对福建李坊重晶石矿床成因的新认识——来自矿石构造、矿物学和流体包裹体的证据

The new cognition of the genesis of the Lifang barite deposit in Fujian province:Evidence from ore structure,mineralogy and fluid inclusions

福建李坊重晶石矿床是东南沿海地区发现的一个大型独立重晶石矿床,已有30余年的开采历史,在沉积重晶石矿床中占有重要地位,然而对该矿床的成因和成矿时代仍众说纷纭。本文通过对福建李坊重晶石矿床中矿石组构的野外调查、电子探针分析和重晶石的流体包裹体测温,取得如下发现和认识:①首次在重晶石矿石中发现了管孔状构造、角砾状构造、蜂窝状构造等热水喷流通道相沉积构造;②首次在重晶石矿石中发现具有热水成因指示意义的同生钡冰长石矿物;③140个重晶石的流体包裹体均一温度值为89.3~208.5℃,均值为162.7℃,表明李坊重晶石矿床属于低温热水沉积矿床;综合矿石构造、矿物学和流体包裹体测温等证据,提出李坊重晶石矿床为"白烟囱型"热水沉积矿床的新认识,为华南地区早古生代热水沉积矿床的研究和找矿勘探提供了重要新资料。

The Lifang barite deposit in Fujian province is a large-scale independent barite deposit discovered in the southeastern coastal areas in China. It plays an important role in the sedimentary barite deposits with a more than thirty years mining history, although its genesis and mineralization epoch are still disputed. This paper undertook investigation of ore structure, electron microprobe analyses and fluid inclusion temperature measurement for barite from the Lifang barite deposit in Fujian province. The following findings and cognition are obtained: ①The hydrothermal exhalative channel phases such as tube structures, breccia structures and honeycomb structures in barite ore were found for the first time. ②The hyalophane mineral in barite ore with indicative feature of hydrothermal sedimentary genesis was found for the first time. ③140 fluid inclusions data yielded the homogenization temperature of fluid inclusion ranging from 89.3℃ to 208.5℃, with an average of 162.7℃, indicating that the Lifang barite deposit belongs to a low temperature hydrothermal sedimentary deposit. Based on evidence such as ore structure, mineralogy and fluid inclusion temperature measurement, this proposed a new cognition that the Lifang barite deposit is a "white chimney" hydrothermal sedimentary deposit. This understanding provides new important information for the study and prospecting exploration for the early Paleozoic hydrothermal deposits in South China.