Browsing Geology by Title
Now showing items 151-170 of 172
-
SULFUR ISOTOPE RECORDS IN NEOARCHEAN CARBONATES: IMPLICATIONS FOR THE EARLY PRECAMBRIAN SULFUR CYCLE
(2017)Mass-independent fractionation of sulfur isotopes found in Early Precambrian records is the main evidence supporting an oxygen-poor atmosphere before ~2.4 Ga when ancient sulfur cycling was different than today. In previous ... -
Sulfur isotopic evolution of Phanerozoic and Ediacaran seawater sulfate
(2013)Dynamics of &sigma34S and &sigma33S of oceanic sulfate and sedimentary pyrite over geologic time has been used to understand and extract information about the marine sulfur cycle. My Ph.D project uses this approach to study ... -
Supercritical Fluid Extraction of Hydrocarbons from the Marcellus Shale by Using CO2
(2014)Supercritical carbon dioxide was used to extract n-aliphatic hydrocarbons from samples of Marcellus shale, and to evaluate recovery as a function of sample matrix particle size (sieve size). Results show that supercritical ... -
Supplementary Research Data for "Brachinites record divergent evolutionary pathways"
(2020)The brachinite family of meteorites records divergent trends of differentiation based on O and S fugacities. We find that S and O-rich materials differentiate into distinct igneous products from reduced counterparts. -
Targeting the spatial context of obesity determinants via multiscale geographically weighted regression
(Springer Nature, 2020-04-05)Obesity rates are recognized to be at epidemic levels throughout much of the world, posing significant threats to both the health and financial security of many nations. The causes of obesity can vary but are often complex ... -
TECTONICS OF ICY SATELLITES DRIVEN BY MELTING AND CRYSTALLIZATION OF WATER BODIES INSIDE THEIR ICE SHELLS
(2015)Enceladus and Europa are icy satellites that currently support bodies of liquid water in the outer solar system Additionally, they show signs of being geologically active. Developing numerical models informed by observations ... -
The tectonics of intraplate regions: Quantifying stress and surface deformation in the central and eastern U.S. and planetary analogs on Mercury and the Moon
(2013)Occurring ~ 1 year apart, the magnitude 3.4 Germantown, Maryland, (16 July 2010) and magnitude 5.8 Mineral, Virginia, (23 August 2011) earthquakes rocked the U.S. national capital region, drawing renewed attention to the ... -
Terrestrial Alteration of CM2 Chondritic Carbonates in a Suite of Paired Antarctic Meteorites.
(2005-06-01)The δ18O, δ17O, δ13C, and δ14C compositions of carbonate grains were measured from paired Antarctic CM2 chondrites (EET96006, EET96016, EET96017, and EET96019). Oxygen isotopic compositions ... -
Theropod guild structure and the tyrannosaurid niche assimilation hypothesis: implications for predatory dinosaur macroecology and ontogeny in later Late Cretaceous Asiamerica.
(Canadian Science Publishing, 2021-06-17)Well-sampled dinosaur communities from the Jurassic through the early Late Cretaceous show greater taxonomic diversity among larger (>50 kg) theropod taxa than communities of the Campano-Maastrichtian, particularly to those ... -
A Time-Series Geochemical Study of the ca. 2.5 Ga Batatal Formation in Brazil: Sulfur and Carbon Isotopic Insights into Environmental Conditions before the Great Oxidation Event
(2013)Neoarchean metasedimentary rocks from the Batatal Formation, Brazil were studied using petrographic, elemental and stable isotopic techniques to provide a better understanding of coupling between the atmosphere-ocean system ... -
Timing of Orogenesis in the Southern Brasília Belt
(2009)The Neoproterozoic-Cambrian Brasília Orogeny records suturing of the passive margin on the western side of the São Francisco Craton with magmatic arcs and the Paranapanema Block in the south or the Amazon Craton in the ... -
Topographic signatures in the Himalaya: A geospatial survey of the interaction between tectonics and erosion in the Modi Khola valley, central Nepal
(2009)Spurred by the recognition that lithologic resistivity to erosion influences the steepness of terrain, the purpose of this study is to enhance our understanding of feedbacks between erosion and tectonics in the Himalaya. ... -
Tracing Continental Weathering Using Lithium and Magnesium Isotopes
(2012)Chemical weathering is an important mechanism that changes the mass and composition of the continental crust and regulates the global CO<sub>2</sub> cycle over geological time scales. Basalt, in particular, is the main ... -
TRACING RETROGRADE METAMORPHIC FLUIDS IN A SUBDUCTION ZONE USING LI: FRANCISCAN COMPLEX, CALIFORNIA
(2012)Centimeter-scale layers of eclogite and blueschist from Tiburon Peninsula, Franciscan Complex, CA were contrasted with a similarly layered sample from Dos Rios, CA. Eclogites from both localities have similar mineral ... -
TRACING SULFUR SOURCES IN AN ARCHEAN HYDROTHERMAL SYSTEM USING SULFUR MULTIPLE ISOTOPES - A CASE STUDY FROM THE KIDD CREEK VOLCANOGENIC MASSIVE SULFIDE DEPOSIT
(2005-07-07)Mass-independent fractionation of sulfur isotopes in the Archean atmosphere resulted in surface sulfur reservoirs with distinct isotopic signatures. These signatures are used to trace the movement of sulfur through an ... -
TRACKING TRANSPORT OF ‘CHEMICAL COCKTAILS’ OF TRACE METALS USING SENSORS IN URBAN STREAMS
(2020)Understanding transport mechanisms and temporal patterns in metals concentrations and fluxes in urban streams are important for developing best management practices and restoration strategies to improve water quality. In ... -
Transport properties and melt distribution of partially molten mantle rocks: insights from micro-computed tomography and virtual rock physics simulations
(2015)Mid-ocean ridges are a fundamental component of plate tectonics on Earth. They are the longest mountain ranges; combined, they stretch over 70,000 km of the Earth’s surface. They are significant sources of volcanism, ... -
TREE TRADE-OFFS IN STREAM RESTORATION: IMPACTS ON RIPARIAN GROUNDWATER QUALITY
(2020)Restoring urban degraded stream channels in efforts to improve water quality often includes substantial alteration of the riparian zone which can require the removal of mature trees. This study assessed the impact of tree ... -
Using Shear Waves to Characterize a Firn Aquifer on the Helheim Glacier in Southeast Greenland
(2019)The Greenland ice sheet is melting at an accelerating rate due to increasing global average temperatures. Ice penetrating radar surveys and ice cores extracted from the southeastern margin of the Greenland ice sheet near ... -
Vegetation-Hydrodynamic Interactions and the Stability of Channel Inlets of Tidal Freshwater Wetlands, Chesapeake Bay System
(2014)To maintain elevation, deposition of mineral and organic sediment in tidal freshwater wetlands (TFWs) must outweigh losses due to sea-level rise, erosion, decomposition, and compaction. Sediment loads into tidal marshes ...