二连盆地马尼特坳陷西部幕式裂陷作用对铀成矿的影响

Effect of the Episodic Rifting in the Western Manite Depression in Erlian Basin on Sandstone-type Uranium Mineralization

二连盆地包括马尼特坳陷早白垩世具有幕式裂陷特点。裂陷幕不同阶段控制铀储层的垂向分布并且控制砂岩型铀矿的垂向分布。在马尼特坳陷西部,有利的储矿层位、有利的铀储层的成因类型和砂岩型铀矿的形成过程都与盆地的幕式演化密切相关。赛汉组为断拗转换期,为最有利的铀储层发育层位;裂陷幕的末期通常伴随弱构造反转,多幕弱构造反转形成的构造斜坡控制古水文地质系统并控矿;不同裂陷幕阶段之间的不整合面和剥蚀作用是氧化带和砂岩型铀矿发育的有利时期;幕式裂陷决定了石油-天然气、煤和砂岩型铀矿的时空配置。根据二连盆地幕式裂陷不同阶段的构造、沉积特征可以明确重点勘探层位、找矿类型和有利找矿部位。

Erlian Basin includingthe Manite Depression is characteristic of episodic rifting in the Early Cretaceous. Different stages of rift episodes control the vertical distribution of uranium reservoir and sandstone-type uranium deposits. In the western Manite Depression, advantageous ore-bearing sequences and uranium reservoir and the forming process of sandstone-type uranium deposits are all closely related to the episodic rifting in the Basin. Saihan Formation is the advantageous uranium reservoir bearing sequence which is in the transition stage from fault depression to sag^Late of episodic rifting usually accompany with weak episodic tectonic inversion. Multi-episodes weak tectonic inversion result in structural slope which contol the paleo-hydrogeology and the mineralization; Unconformity surface and denudation between different rifting episodes are control factors of the development of the oxidized zone and sandstone-type uranium deposits~ Different stages with different features of episode rifting decide the space and time disposition of oil-gas, coal and sandstone-type uranium deposits, which participate in sandstone-type uranium mineralization. According to different structural and depositional features of different stages of episodic rifting, we can determine key exploration sequences and prospecting types and favourable prospecting areas.