Nd Isotopes and Geochemistry of North American Cratonic Sequences: Constraints on Dynamic Topography

在构造稳定的条件下，预计大陆克拉通相对于平均海平面和海洋地壳具有正的起伏。动态地形也是下伏质量、密度和热结构的反映。最近对北美古生代和中生代沉积物的Nd同位素特征分析表明，与古生代造山运动有关的沉积在加拿大地盾上的沉积物在300万年之后没有被侵蚀到暴露基底地盾岩石，这一结果与现有的大规模大陆干舷模型不相容。这项研究将检查加拿大Sverdrup盆地从宾夕法尼亚到晚白垩纪的连续沉积岩，试图探测盾状基底岩石何时首次形成沉积物。加拿大地盾极长负起伏的确认将对这段时间内大陆干舷模型和地幔热结构产生相当大的影响。

9909150PatchettUnder tectonically stable conditions continental cratons are expected to have a positive relief with respect to average sea level and with respect to oceanic crust. Dynamic topography is also a reflections of underlying mass, density and thermal structure. Recent analysis of Nd isotopic signatures of Paleozoic and Mesozoic sediments from North America has suggested that sediments deposited on the Canadian Shield in conjunction with paleozoic orogenies were not eroded to expose the basement shield rocks for as much as 300 My afterwards, a result incompatible with existing models of large-scale continental freeboard. This study will examine and unbroken succession of sedimentary rocks in the Sverdrup Basin of Canada that spans the Pennsylvanian to Late Cretaceous to attempt to detect when shield basement rocks first contributed sediment. Confirmation of very long negative relief of the Canadian Shield will have considerable impact on models of continental freeboard and the thermal structure of the mantle during this time interval.