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Topic: Isotope geochemistry

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	Isotope geochemistry - Wikipedia, the free encyclopedia
		Isotope geochemistry is an aspect of geology based upon study of the relative and absolute concentrations of the elements and their isotopes in the Earth.
		Lead isotope geochemistry is useful for providing isotopic dates on a variety of materials.
		Because the lead isotopes are created by decay of different transuranic elements, the ratios of the four lead isotopes to one another can be very useful in tracking the source of melts in igneous rocks, the source of sediments and even the origin of people via isotopic fingerprinting of their teeth, skin and bones.
	en.wikipedia.org /wiki/Isotope_geochemistry (850 words)

	Geochemistry - Wikipedia, the free encyclopedia
		The field of geochemistry involves study of the chemical composition of the Earth and other planets, chemical processes and reactions that govern the composition of rocks and soils, and the cycles of matter and energy that transport the Earth's chemical components in time and space, and their interaction with the hydrosphere and the atmosphere.
		Isotope geochemistry: Determination of the relative and absolute concentrations of the elements and their isotopes in the earth and on earth's surface.
		Organic geochemistry: A study of the role of processes and compounds that are derived from living or once-living organisms.
	en.wikipedia.org /wiki/Geochemistry (234 words)

	UC Davis Geology: Geochemistry
		Howard Spero (Ph.D., UC Santa Barbara, 1986): Research focuses on the biological and environmental parameters that affect the stable isotope and trace metal geochemistry of the shells of recent and fossil organisms; marine micropaleontology, paleoclimatology, and paleoceanography.
		The results of this study are being used to interpret fossil foraminifera stable isotope data from Indian and Atlantic Ocean deep sea cores in order to reconstruct paleoenvironmental sea surface temperatures, nutrient levels and CO concentrations during the Pleistocene.
		Environmental geochemistry of mineral deposits; mercury contamination and bioaccumulation associated with historical mining; trace metals and colloid transport in surface waters; acid mine drainage; efflorescent sulfate minerals;application of stable and radiogenic isotopes to environmental problems.
	www.geology.ucdavis.edu /research/geochemistry.html (1274 words)

	USGS -- Isotope Tracers -- Resources -- Isotope Geochemistry
		Isotopes are atoms of the same element that have the same numbers of protons and electrons but different numbers of neutrons.
		As a consequence of fractionation processes, waters and solutes often develop unique isotopic compositions (ratios of heavy to light isotopes) that may be indicative of their source or of the processes that formed them.
		Reaction rates depend on the ratios of the masses of the isotopes and their vibrational energies; as a general rule, bonds between the lighter isotopes are broken more easily than the stronger bonds between the heavy isotopes.
	wwwrcamnl.wr.usgs.gov /isoig/res/funda.html (1607 words)

	Geochemistry at UWO (Site not responding. Last check: 2007-11-01)
		Geochemistry is one of the traditional strengths of the Department of Earth Sciences due to the number and quality of the faculty and the range of their research interests.
		Stable isotope hydrogeology is being used to determine the contributions of different water sources to groundwater, to gain an understanding of the interactions among surface water, precipitation and groundwater reservoirs, and to understand better the cause of increased plant and algal growth in surface waters.
		The stable isotope compositions of methane and carbon dioxide are being used to define the pathways by which these gases are produced and consumed, and the cycling of carbon and water in such freshwater systems on a more general basis.
	www.uwo.ca /earth/research/topics/geochemistry.htm (2162 words)

	Isotope Geochemistry Laboratory
		Lambert D.D., Walker R.J., Morgan J.W., Shirey S.B., Carlson R.W., Zientek M.L., Lipin B.R., Koski M.S. and Cooper R.L. (1994) Re-Os and Sm-Nd isotope geochemistry of the Stillwater Complex, Montana: Implications for the petrogenesis of the J-M Reef.
		Shirey S.B. and Walker R.J. (1988) Re-Os isotopes in cosmochemistry and high-temperature geochemistry.
		Brandon A.D., Walker R.J. and Puchtel I.S. (2006) Platinum-Os isotope evolution of the Earth’s mantle: constraints from chondrites and Os-rich alloys.
	www.geol.umd.edu /pages/facilities/igl.htm (4331 words)

	Isotope Geochemistry (Site not responding. Last check: 2007-11-01)
		Isotope Geochemistry (GEOL 712, 3 credits) is offered alternate even years in the spring term and is an introduction to the use of isotopes in the geological sciences.
		Half of the course is dedicated to the systematics and applications of radiogenic isotope geochemistry, and half to stable isotope geochemistry.
		Hydrothermal Geochemistry (GEOL 713, 2 credits) is taught in spring of alternate odd years and covers geochemistry of minerals found in hydrothermal systems, including mineral solubility, phase equilibria and parameters for mineral transport and deposition for both metallic and non-metallic minerals.
	unr.edu /homepage/arehart/Course_List.htm (451 words)

	Isotope Geoscience Home PageWELCOME TO THE UF ISOTOPE GEOCHEMISTRY HOME PAGE
		he Center for Isotope Geoscience is an interdisciplinary center dedicated to the improvement of analytical techniques for measuring isotopic variations in natural and man-made materials, the application of these data to the solution of fundamental problems in the Geosciences, and the communication of this knowledge through educational activities.
		Geochemistry, isotope geology, and geochronology, particularly the study of crustal evolution emphasizing radiogenic isotopes and rock chemistry.
		Petrology and geochemistry, particularly the chemical and isotopic aspects of modern MORB and arc magma genesis.
	web.geology.ufl.edu /iso1.html (382 words)

	SOFIA - Chronology and Isotope Geochemistry of Ground Waters - Proposal 1998
		Concentrations and isotope mass balances will be examined for evidence relating high ammonium in offshore ground waters to potential sources such as waste water and natural sedimentary organic matter.
		Isotopes and chemistry of around waters will be used for calculating reactions that might represent conversion of seawater into reduced marine ground water; information about the sources of organic constituents may be derived; very old waters may be detected.
		Water isotopes are potentially useful for distinguishing water units such as evaporated, meteoric, marine, glacial/intergiacial, etc. A map attached to this summary shows the locations of wells installed in several transects across Florida Bay and the Keys to the offshore reef, plus a number of relatively new wells at various locations in Florida Bay.
	sofia.usgs.gov /proposals/1998/grgeochemp98.html (1774 words)

	Stable Isotope Geochemistry (Site not responding. Last check: 2007-11-01)
		Stable isotope geochemistry is an interdisciplinary science that uses the natural abundance patterns of different forms of elements, called stable isotopes, to determine how earth materials are formed and modified in environmental settings.
		Consequently, stable isotope distributions can be predicted in nature, providing researchers with a powerful tool that allows the isotopic ratios characteristic of environmental compounds to be used to determine their origins.
		The unique isotopic fingerprint of many compounds allows for the source and fate of contaminants to be traced and transformation rates to be determined.
	www.uga.edu /srel/Fact_Sheets/stable_isotope.htm (886 words)

	GRT Jenkin (isotope geochemistry)
		Oxygen isotopic compositions of quartz and feldspar in greenschist-grade mylonites from the Blue Ridge thrust and the Brevard zone in the southern Appalachians were analysed by laser microprobe to examine the effect of deformation on isotopic behaviour.
		Agreement between measured quartz-feldspar isotopic temperatures and calculated temperatures using a finite difference model indicates diffusional exchange occurred between phases during closed-system cooling, and that the measured temperatures in the mylonites are maximum temperatures for the deformation.
		There is limited overlap in isotopic composition between the different fluid types, indicating that fluids flowing through the same host rocks at each stage of orogenesis may be distinguished on the basis of their oxygen and hydrogen isotopic compositions.
	www.le.ac.uk /geology/grtj1/pubs.html (5024 words)

	Environmental Isotope Geochemistry
		Isotope geochemistry provides us with an advanced set of tools, some of which we have developed, or are developing, ourselves.
		Isotope geochemistry is the study of small, but quite measureable differences in the abundance of various stable and natural radioactive elements in geological materials.
		These "heavy stable isotope" measurements will be applied in many areas of geoscience; our current focus is mosty on the environment, but we also appy these measurements in studies of marine sediments.
	www.geology.uiuc.edu /~tmjohnso/JohnsonGroup.html (191 words)

	Isotope Geochemistry Research (Site not responding. Last check: 2007-11-01)
		In the Radiogenic Isotope laboratory at the University of Wisconsin we have been developing a method to directly determine if there was life on Mars, which has general applicability to the search for extraterrestrial life, as well as constraining the evolution of life on Earth.
		Organisms typically produce isotopic fractionations because the chemical bond of a light isotope is weaker as compared to a heavier isotope.
		These inorganic isotope fractionations blur a biological signature making it exceedingly difficult to interpret the isotopic composition of the light stable isotopes in terms of biological or inorganic processes.
	www.geology.wisc.edu /astrobiology/isotope.htm (1542 words)

	Chapter 2: Fundamentals of Isotope Geochemistry
		This is especially true of oxygen and hydrogen isotopes in water; meteoric waters retain their distinctive fingerprints until they mix with waters of different compositions or, in the case of isotopes of dissolved species, there are reactions with minerals or other fluids.
		The isotopic compositions of waters and solutes can be significantly affected by the concentration and types of salts because the isotopic compositions of waters in the hydration spheres of salts and in regions farther from the salts are different (see Horita (1989) for a good discussion of this topic).
		Isotope Biogeochemistry addresses the application of isotopes of constituents that are dissolved in the water or are carried in the gas phase.
	wwwrcamnl.wr.usgs.gov /isoig/isopubs/itchch2.html (13621 words)

	Prof. Stein B. Jacobsen (Site not responding. Last check: 2007-11-01)
		Isotope geochemistry is the study of isotopic variations of various elements in geochemical reservoirs.
		By studying the minute variations in the isotopic makeup of different samples -- variations caused by i) the decay of naturally occurring radioactive elements, ii) isotope fractionation, iii) mixing of isotopic components of different origins -- it is possible to discover much about the age, origin, and history of geochemical reservoirs.
		Piepgras, D.J. and Jacobsen, S.B., 1988: The isotopic composition of neodymium in the North Pacific.
	geochemistry.harvard.edu /~stein (1417 words)

	IFM-GEOMAR: Non-traditional Stable Isotope Geochemistry
		Stable isotope geochemistry is concerned with the measurement and interpretation of mass-dependent enrichments or depletions of the stable isotopes of an element (e.g.
		However, most "non-traditional" stable isotope systems are still in their infancy and the fractionation behavior is little studied.
		Currently, we focus on the analyses of the stable isotope compositions of the earth-alkaline elements Ca, Mg and Sr for applications in marine geochemistry.
	www.ifm-geomar.de /index.php?id=1354&L=1 (340 words)

	Noble Gas Isotope Geochemistry: Earthquake Processes
		Figure 2: Helium isotopic composition (R) normalized to the ratio in air (Ra) plotted as a function of approximate distance from the main strike of the SAF.
		He ratios are diluted with radiogenic 4He produced locally in the crust, generating a vertical gradient in the fault zone helium isotopic composition that depends on the vertical rate of fluid flow.
		Noble gas, carbon and oxygen isotope compositions provide evidence for the involvement of mantle-derived fluids in faulting and that the mantle helium is accompanied by deep crustal or metamorphic water and CO Some or all of the CO may be of deep crustal origin.
	www-esd.lbl.gov /CIG/noblegas/earthquake.html (778 words)

	Center for Isotope Geochemistry: Publications
		Fantle and DePaolo, Sr isotopic composition of ODP Site 807A marine carbonates and pore fluids and the age dependence of calcite recrystallization rates: Application to models of pore fluid Ca and Mg and the interpretation of seawater Ca and Mg concentrations through time.
		Lassiter, J.C., and D.J. DePaolo, Geochemistry of the Wrangellia Flood Basalt Province: Implications for the Role of Continental and Oceanic Lithosphere in Flood Basalt Genesis.
		Wendlandt, E., D.J. DePaolo, and W.S. Baldridge, Nd and Sr Isotope Chronostratigraphy of Colorado Plateau Lithosphere: Implications for Magmatic and Tectonic Underplating of the Continental Crust.
	eps.berkeley.edu /cig/publications (3375 words)

	Isotope Geology
		Reconstruction of fluctuations in carbon isotopes of sedimentary carbonates and organic carbon (Devonian to Permian)
		Reconstruction of the boron isotope composition of Palaeozoic seawater by multicollector-ICP-MS analyses of brachiopod calcite.
		Carbon and oxygen isotope composition of tree ring cellulose from various stations in Mongolia are investigated in order to reconstruct the climatic history.
	www.geol.uni-erlangen.de /index.php?id=90&L=3 (143 words)

	The Radiogenic Isotope Geochemistry Lab at Pitt (Site not responding. Last check: 2007-11-01)
		The Radiogenic Isotope Geochemistry Lab consists of two critical parts: a clean lab for sample preparation and a thermal ionization mass spectrometer lab to house the necessary analytical equipment.
		Modern isotope geochemistry requires an extremely clean work environment to avoid contamination from atmospheric dust, pollution, and scrofulous scurf deposits.
		Historically, most major advances in Pb isotope geochemistry came only after all sampling and lab-related sources of contamination were identified and eliminated.
	mac01.eps.pitt.edu /GeochemWebpage/RadtopeLab.html (799 words)

	Introductions to Isotope Geochemistry, Spectroscopy and Spectronomy, Links for Mineralogists
		The tutorial describes processes affecting isotope ratios such as photosynthesis, evapotranspiration, and respiration; biosphere-atmosphere exchange of isotopes in water and carbon; and how stable isotopes are used to study environmental history.
		USGS projects in the Eastern United States are concerned with the origins of base (copper, lead, and zinc) and precious (gold and silver) metal deposits in the Carolina slate belt and northern Maine and with the environmental effects of weathering of mineral deposits.
		These tools calculate the half-life for selected isotopes; radioactive decay final activity, given the initial activity and decay time; the decay time, given the initial and final activities; and the decay time, given the mass of a solid and the initial activity.
	www.uni-wuerzburg.de /mineralogie/links/teach/isotoptech.html (1226 words)

	Programs in Environmental and Marine Geochemistry at Georgia Tech
		Our research objectives are to characterize the biogeochemical processes which regulate the distribution of inorganic and organic compounds in order to determine their impact on the environment in the past, the present, and the future.
		Besides individual collaborations within EAS and outside the Institute, the Geochemistry group is actively involved in the Focused Research Program in Marine Science and Technology at Georgia Tech.
		The program involves one year of coursework, mostly in the area of environmental and marine geochemistry (typical course schedule), followed by a highly individualized research experience that may involve fieldwork (domestic and international), labwork and/or modeling, according to a student's strengths and interests.
	geochemistry.eas.gatech.edu (565 words)

	Staff Members at RSIL (Site not responding. Last check: 2007-11-01)
		J.K. Bohlke – (Research Hydrologist: jkbohlke@usgs.gov, 703-648-6325) is interested generally in the sources and fates of fluids and dissolved constituents in the Earth's crust, mass transfers and buffering mechanisms during fluid-rock interactions, stable and radioactive isotope geochemistry, and geochronology.
		She is involved in preparation of new isotopic reference materials, and assists in laboratory management and daily operation of the laboratory, analyzing samples submitted for hydrogen, carbon, nitrogen, oxygen, and sulfur isotope ratio determination.
		Kinga M. Revesz – (Research Chemist: krevesz@usgs.gov, 703-648-5865) is concerned broadly with the use of stable isotopes, primarily hydrogen, carbon and oxygen, to examine the dynamics of hydrological systems and associated geochemical problems.
	www.isotopes.usgs.gov /Staff.htm (360 words)

	Amazon.co.uk: Stable Isotope Geochemistry: Books: Jochen Hoefs (Site not responding. Last check: 2007-11-01)
		Stable Isotope Geochemistry is an introduction to the use of stable isotopes in the geosciences.
		It is subdivided into three parts:- theoretical and experimental principles;- fractionation mechanisms of light and heavy elements;- the natural variations of geologically important reservoirs.The 5th edition has been revised and extended and now includes a new chapter on palaeoclimatology.
		For students and scientists alike the book will be a primary source of information with regard to how and where stable isotopes can be used to solve geological problems.
	www.amazon.co.uk /Stable-Isotope-Geochemistry-Jochen-Hoefs/dp/3540402276 (469 words)

	BGR Gas and isotope geochemistry
		For the gas and isotope geochemistry section at the Federal Institute for Geosciences and Natural Resources, the fossil energy source, natural gas, is at the centre of research and development work.
		Gas and isotope geochemical procedures are not only important for research on possible future energy sources, but also for monitoring and assessing geological risks.
		Gas and isotope geochemical methods are also used within research projects on the global carbon cycle.
	www.bgr.bund.de /cln_029/nn_467194/EN/Themen/GG__Geochem__org/Gas__Isotopengeochem/gas__isotopengeochem__node__en.html__nnn=true (242 words)

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