中央アジヤ,小コーカサスのオフィオライト

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Ophiolite associations of Middle Asia develop in the Variscan folded belts and are exposed in the form of separate bodies in the ranges of the Southern Tien Shan and the Kizil-Kum ranges. The total length of the ophiolite belt is over 1,800 km. These ranges are composed of sedimentary, volcanic and plutonic rocks of Precambrian and Paleozoic ages, which are folded complicatedly with overthrust and nappe structures. On the other hand, ophiolite associations of Lesser Caucasus are observed in the Alpine folded belts along the Terter river. They are overlain with a sharp unconformity by the Upper Jurassic-Cretaceous deposits. The inner structures of the ophiolite zones in Middle Asia and Lesser Caucasus are very similar except age of formation. Both serpentinite melange and tectonized olistostrome are formed in the process of tectonic movement. There is no intrusive contact between ultramafic and gabbroic complexes of the ophiolites. Blocks of various ages and rocktypes in serpentinite melange are recognized; ultramafics, gabbro, diabase, spilite, jasper, chert, limestone, sandstone, green-schist and glaucophane-schist. According to A.V. Peive, eugeosynclines originated on the basement composed of oceanic crust, and the former oceanic crust is tectonically squeezed out along the faults; it is altered to the melange and often occurs at the base of major allochthonous slabs. His negation of Stille's eugeosynclinal "initial" magmatism and Steinmann's trinity of the ophiolites brings forward a new problem as to the genesis of ophiolites.
地学団体研究会の論文
1974-01-20

中央アジヤ,小コーカサスのオフィオライト

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