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西奏岭中志留统的层控袖矿床是在沉积作用构成铀源层的基础上,经地下水热液改造富集而成。志留系为被动大陆边缘海的沉积,其南侧为若尔盖古陆。中志留统分为三组,每组的下段均为泻湖相的细碎屑岩,每组的上段均为含炭硅灰泥岩组成的含铀岩组。中志留世时期有大体平行古海岸的水下隆起构成岛链障壁,含铀岩组属于泻湖-礁后潮坪-礁滩相组合。近岸的浅水条件,丰富的陆源细碎屑,局部的还原相带,是形成富铀沉积物的三个基本条件。铀的沉积主要发生在礁滩内缘和礁后潮坪相环境,具中偏低能量、有陆源细碎屑参与、存在生物大量死亡分解而造成的局部还原场,在较缓慢的沉积过程中,海水中的UO_2~(2+)系通过底水与有机质和粘土质等产生充分的渗透扩散和交替吸附而形成。
The Xizhaoling stratigraphic-controlled sleeper deposit in the Middle Silurian is formed by enrichment of groundwater hydrothermal fluids on the basis of sedimentary facies of uranium source. Silurian is the passive continental margin of the sea deposition, the south side of Ruoergai ancient land. The Middle Silurian is divided into three groups, the lower part of each group are fine clastic rocks of lagoon facies, and the upper part of each group is a group of uranium-bearing rocks composed of carbonaceous siliceous mudstone. During the Middle Silurian period, the submarine uplift parallel to the ancient coast formed the island chain barrier, and the uranium-bearing rock formation belonged to the combination of lagoon-reef tidal flat-reef beach. Nearshore shallow water conditions, abundant terrestrial fine debris, and local reduction facies are the three basic conditions for the formation of uranium-rich sediments. The deposition of uranium occurs mainly in the inner margin of the reef and in the tidal flat after the reef, with medium and low energy, with the involvement of terrigenous fine detritus and the local reduction field caused by the massive death and death of the organism. During the relatively slow sedimentation , UO_2 ~ (2+) in seawater is formed by full infiltration diffusion and alternate adsorption of bottom water, organic matter and clay.