同生还是后生?——热液矿床成因研究中争论的焦点问题

Syngenetic or epigenetic origin for some ore deposits——A controvertial focus on ore deposit origin research

秦岭地区钠长角砾岩型矿床、广西大厂锡多金属矿床、广东长坑金银矿床和广东大沟谷金矿床的成因长期存在着同生还是后生的争议。研究表明,这些矿床中的钠长石岩、硅质岩、重晶石岩、电气石岩不是热水沉积成因,而是后期流体结晶和热液交代形成,矿床不存在热水喷流同生沉积成矿作用。矿床成因研究应从多个方面综合考虑,野外宏观地质特征是基础,镜下鉴定和分析测试是辅助手段。层状、纹层状构造和胶状结构、草莓结构不一定是同生沉积的标志,应注意岩石结构及构造和地球化学判别图解具有多解性。地质年代学研究也可作为判别同生与后生的重要手段。进行矿床成因对比研究时应选择正确的参照标准。

Albite breccia type ore deposit in Qinling area, tin-polymetallic ore deposit in Dachang area, Guangxi, Changkeng Au-Ag deposit and the Dagougu Au deposit in Guangdong are syngenetic or epige netic that has been the long-term controvertial focus. Research shows that albtite rock, siliceous rock, barite rock, tourmaline rock in these deposits are not formed by thermal water precipitation but by late fluid crystallization and hydrothermal replacement, i.e. these deposits don＇t contain submarine eruption hydrothermal sedimentary mineralization. Research on ore deposit origin should be considered synthetically in many aspects, more based on macroscopic characteristics in the field and compensated by microscopic i dentification and Lab analysis and test. Layer and laminae structure, colloidal and strawberry texture are not all synsedimentary indicators. It should be taken in mind that strcture and texture of rock and geo chemical diecrimination are of multiple solutions. The geochronology may be important for the discrimination of syngenetic or epigenetic origin. The correct reference standard should be chosen in correlation research on their origin.