【摘要】 <正> 温都尔庙群产于蒙古地槽褶皱带南缘,其本身又可分南带和北带。前者主要分布于集二线朱日和、哈尔哈达、白音诺尔、乌兰敖包一带,后者则分布于集二线以东苏尼特右旗至苏尼特左旗一带。1958年内蒙古区测队首先建群。更多还原

【Abstract】 1. The Wundurmiao Group belongs to the ophiolite complex composed of meta-morphosed tholeiite, ultrabasic rocks, gabbro, diorite, plagioclase granite, spiliticlavas and dikes and siliceous rocks. They show a pseudosequence of strata and aremostly in faulted contact with each other, spanning a long time interval. Its con-ception is different from that of conventional stratigraphic groups, so it should beknown as a complex. 2. The siliceous rocks in the upper part of the group contain Ordovicianradiolarians. The greenschist in the mid-lower of the group has a Rb-Sr age of509±40 m. y. and an initial ⁸⁷Sr/⁸⁶Sr ratio of 0.70434±0.0001, so it belongs to Mid-Late Cambrian deep-marine tholeiite. The K-Ar amphibole age of residual basaltfragments at the base ranges from 540-630 m. y. The emplacement time of ultra-basic rocks is pre-Silurian. The author doubts about Peng Lihong’s report on thepresence of hyolithis fossils in siliceous rocks that have been found in the Meishu-cun Formation at the base of the Cambrian in southern China. 3. The author considers that the absence of early Cambrian （550-600 m. y.）strata was due to Crustal compression before subduction. The Benioff zone wasformed 550±30 m. y. ago. In the stable subduction stage when Cambrian-Ordovi-cian strata were deposited on the continental crust, oceanic-crustal fragments ofthe Wundurmiao Group as well as the Beineimiao island arc were formed. Duringthe Silurian-Devonian, the Sino-Korean plate was obducted northwards, resultingin uplift of continental crust, and so Silurian-Davonian strata were absent andregional metamorphism occurred. Owing to the sledging mechanism of obduction,sialic crust and sima crust were mixed to form a late Caledonian to early Variscangranite zone extending along the convergent zone of plates. Finally the residualsea between plates formed a superposition basin during the Permo-Carboniferous;thus the conversion of oceanic crust to continental crust was completed.更多还原