内蒙古二连盆地哈达图铀矿床地球化学特征及其地质意义

Geochemical Characteristics and Geological Significance of Hadatu Uranium Deposit in Erlian Basin,Inner Mongolian

文章基于大量分析测试数据,在阐述哈达图矿床-矿石特征的基础上,详细分析了矿床的主量元素、微量元素、还原容量、氧化还原能力、酸碱度、共伴生元素等成矿环境地球化学特征、流体包裹体特征和同位素特征,指出哈达图铀矿床具矿化品位高、矿体呈板状、规模大等特征,铀矿物以沥青铀矿为主,分两期,早期呈层状含杂质多,晚期呈鲕粒状较纯净附着早期沥青铀矿表面;低品位(<0.05%)矿石的成矿环境参数特征与巴彦乌拉矿床相似,包裹体均一温度为65~90℃;但高品位(>0.05%)矿石与强氧化还原能力ΔEh、中强酸、富Re等密切相关,包裹体均一温度为125~175℃,且与硫酸盐还原菌(厌氧菌)的作用密切相关;结合同位素年代学和热力学(T)和抬升史分析,说明哈达图矿床具多期多阶段成矿特点。其中,预富集阶段(105~70 Ma)与赛汉组上段沉积后发生的构造正反转形成褶皱有关;主要成矿期(70~35 Ma)与哈达图70 Ma快速抬升形成K2 e/E2 y角度不整合密切相关;叠加改造期(16.0~3.2 Ma)与构造地貌反转和玄武岩喷发密切相关。

Based on a large amount of experimental analysis of the Hadatu deposit and the ore Characteris,detail study was carried out on the fluid inclusions,isotope,and metallogenic environment,content of the major elements,trace elements,and associated elements reducing capacity,oxidation-reduction ability,pH.The analysis results indicate that the Hadatu deposit is of high grade,plate-like ore bodies,and a large scale and can be divided that the main uranium minerals in the Hadatu deposit is pitchblende and can be devided into two phases of mineralization.The earlier phase pitchblende is featured by layer with many impurities,while the late phase pitchblende is oolitic and clean,attaching on the earlier pitchblende.The metallogenic environmental parameters of low-grade ores(<0.05%)are similar to those of Bayanwula deposit,with the homogeneous temperature of 65~90℃.In contrast,the high-grade ores(>0.05%)are closely related to the environment with strong oxidation-reduction capacity(ΔEh),moderate-strong acid,rich Re and so on.The homogenous temperature of inclusions in high-grade ore is 125~175℃,relating to the interaction of sulfate-reducing bacteria(anaerobic bacteria).Combined with isotopic chronology,thermochronology,and thermal history modeling,Hadatu deposit was believed with multi-stage mineralization.In particular,the pre-enrichment stage(105~70 Ma)was related to the formation of inverted tectonic folds after the deposition of the Upper Member of Saihan Formation.The main metallogenic phase(70~35 Ma)was related to the K2e/E2y angular unconformity by rapid uplift since 70 Ma.The superposition reconstruction phase(16~3.2 Ma)was related to the inversion of morphotectonic and basalt eruption.