新疆南天山高压变质岩石的抬升机制

对南天山蓝片岩的变质作用p-T-t轨迹、蓝片岩和相关岩石的构造变形特征以及区域地质特征的综合研究表明,南天山高压变质岩石经历了两个抬升阶段。早期阶段,蓝片岩在增生楔下部的下地壳深处滞留了约100Ma,仅因浮力作用发生轻微抬升,速率约0.05-0.1mm/a。晚期阶段,推覆作用和剥蚀作用快速抬升蓝片岩浅构造层次,速率可能大于1-2mm/a,以致保存蓝闪绿片岩相矿物组合。

UPLIFT MECHANISM OF HIGH-PRESSURE METAMORPHIC ROCKS, SOUTH TIANSHAN, XINJIANG

On the basis of the studies on the metamorphic p - T-t trajectory of the South Tianshan blueschists, structural deformation characters of blueschists and co herent rocks and regional geology in this paper, we suggest that the South Tianshan high-pressure metamorphic rocks had undergone two uplift stages. In earlier stage, blueschists had staled at the lower crust level of accretionary wedge for about 100Ma, only slight uplift having happened, at a rate of about 0.05 - 0.1mm /a, caused by buoyant forces. In later stage, overthrust and erosion uplifted bluechists to upper tectonic level rapidly, at a rate of more than 1 - 2mm /a, then preserved the blueschist-greenschist facies assemblages.