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

9909150帕切特在构造稳定的条件下，大陆地壳相对于平均海平面和洋壳预计会有一个正的起伏。 动力地形也是下垫面质量、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同位素特征的分析表明，加拿大地盾上沉积的沉积物与古生代造山作用一起没有被侵蚀，暴露基底地盾岩石多达300 My之后，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斯维尔德鲁普盆地跨越宾夕法尼亚纪至晚白垩纪的沉积岩的完整序列，试图检测盾牌基底岩石何时首次贡献沉积物。 加拿大地盾的长负起伏的确认将对大陆干舷模型和这段时间内地幔的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.