与赣东北元古代蛇绿岩有关的高温、高压变质岩和重变质作用机制的讨论

The High Temperature and Pressure Metamorphic Rocks Relatied to Ophiolite in Northeastern Jiangxi and a Discussion on the Superimposition metamorphism

赣东北蛇绿岩发育地区产出有高温和高压变质岩。高温变质岩包括多种角岩、透辉石岩和黄长石大理岩,高压变质岩包括文石硬玉蓝片岩、硬柱石片状大理岩和红帘石硬绿泥石片岩。这两类变质岩仅见于元古界地层内,空间分布上仅与本区蛇绿岩有关。在大陆边缘蛇绿岩发育期间,有过一种岩浆作用——热变质作用,高压变质作用叠加在高温变质作用之上,暗示 了高温变质岩与该蛇绿岩发育的洋盆早期拉张阶段的岩浆作用相对应,高压变质岩则与洋盆晚期闭合阶段的构造作用相对应,我们称这种机制为“重变质作用”,与都城秋穗的“对变质作用”不同。

In the Northeastern Jiangxi where ophiolite develops occur high temperature metamorphic rocks including various hornstones, diopsidite and melilite marble and high pressure metamorphic rocks, such as aragonite—jideite blueschist, Iowsonite schistose marble and piemontite-chloritoid schist. Both kinds of these metamorphic rocks are emerged only within the Proterozoic formation and associated in space with the ophiolite. There are indications that a magmatism-thermometamorphic mechanism is occured during the development of the continent margin ophiolite. From mention above and the fact that the high pressure metamorphism is superimposed on the high temperature metamorphic rocks, the authors suggest that the high temperature metamorphism is related with the magmatism in the early stage of extension of the ocean basin where the ophiolite development, and the high pressure metamorphism is occured in the tectonism in the late stage compression of the ocean basin. This mechanism is called by us as 'superimposition metamorphism' which is different from the paired metamorphism.