滇川西部金沙江古特提斯洋盆演化的同位素年代学制约

SHRIMP zircon U-Pb ages of gabbro, anorthosite, and plagiogranite from the ophiolitic complex, and related marginal granite in the Jinshajiang area, provides important geochronological constraints for the oceanic spreding, the subduction and final collision, therefore, which constructs a time framework for the Jinshajiang Paleo-Tethys evolution. The Jinshajiang ophiolite is dated at 329±7 Ma-320±10 Ma，the subduction event, 320±10 Ma-285+/-6 Ma，the oceanic evolution ending at 263±6 Ma, and the timing of final collision, 246 Ma+/-4 Ma-218+/-3 Ma. Besides, the Jicha Alaskan gabbro from neighboring Langchangjiang mafic-ultramafic belt yields the SHRIMP U-Pb age of 294 Ma, indicating that the Paleo-Tethys subduction taken place earlier than this time. .The work also states the Wilson cycle of the Jinshajiang Paleo-Tethys Ocean floor, on the basis of a comprehensive study of the stratigraphy of the passive margin, the molasses formation, the ophiolites and the island arc, as well as the fossils and SHRIMP ages..In the past, the Jinshajiang ophiolite was considered the late Carboniferous and /or Permian，which are mainly radiolarian fossil ages.

主要应用同位素地质年代学结合微体古生物学方法，系统研究与金沙江古特提斯洋盆演化有关的蛇绿岩，火山岩和花岗岩时代，建立金沙江古特提斯洋盆演化的重大构造事件，包括：大陆拉张-海底扩张-俯冲消减-碰撞造山的年代格架，提供古特提斯洋盆演化的同位素年代圃肌