吐哈盆地西南缘砂岩型铀矿目的层后生蚀变特征及成矿意义

Sandstone-type Uranium Deposit Target Layer Epigenetic Alteration Features and Ore-forming Significance in Southwestern Margin of Turpan-Hami Basin

吐哈盆地十红滩地区是我国西北地区一个重要的铀矿成矿基地,已在北矿带、南矿带、八仙口等地段发现了工业矿床。通过对含矿目的层侏罗系西山窑组采样分析及镜下观察,岩石碎屑成分主要为石英、长石及岩屑,后生蚀变作用较强,主要发育有碳酸盐化、石膏化、赤铁矿化、褐铁矿化、粘土矿物相互转化等后生蚀变作用。后生蚀变现象的大量存在表明该区目的层长期经历稳定的热流体改造作用,这与砂岩型铀矿成矿作用密切相关。本区目的层发育有大量炭化植物碎屑,及黄铁矿氧化残留,为铀矿物的还原沉淀提供有利的还原剂条件。

The Shihongtan area in the Turpan-Hami Basin is an important uranium ore-forming base in Northwest China. Industrial sig-nificant deposit has been found in North belt, South belt and Baxiankou area. The analysis and microscopic observation for samplesfrom ore-bearing target Jurassic Xishanyao Formation has found that the component of lithoclasts has quartz, feldspar and debris. Theyhave been after strong epigenetic alteration with carbonation, gypsification, hematitization, limonitization and clay minerals reciprocaltransformation etc. Abundant epigenetic phenomena have shown that the target layer in the area had experienced long-term stable hy-drothermal fluid transformation that closely related to the sandstone-type uranium deposit ore-forming. Target layer in the area devel-oped large amount of carbonized plant debris and pyrite oxidized residues, the reducing agents provided favorable condition for urani-um mineral reduction precipitation.