Unusually High Thermal Stability of the Uranium-Xenon Isotopic System in Nonmetamict Zircons

摘要

Modern isotopic geology requires new approaches to geothermochronological problems for deciphering temperature evolution of magmatic and sedimentary rocks and related geological processes. One of the future research avenues in this field is the simultaneous application of genetically interrelated isotopic geochro-nological systems of noble gases: not only U-Th-He [1], but also U-Xe_s, U-Xe_n, U-Kr_s, and U-Kr_n [2, 3] in combination with the U-Th-Pb isotopic system (Xe and Kr are the products of spontaneous and neutron-induced fission [4]). This will maximally increase the geochronological reliability of the obtained ages and give opportunities unique for geothermogeochronology owing to a common mechanism of migration of different radiogenic isotopes having different kinetic parameters of migration. In order to make this approach applicable to practice, it is necessary to carry out extensive studies of migration characteristics of He, Xe, and Kr and the stability of the Xe/U, He/U, and Kr/U isotopic systems in mineral geochronometers, primarily, zircons.