华北聚煤区南部煤变质作用类型及其控制因素探讨

Discussion on the Coal Metamorphic Types and Their Controlled Factors in the Southern Part of the North China Coal-bearing Region

华北聚煤区南部晚古生代煤系的煤在深成变质基础上,普遍经历了古地热场的叠加作用,促使高变质煤种的形成和明显的煤变质分带性。本文结合区域地质背景,研究本区煤变质特征,尤其强调了区域构造格局及其演化对煤变质作用的控制。从古地热异常形成机制出发,提出热液变质作用模式以及古地热-变质系统的概念。根据变质作用类型及其控制因素,划分出三个煤变质分区:豫西气水热液变质区、永夏淮北岩浆热变质区、平顶山淮南深成变质区。

On the basis of geothermal metamorphism, the Late Palaeozoic coal in the southern part of the North China Coal-bearing Region was generally superimposed with the secondary metamorphism imposed by the palaeogeothermal field, leading to the high-rank metamorphic coal formation and visible metamorphic zonation. The paper discusses the metamorphic characteristics in combination with the analysis of regional geological setting, and puts the emphasis on the regional tectonic framework and its evolution in the control of coal metamorphism. Based on the mechanism of palaeogeothermal field formation, a hydrothermal metamorphic mode and the concept of palaeogeothermal metamorphic system are presented. The research area could be divided into three coal metamorphic zones according to the metamorphic types and their controlled factors, i.e. the Yuxi hydrothermal metamorphic zone, the Yong Xia-Huaibei magmatic metamorphic zone and the Pingding Shan-Huainan geothermal metamorphic zone.