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Encyclopedia topic: Radiometric dating   (Site not responding. Last check: 2007-10-10) Radiometric dating is a technique used to date materials based on a knowledge of the decay rates of naturally occurring isotope (One of two or more atoms with the same atomic number but with different numbers of neutrons) s, and the current abundances. Radiometric dating can be performed on samples as small as a billionth of a gram using a mass spectrometer (Spectroscope for obtaining a mass spectrum by deflecting ions into a thin slit and measuring the ion current with an electrometer). Finally, "fission track dating" involves inspection of a polished slice of a material to determine the density of "track" markings left in it by radioactive decay of uranium-238 impurities. www.absoluteastronomy.com /encyclopedia/r/ra/radiometric_dating.htm   (2441 words)

Fission track dating Fission track research at our laboratory started in 1983 with a study by P. Van den haute on the track etching characteristics of fission tracks in glass and on the application of apatite fission track dating to the Precambrian basement rocks underlying the East-African rift shoulders in Rwanda and Burundi. Fission Tracks (FT) are micrometer-sized, linear damage tracks that occur in insulating minerals and that are caused by the spontaneous fission of heavy, unstable nuclides (mostly Thermal annealing is reflected by a shortening of the track length. users.ugent.be /~pvdhaute/fission.htm   (1131 words)

Fission Tracks Fission tracks are submicroscopic linear disordered regions in the crystal lattice, formed along the trajectories of the nuclear fragments ejected by the fissioning uranium nucleus. The lattice damage along a track is gradually restored at elevated temperatures, resulting in a decrease of the length of the fission track. Fission-track dating is based on measurements of the number of tracks that have accumulated since the crystal last cooled below the temperature at which the tracks are retained. www.mpi-hd.mpg.de /archaeometry/fission_tracks.html   (327 words)

Publications Deciphering erosion history and thermotectonic evolution of the Swiss Alps by fission track dating on clastic sediments of the foreland basin. Fission track dating on clastic sediments of the foreland basin: Implications for the thermotectonic evolution of the Swiss Alps. The exhumation history of the Central Alps: A combined approach of zircon fission track dating, Nd isotope geochemistry, and the sediment budget of the foreland basins. homepages.uni-tuebingen.de /cornelia.spiegel/html/publications.html   (683 words)

AskWhy! Dating - Physical Methods - Jewish Scriptures   (Site not responding. Last check: 2007-10-10) One of the most reliable chronometric dating techniques is based on the fact that annual growth rings on shallow rooted trees vary in width with the amount of water available each season and with temperature fluctuations from winter to summer. Fission track dating is based on the fact that some crystalline or glass-like minerals, such as obsidian and mica, contain trace amounts of uranium-238, which is an unstable isotope. Dating events down to 70,000 BP is done with radiocarbon dating, amino acid racemization, thermoluminescence, electron spin resonance and fission track dating. www.askwhy.co.uk /judaism/0495DatingPhysicalMethods.html   (3918 words)

fission-track dating --  Britannica Concise Encyclopedia - The online encyclopedia you can trust! The fission results in radiation damage, or fission tracks, that can be made visible by preferential leaching (removal of material by solution) of the host substance with a suitable chemical reagent; the leaching process allows the etched fission-track pits to be viewed and counted under a microscope. Thus, the ratio of naturally produced, spontaneous fission tracks to induced fission tracks is a measure of the age of the sample. The dating of the Chu graves of Changsha www.britannica.com /ebc/article-9364503   (907 words)

Comprehensive Publication Listing Stöckhert, B., Brix, M.R., Kleinschrodt, R., Hurford, A. and Wirth, R. Fission tracks in zircon and microstructures of quartz in the Austroalpine basement to the south of the western Tauern window, eastern Alps: constraints on the temperature of the brittle-ductile transition in the continental crust. Hurford, A. Fission track analysis of apatite from the NAGRA boreholes of Böttstein, Weiach, Schafisheim and Riniken, Northern Switzerland. Unravelling the thermotectonic evolution of the Alps: a contribution from fission track analysis and mica dating. www.es.ucl.ac.uk /research/fissiontrack/PUBLICATION/pub.html   (5025 words)

Dating Exhibit Fission tracks are created at a constant rate throughout time so that from the number of tracks present it is possible to determine the amount of time that has past since the track accumulation began. Spontaneous fission is accomplished by causing the nucleus of one parent uranium atom to split in two with such a force that it leaves a trail (track) of damage on the crystal in a mineral. Fission is induced through controlled irradiation with thermal neutrons of Uranium 235 (0.7 x 10 9 half-life) in a nuclear reactor. www.mnsu.edu /emuseum/archaeology/dating/dat_fission.html   (658 words)

Amazon.com: Statistics For Fission Track Analysis (Interdisciplinary Statistics): Books: Rex F. Galbraith   (Site not responding. Last check: 2007-10-10) Fission tracks can be represented mathematically by a stochastic process of randomly oriented line segments in three dimensions, and this "line segment" model can describe and explain the essential statistical features of the data, providing a rigorous foundation for quantitative modelling and simulation studies. The author derives the equations for fission track data and the theoretical probability distributions for the number, orientation, and length measurements of the tracks. Whether you work in a fission track lab, in archaeological, geological, or geochronological research, or in geological applications of statistics, you will find the background material and practical tools you need to optimize the use of fission track analysis in your work and to make further advances in the field. www.amazon.com /exec/obidos/tg/detail/-/1584885335?v=glance   (577 words)

Scientific Theology--The Pentateuch, Part 3   (Site not responding. Last check: 2007-10-10) Of the dating methods which have been discussed, potassium/ argon dating of basalts is slightly in favor of a short chronology, rubidium/strontium dating is against a long chronology, and the others are not much help in either direction, with the exception of uranium/lead dating, in which the data reported by Gentry et al. Tracks that have been partially annealed do not begin increased fading until a higher temperature is reached, so the spontaneous tracks reach a higher ratio to the induced tracks before starting to fade. In addition, published data concerning the length of fission tracks and the annealing of minerals imply that the basic assumptions used in an alternative procedure, the length-reduction-correction method, are also invalid for many crystal types and must be approached with caution unless individually justified for a particular mineral. www.scientifictheology.com /STH/Pent3.html   (10213 words)

Rock dating (Chris M. Hall; Frank Crary) The recoiling fission fragments cause crytal damage in the mineral that hosts them, and this damage can remain unhealed for millions of years. By cutting, polishing and acid etching the sample, it's possible to open up these fission tracks to the point where they are visible with an optical microscope. As for the age of formation, as well as the age of the carbonates and the date of shock events, that's all from isotope dating. yarchive.net /physics/rock_dating.html   (778 words)

OnTrack: Newsletter no.10 From the simple and fast computerised measurement of track size distributions of both spontaneous tracks and those induced in the lab for heated glasses, we have found that a wide variety of silicic glasses from different source areas, and of ages spanning the Cenozoic, can be corrected for partial track fading. The fission track ages from samples RD15-36 and -37 are higher than those of neighbouring samples with more typical Cl contents (like sample RD15-35), but this owes as much to their differing Cl contents as it does to their thermal history! Because of effects such as these, mapping measured fission track ages on their own is not very useful if we want to reveal thermal history trends, as the variation will be very sensitive to the occurrence of Cl-rich apatites. www.lib.utexas.edu /geo/ontrak11   (6324 words)

english The fossil tracks are counted by focussing on the grain surface, through the external detector, the induced tacks by focussing on the underside of the detector itself. Having already achieved a break-through using infrared laser light which stimulates the feldspar components only, it was shown that the essential requirements for dating are valid for surfaces, too: the luminescence signal is, on one hand, erased by a very short exposure to sunlight and is, on the other hand, stable over thousands of years. On the other hand, dating of fluvial relocated sediments still raise substantial difficulties that are to be systematically investigated and methodologically processed. www.mpi-hd.mpg.de /archaeometry/2000english.html   (3124 words)

Fission-track paper The use of the common variable "time" in a plot of uplift rate versus mean sample age results in a pronounced distortion, incorrectly interpreted as increasing uplift rates, which is solely a function of the variance in determining closure age in the two fission-track systems. The concept of a closure temperature is a bit of an oversimplification; instead of a single temperature threshold where fission tracks suddenly become stable, there exists instead a wide temperature zone with gradually decreasing annealing, called the partial annealing zone. First of all, as England and Molnar (1990) discuss, fission track data reflect the removal of overlying material, that is, exhumation, not surface uplift. www.ldeo.columbia.edu /users/gregory/fission.html   (4877 words)

Union College Fission-track lab   (Site not responding. Last check: 2007-10-10) Preferential thermal resetting of fission tracks in radiation-damaged detrital zircon grains: Case study from the Laramide of Arizona; Geological Society of America Abstract with Programs, v. Isotopic dating of the collision on Northern Kamchatka. J.I., 1999, The PAZ of zircon alpha damage and fission tracks: field evidences and consequences for FT annealing experiments.EUG10, J. Conf. idol.union.edu /~garverj/FT/research   (4230 words)

fission track   (Site not responding. Last check: 2007-10-10) Fission track Lab, Union College Since 1990, the Union fission track lab has been conducting studies using fission-track dating to solve tectonic problems. Fission-track dating is one type of radioactive dating method used by archaeologists to determine the... History Fission track research at our laboratory started in 1983 with a study by P. and on the application of apatite fission track dating to the Precambrian basement rocks... www.online-dating-search.net /fission-track.htm   (421 words)

[No title] Published apatite fission track ages from the Bergell area, bracketed in the time interval 15 to 8 Ma, indicate that the Bergell block must have been uplifted earlier and cooled down to 120°C more rapidly than the surrounding area from which it is separated by the 4 main discontinuities (Wagner et al., 1979). New zircon and apatite fission track ages from several cross-sections through the border first order faults better constrain these cooling curves for the Bergell area and the time evolution of the Periadriatic fault system during the early Neogene times. Wagner, A. et al., 1979, Fission track ages on apatite of Bergell rocks from Central Alps and Bergell boulders in Oligocene sediments. homepages.uni-tuebingen.de /uni/ep/epifr03/TGAvol/-010.html   (1096 words)

Fission track dating of zeolites The fission track method has become acceptable in geochronology, not only in straightforward dating of igneous and metamorphic events but also in stratigraphic studies by the dating of ash layers However, fission tracks can be developed and observed under the optical microscope in most minerals We report here on reconnaissance studies of fission track dating of zeolites, a complex group of tectosilicates, which is, for example, widely developed in basaltic rocks after their emplacement by later stage processes. www.nature.com /nature/journal/v294/n5839/abs/294347a0.html   (318 words)

Practice Quiz for Chronometric Techniques: Part II The oldest radiocarbon dates that potentially can be obtained with the accelerator mass spectrometry method go back to about ____________ years ago. There is no danger of contaminating radiocarbon dating samples by handling them with bare hands. Radiocarbon dating is not often used because it can only date organic matter which rarely survives in the ground. anthro.palomar.edu /time/quizzes/timquiz5.htm   (471 words)

Abstracts: B The factors computed using track densities corresponding to plateau age determinations are reciprocally well consistent and substantially agree with those of the FTC and Durango apatites, although data suggest a slight systematical deviation. The Moldavites least affected by track annealing are those from the Jankov deposit (Middle Miocene): this glass appears the most convincing potential age standard among those studied here. Chemical analyses and fission-track dating have enabled characterisation of these sources and determination of the origin of more than 600 artefacts found on sites of between the 4th and 1st millennia BC. www.peak.org /obsidian/abstracts_b.html   (1810 words)

Autoscan Systems Pty. Ltd. - Typical System Applications The key reason why our clients have purchased the Autoscan system is because of the high-precision repositioning capability of the stage, which allows the client to revisit the points of interest within +/- 2 micron in X and Y and +/- 0.2 micron in Z (focus). Also, the execution of the FTD technique is a highly tedious process which our equipment not only simplifies, but for which it delivers a time saving estimated to be at least 85% for an experienced operator. This allows automated counting and measurement of the tracks, and an assessment of the level of radiation to which the detector (and thus the wearer of the badge) has been exposed. www.autoscan.com.au /applications.html   (1351 words)

Barry Kohn   (Site not responding. Last check: 2007-10-10) He was awarded the Cotton Prize for postgraduate research in 1973, was a Wexler Fellow at the University of Pennsylvania (1982-83) and was part of the team awarded the Gold Medal for Excellence in Research by the Australian Institute of Nuclear Science and Research in 1996. O'Sullivan, P.B., Kohn, B.P., Foster, D.A. and Gleadow, A.J.W. Fission track data from the Bathurst batholith: evidence for rapid middle Cretaceous uplift and erosion within the eastern highlands of Australia. Seward, D. and Kohn, B.P. New zircon fission track ages from New Zealand Quaternary tephra: an interlaboratory experiment and recommendations for the determination of young ages. www.earthsci.unimelb.edu.au /people/kohn   (1018 words)

REFERENCES Confined track lengths in apatite—a diagnostic tool for thermal history analysis. Standardization of fission track dating calibration: recommendation by the Fission Track Working Group of the I.U.G.S. Subcommission on Geochronology. Thermal annealing of fission tracks in apatite—a quantitative analysis. www-odp.tamu.edu /publications/161_SR/chap_21/c21_8.htm   (397 words)

Robert M. Walker Another important research topic is the study of interplanetary dust particles and their relationship to other extraterrestrial materials. Long interested in the application of science to international development, Walker was a founder and the first president of Volunteers in Technical Assistance (VITA), a volunteer organization of over 5,000 engineers and scientists who work on practical problems relevant to developing countries. Major current interests include the laboratory study of extraterrestrial dust particles collected in the upper atmosphere and the location and identification of preserved interstellar dust in primitive meteorites. news-info.wustl.edu /sb/page/normal/484.html   (609 words)

Dr Barry Kohn   (Site not responding. Last check: 2007-10-10) Kohn, B.P., O'Sullivan, P.B., Cox, S.J.D., Gleadow, A.J.W. and Foster, D.A. Recognition and visualisation of basement reactivation in eastern Australia using apatite fission track thermochronology. O'Sullivan, P.B. and Kohn, B.P. Apatite fission track thermochronology of Tasmania, Australia: Results from the TASGO NGMA project. Coughlin, T.C., O'Sullivan, P.B., Kohn, B.P., and Holcombe, R. Apatite fission track thermochronology of the Sierras Pampeanas, central west Argentine; implications for the mechanism of plateau-uplift in the Andes. www.geology.latrobe.edu.au /ESWeb_site/Staff/Kohn.html   (863 words)

Fission Track Dating - OneLook Dictionary Search We found 4 dictionaries with English definitions that include the word Fission Track Dating: Tip: Click on the first link on a line below to go directly to a page where "Fission Track Dating" is defined. fission track_dating : Illustrated Glossary of Geologic Terms [home, info] www.onelook.com /?w=Fission+Track+Dating&ls=a   (86 words)

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