西秦岭中志留统“硅、灰、泥岩”型层控铀矿的沉积特征及控矿条件  

SEDIMENTARY CHARACTERISTICS AND ORE-CONTROLLING FACTORS OF " SILICEOUS ROCK- CARBONATE ROCK- MUDROCK"TYPE STRATABOUND URANIUM DEPSITS OF MIDDLE SILURIAN IN WEST QINLING RANGE

作　　者：唐朝晖[1] 曾允孚[2] 

机构地区：[1]中国科学院地质研究所 [2]成都地质学院沉积所

出　　处：《沉积学报》1990年第2期33-41,共9页Acta Sedimentologica Sinica

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。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.

关 键 词：铀矿 沉积相 中志留世 控矿条件 

分 类 号：P619.140.5[天文地球—矿床学]