西秦岭洛坝铅锌矿床矿质运移过程中有机流体作用的模拟实验研究

在高压热水实验条件下,利用有机流体和无机流体对秦岭洛坝热水沉积改造型铅锌矿床中的硅化灰岩、千枚岩、硅质岩和生物碎屑灰岩进行了Pb-Zn元素的驱替模拟实验.结果表明:在不同囤压和驱替压力条件下,流体对成矿元素的迁移能力存在明显差异,在围压由45 MPa→15 MPa→9.8 MPa的条件下,千枚岩在无机流体中Pb,Zn的淋滤率由0变为0.019%,4.1%和12.21%,0.15%;在有机流体中由0变为0.278%,4.524%和12.37%,0.19%;淋滤率表现为增涨的趋势;碳酸盐岩在无机流体中Pb,Zn的淋滤率由0.034%,0.02%变为0.53%,0.45%;在有机流体中由0.049%,0.03%变为0.53%和0.45%,Pb-Zn的淋滤率均有上升的趋势;围压和驱替压力的降低有利于流体对铅、锌成矿元素的迁移.有机流体较无机流体更易于活化迁移铅、锌成矿元素.4种岩石类型的淋滤率分别是:对Pb是硅化灰岩千枚岩硅质岩生物碎屑灰岩,而对Zn是硅化灰岩硅质岩生物碎屑灰岩千枚岩.硅质岩、硅化灰岩、生物碎屑灰岩与千枚岩在矿床的形成中可能分别起到了矿源层、储集层和盖层的作用.

THE ROLE OF ORGANIC FLUID DURING THE MIGRATION OF ORE-FORMING ELEMENTS: A CASE OF SIMULATION EXPERIMENT FOR LUOBA LEAD-ZINC DEPOSIT, WESTERN QINLING

Simulating experiments of high temperature were conducted and organic and inorganic fluids were used to leach ore-forming elements from four kinds of wall rocks in Luoba lead-zinc deposit in western Qinling,which was a hydrothermal sedimentary and reworked deposit.The results showed that(1)Organic fluid had stronger ability to mobilize and transfer lead and zinc elements than inorganic fluid.(2)The ability that fluid mobilized and transferred ore-forming lead and zinc elements was distinct at different confining and displacement pressure.The reduction of confining and driving pressure was favorable for migrating lead and zinc elements from rocks.(3)The wall rocks(such as chert,siliceous limestone,bioclastic limestone and phyllite)played different roles in the formation of deposit.(4)Siliceous rock and siliceous limestone were most likely the source beds,and bioclastic limestone was possibly the reservoir and phyllite play a role of cap rock.