Provenance in the lower Belt-Purcell Supergroup is constrained based on geochemical systematics and chemical monazite ages of argillites and sandstones. Rare earth element (REE), Cr-Ni, and Th/Sc-Sc systematics is equivalent for both facies and consistent with a dominantly post-Archean source area. Detrital monazite chemical ages restrict major provenance for the Appekunny and Grinnell sandstones and argillites to Paleoproterozoic terranes at ~1800-1600 Ma, minor contributions at ~1600-1500 Ma, and marginal contributions from Archean terranes at ~2600, likely in Laurentia. Similar detrital age spectra for monazites of argillites and sandstones of the Appekunny Formation are consistent with a common provenance for the two facies.</p> <p>The Belt-Purcell sequence records three major diagenetic stages displayed in argillites and sandstones: (1) K-addition and rare earth element post-Archean upper continental crust (PA-UCC)-like pattern; (2) a stage characterized by heavy REE enrichment relative to light REE and HFSE fractionation, and U and Ce mobility; and (3) local dolomitization with REE and high field strenght elements (HFSE) mobility. REE and HFSE mobility are interpreted as the result of oxidized alkaline brines developed by dissolution of evaporites. Monazites from the Appekunny and Grinnell formations differ compositionally and texturally in two groups. Rounded or inclusions with ages >~1400 Ma, interpreted as detrital, have higher Th2O, Y2O3 and lower LREE/HREE contents than euhedral individual monazite grains with chemical ages <~1400 Ma that posses opposed compositional characteristics, and viewed as diagenetic. Monazites that span <~1400 to 300 Ma could be the result of basinal brine activity during stages (2) and (3). </p> <p>Chemical index of alteration (CIA) for argillites and sandstones, corrected for a diagenetic K-addition average 73 and 66 respectively. These results, coupled with correlation of CIA with Eu/Eu*, low K/Cs ratios, and low Sr, Ca, and Na relative to PA-UCC, could be interpreted as the result of an moderate weathered provenance in a hot, wet climate being drained by a large-scale river system. Presence of minor pristine feldspars lowers the CIA values, and may signify minor contributions from proximal source with short-river transport under the arid to semi-arid climate in the depositional setting. Moderate to intense weathering of the larger provenance may be associated with elevated levels of atmospheric CO2 degassed from a mantle plume implicated in the rifting of the supercontinent Columbia at ~1500 Ma.

Water samples were collected from coastal region off southwestern Taiwan during two cruises in different seasons (October, 2008 and March, 2010). In order to provide information for trace elements in this region, this study investigated the distribution and partitioning of dissolved trace elements (Cd, Cu, Ni, Zn), and to relate the influences of complicated hydrological conditions to trace element distributions. Fractionation of dissolved trace elements was applied by a one-step preconcentration technique which uses cationic and anionic exchange columns. Trace element fractions were separated to operationally defined reactive (Chelex-labile), organically complexed (anionic-organic), and stable (inert) species. Distributions of trace elements from near-shore surface waters off southwestern Taiwan were mainly affected by temporally variable terrigenous inputs and hydrological conditions. The most significant sources of trace elements were from the Gao-Ping, Er-Ren, and Tseng-Wen Rivers. Some near-shore vertical profiles of trace elements and nutrients showed abnormal distributions that could be attributed to complicated currents in this region. Trace elements in waters at offshore stations in this study showed nutrient-type distributions, and that is similar to other open ocean vertical profiles, except for the upper layers, where terrestrial influences were pronounced in this study. The major proportions of trace elements determined in this study were of the Chelex-labile fractions, indicating that they were reactive and bioavailable. There is a small part of inert fraction, and the proportions are different between inshore and offshore waters, with pronounced inert fractions in near-shore waters.

Thesis (Ph. D.)--Rutgers University, 2008. / "Graduate Program in Environmental Sciences." Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 82-95).

Thesis (M. Phil.)--University of Hong Kong, 1983.

Thesis (M. Phil.)--University of Hong Kong, 1984.

A small piece of sample collected from a contact calcium-skarn aureole in San Shek Wan of Lantau Island surprisingly shows abundance of Thorium (Th) and Rare Earth Elements (REEs). Concentration of these trace elements in skarn is of special interest for its impact to human health and its economic values. Concentration of these elements in skarn is closely related to the tectonic setting, the initial magma chemistry and the depth of magma intrusion where the skarn is being formed. These variables in skarn formation process can be analyzed by studying the geology of the area, accompanied by analyzing mineralogy of the skarn. Mineral zoning of garnet-pyroxene prograde skarn and chemical zoning within garnet crystal also provide clues to the pressure-temperature condition when the skarn aureole was formed. Impact of these elements to human health is evaluated by abundance of these elements exposed and assessed through various means – radiation, inhalation and ingestion. / published_or_final_version / Applied Geosciences / Master / Master of Science

published_or_final_version / Zoology / Master / Master of Philosophy

Sulfate, nitrate, and certain trace elements are common groundwater contaminants observed at mining sites. Their source, fate, and remediation were investigated at a former uranium mining site. First, groundwater samples collected across the site were analyzed for geochemistry, stable isotopes, and trace elements. Then, two pilot-scale ethanol injection tests were conducted for biostimulation of nitrate and sulfate reduction. Groundwater was monitored in the test area before and after the tests. The results showed a mixing of two discrete sources of sulfate. Quantification of these two sources using two methods showed that sulfide-mineral oxidation of the mine tailings served as a steady but low-discharge source while sulfuric acid (applied during ore processing in the 1960s) served as a variable, strong source. It appears that sulfuric acid served as a sustained source of sulfate for approximately 40 years. This source may be from accumulation of sulfate salts (formed from sulfuric acid) in the source zone due to the arid climate of the site. Results showing correspondence of isotopic compositions of ammonium and nitrate confirmed the generation of nitrate via nitrification. Moreover, it was observed that ammonium concentration is closely related to concentrations of uranium and a series of other trace elements including chromium, selenium, vanadium, iron, and manganese. It is hypothesized that ammonium-nitrate transformation processes influence the disposition of the trace elements through mediation of redox potential, pH, and possibly aqueous complexation and solid-phase sorption. As for the biostimulation, sulfate reduction condition has been maintained for a period of approximately 3 years after a single input. Atypical fractionation behavior of the delta34S in sulfate was hypothesized to be caused by release of sulfate from sulfate minerals associated with the sediments. Elevated hydrogen sulfide concentrations were not observed until approximately four months after the start of the test. This behavior, in concert with the observed changes in aqueous iron and manganese species, suggests that hydrogen sulfide produced from sulfate reduction was precipitated, presumably in the form of iron sulfides, until the exhaustion of readily reducible iron oxides. Hydrogen sulfide produced thereafter appears to have been in part re-oxidized.

No description available.