Geological and Geochemical Features of the Neoproterozoic Ophiolites Along the Folded Siberian Platform Margin

查看全文 作　　者：Konnikov Eduard G. (Institute of Experimental Mineralogy, 142432 Chernogolovka, Moscow D istr., Russia) Tsygankov Andrey A. (Geological Institute of Siberian Branch of RAS, Sakhyanovoy 6a, 6700 47 Ulan-Ude, Russia) Vernikovsky Valery A. (Institute of 出　　处：《Global Geology》索引1999年第4卷第2期,共11页 摘　　要：The data of the last decade investigations of ophiolites in western m argin of Siberian platform were summarized. The study of geology, geoche mistry and geochronology show that the interrupted ophiolitic belt of Neoprotero zoic age is 2000 km long, from the Taimir Peninsula to the Northern Transbaikali a Region through the Yeniseyski Khryazh and the Sayanskii Range. These studies i ndicated that the major differences of the Neoproterozoic ophiolites from younge r Phanerozoic ophiolite complexes are as follows: 1) occurrence of komatiite and picritie-like, high-magnesium rocks among the ophiolite volcanics; 2) ophioli te volcanics with both MOR and island-arc tholeiites; 3) ophiolite sequence where sheeted dikes and layered complex ('low gabbro') are usually absent. These pecu larities indicate that the Neoproterozoic ophiolites of Eastern Siberia were gen erated at suprasubduction environment and the Neoproterozoic oceanic crust was n ot as thick as Phanerozoic one. 关 键 词：OPHIOLITES specific structure composition PRECAMBRIAN East Siberia