U.S.-China Cooperative Research: Mechanisms of Pluton Emplacement; Study of East China and North America Batholiths

该奖项支持明尼苏达大学的克里斯蒂安·泰西尔和中国地质大学的温天芳在岩体位进机制方面的合作。PI的核心研究重点是验证花岗岩类岩体位于地壳上尺度裂缝之间的张拉桥的假设。这项研究目前正在内华达山脉基岩进行，这是环太平洋的一个主要大陆弧。本项目的目的是将岩体侵位机制的分析扩展到中国东部与内华达山脉经历相似构造过程的地区。内华达山脉所采用的方法包括野外和实验室的构造分析，以及花岗岩类岩石磁化率的各向异性分析，以获取侵位期间岩浆流动的信息。在华东地区，将有可能为该项目增加一个新的组成部分，即岩体重力异常分析，以确定它们的三维形状。这项技术很难在内华达山脉成功应用，因为崎岖的地形会导致很大的误差。相比之下，中国东部的岩体暴露在地形平坦的地区，确保了这种分析将提供高于背景噪声的有用信号。确定岩体的三维形状，特别是岩体的根区，是有待检验的假设的一个关键因素。由万教授率领的中国研究小组，在过去两年中，定期与国际和平组织通信，讨论分析深部岩体位的方法。中国东部的两个研究区域经过精心选择，与内华达山脉构造相似，野外暴露良好，地形平缓，以确保分析结果有意义，从而有效地测试不同的花岗岩就位模型。中国小组带来了他们在区域地质学方面的知识和在该领域的经验。美国的研究小组带来了岩石磁学和重力测量技术，这些技术应用于岩体。工作的所有阶段，从现场分析到实验室测量，都将共同进行，结果将由合作撰写。

9507687 Teyssier This award supports collaboration between Christian Teyssier, University of Minnesota, and Wen TianFang, China University of Geosciences on Mechanisms of pluton emplacement. The PI's core research is focused on testing the hypothesis that granitoid plutons are emplaced in the upper crust in tensional bridges between crustal-scale fractures. This research is presently being conducted in the Sierra Nevada batholith, a major continental arc in the Circum-Pacific. The aim of the proposed project is to extend the analysis of pluton-emplacement mechanism to East China in areas that underwent similar tectonic processes as the Sierra Nevada. The methods used in the Sierra Nevada involve structural analysis in the field and in the laboratory, and the analysis of anisotropy of magnetic susceptibility of granitoid rocks in order to retrieve information about magma flow during emplacement. In East China, it will be possible to add a new component to this project, the gravity-anomaly analysis of plutons, in order to define their three-dimensional shape. This technique is difficult to apply successfully within the Sierra Nevada because the rugged topography induces large errors. In contrast, the plutons of East China are exposed in areas of smooth topography, ensuring that this analysis will provide a useful signal above the background noise. Defining the three-dimensional shape of plutons, and particularly the root zones of plutons, is a key element in the hypothesis to be tested. The Chinese group, led by Professor Wan, has corresponded with the PI regularly in the past two years on the methods of pluton emplacement analysis. The two study areas in Eastern China were carefully chosen - in terms of tectonic similarity to the Sierra Nevada, good field exposure, and gentle topography - to insure meaningful results from the analyses and thereby test different models of granitoid emplacement effectively. The Chinese group brings their knowledge of the regional geology and their experience in the field. The American group brings techniques of rock magnetism and gravimetry applied to plutons. All stages of the work, from field analysis to laboratory measurements, will be conducted jointly, and the results will be written collaboratively.