Geochronological Evaluation of Circa 600 Ma Events in Northwest Svalbard, Arctic Caledonides

该奖项支持美国与瑞典地质学家合作评估斯瓦尔巴特群岛西北部Richarddalen群地质年代学的项目。 这些岩石最近产生了“泛非洲”年龄的锆石（6.2亿至6.6亿年），这些锆石是神秘的，因为在北极或斯堪的纳维亚加里东地区几乎没有其他证据表明这个年龄的岩石形成或变质/变形事件。 基于野外和显微构造研究的详细年代学研究以及高精度U-Pb方法将用于直接测定变质和变形组构的年代。 铅-207/铅-206年龄将通过直接蒸发单个锆石颗粒来测量，以测试是否存在较老的（继承的）成分，从而进一步限制对现有锆石年龄的解释。 这些新的数据将允许直接评估同位素年龄是否反映原岩，变质或变形，或混合的年龄，以及这些岩石在新元古代全球构造重建的意义。

This award supports a US contribution to a collaborative project with Swedish geologists to evaluate the geochronology of the Richarddalen Group of northwestern Svalbard. These rocks have recently yielded "Pan African" aged zircons (620-660 million years old) that are enigmatic because there is little other evidence in the Arctic or Scandinavian Caledonides to rock-forming or metamorphic/deformational events of this age. Detailed geochronologic studies based on field and micro-structural study, and high-precision U-Pb methods will be used to directly date metamorphic and deformational fabrics. Lead-207/Lead-206 ages will be measured by direct evaporation of single zircon grains to test for the presence of older (inherited) components, thereby further constraining the interpretation of existing zircon ages. These new data will permit a direct assessment of whether the isotopic ages reflect protolith, metamorphic or deformational, or mixed ages, and the significance of these rocks to global tectonic reconstructions in the Neoproterozoic.