Magma thermal metamorphism of the Longtan formation coals in Zhina coalfield, Guizhou
Abstract：There is a specific relationship between the metamorphism of the Longtan formation coals and the Qianzhong uplift in central-northern Guizhou including the Zhina coalfield. Based on the analysis to the previous information on regional hydrothermal activity, the annular oc- currrence of coal rank and the abnormal vitri＇nite reflectance gradient in Zhina are found. It is suggested that the increase of the coal rank in Zhina might be resulted mianly from the uneven magma thermal metamorphism of the Qianzhong uplift combined with the higher carbon dioxide concentration in individual drillings of the Agong syncline and the regional gravity anomaly. Coalification degeree is evidently affected by the distance between the insidious magmatites and Longtan formation. Strata under the Longtan formation in Zhina was severely eroded, which was in favor of the upward conductivity of the heat flow. This might be why the higher coal rank and abnormal reflectance gradient of 0. 3%-0.4%/100m occur in the Zhina coalfield.
Keywords：Zhina coalfieldburied igneous rocksLongtan formationcoal thermal metamor-phism
Publication Date：2012-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：9( 406-414 )