Description:

An exact definition of a craton will likely never come to be, but it is agreed that a craton is an old stable piece on continental crust. In an effort to thermally characterize a craton, PIÕs K. Condie, M.T. Heizler, S. Kelley and Pat Bickford are current funed by an NSF grant to conduct a thermochronological study across the Trans Hudson Origin (THO). Bickford at Syracuse is conducting accessory mineral U-Pb studies, while Heizler carries out 40Ar/39Ar analyses and Kelley does fission-track dating. Combined these techniques elucidate the temperature range from about 700 to 100¡C. A 1000 km traverse across the THO was carried out during the summer of 1998, and over 100 minerals have been dated thus far. Considering the complexity of the THO and the well-mapped "domains", the argon thermochronology is remarkably consistent across the origin. Most micas and amphiboles are ~1760 Ma suggesting that a large region of crust (e.g. a craton) had stabilized by this time and has not been significantly reactivated (at least thermally) since. Thus, perhaps thermal stability relatively soon after amalgamation may be a definable property of a craton thereby adding to the ability to define the process of cratonization. Publications.