Petrological and Tectonic Investigations of High Pressure Metamorphism in NE Oman

阿曼东北部Saih Hatat峰顶的基底和陆台矿床中产有蓝片岩、C型榴辉岩等高压变质岩。蓝片岩和榴辉岩构成了一个连贯的原地地体，结构上覆盖着两个包含较低级别高压变质组合的逆冲桩。整个层序被Smail蛇绿岩推覆构造所覆盖。这些高压变质岩的构造环境是独特的，因为它们赋存于未经历陆陆碰撞的被动大陆边缘，以及它们与未变质的特提斯-斯梅姆蛇绿推覆构造的关系。要求国家科学基金会提供为期两年的支持，以继续对阿曼东北部的高压变质作用进行详细的野外、岩石学、地球化学和地质年代学研究。这项研究的目的是：(A)约束变质作用的压力-温度条件，重建不同构造地体的压力-温度-时间路径；(B)建立高压变质岩不同岩性的岩石成因格网；以及(C)确定这些区域的变质年龄和隆升速率。这一研究结果将约束阿曼高压变质作用与蛇绿岩侵位的关系，并将用于建立对大规模构造事件具有足够时间控制的构造模型。这项研究的最终目的是解释为什么在没有大陆-大陆碰撞或大陆边缘之下洋壳俯冲的情况下高压变质作用的形成。

Blueschists, type-C eclogites and other high pressure metamorphic rocks occur in the basement and continental platform deposits of the Saih Hatat culmination in northeastern Oman. The blueschists and eclogites constitute a coherent in situ terrain structurally overlain by two thrust piles containing lower-grade high pressure metamorphic assemblages. The entire sequence is overlain by the Semail ophiolite nappe. The tectonic setting of these high pressure metamorphic rocks is unique given their occurrence in a passive continental margin that has not undergone continent-continent collision and their structural relations to the unmetamorphosed Tethyan Semail ophiolite nappe. The NSF is requested to provide two-year support to continue a detailed field, petrological, geochemical and geochronological study of high pressure metamorphism in NE Oman. This study is aimed at (a) constraining the pressure-temperature conditions of metamorphism and reconstructing the pressure-temperature-time paths of the different structural terrains (b) developing petrogenetic grids for the various lithologies of the high pressure metamorphic rocks; and (c) establishing the ages of metamorphism and uplift rates of these domains. The results of this study will constrain the relationship between high pressure metamorphism and ophiolite emplacement in Oman and will be used to develop a tectonic model that will have sufficient temporal control on the large-scale tectonic events. The ultimate goal of this research is to explain why high pressure metamorphism developed in the absence of continent- continent collision or oceanic crust subduction beneath the continental margin.