Deciphering the Interconnected Roles of Climate and Tectonics in Reconstructing the Early Evolution of a Rifted Continental Margin

摘要Fedo断裂型大陆边缘从其历史早期的构造和火山活动演化到边缘成熟后的被动阶段。 这种地质事件发生在当地和全球气候条件的背景下，可能与大陆漂移到不同纬度有关。 因此，构造和气候都可能对裂谷过程产生的沉积物的组成产生重大影响。 在这方面，在大陆碎裂过程中和碎裂之后沉积的硅质沉积岩的成分不仅记录了源岩成分的演变和相对于裂谷侧翼的位置，而且记录了分离期间的主要气候条件。 拟议的调查努力严格审查新元古代和寒武纪年龄的硅质岩在美国西南部的沉积过程中，并在之后，Rodinia的分裂。 一个目标是确定构造和气候在形成沉积物成分方面的相对重要性。 这些资料，再加上现存的沉积学和地层学数据，将用于建立一个综合数据库，以破译这一断裂大陆边的早期地质历史，其演变仍有很大的争议。 在这项研究中收集的数据将主要是岩相学，地球化学和同位素，并考虑化学风化和成岩过程，旨在跟踪矿物和元素丰度从源岩转移到沉积物。 这项研究还将侧重于确定全岩和碎屑长石同位素组成（Sm-Nd、Pb/Pb）以及单晶锆石U-Pb分析，以此作为确定具体烃源岩和地点及其随时间推移的相对丰度的机制。

ABSTRACT9909308FedoRifted continental margins evolve from tectonically and volcanically active early in their history, to a more passive phase once the margin matures. Such geologic events occur on a backdrop of local and global climatic conditions that may be linked to the drifting of continents into different latitudes. Consequently, both tectonics and climate could exert significant influence on the composition of sediments that result from rifting processes. In this regard, the composition of siliciclastic sedimentary rocks deposited during and subsequent to the fragmentation of a continent serve as a recording of not only evolving source rock compositions and positions relative to rift flanks, but also of the prevailing climatic conditions during the time of separation. The proposed investigation endeavors to critically examine Neoproterozoic- and Cambrian-aged siliciclastic rocks in the southwestem United States that were deposited during, and in the wake of, the fragmentation of Rodinia. A goal is to determine the relative significance of tectonics and climate in shaping the composition of the sediments. This information, coupled with extant sedimentologic and stratigraphic data, will then be used to build a comprehensive data bank in which to decipher the early geologic history of this rifted continental margin, whose evolution is still in great debate. Data collected in this study will be principally petrographic, geochemical, and isotopic, and aimed at tracking mineral and elemental abundances transferred from source rocks to sediments by considering chemical weathering and diagenetic processes. The study will also focus on determining the whole-rock and detrital feldspar isotopic compositions (Sm-Nd, Pb/Pb), as well as single-crystal zircon U-Pb analyses, as mechanisms to identify specific source rocks and localities, and their relative abundances through time.