A5050939502- Geological and Geochemical Analysis
- Geochemistry and Geologic Mapping
- Geology and Paleoclimatology Research
- earthquake and tectonic studies
- Mineralogy and Gemology Studies
- Radioactive element chemistry and processing
- High-pressure geophysics and materials
- Radioactive contamination and transfer
- Groundwater and Isotope Geochemistry
- Groundwater flow and contamination studies
- Isotope Analysis in Ecology
- Geological Studies and Exploration
- Radioactivity and Radon Measurements
- Mercury impact and mitigation studies
- Hydrocarbon exploration and reservoir analysis
- Water Quality and Resources Studies
- Geological formations and processes
- Marine and environmental studies
- Heavy metals in environment
- Geochemistry and Elemental Analysis
- Paleontology and Stratigraphy of Fossils
- Atmospheric and Environmental Gas Dynamics
- Landslides and related hazards
- Astro and Planetary Science
- Botany, Ecology, and Taxonomy Studies
United States Geological Survey
2013-2022
Denver Federal Center
2008-2021
Denver School of Nursing
2017
Pacific Island Ecosystems Research Center
2006-2008
Royal Ontario Museum
1998
Institute of Precambrian Geology and Geochronology
1993-1997
We present strontium isotopic (88Sr/86Sr and 87Sr/86Sr) results obtained by 87Sr–84Sr double spike thermal ionization mass-spectrometry (DS-TIMS) for several standards as well natural water samples mineral of abiogenic biogenic origin. The detailed data reduction algorithm a user-friendly Sr-specific stand-alone computer program used the calibration are also presented. Accuracy precision our δ88Sr measurements, calculated permil (‰) deviations from NIST SRM-987 standard, were evaluated...
Abstract Garnet granulite facies xenoliths hosted in Devonian lamprophyres from the Kola Peninsula are interpreted to represent high-grade metamorphic equivalents of continental flood tholeiites, emplaced into Baltic Shield Archaean lower crust early Proterozoic time. Geochronological data and similarities major trace element geochemistry suggest that formed during same plume-related magmatic event created a widespread Palaeoproterozoic large igneous province (LIP) at 2·4–2·5 Ga. They are,...
The Pea Ridge iron oxide-apatite (IOA) deposit is one of the major rhyolite-hosted magnetite deposits St. Francois Mountains terrane, which located within Mesoproterozoic (1.5–1.3 Ga) Granite-Rhyolite province in U.S. Midcontinent. Precise and accurate determination timing duration oreforming processes this crucial for understanding its origin placing it a deposit-scale regional geologic context. Apatite monazite, well-established U-Pb mineral geochronometers, are abundant orebody. However,...
ABSTRACT U-Pb zircon geochronology of Mesoproterozoic (Subjotnian) rapakivi complexes in central Sweden yields: 1526 ± 3 Ma (Mullnäset), 1524 (Mårdsjö), 1520 (Nordsjö) and 1497 6 (Rödön). Together with further S Sweden, they constitute the westernmost, youngest (1·53−1·47 Ga) belt magmatism Fennoscandian shield. The low initial ε Nd values (−8·9 to −4·8) all studied Subjotnian basic, intermediate silicic rocks, require an input from old (Archaean) low-radiogenic source component, as evidence...
New high-resolution chemostratigraphy, in combination with updated biostratigraphy, refines the chronostratigraphic resolution of nearly 2 km thick Ordovician section below Anticosti Island. A total 1414 horizons, spaced at 1.0–1.5 m intervals, were sampled from Associated Consolidated Paper (NACP) drill core and analyzed for major trace elemental composition by portable X-ray fluorescence analyzer (pXRF). Select micrite calcareous shale powders then δ 13 C carb (number samples, N = 364) 87...
Abstract Textural, geochronological, and geochemical data are presented here for cassiterite from the giant (149.7 million tonnes [Mt]) Mesoproterozoic Sullivan Pb-Zn-Ag deposit, which has been subjected to several tectonothermal events. These provide constraints on age origin of tin concentrations new insights into related base metal mineralization. is rare among sediment-hosted, stratiform deposits in having high contents ore (up 2.5 wt %; avg 310 ppm Sn). Cassiterite occurs all facies...
The Aammeberg Zn-Pb ore district constitutes the southern margin of Bergslagen mining in south-central Sweden. It is hosted by a succession Paleoproterozoic supracrustal units belonging to Svecofennian domain and was considered as genetically distinct within already at beginning this century. most prominent deposit Zinkgruvan which has been major zinc producer for more than 100 years. In paper, results from an investigation stratigraphy, geochemistry, U-Pb Sm-Nd isotope systematics are...