Browsing Geology by Title
Now showing items 64-83 of 172
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HIGH PRESSURE REDOX GEOCHEMISTRY OF TUNGSTEN IN METAL-SILICATE SYSTEMS: IMPLICATIONS FOR CORE FORMATION IN THE EARTH
(2011)Geochemical models of core formation are commonly based on core and mantle abundances of siderophile elements. Because of the affinity of these elements for metallic phases, they are thought to be highly concentrated in ... -
High-Precision Tungsten Isotopic Analysis by Multicollection Negative Thermal Ionization Mass Spectrometry Based on Simultaneous Measurement of W and 18O/16O Isotope Ratios for Accurate Fractionation Correction
(ACS Publications, 2016-01-11)Determination of the 182W/184W ratio to a precision of ±5 ppm (2σ) is desirable for constraining the timing of core formation and other early planetary differentiation processes. However, WO − ... -
Highly Siderophile Element and Tungsten Systematics of Hawaiian Picrites
(2009)A suite of Hawaiian picrites (MgO > 13 wt.%), and associated basalts, that represent some of the most primitive melts from the Hawaiian mantle source regions were analyzed for their W, highly siderophile element (HSE: Os, ... -
Highly Siderophile Elements and the Rhenium-Osmium System in Chondritic Components
(2012)Chondritic meteorites and their components provide information about the early solar system, as well as processes that affected meteorite parent bodies post-accretion. The rare earth element (REE) abundances, highly ... -
Highly Siderophile Elements, 187Re-187Os and 182Hf-182W Isotopic Systematics of Early Solar System Materials: Constraining the Early Evolution of Chondritic and Achondritic Parent Bodies
(2016)Highly siderophile element (HSE) abundances and 187Re-187Os isotopic systematics for H chondrites and ungrouped achondrites, as well as 182Hf-182W isotopic systematics of H and CR chondrites are reported. Achondrite ... -
Hydrograph separation analyses to determine runoff sources in a large, urban watershed
(2010)Hydrograph separation techniques were used to determine contributions of old and new water during storm events at four sites within the urban Anacostia River watershed. Multiple storm hydrographs were successfully separated ... -
HYDROLOGICAL, BIOLOGICAL, AND GEOCHEMICAL RELATIONSHIPS AMONG CARBON, NITROGEN, AND BASE CATIONS IN RESTORED AND UNRESTORED URBAN STREAMS
(2017)Urban infrastructure changes hydrologic flowpaths of water into streams and alters ecosystem function. Geomorphic stream restoration is commonly implemented to stabilize channels, while ecosystem function, and nutrient ... -
Hydrothermally Altered Basalt as a Source for Indium in Ore Deposits
(2018)Indium is an element integral to various emerging technologies. Despite the demand for indium, little is known about its geochemical behavior in hydrothermal systems that generate economic deposits. The aim of this study ... -
Impact of Isotopic Heterogeneity in Shallow Systems on Modeling of Stormflow Generation
(1993)A major uncertainty in hydrologic and geochemical modeling of stormflow generation in watersheds has been quantification of the contributions of water and solutes from different sources and hydrologic pathways to streamwater. ... -
Impacts of Intermediate Water Formation in the North Pacific on Indonesian Throughflow and Equatorial Thermocline Depth: A High Latitude Control for ENSO Variability?
(2008-05-19)Long-term variability in the strength and frequency of the El Niño - Southern Oscillation (ENSO) may be attributable to changes in background climatology. During times of cold climate events in the high latitudes, El Niño ... -
In search of late-stage planetary building blocks
(Elsevier - Chemical Geology, 2015)Genetic contributions to the final stages of planetary growth, including materials associated with the giant Moon forming impact, late accretion, and late heavy bombardment are examined using siderophile elements. Isotopic ... -
INDIUM PARTITIONING BETWEEN FERROMAGNESIAN PHASES AND FELSIC MELTS: SIGNIFICANCE FOR ORE FORMATION AND EXPLORATION
(2017)Indium demand has increased due to the production of cell phone screens, solar cells, alloys, and LED displays. This suggests a need for increased exploration, which can aide in constraining where in space and time ... -
Inference of Mass Anomalies in Planetary Interiors Using a Bayesian Global Gravity Field Inversion
(2020)Knowledge about the interior density distribution of a planetary body can constraingeophysical processes and reveal information about the origin and evolution of the body. Properties of this interior distribution can be ... -
INSIGHTS TO THE GENETICS, AGE AND CRYSTALLIZATION OF GROUP IC AND IIC IRON METEORITES
(2020)Siderophile element isotopic compositions and abundances were determined for the IC and IIC iron meteorite groups to assess whether the members of each group can be related by crystal-liquid fractionation models, constrain ... -
An Integrated Isotopic and Biomarker Analysis of the Glaciogenic Vazante Group, Brazil
(2012)The Vazante Group, a meta-sedimentary succession located in south-central Brazil, contains several intervals of diamictite, interpreted as glacial in origin, bracketed by well-preserved carbonate and shale. This glacial ... -
Inverse Spectral Methods in Acoustic Normal Mode Velocimetry of High Reynolds Number Spherical Couette Flows
(2016)Experimental geophysical fluid dynamics often examines regimes of fluid flow infeasible for computer simulations. Velocimetry of zonal flows present in these regimes brings many challenges when the fluid is opaque and ... -
Investigating the Internal Structure of Earth and Mars with Seismic Body Waves
(2020)Seismic waves propagating through the interior of planetary bodies arepowerful imaging tools for revealing a high-resolution picture of their internal structures. Owing to the abundant seismic data on Earth, seismology has ... -
Isotope and Organic Geochemistry of a Unique Proterozoic, Postglacial Succession: The Lapa Formation, Vazante Group, Brazil
(2007-05-09)This study is the second to investigate biological characteristics associated with Proterozoic glaciation via molecular fossils from organic matter preserved in shale. In the Vazante Group, Minas Gerais, Brazil, the Serra ... -
ISOTOPE GEOCHEMISTRY OF ORGANIC SULFUR COMPOUNDS WITH LINKS TO BIOGEOCHEMICAL SULFUR CYCLING AND RADICAL CHEMISTRY
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THE ISOTOPIC ABUNDANCE OF CESIUM IN TRINITITE: IMPLICATIONS FOR POST-DETONATION ANALYSIS OF NUCLEAR MATERIALS
(2013)Currently, there are few studies of post-detonation materials due to their extremely complex nature. The cesium isotopic composition of trinitite, the product of the first nuclear detonation, was determined using multi-collector ...