黄陵背斜北缘沉积盖层中热液脉状重晶石地质地球化学特征及成因探讨

Geological,Geochemical Characteristics and Genesis of Hydrothermal VeinBarite Hosted in Sedimentary Caprock in Northern Huangling Anticline

鄂西黄陵背斜北缘的沉积盖层区广泛发育重晶石、铅锌、金等热液型矿产,但对于脉状重晶石矿的研究较薄弱。选取该区蚂蟥冲重晶石矿点、六冲坪金矿点(含重晶石),在成矿地质特征分析基础上,开展主微量元素、S同位素和流体包裹体研究,探讨脉状重晶石的成因。研究表明,重晶石主要呈脉状赋存于沉积盖层中的陡倾断裂破碎带和裂隙带中;成矿流体为大气降水演化形成的中低温(148~310℃)、低盐度(2.07%~16.89%NaCleq)流体,成矿深度较浅(0.43~1.26 km),Ba、S可能主要来源于流体对寒武系地层等盖层岩石的溶滤萃取。该区脉状重晶石属赋存于碳酸盐岩盖层中的中低温热液型重晶石。

Barite,lead-zinc,gold and other hydrothermal deposits(occurrences)are widely developed in the sedimentary caprock of the northern Huangling anticline,western Hubei,but the research on vein barite is weak.Based on the analysis of ore-forming geological characteristics,the main and trace elements,S isotopes and fluid inclusions are studied to explore the genesis of vein barite in Mahuangchong barite occurrence and Liuchongping gold occurrence(containing barite)in this area.Studies show that barite mainly occurs in steep dipping fracture zones and fractures in sedimentary caprock as veins;the ore-forming fluid is the medium-low temperature(148-310℃)and low salinity(2.07%-16.89%NaCleq)fluid formed by the evolution of atmospheric precipitation.The ore-forming depth is relatively shallow(0.43-1.26 km).Ba and S may be mainly derived from the fluid leaching and extraction of caprock such as Cambrian strata.The vein barite in this area belongs to medium-low temperature hydrothermal type occurring in carbonate caprock.