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

北美克拉通层序的 Nd 同位素和地球化学：动态地形的约束

• 批准号: 9909150
• 负责人: P. Jonathan Patchett
• 金额: $ 11.98万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-01-01 至 2002-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9909150&HistoricalAwards=false
• 关键词: Nd; Isotopes; Geochemistry; North; American

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.

9909150斑块在构造稳定的条件下，大陆克拉通预计会对平均海平面和洋壳产生积极的缓解作用。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同位素特征的分析表明，与古生代造山作用一起沉积在加拿大地盾上的沉积物没有受到侵蚀，此后暴露在基底屏蔽岩中的时间长达300My，这与现有的大规模大陆干板模式不相容。这项研究将研究加拿大斯维尔德鲁普盆地的沉积岩的完整序列，该盆地横跨宾夕法尼亚纪到晚白垩世，试图探测屏蔽层基底岩石何时首次贡献沉积物。确认加拿大地盾存在很长时间的负起伏，将对大陆干板模式和这段时间内地幔的热结构产生相当大的影响。