鄂尔多斯盆地南缘彬县地区铀成矿关键时期的古地貌特征

中侏罗世为直罗组下段沉积期,辫状河道为有利的铀储层砂体,铀矿(化)体主要赋存于辫状河砂体中,受沉积古地貌控制,主要发育在低洼区。晚侏罗世、早白垩世-古新世、始新世-中新世是砂岩型铀成矿期,古地貌控制了地下古水流的流向,控制着氧化还原带的分布和铀矿的富集:晚侏罗世铀预成矿期,古隆起区受到潜水淋滤,含铀物质向斜坡和低洼区迁移;早白垩世-古新世铀主成矿期,古地貌控制了含氧含铀水的水流方向,氧化还原带主要分布在古地貌斜坡区。

Palaeogeomorphologic features in the critical period of uranium mineralization in Binxian area, southern Ordos Basin

During Middle Jurassic period, i.e., the sedimentary period of Lower Zhiluo Formation, the braided channel was a favor-able sand body of uranium reservoir that hosted uranium, and uranium was mainly controlled by palaeogeomorphology and mainly developed in low-lying areas. The Late Jurassic, Early Cretaceous-Paleocene and Eocene-Miocene were main uranium mineralization stages. Palaeogeomorphology controlled the migration of underground water, the distribution of the redox zone and the enrich-ment of uranium deposits. During the Late Jurassic uranium pre-mineralization period, diving leaching caused the migration of uranium-bearing materials from the uplift to the slope and low-lying areas; during the main uranium mineralization period of Early Cretaceous-Paleocene, palaeogeomorphology controlled the direction of the water flow with oxygen and uranium, and the redox zone was distributed mainly in the slope area of the ancient landform.