鄂尔多斯深盆气与铀矿化关系初探

Preliminary discussion on relationship between deep-basin gas and uranium mineralization in Ordos basin

深盆气是非常规的天然气藏。鄂尔多斯深盆气与铀矿化有密切关系 ,上古生界气源层铀含量丰富、易浸出 ,故也为铀源层。在铀源层成岩时所形成的压榨水 (即深层水 ) ,经燕山期热事件快速增温增压 ,使铀的溶解度大大增加。此时也正是盆地生气高峰期 ,气压远远大于水压 ,气体推动深层水沿断裂向上扩散。在上覆透水层 ,由于地表水的参与形成复杂的气水地球化学垒 ,使铀沉积成矿。

Deep-basin gas in a kind of non-traditional natrual gas deposit.The deep-basin gas in Ordos basin is closely associated with uranium mineralization.Upper Paleozoic in the basement of the basin represents both gas-sourced and uranium-sourced beds and uranium in Paleozoic strata is easily leachable.The squeezed water(i.e.deep-bed water)formed during the diagenetic process of uranium-sourced bed was rapidly heated and pressed making the uranium solubility in it greatly increased.It was just the peak-period of gas generation in the basin,and gas pressure greatly exceeded water pressure.So,the gas made deep-bed water moved and diffused upwards along faults.Because of the complicated gas-water geochemical barrier formed by the involvement of surface water,the precipitation of uranium occurred in overlying aquifers to form uranium deposit.This paper has summarized prospecting criteria of such uranium deposit as well.