淮北宿临矿区构造煤中黄铁矿赋存特征及其地质控制

Pyrite occurrence characteristics and geological control in tectonically deformed coal from the Linsu mining area, Huaibei coalfield, China

摘要通过淮北宿临矿区不同类型构造煤中黄铁矿形态和分布的显微观测，结合常量及伴生元素分布特征分析，探讨了构造煤中黄铁矿的分布规律、形成机制及其地质控制作用。黄铁矿是典型的多期成因矿物，其分布受沉积环境和应力-应变环境共同作用，可划分为4个形成阶段12种类型；构造煤中的Co、Sb、Mn等元素与黄铁矿关系密切，其分布反映应力-应变环境；进一步发现构造煤中的Hg与硫化铁硫（Sp.d）呈良好相关性，随构造煤变形程度的增加呈“高-低-高”的演变趋势，受构造煤形成的动力学机制影响；构造煤中的黄铁矿可分为同生和后生两种模式，前者受控于沉积环境和古构造条件，而后者与构造改造和构造煤变形相关。分析认为，脆性变形阶段煤体结构的物理变化及过程为黄铁矿发育提供了赋存空间和条件，而韧性变形阶段中的动力变质和力化学作用为元素的迁移、散失及富集提供了动力，从而影响了黄铁矿的形成类型和分布。

The pyrite morphology and distribution in tectonically deformed coal （TDC） were observed by electron microscope （EM） and scanning electron microscope （SEM）, combined with structural distribution constants and associated elements in coal, the distribution of pyrite and its tectonic control was discussed. The formation mechanism of pyrite in TDC is the result of the sedimentary environments and tectonic stress, according to the pyrite morphology the formation can be divided into 4 stages, 12 types, and the pyrite forms are closed to the stress-strain conditions. We further find that there is good correlation between mercury （Hg） and sulfur in pyrite sulfur （Spd）, the Hg concentration presents a high-low-high temporal changing pattern with the increase of the degree of TDC deformation, which influenced by tectonic coal formation mechanism. Formation mechanism of pyrite in TDC can be divided into two modes： syngenetic mode and epigenetic mode. The former was controlled by sedimentary environments and tectonic conditions, and the latter was related to structural reworking and TDC deformation. We conclude that physical change process provides the occurrence space and conditions of pyrite in brittle deformation stage, and dynamic metamorphism and mechanochemical provides the motivation for the redistribution （include migration, disperse and aggregation） of elements, all that influence the formation of pyrite type and distribution in TDC.