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Topic: Geochronology

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	Geochronology
		Geochronology is the science of dating and determining the time sequence of events in the history of the Earth.
		Uranium series geochronology is typically used to date authigenic minerals in sediments or fossils, but has also been used to date speleothems, calcite veins, rock varnishes, salts, and other materials.
		Fission-track geochronology is most useful for volcanics with zircons or glass for materials that fall in the range of late Tertiary to late Precambrian.
	wrgis.wr.usgs.gov /wgmt/common/geochronology.html (1843 words)

	Geochronology - Wikipedia, the free encyclopedia
		Geochronology is the science of determining the absolute age of rocks, fossils, and sediments, within a certain degree of uncertainty inherent within the method used.
		Radiometric techniques measure the decay of radioactive isotopes, and other radiogenic activity.
		Renne, P.R., Ludwig, K.R., and Karner,D.B. (1998), "Progress and challenges in geochronology", Science Progress, v.
	en.wikipedia.org /wiki/Geochronology (754 words)

	Roth, A. A. --- Some Questions about Geochronology
		There are time-dependent factors which, according to their present rates of change, are in disagreement with the standard scenario of thousands of millions of years for the geochronology of the crust of the earth.
		By noting the rates at which the surfaces of the continents are eroded and carried away by rivers to the oceans (see section 2 for specific values), one can calculate the length of time required to remove a given thickness of the continents.
		The challenge to standard geochronology is that if mountains have been uplifting at current rates or even much slower, the lower parts of the geologic column which are many hundreds to thousands of millions of years old should have been uplifted and eroded away long ago.
	www.grisda.org /origins/13064.htm (6995 words)

	Biostratigraphy and Geochronology
		Biostratigraphy and geochronology are fundamental aspects of all geological training programs in education, with all courses providing some tuition in the construction and interpretation of the geological time scale.
		It is anticipated that the continuing demand from end-users of biostratigraphy and geochronology will be for continued refinement of biozonation schemes and time scales with improvements in accuracy, precision and the measurement of uncertainty (Kidd and Hailwood, 1993).
		Both biostratigraphy and geochronology contain elements of uncertainty, yet this is not always appreciated by the end-user of our work, often leading to the accusation that we "have changed our minds" if at some point in the future we refine the information we have provided.
	www.nhm.ac.uk /hosted_sites/paleonet/paleo21/biostrat.html (4230 words)

	EXTECH IV: Athabasca Uranium multidisciplinary study - Geochronology
		Constrain the regional stratigraphic geochronology of Paleoproterozoic sequences with which the Athabasca Basin has been or may be correlated by empirical stratigraphy.
		SHRIMP geochronology of detrital zircon and monazite of the Paleoproterozoic Athabasca Group of Northern Saskatchewan and Alberta, to be co-led by Rob Rainbird, Richard Stern (GSC) and Dave Quirt (SRC), with input by Charlie Jefferson & Jerry Ross (GSC) and Gary Yeo (SEM).
		SHRIMP geochronology of authigenic xenotime of the Paleoproterozoic Athabasca Group of Northern Saskatchewan and Alberta, to be co-led by Rob Rainbird, Richard Stern (GSC), and Dave Quirt (SRC).
	gsc.nrcan.gc.ca /extech/extech4/geochronology_e.php (320 words)

	UAF Geology and Geophysics-Geochronlogy
		Geochronology is the study of time in relationship to the history of the Earth.
		Geochronology has played a major role in understanding this relationship and an ongoing research effort in the lab is intended to better constrain the time of gold formation.
		The Geochronology Laboratory is currently involved in research in working out the Quaternary history of this region.
	www.uaf.edu /geology/Research/research/geochron.html (2752 words)

	Amino Acid Geochronology Laboratory
		Amino acid geochronology is best suited as a relative-dating tool, or as a calibrated-dating method in conjunction with other dating techniques.
		Amino acid racemization (or AAR) is the interconversion of amino acids from one chiral form (the L - laevo amino acids which are the building blocks of proteins) to a mixture of L- and D- (dextro) forms.
		The extent of racemization is measured by the ratio of D/L isomers and increases as a function of time and temperature, and can be used for geochronology or paleothermometry.
	jan.ucc.nau.edu /~dsk5/AAGL/method.html (168 words)

	LANL OSL Home (Site not responding. Last check: 2007-11-02)
		Research conducted in the EES-10 Luminescence Geochronology Lab (LGL) is directed towards advanced geologic applications of and technique development for luminescence dating.
		The Luminescence Geochronology Lab is affiliated with EES-10 the Environmental Dynamics and Spatial Analysis group and is located at TA-51.
		The LANL Luminescence Geochronology Lab is currently the only facility in the North America to have single-grain OSL measurement capacity.
	www.ees10.lanl.gov /osl/OSL_home.htm (378 words)

	Geochronology: Linking the Isotopic record with Petrology and Textures Geoscience Canada - Find Articles
		In determining the age of minerals and rocks it is often possible to derive a precise number that can be interpreted as a date, it is another matter to accurately interpret the number in terms of the timing of a discrete geological event or process.
		This is the challenge addressed by the contributors to an edited volume in the Geological Society Special Publication series entitled Geochronology: Linking the isotopic record with petrology and textures.
		The important role of fluids and deformation to the interpretation of thermal histories of minerals is highlighted.
	www.findarticles.com /p/articles/mi_m0QQS/is_3_32/ai_n15950863 (831 words)

	geochronology - Ask.com Web Search
		Geochronology is the science of determining the age of rocks, fossils, and sediments.
		Non-profit scientific research institution dedicated to establishing the history of the Earth, its various inhabitants, and its interactions...
		U-Pb geochronology of zircon, baddelyite, and monazite is used for determining the age of emplacement of igneous rocks of all compositions,...
	search.ask.com /web?q=geochronology (278 words)

	Isotope Geochemistry and Geochronology Research Centre (IGGRC) - Research Highlights
		U-Pb geochronology analyses of subdomains of zircon and monazite crystals in conjunction with imaging techniques establish ages of more than one growth, recrystallisation and/or Pb-loss event in crystals with complex history.
		U-Pb geochronology studies to constrain timing of deformation and metamorphism in high-grade rocks of the Canadian Cordillera and Grenville Province; implications for geologic process and tectonics during the formation of mountain-belts.
		TIMS U-Pb geochronology studies paired with MC-ICP-MS data from Hf in dated zircons to constrain age and source of rocks.
	www.carleton.ca /iggrc/highlights.htm (386 words)

	SOFIA - Geochronology in the South Florida Ecosystem and Associated Ecosystem Programs
		The objectives of the project is to measure the distribution of short- lived radionuclides to provide a temporal component to the processes at work within the Ecosystem.
		Geochronology and Metal Deposition in the South Florida Ecosystem (from the South Florida Restoration Science Forum, May 1999)
		Geochronology of Terrestrial Sediments: South Florida ecosystem (1997)
	sofia.er.usgs.gov /projects/sed_geochron (414 words)

	John Woodmorappe's Geochronology
		The Phanerozoic section is subdivided into Woodmorappe's claims regarding the selective publication of dating results, the dating of sedimentary rocks, supposed rationalizations for discrepant igneous dates from petrographic and regional geologic evidence, and what he considers to be problematic results from the radiometric dating of biostratigraphically-bracketed igneous rocks.
		Data accumulating from various geochronology laboratories appear to indicate that glauconite is of dubious usefulness for the purpose of obtaining accurate dates of sedimentary strata by the potassium-argon method.
		But they go on to argue that it can be used if the samples are collected carefully with regard to their geologic history and spend some time discussing the factors which are detrimental to the accuracy of K-Ar dates from glauconites.
	www.talkorigins.org /faqs/woodmorappe-geochronology.html (8858 words)

	Canadian Geochronology Knowledgebase - Web Services
		Geochronology data contained in the Canadian Geochronology Knowledgebase is accessible through XML Web services.
		This page describes what is available, states where it can be located, and hints at how you can retrieve the data programmatically.
		For these geochronology Web services, most of this information is given on the previous page.
	gdr.nrcan.gc.ca /geochron/ws_e.php (674 words)

	USGS-GD-Scientific Capabilities - Geochronology
		Quaternary dating provides a record of climate change and geologically recent changes in environment.
		U-Pb geochronology of zircon, baddelyite, and monazite is used for determining the age of emplacement of igneous rocks of all compositions, ranging in age from Tertiary (last 65 million years) to Early Archean (3.8 billion years).
		U-Pb ages of metamorphic minerals, such as zircon, sphene and monazite are used to date thermal events, including terrestrial meteoritic impacts, and to determine thermochronologic histories of terranes.
	geology.cr.usgs.gov /capabilities/gronemtrac/geochron/geochron.html (265 words)

	LANL \| EES \| Luminescence Geochronology Lab
		Anticipated strengths of the LANL Luminescence Geochronology Lab
		The LANL Luminescence Geochronology Lab is currently the only facility in the North America to have single-grain OSL measurement capacity. Members of the LGL can also draw upon the vast resources and expertise at LANL in the areas of environmental radiation monitoring and dosimetry.
		Provide a geochronologic framework for a wide range of environmental research including: (i) sediment redistribution dynamics in local canyons, (ii) carbon sequestration in arid / semi-arid soils (iii) Be in the soil / sediment environment.
	www.ees.lanl.gov /osl.shtml (421 words)

	Research Groups in GES - Geochronology and Thermochronology
		Stanford's geochronology and thermochronology laboratories, faculty and staff offer a wide range of techniques and expertise to address problems in the earth sciences that are constrained by time and temperature.
		Calibration of mineral pairs, multi-technique geochronology and thermochronology
		Please contact the GES webmaster with suggestions or comments.
	pangea.stanford.edu /GES/research/geochronology.html (142 words)

	Isotope Geochemistry and Geochronology (Site not responding. Last check: 2007-11-02)
		Methods of isotope geochemistry and geochronology being developed and used in IGEM in technical respect are based on the achievements of modern high sensitivity and high precision mass-spectrometry which enables measurements of isotope composition of elements from samples as small as 10
		Isotope laboratory of IGEM is ready to establish contacts with scientific organizations, geological and mining companies and start studies of their interest.
		Head of Laboratory of Isotope Geochemistry and Geochronology - Prof.
	www.intertec.co.at /itc2/partners/IGEM/isote.html (556 words)

	UMass monazite research
		Although core domains in some grains may be large enough to be dated by ion probe or other isotopic means, dates on narrow rim domains or irregularly shaped internal domains require the micron-range resolution that only the electron microprobe can provide.
		Although less precise than isotopic methods, microprobe dating can therefore contribute substantially to a complete understanding monazite geochronology.
		At UMass, we are carrying out monazite dating as part of mapping and tectonic analysis of the Western Churchill Province, Canada, in the Southwestern US, and collaboratively in a number of other areas around the world.
	www.geo.umass.edu /probe/Monazite1.htm (409 words)

	Open Directory - Science: Earth Sciences: Geology: Geochronology (Site not responding. Last check: 2007-11-02)
		Berkeley Geochronology Center - Non-profit scientific research institution dedicated to establishing the history of the Earth, its various inhabitants, and its interactions with the rest of our Solar System, throughout the 4.6 billion years of our Planet's existence.
		Geochronology Working Group at Vienna University - Uses radiometric dating and classical geochronological methods to constrain the timing of geological processes, primarily in the Eastern Alps, the Carpathian - Pannonian region and adjoining area, and the Bohemian Massif.
		Geologic Time - USGS on-line publication about the relative and radiometric geologic time scales, age of the earth, index fossils, and related topics.
	dmoz.org /Science/Earth_Sciences/Geology/Geochronology (229 words)

	UNL Geosciences Luminescence Geochronology Lab (Site not responding. Last check: 2007-11-02)
		Luminescence dating determines the time since a sample was last exposed to light or heat.
		The UNL Geosciences Luminescence Geochronology Laboratory uses the Optically Stimulated Luminescence (OSL) Single Aliquot Regenerative (SAR) technique to determine the burial age of coarse-grained (100 - 250
		The UNL Luminescence Geochronology Laboratory accepts samples for commercial dating, but collaborative research projects are preferred due to the limited laboratory facilities.
	www.geosciences.unl.edu /OSL/index.htm (125 words)

	BGC Berkeley Geochronology Center: Research Faculty
		Geochronology and volcanology especially in autobrecciation of lava and eruptive processes; K/Ar and 40Ar/39Ar dating, geologic timescale, calibration of teritiary mammal stage ages and calibration of hominoid-hominoid evolution.
		Applications of geochronology and paleomagnetism to various problems in the evolution of the lithosphere, hydrosphere, atmosphere, and biosphere
		Low-temperature and 4He/3He thermochronometry, deciphering influences of long-term climate variability on planetary surfaces, erosion histories of mountain ranges, near-surface thermal history of Mars, geochronology of chemical weathering, kinetics of noble gas diffusion
	www.bgc.org /people/faculty.html (108 words)

	E.L. Cord Geochronology Laboratory
		DRI's Luminescence Geochronology Laboratory has the capacity to determine the burial age of feldspar and quartz bearing sediments, from a range of a few decades to several hundred thousand years, depending upon sample conditions.
		Thus, geological, paleoseismic, archeological, anthropological and paleoenvironmental chronology problems can be tackled that are either outside the range of other dating methods or for which suitable materials for use by other methods are not available.
		Glenn Berger directs the E.L. Cord Geochronology Laboratory that has in place or on order the latest equipment for luminescence dating.
	www.dees.dri.edu /Facilities/el-cord.htm (152 words)

	Nevada Isotope Geochronology Laboratory, UNLV
		He in rocks exposed at the Earth's surface has recently opened new areas of geologic research, most notably in dating very young or recently exposed rocks not amenable to other dating methods.
		Surface exposure dating has been applied to research aimed at understanding climate change, development of landforms, constraining erosion rates, and nuclear waste site assessment, and is a rapidly growing and exciting new field in geochronology.
		The combination of these isotopic dating techniques in a single laboratory will permit visitors, faculty, and students to conduct research on a large variety of problems in geoscience involving materials spanning the entire range of geologic time.
	www.unlv.edu /Colleges/Sciences/Geoscience/pub/NIGL/niglaug99.html (413 words)

	NMBGMR Laboratories: New Mexico Geochronology Research Laboratory
		Bill McIntosh and Matt Heizler who have over 30 years combined experience in the field of argon geochronology and thermochronology.
		Necessary in this regard is the software developed by Dr. Al Deino at the Berkeley Geochronology Center in Berkeley, California which allows for full automation of extraction line and mass spectrometer functions.
		The software controls all crucial extraction line and mass spectrometer valves which are operated via pneumatic air drivers.
	www.geoinfo.nmt.edu /labs/argon (435 words)

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