柴达木盆地北缘西段榴辉岩相变质泥质岩的确定及意义

Eclogitic metapelites in the western segment of the north Qaidam basin and their geological implications

在柴北缘西段的鱼卡—落凤坡一带,识别出榴辉岩相的变质泥质岩,其典型的矿物组合为石榴子石+蓝晶石+硬绿泥石+多硅白云母±十字石±钠云母+石英+金红石。温压估算获得其峰期变质条件为p=2.3～3.1GPa,T=615～700℃,与相邻榴辉岩形成的温压条件相似。结合大理岩和正片麻岩中保存有残留的榴辉岩相的矿物,认为榴辉岩与围岩经历了共同的变质历史,它们之间的关系是“原地”关系,而不是“构造侵位”关系。

Eclogitic metapelites occur in Yuqia-Luofengpo area of the north Qaidam basin. Their typical mineral assemblages are garnet + kyanite + chloritoid + phengite ± staurolite ± paragonite + quartz + rutile. p-T estimations gave a peak metamorphic conditions at about 615～700℃ and 2.3～3.1GPa respectively. The comparison of eclogitic mineral relics in marbles and orthogneisses enclosing eclogites suggests that the relationship between eclogites and their country rocks is 'in situ' rather than 'tectonic emplacement'.