华南铀矿省铀矿构造成矿作用及其时空演化

华南铀矿省内已发现的工业铀矿床类型有花岗岩型、火山岩型、碳硅泥岩型、碳酸盐岩型和砂岩型。在空间上。铀矿床受环形及线性构造控制,并受上地幔构造制约。幔凸、幔凹阳地幔变异带互相交错,造成本区地幔的极不均一性,这是本矿省成矿的深部地质构造背景。通常铀矿床呈面型成环状分布,大型环形构造控制铀矿省,中型和小型环形构造控制铀矿田和矿床的产出。

TECTONIC METALLOGENESIS OF URANIUM AND ITS TIME-SPACE EVOLUTION IN URANIUM META LOGENIC PROVINCE OF SOUTH CHINA

Uranium deposits of economic importance such as granite-type, volcanite-type, carbonate-siliceous-pelitic rock-type, carbonate-type and sandstone-type have been discovered in the uranium metallogenic province of South China. In space, uranium deposits are controlled by ring structure and linear structure and restricted by the structure of the upper mantle. The mutual intersection of mantle bulge, mantle sag and mantle-slope belt gives rise to the heterogeneity of mantle in the region. This is the background of deep-seated structure for uranium occurrences. In general, the distribution of uranium deposits is planar along the ring structure. Large ring structures control uranium provinces and medium and minor ring structures control uranium ore fields and deposits. This paper discusses grade-sequences and clusters of linear structures and ore-concentrating structures controlling uranium mineralization. Time-space evolutional model of uranium in metalogenic province is suggested. The time-bound interval of uranium commercial concentration is about 35 Ma. It is just in the transitional period between two tectonic episodes of Yanshanian and Himalayan tectonic cycles respectively, and it is consistent with maximum mobility period and residual mobility period of the Diwa stage. Econimic concentration of uranium took place in Mesozoic period which was a relatively stable period for the continental crust changing from the stage of compression into tcosion under the action of plate tectonics. With the strong tectonic reactivation in Mesozoic and Cenozoic period, uranium was further increased in the tectonic-geochemical environments of uranium-rich strata (body). Under the mutual action of various uranium sources, fluid sources and heat sources, uranium in the partiular tectono-geochemical barriers was enriched and uranium deposits were formed.