C. J. Eastoe

University of Arizona

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Tadeusz Marek Peryt

Polish Geological Institute

Austin Long

California State University, Northridge

Arturo Hernández‐Antonio

Tecnológico de Monterrey

C. Tamez-Meléndez

TU Wien

A. Ramírez-Orozco

Tecnológico de Monterrey

Robert M. Kalin

University of Strathclyde

José Alfredo Ramos‐Leal

Institute for Scientific and Technological Research

Paul E. Damon

University of Arizona

Jürgen Mahlknecht

Tecnológico de Monterrey

Ailiang Gu

University of Arizona

Cooperative Institutions

University of Arizona

Chinese Academy of Sciences

Tecnológico de Monterrey

National Academy of Sciences of Ukraine

New Mexico Institute of Mining and Technology

New Mexico Bureau of Geology and Mineral Resources

Arizona Geological Survey

University of Michigan–Ann Arbor

University of Chinese Academy of Sciences

Polish Geological Institute

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Groundwater flow processes and mixing in active volcanic systems: the case of Guadalajara (Mexico)

Hydrology and earth system sciences (2015)

Arturo Hernández‐Antonio Jürgen Mahlknecht C. Tamez-Meléndez José Alfredo Ramos‐Leal A. Ramírez-Orozco

Abstract. Groundwater chemistry and isotopic data from 40 production wells in the Atemajac and Toluquilla valleys, located in and around the Guadalajara metropolitan area, were determined to develop a conceptual model of groundwater flow processes and mixing. Stable water isotopes (δ2H, δ18O) were used to trace hydrological processes and tritium (3H) to evaluate the relative contribution of modern water in samples. Multivariate analysis including cluster analysis and principal component analysis were used to elucidate distribution patterns of constituents and factors controlling groundwater chemistry. Based on this analysis, groundwater was classified into four groups: cold groundwater, hydrothermal groundwater, polluted groundwater and mixed groundwater. Cold groundwater is characterized by low temperature, salinity, and Cl and Na concentrations and is predominantly of Na-HCO3-type. It originates as recharge at "La Primavera" caldera and is found predominantly in wells in the upper Atemajac Valley. Hydrothermal groundwater is characterized by high salinity, temperature, Cl, Na and HCO3, and the presence of minor elements such as Li, Mn and F. It is a mixed-HCO3 type found in wells from Toluquilla Valley and represents regional flow circulation through basaltic and andesitic rocks. Polluted groundwater is characterized by elevated nitrate and sulfate concentrations and is usually derived from urban water cycling and subordinately from agricultural return flow. Mixed groundwaters between cold and hydrothermal components are predominantly found in the lower Atemajac Valley. Twenty-seven groundwater samples contain at least a small fraction of modern water. The application of a multivariate mixing model allowed the mixing proportions of hydrothermal fluids, polluted waters and cold groundwater in sampled water to be evaluated. This study will help local water authorities to identify and dimension groundwater contamination, and act accordingly. It may be broadly applicable to other active volcanic systems on Earth.

10.5194/hess-19-3937-2015

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Intercomparison of High-Precision ¹⁴C Measurements at the University of Arizona and the Queen's University of Belfast Radiocarbon Laboratories

Radiocarbon (1995)

Robert M. Kalin F. G. McCormac Paul E. Damon C. J. Eastoe Austin Long

High-precision measurements were completed concurrently at the University of Arizona and the Queen's University of Belfast on blind samples of Irish oak originally measured for the 1986 radiocarbon calibration curve. Subsequent single-year Sequoiadendron results were decadally averaged and compared with published results on decadal Douglas-fir samples. The results of these intercomparisons show that the Arizona high-precision results compare favorably with published values from the University of Washington, but show a systematic offset with published Belfast data.

Queen (butterfly)

Northern Ireland

10.1017/s0033822200014764

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Stable and Radiogenic Isotope Evidence Relating to Regional Groundwater Flow Ssystems Originating in the High Sacramento Mountains, New Mexico

AGUFM (2005)

C. J. Eastoe Barry J. Hibbs

Radiogenic nuclide

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Isotopic composition of carbonates in the SNC meteorites, Allan Hills 84001 and Zagami

Journal of Geophysical Research Atmospheres (1997)

A. J. T. Jull C. J. Eastoe S. Cloudt

We have measured the 13 C/ 12 C and 14 C/ 12 C ratios in CO 2 released by acid etching of the meteorites Zagami and Allan Hills 84001. We use the 14 C as a label to identify extraterrestrial carbonate phases, as they will have a low 14 C/ 12 C ratio (< ∼ 4% modern terrestrial ratio) compared to recent terrestrial material. The new studies on Allan Hills 84001 confirm previous conclusions that the Fe, Mg‐rich carbonate grains in this meteorite contain carbon with δ 13 C as high as +45‰. In contrast, the carbon released from Zagami is depleted in 13 C with δ 13 C as low as ∼20‰. We conclude that the isotopic composition of the carbon as carbonate released from acid etching of Zagami is different from the carbonates observed in both Allan Hills 84001 and Nakhla. With the assumption that all of these meteorites sample the surface of Mars, we propose that the Zagami carbonate samples a different carbon reservoir on this planet, such as a magmatic source. With this interpretation, the high δ 13 C values of carbonate observed in Allan Hills 84001 and Nakhla can be ascribed to a fractionated source compared with the originally light carbon. A likely origin for this 13 C‐enriched component is an isotopically heavy Martian atmosphere; however, given the possibility of biological activity involving Allan Hills carbonates, we cannot exclude this as a source of the isotopic fractionation.

10.1029/96je03111

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Stable chlorine isotopes in Phanerozoic evaporites

Applied Geochemistry (2006)

C. J. Eastoe Tadeusz Marek Peryt Oleh Y. Petrychenko D. Geisler-Cussey

Halite

10.1016/j.apgeochem.2006.12.012

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Citations (89)

New trial methods for the detection of carbon and nitrogen in quartz samples

Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms (2007)

Kyeong Ja Kim W.J. Trompetter C. J. Eastoe M. Spilde

Carbon fibers

Neutron Activation Analysis

Isotopes of nitrogen

10.1016/j.nimb.2007.01.177

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Stable chlorine isotopes in hydrothermal processes

Geochimica et Cosmochimica Acta (1992)

C. J. Eastoe John M. Guilbert

Fluorite

Halite

δ34S

10.1016/0016-7037(92)90265-k

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Citations (78)

Stable chlorine isotope evidence for non‐marine chloride in Badenian evaporites, Carpathian mountain region

Terra Nova (1999)

C. J. Eastoe Tadeusz Marek Peryt

Routine trace‐element geochemistry suggests that components in putative marine halite evaporites may be partly of nonmarine origin, but such interpretations are commonly ambiguous. Stable chlorine isotopes may provide a less‐ambiguous marker of chloride origin where δ 37 Cl departs from the range predicted for evaporite formation from seawater. Bedded halite with primary sedimentary textures preserves original δ 37 Cl values. Measurable change in δ 37 Cl can be generated by incongruent dissolution of halite, but only if less than half the original halite remains. Badenian (middle Miocene) halite from the Forecarpathian and from the East Slovakian and Transcarpathian basins has a δ 37 Cl range of – 0.2 to 0.8‰. Two phenomena cannot be explained by simple evaporation of 0.0‰ seawater. At Wieliczka, the Shaft Salt has distinctive δ 37 Cl values (– 0.2 to 0.0‰) relative to neighbouring salt beds (0.2 to 0.6‰), requiring a large, abrupt input of brine with negative δ 37 Cl. Halite with high (0.6 – 0.8‰) δ 37 Cl near the base of the East Slovakian and Transcarpathian evaporites requires a large input of chloride with positive δ 37 Cl into the basins. Expulsion of basin brine with non‐0‰δ 37 Cl into the evaporite basins may account for the nonmarine chloride sources.

Halite

Brine

10.1046/j.1365-3121.1999.00235.x

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Citations (60)

Reservoir Corrections for Marine Samples from the South Atlantic Coast, Santa Catarina State, Brazil

Radiocarbon (2002)

C. J. Eastoe S. Fish Paul R. Fish Maria Dulce Gaspar Austin Long

Coeval shell and charcoal from Santa Catarina State, Brazil, differ systematically in 14 C content, indicating a reservoir effect in marine samples. For modern samples (AD 1939–2000) and archeological samples (2500–1595 BP), the mean 14 C age difference between marine and atmospheric carbon is 220 ± 20 years, the marine carbon being older. For three samples dated AD 1939–1944, a distinct reservoir correction of 510 ± 10 years is also observed. The ages of archeological shell samples from Jabuticabeira may be corrected by subtracting 220 years from the apparent 14 C ages.

Charcoal

10.1017/s0033822200064742

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Citations (37)

Paleoclimate Reconstruction Based on Isotope Amount Effects: Caveats Arising from Multi-Decade Records for Tucson, New Delhi and Hong Kong

AGU Fall Meeting Abstracts (2013)

C. J. Eastoe David L. Dettman

Paleoclimatology

New delhi

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Citations (1)