大别山榴辉岩的成因:原岩属性提供的证据

ORIGIN OF ECLOGITES FROM THE DABIE MOUNTAINS: EVIDENCE FROM PROTOLITH

大别山榴辉岩的地质产状、岩石化学及地球化学特征表明,其原岩一部分是大陆拉张时期侵位的辉长岩,另一部是原始表壳岩系中的(变质)大陆拉斑玄武岩,少数与大理岩或富钙片麻岩共生者为泥灰岩。这些岩石做为俯冲大陆板片的组成部分,在扬子-华北板块碰撞过程中经原地高压变质作用转变成榴辉岩。

The occurrence, petrochemistry, REE and Sr isotope geochemistry indicate that the pro- tolith of eclogites from the Dabie Mountains are either gabbros formed during continental extension or bedded continental tholeiites corresponding to Late Archean supercrustal rocks, only a minority of eclog- ites which are associated with marbles and calcic gneisses is derived from lime mudrocks. As a part of subducted continental slab, those rocks underwent in situ high-pressure metamorphism and transformed into eclogites during the collision of the Yangtze plate and the North China Plate.