Petrogenesis of Proterozoic Anorogenic Granites in the Central United States

拟议工作的目标是调查 1.1 ~ 1.8Ga非造山花岗岩成因及构造环境 构成了美国中部地壳的很大一部分 States. 这项研究将采用Nd、Sr、Pb的同位素变化 和O，以及微量元素模式，以阐明 花岗岩源区、岩浆成因过程及 岩浆的演化 来自600-1000公里宽的带的非造山花岗岩， 横跨北美大陆 他们被安置在 在1.1和1.8 Ga之间的几个事件中， 和微量元素的化学成分， 花岗岩的种类 提出的假设， 非造山花岗岩的化学和构造来源是 极其多样化，包含对立的极端。 一 全面的同位素和化学数据库将有助于 限制可能性。 本研究集中在四个 位于威斯康星州、密苏里州州和德克萨斯州的综合体。 都有 已知的U-Pb年龄，每一个都是岩石学和化学上的 表征了 具体的岩体将特别针对 详细的取样和研究。 这种方法允许研究两者 详细的岩浆成因在一个特定的岩体，并比较 不同地壳省和侵入体之间的岩体 情节。 需要两种观察尺度来识别 解释了非造山岩浆成因的主要特征。

The objective of the proposed work is to investigate the origin and tectonic setting of 1.1 to 1.8 Ga anorogenic granites that make up a large part of the crust in the central United States. The study will employ isotopic variations in Nd, Sr, Pb and O, and trace element patterns to elucidate the nature of granite source regions, the process of magma genesis, and the evolution of the magmas. Anorogenic granites from a 600-1000 km-wide band that extends across the North American continent. They were emplaced during several episodes between 1.1 and 1.8 Ga, and have a major and trace element chemistry that distinguishes them from other types of granites. Suggested hypotheses regarding both the chemical and tectonic sources of anorogenic granites are exceedingly diverse and encompass antithetic extremes. A comprehensive isotopic and chemical data base would help constrain the possibilities. This study focusses on four complexes located in Wisconsin, MIssouri, and Texas. All have known U-Pb ages, and each is petrographically and chemically characterized. Specific plutons will be targeted for especially detailed sampling and study. This approach allows study of both details of magma genesis in a specific pluton, and the comparison of plutons among different crustal provinces and intrusive episodes. Both scales of observation are required to identify and explain the main features of anorogenic magma genesis.