Geochemistry Commons^™

Ecosystem Regime Change Inferred From The Distribution Of Trace Metals In Lake Erie Sediments, Fasong Yuan, Richard Depew, Cheryl Soltis-Muth

Biological, Geological, and Environmental Faculty Publications

Many freshwater and coastal marine ecosystems across the world may have undergone an ecosystem regime change due to a combination of rising anthropogenic disturbances and regional climate change. Such a change in aquatic ecosystems is commonly seen as shifts in algal species. But considerably less detail is known about the eutrophication history in terms of changes in algal productivity, particularly for a large lake with a great deal of spatial variability. Here we present an analysis of trace metals (Cu, Ni, Cd, and Pb) on a sediment core recovered from Lake Erie, off the Vermilion coast of northern Ohio, USA, …

Toward Understanding The Thermodynamics And Mechanisms Of Actinide Sorption Reactions, Shanna Estes

All Dissertations

The environmental fate of actinides is greatly influenced by interfacial reactions, including sorption onto solid surfaces. Because changes in the primary hydration sphere of the actinide are expected to greatly influence the thermodynamics (i.e., reaction enthalpy and entropy) of these reactions, examining actinide sorption thermodynamics may provide insight into actinide sorption mechanisms. Additionally, examining actinide sorption thermodynamics may enhance the ability to model or predict these reactions in environmental or engineered systems where variable or elevated temperatures are expected. However, few researchers have studied actinide sorption thermodynamics. Therefore, this research examined the thermodynamics of Eu(III) (a trivalent actinide analog), Th(IV), …

Subalklaine Volcanism In The Eastern Basin And Range Province: Examples From The Miocene Mccullough Range Volcanic Field And The Pliocene To Holocene Black Rock Desert Volcanic Field, Racheal Leighann Johnsen

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation is composed of three papers that apply geologic mapping, whole rock geochemical and isotopic analysis, and mineral chemistry to describe two large, long-lived (~6 million years), and compositionally heterogeneous volcanic fields and posit sources of the rock types present in each. These fields are the McCullough Range in southern Nevada, which was a locus of volcanic activity from ~19 - 12 Ma and the Black Rock Desert volcanic field in west-central Utah, which began forming at ~6 Ma and is still active today, with the most recent eruption occurring ~720 years ago.

Chapter Two is composed of a …

New Early Miocene 40ar/39ar Ages For Nakwai, Northwest Kenya, Africa, And Paleontological Analysis Of Meroehyrax Kyongoi Dentition, Dawn Elena Reynoso

UNLV Theses, Dissertations, Professional Papers, and Capstones

Nakwai is a fossiliferous region in the Turkana Basin of northwestern Kenya. Until recently the only ages for the Nakwai formation were based on biostratigraphic correlation with Losodok; a late Oligocene site located to the north of Nakwai. The new 40Ar/39Ar ages in this study range from 23 Ma to 15 Ma and constrain the upper portions of the Nakwai section to the early Miocene. These ages make it the only securely dated fossil locality in the region that represents the earliest Miocene; all of the other early Miocene fossil localities date back to ~20 Ma or younger. The time …

Range Of Horizontal Transport And Residence Time Of Nitrate In A Mature Karst Vadose Zone, Jiri Kamas, Jiri Bruthans, Helena Vysoka, Miroslav Kovařík

International Journal of Speleology

Nitrate concentrations in drips in Amaterska, Spolecnak, and Holstejnska caves situated below a 25 to 120 m thick vadose zone in the Moravian Karst, Central Europe were studied during several periods from 1992. Each cave runs below a land-use boundary between fertilized lands and forest, which enabled study of the range of horizontal components of nitrate transport in the vadose zone. Parts of the fertilized land were turned into grassland in 1998 and 2003, and the cave drips were sampled both prior and after the changes in land use. The mean residence time of nitrate is - 30 m thick …

Can Xrf Scanning Of Speleothems Be Used As A Non-Destructive Method To Identify Paleoflood Events In Caves?, Martin Finné, Malin Kylander, Meighan Boyd, Hanna S. Sundqvist, Ludvig Löwemark

International Journal of Speleology

We have developed a novel, quick and non-destructive method for tracing flood events in caves through the analysis of a stalagmite thick section with an XRF core scanner. The analyzed stalagmite has multiple horizons of fine sediments from past flood events intercalated with areas of cleaner calcite. Flood events detected from the elemental XRF core scanning data show good agreement with the position of flood horizons identified in petrographic thin sections. The geochemical composition of the individual flood layers shows that in certain cases the clay horizons had a distinct geochemical fingerprint suggesting that it may be possible to distinguish …

Mantle-Crust Interaction In Granite Petrogenesis In Post-Collisional Settings: Insights From The Danubian Variscan Plutons Of The Romanian Southern Carpathians, Ciprian Cosmin Stremtan

USF Tampa Graduate Theses and Dissertations

The issue of granite petrogenesis plays a key role in our overall understanding of the growth and differentiation of continents, as well as in our ability to unravel the tectonic histories of orogenic belts. Granites are ubiquitous magmatic products found in almost all tectonic settings: oceanic and continental rifts (i.e., plagiogranites - extreme basalt differentiates), active continental margins (e.g,. the granitic batholiths of central and southern Andes), continent-continent collision zones (e.g., the orogenic batholiths of the Himalayas, Western Anatolia), post-collisional settings (e.g., the Variscan provinces of Europe), complex within-plates settings (e.g., Limmo massif, Afar, Ethiopia). Furthermore, granitoids are characterized by …

Sedimentology Of The Upper Scotland Formation (Eocene), Barbados, Krishna Mahabir, Nazrul I. Khandaker, Jay P. Persaud, Stanley Schleifer

Publications and Research

Representative samples collected from the Lower Scotland Formation (Eocene) outcropping in northeastern Barbados were investigated in conjunction with overall facies distribution and stratigraphic and sedimentological characteristics to interpret depositional environment and provenance of the fine-grained clastics. The Lower Scotland Formation is, for the most part, a fine-grained clastic-dominated sequence with occasional thin intercalations of gypsum, ironstone, and kaolinite. Distinctive deep-water-facies have been well-documented in dark gray shale units containing load cast, flutes, grooves and prods. In addition, turbiditic brown sandstone with a sharp erosive base and pelagic caps also characterize the base of the formation. Notable marine fauna observed include …

Iron Sources And Dissolved-Particulate Interactions In The Seawater Of The Western Equatorial Pacific, Iron Isotope Perspectives, M. Labatut, F. Lacan, C. Pradoux, J. Chmeleff, A. Radic, J. W. Murray, F. Poitrasson, Anne M. Johansen, F. Thil

All Faculty Scholarship for the College of the Sciences

This work presents iron isotope data in the western equatorial Pacific. Marine aerosols and top core margin sediments display a slightly heavy Fe isotopic composition (δ⁵⁶Fe) of 0.33 ± 0.11‰ (2SD) and 0.14 ± 0.07‰, respectively. Samples reflecting the influence of Papua New Guinea runoff (Sepik River and Rabaul volcano water) are characterized by crustal values. In seawater, Fe is mainly supplied in the particulate form and is found with a δ⁵⁶Fe between −0.49 and 0.34 ± 0.07‰. The particulate Fe seems to be brought mainly by runoff and transported across continental shelves and slopes. …

Geogram 2014, David J. Keeling Editor, Wku Department Of Geography And Geology

Earth, Environmental, and Atmospheric Sciences Publications

No abstract provided.

The Interaction Between Arsenic And Struvite During Coprecipitation And Adsorption Processes, Ning Ma

Dissertations, Theses, and Capstone Projects

The formation of struvite, MgNH4PO4*6H2O (MAP), from wastes is one of the methods that can be used to recover P from wastes efficiently. However, since there are usually toxic components in the wastes, like arsenic (As), the possibility of having toxic contaminants in MAP is a big concern. So, the interaction between As and MAP during coprecipitation (CPT) and adsorption (ADS) processes were studied at pH 8-11. MAP precipitated without As at pH 8-11 was also characterized.

During CPT process, the MAP was precipitated from a MgCl2-(NH4)2HPO4-NaCl-H2O system spiked with As at an initial pH (pHi) of 8-11. The batch …

Noble Gases Identify The Mechanisms Of Fugitive Gas Contamination In Drinking-Water Wells Overlying The Marcellus And Barnett Shales, Thomas H. Darrah, Avner Vengosh, Robert B. Jackson, Nathaniel R. R. Warner, Robert J. Poreda

Dartmouth Scholarship

Horizontal drilling and hydraulic fracturing have enhanced energy production but raised concerns about drinking-water contamination and other environmental impacts. Identifying the sources and mechanisms of contamination can help improve the environmental and economic sustainability of shale-gas extraction. We analyzed 113 and 20 samples from drinking-water wells overlying the Marcellus and Barnett Shales, respectively, examining hydrocarbon abundance and isotopic compositions (e.g., C2H6/CH4, δ13C-CH4) and providing, to our knowledge, the first comprehensive analyses of noble gases and their isotopes (e.g., 4He, 20Ne, 36Ar) in groundwater near shale-gas wells. We addressed two questions. (i) Are elevated levels of hydrocarbon gases in …

Economic Geology Of The San Bernardino Mountains, California, Nicolette Deannah Grill

Electronic Theses, Projects, and Dissertations

The San Bernardino Mountains are well known for their rich mining history, especially, gold in the mid-1800s and the current mining of one of the world’s largest deposits of high purity limestone. The purpose of this study was to compile new, current, and historical data of the major economic resources that are present and mining that has gone on in the San Bernardino Mountains. It is estimated that historical mining of the Holcomb Valley recovered $457,660,000 of gold or about 350,000 troy ounces based on samples collected for this study and 2013 gold price. The current major geologic resource is …

History And Dynamics Of Net Rotation Of The Mantle And Lithosphere, Maxwell L. Rudolph, Shijie Zhong

Geology Faculty Publications and Presentations

The net rotation of Earth’s lithosphere with respect to the underlying mantle is the longestwavelength component of toroidal flow in the mantle and is sensitive to both mantle buoyancy structure and lateral viscosity variations. The lithospheric net rotation in the geologic past implied by plate reconstructions using a hotspot reference frame for the past 100 Myr is up to five times greater than the presentday rate of lithospheric net rotation. We explore the role of lateral viscosity variations associated with subcontinental keels in producing the lithospheric net rotation for the geologic past and find that the introduction of subcontinental keels …

Assessing The Influence Of Mineral Surface Chemistry On Soil Organic Matter Stability In The Us In Response To Climate Change, Alexandra Toledo, Katherine Heckman

STAR Program Research Presentations

Soils represent a significant pool for carbon storage and sequestration. Previous field experiments have indicated that some mineral compositions are more effective in preserving soil organic matter (SOM) from microbial degradation. Due to climate change, it is important to quantify which soil types are changing in mineral surface chemistry. One way to do that is by differentiating the SOM stabilization mechanisms in different soil types at various depths. This study focused on examining the distribution of soil mass and composition by the soils density and mineral classification and the soils stability by measuring the amount of carbon and radiocarbon abundance. …

Geochemical Analysis Of Ice Age River Deposits From Turlock Lake Formation, Cemex Quarry Fresno, Ca, Ray J. Bargas

STAR Program Research Presentations

Nineteen bags of Pleistocene Age river deposited samples were taken from the Cemex Quarry in Fresno, CA. There are three formations in the area, deposited from rivers derived from glaciers, consisting of the Modesto, Riverbank, and Turlock Lake; youngest deposited to oldest respectively.

Phi sizes refer to each of the individual grains diameter, larger sized grains are in the negative spectrum while smaller grains are positive. Each sample has phi size bags that range in sizes from -5 to 4+, excluding phi size -2. For the phi sizes of -3 to -5, each individual rock was measured on its three …

Carbon Cycling Dynamics Inferred From Carbon Isotope Sourcing In A Mid-Latitude Karst-Influenced River, Kegan N. Mcclanahan

Masters Theses & Specialist Projects

As ever-increasing levels of carbon dioxide alter the chemistry of the Earth’s atmosphere, understanding the global carbon cycle becomes increasingly important. A particularly important component is the riverine carbon cycle, as rivers are the primary conduits for dissolved inorganic carbon from terrestrial watersheds to ocean basins. Stable carbon isotopes (13C/12C) were collected weekly and input into the mixing model IsoSource to delineate seasonal carbon sourcing along two nested basins in the upper Green River System, Kentucky. In the more siliciclastic upstream catchment, dissolved inorganic carbon (DIC) was primarily derived from soil respiration (34%). Groundwater dissolving carbonate bedrock and carbonate dissolution/precipitation …

The Monica (Monitoring Of Ice Within Caves) Project: A Multidisciplinary Approach For The Geophysical And Paleoclimatic Characterization Of Permanent Ice Deposits In The Southeastern Alps, Renato R. Colucci, Emanuele Forte, Barbara Stenni, Marco Basso Bondini, Mauro Colle Fontana, Costanza Del Gobbo, Daniele Fontana, Doriana Belligoi, Valter Maggi, Marco Filipazzi

The International Workshop on Ice Caves

On days 30 September and 1-2 October 2013, a 7.8 m long ice core has been extracted from a permanent ice cave deposit in the Southeastern Alps (Vasto’s cave, Mt.Canin - Julian Alps). Each 20 to 100 cm long section of the ice core have been immediately stored in plastic bags and preserved thanks to dry ice. The ice samples, thanks to the helicopter, has been subsequently brought on valley and promptly stored in a refrigerated van, made available by BoFrost. Thus the ice cores has been transported intact to the EUROCOLD laboratory in Milan. These operations have been carried …

Ice Caves On Extraterrestrial Bodies: What Are The Prospects For Speleogenesis And Detection?, Penelope J. Boston

The International Workshop on Ice Caves

Potential mechanisms for creating cavities in icy extraterrestrial bodies have been tentatively explored by several authors. On one hand we have examples of mechanisms that create caves in water ice here on Earth. In addition, there may be unique mechanisms on other Solar System objects that do not occur on Earth but might produce cavities, e.g. sublimation of comets upon perihelion passage. The methods of detecting such cavities depend upon the nature of the icy body in question, the potential for orbital or landed missions to visit those bodies in the future, and remote or landed methods for detecting the …

Porphyry Copper Exploration Of The Hualapai Mountains, Mohave County, Arizona, Usa: A Multi-Faceted Approach, Patrick Kevin Meazell

UNLV Theses, Dissertations, Professional Papers, and Capstones

A variety of exploration methods including geologic mapping, trace- and major-level geochemical analyses, fluid inclusion petrography, remote sensing, and SWIR clay spectroscopy were used to investigate the potential for porphyry Cu-Mo mineralization at the Wikieup prospect, in the southern Hualapai Mountains of northwestern Arizona. Aspects of the Mineral Park mine were used as an analogue to guide exploration due to the proximity and similar geology of the area.

The Hualapai Mountains are a series of northwest-trending Precambrian gneisses, schists, granitoids and amphibolites that have been cut by younger intrusive rocks. Within the Wikieup study area, the intrusive rocks include aplite …