摘要
以河南省东秦岭造山带北缘山西组二_1煤层的煤岩、煤质、煤有机地球化学和“晶核”结构的综合研究为前提,结合板块构造和地球物理场的研究分析,认为该区二_1煤的变质热源主要与长期复杂的板块俯冲、A型碰撞所引起的地壳结构调整而使前陆盆地区岩石圈结构变化,大地热流急增的结果有关。二_1煤的变质主要经历了早期(印支期前)的区域深成变质(达肥-气煤)和后期(印支-燕山期)的典型异常热变质作用(达无烟煤-高阶无烟煤)。
On the basis of the study of coal petrology, coal organic chemistry and plate tectonics on the north margin of the East Qinling erogenic belt, this paper asserts that the formation of coal-rank patterns in the Late Paleozoic coal measures in the area might not result entirely from regional burial metamorphism or magmatic thermal metamorphism, but mainly from the abnormal thermal metamorphism probably caused by the plate tectonism on the south margin of the North China plate. The heat for metamorphism of coal-bed II1 was derived dominantly from the differentiation of the lithospheric thermal structure in the foreland basin due to the adjustment of the litho-spheric structure caused by long-continued plate subduction and A-type collision. The metamorphism of coal bed II1 can be divided into three stages; (1) Before the Middle Triassic, coal underwent mainly regional burial metamorphism and attained about gas-fat coal. (2) From the Late Triassic to Jurassic, coal underwent high-temperature and high-pressure metamorphism owing to thermal anomaly caused by plate tectonic movement, and was metamorphosed to about anthracite or meta-anthracite. (3) In the Yanshanian movement, in some areas, coal underwent small-scale magmatic thermal metamorphism and was metamorphosed to blind coal. Thus the superimposi-tion of coal ranks of different metamorphic orgins formed in three different stages gave rise to the present patterns of coalification.
出处
《地质论评》
CAS
CSCD
北大核心
1996年第1期7-13,共7页
Geological Review
关键词
煤
变质作用
前陆盆地
岩石圈
热演化
板块构造
coalification, foreland basin, thermal evolution of the lithosphere
