华北板块南部高变质煤条带成因机制

 为确定华北板块南缘高变质煤条带形成机制与形成时代,通过研究华北板块南缘中二叠统山西组二1煤层煤级分布和岩浆岩空间展布特征,结合华北板块与扬子板块碰撞历史,利用地质学"重力均衡"原理和日本岩石学家都城秋穗提出的"双变质带"理论,建立碰撞热流模型并合理解释导致高变质煤条带形成的热流来源,得出:1)扬子板块向华北板块的俯冲作用,在华北板块南缘前陆盆地形成高温低压带,促进了煤化作用,形成高变质煤条带;2)结合地质资料和区域构造特征分析,发现高变质煤带走向与印支期构造走向(东-西)一致,该高变质煤条带形成于印支期。燕山期岩浆控制了华北板块南缘大部分煤变质作用,但是在晋城-济源一带其煤变质是由于印支期板块碰撞形成的异常热作用的结果。

Formation mechanism of high metamorphism coal belt in the south of the Northern China plate

This paper aims to confirm the formation mechanism and the age of high metamorphism coal belt in the south of the North China plate. Considering the collison history of the North China plate and Yangtze plate, we analyze the distribution features of magmatic rock and coal rank. The coal seam belongs to the Shanxi Formation, lower Permian. Using the "gravity isostasy" principle and the theory of "paired metamorphic belt" proposed by Miyashiro, we construct the heat flow model to explainthe source of heat which caused the formation of high metamorphism coal belt and draw the following conclusions:1) Since the collision of the Yangtze plate and North China plate, there was a high-temperature and low-pressure belt in the foreland basin in the south of the North China plate, which promoted the coalification and led to formation of a high metamorphism belt; 2) According to the geological data and tectonic characteristics, the strike of high metamorphism coal belt was the same as the tectonics strike in the Indo-Chinese epoch, which is nearly east-west. Therefore, we speculate thatthe high metamorphism coal belt formed in the Indo-Chinese epoch. The magmatic rock in Yanshanian played an important role in the process of coal metamorphism in the south of the North China plate, but the coal metamorphism in Jincheng and Jiyuan areas was controlled by platecollision which formed the abnormal heat flow.