the deposits at Olduvai Gorge. Provenance analysis of detrital grains A number of datable minerals occur as common detrital grains in sandstones, and if the strata have not been buried too deeply, these minerals grains retain information about the source rock. Fission track analysis of these minerals provides information about the thermal evolution of the source rocks and therefore can be used to understand provenance and the evolution of mountain belts that shed the sediment. This technique of detrital analysis is most commonly applied to zircon because it is very common and robust in the sedimentary system, and in addition it has a relatively high annealing temperature so that in many sedimentary basins the crystals are not reset by later heating. Fission-track dating of detrital zircon is a widely applied analytical tool used to understand the tectonic evolution of source terrains that have left a long and continuous erosional record in adjacent basin strata. Early studies focused on using the cooling ages in detrital zircon from stratigraphic sequences to document the timing and rate of erosion of rocks in adjacent orogenic belts (mountain ranges). A number of recent studies have combined U/Pb and/or Helium dating (U+Th/He) on single crystals to document the specific history of individual crystals. This double-dating approach is an extremely powerful provenance tool because a nearly complete crystal history can be obtained, and therefore researchers can pinpoint specific source areas with distinct geologic histories with relative certainty. Fission-track ages on detrital zircon can be as young as 1 Ma to as old as 2000 Ma. See also Thermochronology References Further reading Naeser, C. W., Fission-Track Dating and Geologic Annealing of Fission Tracks, in: Jäger, E. and J. C. Hunziker, Lectures in Isotope Geology, Springer-Verlag, 1979, U. S. G. S., Fission Tracks: Technique, https://web.archive.org/web/20161208062155/http://geology.cr.usgs.gov/capabilities/gronemtrac/geochron/fission/tech.html Retrieved 27 October 2005. Garver, J.I., 2008, Fission-track dating. In Encyclopedia of Paleoclimatology and Ancient Environments, V. Gornitz, (Ed.), Encyclopedia of Earth Science Series, Kluwer Academic Press, p. 247-249. Wagner, G. A., and Van den Haute, P., 1992, Fission-Track Dating; Kluwer Academic Publishers, 285 pp. Enkelmann, E., Garver, J.I., and Pavlis, T.L., 2008, Rapid exhumation of ice-covered rocks of the Chugach-St. Elias Orogen, Southeast Alaska. Geology, v. 36, n.12, p. 915-918. Garver, J.I. and Montario, M.J., 2008. Detrital fission-track ages from the Upper Cambrian Potsdam Formation, New York: implications for the low-temperature thermal history of the Grenville terrane. In: Garver, J.I., and Montario, M.J.