibaldi, Paolo Oppizzi, John S. Gierke, Thomas Oommen, Nino Tsereteli, Zurab Gogoladze

Department of Geological and Mining Engineering and Sciences Publications

The Enguri dam and water reservoir, nested in the southwestern Caucasus (Republic of Georgia), are surrounded by steep mountain slopes. At a distance of 2.5 km from the dam, a mountain ridge along the reservoir is affected by active deformations with a double vergence. The western slope, directly facing the reservoir, has deformations that affect a subaerial area of 1.2 km2. The head scarp affects the Jvari–Khaishi–Mestia main road with offsets of man-made features that indicate slip rates of 2–9 cm yr−1. Static, pseudostatic and Newmark analyses, based on field and seismological data, suggest different unstable …


Using A Case Study Approach To Teach Invasive Species And Climate Change, Amanda Hoover, Bradley Blaha, Jacob Englin, Madhav P. Nepal, Larry B. Browning, Matt L. Miller, P. Troy White Jan 2019

Using A Case Study Approach To Teach Invasive Species And Climate Change, Amanda Hoover, Bradley Blaha, Jacob Englin, Madhav P. Nepal, Larry B. Browning, Matt L. Miller, P. Troy White

iLEARN Teaching Resources

In this teaching module, students will explore emerald ash borer (EAB), its impacts on the ash trees, and how warming temperatures could affect EAB populations. The emerald ash borer is a green buprestid or jewel beetle native to north-eastern Asia that causes devastating disease in ash trees.


Northeastern China 4.2ka Database, Louis A. Scuderi, Xiaoping Yamg, Samantha Ascoli, Hongwei Li Jan 2019

Northeastern China 4.2ka Database, Louis A. Scuderi, Xiaoping Yamg, Samantha Ascoli, Hongwei Li

Paleoclimate Datasets

The Hunshandake Sandy Lands of northeastern China, currently a semiarid lightly vegetated region, were characterized by perennial lakes and forest stands in the early and middle Holocene. Well-developed dark grassland-type paleosols (mollisols) at the southern edge of the Hunshandake OSL-dated to between 6.93 +0.61 and 4.27 +0.38 ka along with lacustrine sands at higher elevations that date to between 5.7 +0.3 and 5.2 +0.2 ka and thick gray lacustrine sediments suggest a wetter climate. Between 4.2 and 3.8 ka, the region experienced extreme drying that was exacerbated by lake overflow drainage and sapping that depleted the groundwater table. The region …


The Molluscan Taphofacies Of And Influence Of Callianassid Shrimp On A Carbonate Lagoon (St. Croix, Us Virgin Islands), Rowan Lee Jan 2019

The Molluscan Taphofacies Of And Influence Of Callianassid Shrimp On A Carbonate Lagoon (St. Croix, Us Virgin Islands), Rowan Lee

Honors Papers

Sediments collect in reef lagoons, and the shells within these can record changes in the environment as they accumulate. Smuggler’s Cove (St. Croix, USVI) has been accumulating a sediment package for at least 5,000 years based on radiocarbon ages. Callianassid shrimp severely bioturbate this lagoon’s sediment package by moving shell material into shelly, subsurface lags that have a high chance of becoming fossilized. Shell condition (taphonomy) was compared between surface and lag to see whether the lag is an accurate representation of the living surface fauna. Guild membership, taxon, and mollusk size between surface and lag assemblages were analyzed. It …


Meteorological Comparison Of Three Cave Systems, Matthew Wine Jan 2019

Meteorological Comparison Of Three Cave Systems, Matthew Wine

Mahurin Honors College Capstone Experience/Thesis Projects

Cave systems are home to delicate underground ecosystems that can be affected by changes in surface atmospheric conditions which in turn affect underground meteorology. Modern human use of caves is typically for tourism, so understanding surface-underground weather-climate interactions is important when caves carry streams that are prone to flooding in response to surface precipitation. The purpose of this research is to document the effects of surface weather conditions on cave meteorology in three different cave system types located in different geographic locations including an island, the central USA, and at high elevations in British Columbia. The study caves include Kaumana …


Ua84 Sigma Chi, Wku Archives Jan 2019

Ua84 Sigma Chi, Wku Archives

WKU Archives Collection Inventories

Records created by and about the WKU chapter of Sigma Xi.


Ua66/8/2 Ogden College Of Science & Engineering Geography & Geology Centers & Institutes, Wku Archives Jan 2019

Ua66/8/2 Ogden College Of Science & Engineering Geography & Geology Centers & Institutes, Wku Archives

WKU Archives Collection Inventories

Records created by and about Centers and Institutes administered by the Geography & Geology Department. Including:

  • Center for Cave & Karst Studies
  • Center for Local Government Services
  • Hoffman Environmental Research Institute
  • Kentucky Climate Center
  • Resources Management Institute
  • Small Public Water System Technology Center


Ua66/8/1 Ogden College Of Science & Engineering Geography & Geology Events, Wku Archives Jan 2019

Ua66/8/1 Ogden College Of Science & Engineering Geography & Geology Events, Wku Archives

WKU Archives Collection Inventories

Records created for Geography & Geology department events.


Ua66/8/5 Ogden College Of Science & Engineering Geography & Geology Student Organizations, Wku Archives Jan 2019

Ua66/8/5 Ogden College Of Science & Engineering Geography & Geology Student Organizations, Wku Archives

WKU Archives Collection Inventories

Records created by and about student organizations associated with the Geography & Geology department, including the Geography & Geology Club aka Semple Geographic Society.


The Bear River's Diversion And The Cutting Of Oneida Narrows At ~55-50 Ka And Relations To The Lake Bonneville Record, Joel L. Pederson, Tammy M. Rittenour, Susanne U. Jänecke, Robert Q. Oaks Jr. Jan 2019

The Bear River's Diversion And The Cutting Of Oneida Narrows At ~55-50 Ka And Relations To The Lake Bonneville Record, Joel L. Pederson, Tammy M. Rittenour, Susanne U. Jänecke, Robert Q. Oaks Jr.

Geosciences Presentations

The Bear River’s course has shifted over Quaternary time, and its late Pleistocene integration into the Bonneville basin long has been recognized as a possible explanation for why Lake Bonneville was apparently larger than the preceding lakes in its basin, and the only one to overflow its topographic threshold.

The middle-Pleistocene Bear River joined the Snake River to the north, likely via the Portneuf River drainage. Then an episode of volcanism in the Blackfoot-Gem Valley volcanic field ~100–50 ka diverted the Bear River southward into Gem Valley. Previous chronostratigraphic and isotopic work on the Main Canyon Formation in southern Gem …


Stable Isotopes Of Clay Minerals From Autoclave Tests Of Oil Sands: Implications For Clay Formation During Steaming Of Alberta Clearwater Oil Sands, Shaoneng He, Fred J. Longstaffe, Zhihong Zhou Jan 2019

Stable Isotopes Of Clay Minerals From Autoclave Tests Of Oil Sands: Implications For Clay Formation During Steaming Of Alberta Clearwater Oil Sands, Shaoneng He, Fred J. Longstaffe, Zhihong Zhou

Earth Sciences Publications

In an effort to evaluate mineral-water isotopic exchange during cyclic steam stimulation (CSS), solutions and<2 μm berthierine-dominated solids from the Clearwater Formation oil sands of Alberta, Canada were analyzed for stable isotope compositions before and after reaction in autoclaves for 1008 h at 250 °C. There was no significant change in solution δ18O and δ2H, which is consistent with the high water/mineral ratio used in the experiments. The solids showed a marked decrease in both δ18O and δ2H following the experiments. Pre-run solids have δ18O of +9.5 to +12.9‰and …


Fluid-Present Anatexis Of Neoarchean Tonalite And Amphibolite In The Western Shandong Province, Chris Yakymchuk, Wenran Zhao, Yusheng Wan, Shoufa Lin, Fred Longstaffe Jan 2019

Fluid-Present Anatexis Of Neoarchean Tonalite And Amphibolite In The Western Shandong Province, Chris Yakymchuk, Wenran Zhao, Yusheng Wan, Shoufa Lin, Fred Longstaffe

Earth Sciences Publications

Metatonalite and amphibolite from the Taishan region of the Western Shandong Province in the North China Craton record c. 2.60 Ga fluid-present partial melting via the breakdown of biotite, plagioclase and quartz to produce peritectic hornblende and anatectic melt. Eight paired leucosome–melanosome samples from metatonalite and three paired samples from amphibolite were investigated to evaluate the composition of the melt. Hornblende, biotite and plagioclase in the leucosomes and hornblende and plagioclase in melanosomes from both rock types have similar compositions. Two leucosome samples from the metatonalite were influenced by the removal of heavy rare earth element-rich hornblende and the accumulation …


Stable Isotopic Characterization Of A Coastal Floodplain Forest Community: A Case Study For Isotopic Reconstruction Of Mesozoic Vertebrate Assemblages, Thomas M. Cullen, Fred Longstaffe, Ulrich G. Wortmann, Mark B. Goodwin, Li Huang, David C. Evans Jan 2019

Stable Isotopic Characterization Of A Coastal Floodplain Forest Community: A Case Study For Isotopic Reconstruction Of Mesozoic Vertebrate Assemblages, Thomas M. Cullen, Fred Longstaffe, Ulrich G. Wortmann, Mark B. Goodwin, Li Huang, David C. Evans

Earth Sciences Publications

Stable isotopes are powerful tools for elucidating ecological trends in extant vertebrate communities, though their application to Mesozoic ecosystems is complicated by a lack of extant isotope data from comparable environments/ecosystems (e.g. coastal floodplain forest environments, lacking significant C4 plant components). We sampled 20 taxa across a broad phylogenetic, body size, and physiological scope from the Atchafalaya River Basin of Louisiana as an environmental analogue to the Late Cretaceous coastal floodplains of North America. Samples were analysed for stable carbon, oxygen and nitrogen isotope compositions from bioapatite and keratin tissues to test the degree of ecological resolution that can …


Prehistoric Chaco Canyon, New Mexico: Importation Of Meat And Mmaize, Larry V. Benson, Deanna Grimstead, John R. Stein, David A. Rith, Terry L. Plowman Jan 2019

Prehistoric Chaco Canyon, New Mexico: Importation Of Meat And Mmaize, Larry V. Benson, Deanna Grimstead, John R. Stein, David A. Rith, Terry L. Plowman

United States Geological Survey: Staff Publications

In a recent paper, Benson and Grimstead (2019) determined that only minimal amounts of maize could have been grown in Chaco Canyon due to its aridity, short growing season, and frequent summer flooding of the valley floor. In this paper it is shown that deer and rabbit densities within semiarid regions such as the Canyon are such that 2300 Canyon residents would eliminate essentially all small and large mammals within a year. This implies that food (meat and maize) must have been imported from one or more outlying areas to feed the Canyon's residential population. This would have entailed ~18,000 …