我国西部祁连山区的古海洋地壳及其大地构造意义

祁连山是我国西部的重要山系之一。解放后,在伟大领袖毛主席和中国共产党的英明领导下,不仅进行了大量矿产普查、勘探工作,而且广泛开展了区域地质调查,特别是无产阶级文化大革命以来,积累了丰富的实际资料。综合本区历年的地质成果,结合本人近年的实际观察,我们发现祁连山具有典型的古板块构造特点。本文试图从岩石和大地构造学出发,对祁连山古海洋地壳的空间分布和时代及其构造演化作一概略分析,并进而探讨板块构造在祁连山的细部表现。

PALEO-OCEANIC CRUST OF THE CHILIENSHAN REGION, WESTERN CHINA AND ITS TECTONIC SIGNIFICANCE

The remnants of Sinian, Mid-Cambrian and Early Ordovician oceanic crust and mantle are exposed almost continuously along the Chilienshan, in the northern margin of Tsaidam old land. They are distributed along four parallel belts in the Chilienshan, with a total length of about 600-1000 km. The remnants of the oceanic crust and mantle of the region, which occur only in the hanging wall of the deep thrust faults, are composed of four principal units of the same component, such as the peridotite, harzburgite, tholeiite, spilite, radiolarian chert, siliceous limestone and graywacke.On the basis of the recent investigations at least four underthrusting zones have been found to exist during the Palaeozoic and extend for a width of 200 km within the Chilienshan region. The geological features (stratigraphy, structure and lithology) involved are discussed separately in detail by the authors.