REGIONAL GEOLOCY OF SHANXI PROVINCE

Except for the Siluxian and Devonian, strata from the lower, middle and upper Precambrian to various systems of the Paleozoic, Mesozoic and Cenozoic are all distributed and exposed. The Lower and Middle Cambrian strata are represented by strongly folded metamorphic rock series, forming the crystal- line basement of Shanxi. The covers overlying the crystalline basement consist of strata from the Changcheng System to the Ordovician dominated by neritic carbonate rocks （with clastic rocks at base）, Carboniferous strata dominated by paralic, coal-bearing sandy shale, Permian strata dominated by neritic- alluvial sandy shale and Triassic, Jurassic, Cretaceous and lower Tertiary strata dominated by sandy mudstone of inland basin and intermontane basin facies. Widespread, loose deposits belong to the upper Tertiary and Quaternary. The magmatic rocks in Shanxi has a relatively small exposed area but show the characteristics of polyphase, multi-stage, polygenetic rock types. According to their ages,magmatic rocks of eight phases may be distinguished; they are the pre-Wutaiian, Wutaiian, Luliangian, Jinningian, Hercynian, Indosinian, Yanshanian and Himalayan magmatic rocks,of which the Wutaiian, Luliangian and Yanshanian ore deposits are the most important. Besides, more subphases and stasges may be recognized. Regional metamorphism involves three major phases:the pre-Wutaiian, Wutaiian and Luliangian phases. The pre-Wntaiian metamorphism reaches higher amphibolite facies-granulite facies;the Wotaiian metamorphism concerns lower amphibolite facies,higher greenschist facies and lower greenschist facies; the Luliangian metamorphism is dominated by regional dynamic metamor- phism and only reaches the slate and phyllite grade of lower greenstone faci- ess. Tectonically, Shanxi lies in between two gigantic latitudinal structural belts:the Tianshan-Khingan structural belt and the Qinling structural belt, and constitutes an important component part of the North China fault block region. The entire geological history of Shanxi comprises four tectonic cycles. The pre-Wutaiian cycle generated a series of vortex structures with the inner side of a vortiacl surface rotating counterclokwise, thus forming an old conti- nental nucleus of Shanxi. The Wutaiian-Luliangian cycle includes two subcy- cles:the Wutaiian subcycle gave rise to a series of fault-fold belts characterized by recumbent and superposed folds; the Luliangian subcycle produced a downwarping folded belt characterized by synclinoria whose subsidiary folds are overturned inwards. The Jinningian-Shanxiian cycle is quite important in Shanxi, determinins the dominantly NNF-trending block fault structures that are observed now in Shanxi. The Himalayan cycle is now still in the initial stage of extension, which is mainly manifested in central Shanxi, forming a series listric taphrogens that run from north to south through Shanxi.