煤中黄铁矿的成因研究

THE GENESIS OF PYRITES IN COAL

本文在系统地研究四川晚二叠世高硫煤中黄铁矿矿物学的基础上,运用微区电子探针、中子活化、X光电子能谱和硫同位素等多种方法综合地研究煤中黄铁矿的结构、成分、价态及同位素等成因标型特征,对黄铁矿标型特征进行了成因探讨,有效地判别了成岩期形成的Ⅰ型脉状黄铁矿及后生热液Ⅱ型脉状黄铁矿。同时提出直接沉淀系列(自形晶→集合→聚晶)和复杂成因(微粒、莓粒→圆球→结核→团块)等两大类成因演化模式,它不仅对不同类型黄铁矿成分的差异加以解释,而且对了解黄铁矿物性(磁性、表面性)形成机制等都具有重要的理论及现实意义。

On the basis of a systematic study of the mineralogy of pyrites in Late Permian high-sulfur coals in Sichuan, such topomorphic characteristics as the textures, composition, chemical valence and isotopes of pyrites in coals have been studied by using multiple techniques including the SEM-EDS, WDX INAA, XPS and sulfur isotope technique. Using these topomorphic characteristics, the genesis of the pyrites is discussed and Ⅰ-type (diagenetic) pyrite veins and Ⅰ -type (epigenetic and hydrothermal) pyrite veins may be distinguished effectively. Besides, the authors also propose two models of genetic evolution, i. e. , the pyrite series of direct precipitation (euhedral crystals→aggregates→glomerocrysts) and the pyrite series of complex orgin (microparticles and framboidal spherules→globules→nodules). The two models have important theoretical and practical significance not only in the explanation of the difference in composition of different types of pyrites but also in the understanding of the formative mechanisms of physical properties (mag-matism and surface properties) of pyrites.