热液变质煤与金属矿床的关系

热液通过渗滤和浓度扩散作用在煤层中运移,使煤变成煤种单一的高变质煤。随煤变质程度增高,煤中的活泼金属元素迁出,并加入到热液中,而热液中的过渡金属系元素则被煤层部分吸收,使煤灰分向着降低和增加两个相反方向变化。与热液有关的金属矿床矿物中包裹体常含煤成气成分,说明煤成气参与了金属成矿作用。小规模高变质煤附近,常发现大型金属矿床和小型煤成气田;大规模高变质煤附近,常发现小型金属矿床(点)和大型煤成气田。

A PRIMARY STUDY ON THE RELATION OF HYDROTHERMAL METAMORPHOSED COALS TO METALLIC ORE DEPOSITS

Coals may be changed into high-rank metamorphosed ones when they areinfluenced by hydrothermal solutions, transferring to coal beds ininfiltration and diffusion. As the same coal bed is metamorphosed byhydrothermal solutions, the ash content of coal will be changed in twoopposite directions. The fluid inclusions in minerals for metallic oredeposits generally contain coal-type gaseous components such as CH_4,C_2H_6, C_3H_8, CO_2, N_2, CO and Ar. Coal-type gases are intersections linkingmetallic ore deposits with hydrothermal metamorphosed coals. Ore-formingprocesses are similar to gas-forming processes in time, space, structuraltypes and high contents of active metallic elements. Volatile contents of coal,together with transition metallic elements,will constitute stable metal chelatecompounds when they go into hydrothermal solutions, but they will formcoal-type gas reservoirs when they transfer to faults and porous rocks. Alarge-scale coal field can deplete hydrothermal solutions greatly. Theremanent hydrothermal solutions can't have metallic elements in neighbouringrocks activate, transfer and enrich on a large scale. Therefore, small-scalemetallic ore deposits (or mineralized zones) and large-scale coal-type gasfields may be found nearby a large-scale high hydrothermal metamorphosedcoal fields. On the contrary, whereas large-scale metallic ore deposits andsmall-scale coal-type fields nearby a small-scale high hydrothermalmetamorphosed coal fields.