MAIN ACHIEVEMENTS IN REGIONAL GEOLOGICAL SURVEYS IN HUBEI PROVINCE

Through 27 years of regional geological surveys, systematic and abundant data have been obtained in Hubei province and major advances have been made in respects of stratigraphy, petrology and geological structure of the regional geology of the province. It has been essentially ascertained that Precambrian, Paleozoic, Mesozoic and Cenozoic strata are exposed in the province and may fall into 42 sediment types of marine, continental and paralic facies （pelagic sediments excluded）, which beIong to the mobile, stable and transitional sedi- mentary sequences respectively. The dorminant rocks include intrusive and extrusive roeks of ultrabasic, basic, intermediate, intermediate-acid, acid, alkaline and carbonate compositions as well as mantle-derived ultrabasic and basic rocks and crustal-mantle syntectic, crustal anatectic and metasomatic acid to intermediate-acid rocks formed by the Dabieian, Yangtzeian, Caledonian and Yanshanian-Himalayan magmatic activities. Regional metamorphism of the Dabieian, Yangtzeian, Caledonian and Yanshanian-Himalayan stages had occurred in the province, thus giving rise to low- and moderate-pressure regional dyna- mothermal metamorphism and moderate- and high-pressure regional metamor- phism and regional dynamic metamorphism and forming granulite, lower amphibolite, higher greenschist, glaucophane greenschist and slate-phyllite facies and more 150 kinds of regional metamorphic rocks. According to the mqrked differences in stratigraphy. magmatic rocks, metamorphic rocks, struc- tural deformation, paleogeographical environments and mineral deposits, two first-order tectonic units- the Qinling fold system in the north and the Yangtze paraplatform in the south-have been distinctly distinguished in the province with the Qingfeng-Xiangfan-Guangji fracture as the boundary. This tectonic framework was created by the Dabieian, Yangtzeian, Caledonian and Variscan-Indosinian tectono-magmatic cycles. ln the Yanshanian-Himalayan cycle, the northern and southern parts both belong to the circum-Pacific con- tinental-margin mobile belt. In summary, the regional geological characteris- tics of Hubei province are the eventual result of the polycyclic evolution of the crust and mantle of Hubei province from the stage of the development of an early-middle Proterozoic geosyncline.