Collaborative Research: Investigation of a Proposed Suture Between East and West Gondwana - - An Integrated Field, Geochronologic, and Remote-Sensing Analysis In East Madagascar

该项目将调查马达加斯加东部一条拟议的地质缝合线（Betsimisaraka缝合线）的年龄、结构几何形状和区域范围，该缝合线宽约50公里，长700多公里，连接着东冈瓦纳和西冈瓦纳的大陆碎片。缝合线假说构成了一个根本性的挑战，目前的范式有关的配置Rodinia和冈瓦纳的转变。本研究的目的是确定的结构聚散，运动学，和时间的EAO的关键部分，具有重要的全球规模的新元古代构造的影响的沉积-增生和终端-增生事件。研究将通过地质测绘和结构分析的综合方案进行，同时进行遥感分析（Landsat TM和SIR C/X雷达）、U-Pb年代学、地球化学和放射性同位素（Re-Os、Sm-Nd）调查。结构调查和样品采集将沿着沿着五条穿越拟定缝合线的河流断面进行。在拟议的缝合线是米和公里规模的橄榄岩，hartzbursts，辉长岩，玄武岩块解释为前莫桑比克海洋的遗迹。地球化学和地质年代学分析这些将限制其年龄和起源，并提供了一个重要的测试缝合假说。结构调查和U-Pb测年的岩石内和附近的建议缝合线将使我们能够评估其他关键要素的假设，并放置在冈瓦纳大陆的构造上的重要限制。TM成像和SIR C/X雷达分析将揭示宏观尺度的运动学关系，并为将缝合线外推到更大尺度提供依据。这项工作将导致一个新的认识运动学，年龄和整体结构聚散的关键，东部的EAO强烈分歧的意见，其演变正在出现。这项研究将涉及马达加斯加和美国的专业同事之间的合作，并允许美国和马达加斯加学生参与和培训实地和实验室研究。

This project will investigate the age, structural geometry, and regional extent of a proposed geological suture (the Betsimisaraka suture) in East Madagascar, approximately 50 km wide and over 700 km long, that welds the continental fragments of East and West Gondwana. The suture hypothesis poses a fundamental challenge to the current paradigm regarding the configuration of Rodinia and its transformation to Gondwana. The objectives of this research are to determine the structural vergence, kinematics, and timing of terrane-accretion and terminal-suturing events in the critical part of the EAO that have important global-scale implications for Neoproterozoic tectonics. Research will proceed through an integrated program of geologic mapping and structural analysis, together with remote sensing analysis (Landsat TM and SIR C/X radar), U-Pb geochronology, geochemical, and radiogenic isotope (Re-Os, Sm-Nd) investigations. The structural investigations and sample collections will be made along five river transects that traverse the proposed suture. Within the proposed suture are meter-and km-scale blocks of peridotite, hartzburgite, gabbro, and basalt interpreted as relicts of the former Mozambique Ocean. Geochemical and geochronological analysis of these will place constraints on their age and origin, and provide an important test of the suture hypothesis. Structural investigations and U-Pb dating of rocks within and adjacent to the proposed suture will allow us to evaluate other critical elements of the hypothesis, and place important constraints on the configuration of continental terranes within Gondwana. TM imaging and SIR C/X radar analysis will reveal macro-scale kinematic relations and provide a basis for extrapolation of the suture to a larger scale. This work will lead to a new understanding of kinematics, age and overall structural vergence in the critical, eastern part of the EAO where strongly divergent views of its evolution are emerging. The research will involve collaboration between professional colleagues in Madagascar and the U.S., and allow for the participation and training of American and Malagasy students in field- and laboratory-based research.