| 中国北方震旦-寒武纪磷块岩的地质特征 |
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| 引用本文：.1983.Geological Characteristics Of The Sjnlran-Cambrian Phosphorite Deposits In North China[J].Mineral Deposits,2(4):78~88 |
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| Geological Characteristics Of The Sjnlran-Cambrian Phosphorite Deposits In North China |
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| Abstract:The phosphorite deposits of the Sinian-Cambrian ages are distributed mainly in Asia and Australia, and mostly in China, According to their geotectonic positions, these deposits might be assigned to six regions: 1) Altai-East Sayan Ergune fold belt; 2) Urutau-Tienshan-Xinggan fold belt; 3) Sino-Korean Paraplatform; 4) Yaigzi Paraplatform; 5) Tarim platform and 6) Qinling-Qilian- Kunlun fold belt. The phosphorite deposits occurring in lst and 2nd regions are of geosyacline type and those in the 3rd to 6th regions are of platform type. The phosphorite deposits of geosyncline type occurring along the border or in the intermediata massifs of the geosyncline are chiefly distributed in the USSR and Mongolia. They were formed during the early stage or the adult stage of the development of geosyncline. This important sort of deposits has not yet been discovered in China. The deposits of the platform type formed in the relatively stable stage of the platform are distributed in China, and mainly in south China. The Sinian deposits occur in the depressed belt within the platform, while the Lower Cambrian ones are found in the marginal region of the platform. The Sinian-Cambrian deposits are characterized by a marked zonal distribution and their fixed stratigraphic positions. In the geosynclinal areas from north southward, the phosphorite deposits of the above lst region occur in Wende series (corresponding to Sinian series), belonging to the miogeosyncline type and existing in the Caledonian fold belt, while those of the 2nd region occur in Lower Cambrian, belonging to the eugeosyncline type and existing in the Hercynian fold belt. As for things on platforms, from south to north, the Sinian deposits are distrbuted separately in the Yangzi paraplatform and in the southern part of the Qinling fold belt, the stratigraphic Positiops of the Lower Cambrian deposits are higher in the northern part than in the southern part, i.e., they occur in the Lower Cambrian strata in the southern part of Qinling, but in the Middle Lower Cambrian strata on Sino-Korean paraplatform, and the deposits in Tarim and Qinling-Qiliari-Kunlun regions seem to exist mostly between these two stratigraphic positions. and partly at the same position as those on the Sino-Korean paraplatform. The major deposits observed in geosynclinal regions of the North and Yangzi paraplatform of the South are of large dimensions and those in areas between these two regions are of medium or small sizes. This might have something to do with the time of the transgression of the northern and southern seas as well as the changes in paleoclimate in these regions. The phosphorite deposits on the whole overlie tillite beds, which suggests a genetic relationship between them. The phosphorite deposits have very similar rock formations provided that their stratigrapnic positions are identical. As regards the large-sized deposits, especially the Sinian deposits of both geosyncline and platform types, all phosphorite- bearing sedimentary rock series are of dark shale-silicilith-carbonate for mation, whereas the medium or small sized phosphorite deposits are unexceptionally in existence within the Middle Early Camlbrian strata and belong to terrigerlous-carbonate formation. |
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