SEDIMENTARY CHARACTERISTICS AND ORE-CONTROLLING FACTORS OF "SILICEOUS ROCK- CARBONATE ROCK- MUDROCK"TYPE STRATABOUND URANIUM DEPSITS OF MIDDLE SILURIAN IN WEST QINLING RANGE
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摘要: 本文详细研究了西秦岭南带中志留统“硅、灰、泥岩”型层控铀矿含矿岩系的沉积相类型及特征,查明了本区中志留世各期的岩相古地理特征。着重讨论了铀矿田内控矿的地质条件。Abstract: Siliceous rock-carbonate rock-mudrock" type stratabound uranium deposits refer to those occured in special lithologic formations consisting mainly of siliceous rocks, carbonate rocks and mudrocks. Presently, this kind of ore deposits is one of the unique types of uranium deposits in China.The Silurian in this area is also called Bailongjiang Group which is a suit of fine-grained terrigenou. clastic rocks such as siltstone, mudstone and sandstone, interbedded with siliceous rocks, and carbonaterocks.The Middle Silurian series of orefield in the area can be fallen into three: Yangchanggou Formation Taer Formation, and Lalong Formation. The lower part of each formation consists of fine- grained terrigenous clastic rocks, the upper part of each formation consists of siliceous rocks, carbonate rocks and mudrocks. Almost all of the uranium deposits are occured in the strata of siliceous rocks, carbonat rocks ami mudrocks, upper part of each formation of Middle Silurian.According to the comprehensive reserch of sedimentary facies of Silurian, two facies areas have beet recognized: the restricted shelf facies area in western region, and the open shelf facies in eastern region.The former can be subdivided into: restricted inner shelf facies, gulf facies, and the comples of orgam reef/ shoal facies and tidal flat/ lagoon facies (isolated platform facies) . The latter can be subdivides into: inner-outer shelf facies, and the neritic shoal facies. As a result of discovering of Stromatopora organ ic reef and other shallow-water criteria, a entirely new view of lithofacies arid paleogeography of Silurian in this area has been obtained. In Silurian, it should belong to a marginal neritic environment in north of deep sea environment believed by earlier authors. Because of the existence of Baiyi subaqueous uplift, a isolated platform was developed in the restricted inner shelf environment during the reef- forming period of Middle Silurian, and formed the special complex of organic reef/ shoal facies and tidal flat/ lagoon facies.Eastwardly, it was a open shelf to sub-deep marine environment in this period.The uranium deposits are obviously controlled by the strata and lithofacies. Both the uranium sources and mineralizer came from the strata of siliceous rocks, carbonate rocks and mudrocks.It can be concluded that the uranium deposits in this area are typical stratabound deposits reformed by midium-lower temperature hydrothermal solutions based on the nature of ore-forming solutions, the physico-chemical conditions and the metallogtenic epoch.The ore-controlling factors for the uranium deposits are mainly as follows:(1) The strata of "siliceous rock-carbonate rock-mudrock" of Middle Silurian.(2) The complex of organic reef/ shoal facies and tidal flat/ lagoon facies, the main roles include: I. the lagoon facies is favourable for forming of uranium sourcebeds, Ⅱ the lithologic formations in the complex is favourable for enrichment of uranium during the metallogeic processes.(3) The uranium deposits in the orefield are almot dstributed along the nearly EW faulting structures.(4) The preserval conditions of uranium deposits.
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[1] (1)刘宝君、曾允孚主编,1986,岩相占地理基础与工作方法,地质出版社。
(2)李建林等,1987,西秦岭白依沟群的沉积环境及其时代的探讨,矿物岩石,第2期7-15 05
(3)中国地层委员会,1964,中国的志留系,科学出版社。
(4)秦锋、甘一研,1976,西秦岭占生代地层,地质学报,第1期
(5)傅力溥等,1983,西秦岭的志留系,地层学杂志,第7卷,第4期。
(6)黄广荣、庞玉惠,1985,华南地区碳酸盐型层控铀矿的岩相控矿作用,南岭地质矿产文集,第5集,地质出版社
(7)张待时,1985,硅质岩和灰岩中铀矿床的稳定同位素研究及矿床成因,国际地质交流文集5,地庾出版社。
(8)北京铀矿地质研究所,1982,碳硅泥岩型铀矿床文集,第68-78和I8--84页,原子能出版社
(9)Wilson, J L.. 1981,的地质历史中的碳酸盐相(中译本),冯增昭等译,地质出版社
(I0)Maynard, J. Berry, 1983. Geochemistry of Sedimentary Ore Deposits, Sprmger- Verlak New York.
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