煤系脉体包裹体地球化学特征——山西南部高煤级煤区域热变质成因探讨

Geochemistry of Vein Mineral Inclusions in Coal Measures in Southern Shanxi: A Reference to the Regional ThermalMetamorphism of HighRank Coal

通过对山西南部晚古生代煤系脉体流体包裹体形成温度、压力、气相和液相成分、稳定同位素组成等地球化学特征的研究，探讨了该区高煤级煤形成的区域古地热场背景．结果表明：该区在燕山中期存在着高热异常古地热场，导致其形成的附加热源可能主要来源于岩浆侵位于地壳不同深度造成的热传导；异常古地热场与正常古地热场背景的叠加，是造成了本区“东高西低、南高北低、高煤级煤展布于东部和南部”的煤级现代分布格局的主要原因．

In the paper, the paleogeothermal field that resulted in the occurrence of the Late Paleozoic highrank coals in southern Shanxi was studied based upon the inclusion geochemistry such as tempreture,pressure,liquid and gas components and stable isotopic composition.The results indicated that there existed an abnormally highheat paleogeothermal field during the middle Yanshan movement(the Early Cretaceous),which might be originated from the secondary heat source predominantly from the thermal conduction of the magmatic bodies emplaced at various depth of the crust.The modern rank of the Late Paleozoic coals in the area is relatively high in eastern and southern parts where the highrank coals exist.The superimposed metamorphism of the abnormal paleogeothermal field over the normal field could be the reason why the modern rank distribution was occurred.