印度与亚洲板块碰撞及碰撞时限的新证据——日喀则卡堆蓝片岩Ar-Ar定年

New evidence of India-Eurasia collision and its timing—Ar-Ar dating of the Kardoi blueschist in Xigazê, Tibet, China.

几十年来,关于印度板块与亚洲板块碰撞启动和完成碰撞的时间,科学家们从不同的角度给予解释并建立了多种模式。高压变质带是板块碰撞过程中重要的事件记录,高压矿物的变质年龄是确定板块碰撞时间最直接的方法之一。从雅鲁藏布江缝合带南侧卡堆蓝片岩的蓝闪石中获得59.29Ma±0.83Ma的Ar-Ar加权平均年龄,是目前雅鲁藏布江高压变质带唯一的蓝闪石年龄。该年龄与利用海相沉积、最高海相层位、地层古生物、古地磁等研究方法获得的结论相吻合,印度河-雅鲁藏布江缝合带的闭合时间应在59Ma左右,也是洋壳消亡和印度与亚洲板块碰撞的时间约束。

In the last few decades, scientists have attempted to interpret the timing of initiation and completion of India-Eurasia collision from different angles and construct several models. HP metamorphic belts are important records of the process of plate collision and dating of HP minerals is one of the most direct method for determining the collision age. Glaucophane from the Kardoi blueschist at the south side of the Yadung Zangbo suture gives an Ar-Ar weighted average age of 59.29±0.83 Ma, which is the only glaucophane obtained from the Yarlung Zangbo HP metamorphic belt up to now. This age coincides with the results obtained by studying marine deposits, the highest marine horizon, stratigraphy, paleontology and paleomagnetism. The closure age of the Indus-Yadung Zangbo suture should be ～59 Ma, which is also the time constraint on the consumption of oceanic crust and India-Eurasia collision.