Mineral compositions and organic matter occurrence modes of Lower Silurian Longmaxi Formation of Sichuan Basin.

In order to study the mineral properties, composition and the relationship with the organic matter characteristics in Lower Silurian Longmaxi Formation shale, 30 samples from Longmaxi Formation fresh outcrop cross sections located in Shuanghe Town, Changning County in Sichuan Basin were analyzed by scanning electron microscopy (SEM), electron probe micro analyzer, X-ray diffraction (XRD) and Cathode luminescence analysis (CL). Form the bottom up to top developed black-dark gray graptolite shale, carbonaceous shale, siliceous shale and silty shale pelitic silstone. The analysis results show that mineral compositions are brittle (fragment) minerals: quartz, feldspars, mica, pyrite; siliciclastic and calcite minerals: Chalcedony, calcite and dolomite; and clay minerals: Illite, chlorite and montmorillonite. The organic matter occurrence modes have important relationship with the mineral character. The finer fracture in the fragment minerals have huge influence to the produce and travel of the shale gas. [ABSTRACT FROM AUTHOR]