Radiogenic Isotopic Study of Diagenesis and Low-grade Metamorphism Pelites

沉积和低品位变质泥质岩记录了与地壳流体相互作用的产状、时间和强度，但由于关键矿物，特别是粘土矿物来源的非均质性，对这类岩石和事件的放射性成因同位素研究结果不明确。该项目将结合放射性成因同位素研究（Rb-Sr和K-Ar）和扫描透射电子显微镜（STEM）的详细表征，以便为同位素数据的解释提供坚实的基础。该提议是基于一个成功的“试点项目”，该项目开发了墨西哥湾沿岸页岩的Rb-Sr分析方法，该方法已经通过构造诱导的流体流动验证了“幕式”成岩作用。这项研究将把研究扩展到整个成岩作用范围——通过对墨西哥湾沿岸页岩的进一步研究，以及对纽约北部和威尔士的连续序列的分析，从晚期成岩作用到绿片岩相变质作用。

Sedimentary and low-grade metamorphic pelitic rocks record the occurrence, timing and magnitude of interaction with crustal fluids, but radiogenic isotopic studies of such rocks and events lead to ambiguous results due to heterogeneity of source of the key minerals, especially clay minerals. The project will combine radiogenic isotopic studies (Rb-Sr and K-Ar) with detailed characterization by scanning transmission electron microscopy (STEM) in order to provide a firm basis of interpretation of the isotopic data. The proposal is based on a successful "pilot project" development of methods for Rb-Sr analysis of Gulf Coast shales that have verified "episodic" diagenesis by tectonically- induced fluid flow. This research will expand the studies to the full range of diagenesis - low-grade metamorphism with further studies of Gulf Coast shales, and analyses of continuous sequences across northern New York and in Wales that span the range from late diagenesis to greenschist facies metamorphism.