川东南地区下志留统龙马溪组海相页岩中发育有较多的形态清晰的笔石碎屑和孔隙充填无定形固体沥青，准确区分两者是研究该地区热演化程度的基础。川东南地区多口钻井龙马溪组页岩反射率测试结果显示，笔石反射率比沥青反射率在区域分布上具有更好的一致性，笔石反射率均大于3．0％，略高于沥青反射率，并沿西南—东北方向热成熟度逐渐增大，对应等效镜质体反射率在2．0％以上，指示川东南龙马溪组页岩处于高—过成熟阶段。但是，笔石反射率与等效镜质体反射率换算关系仍存在不确定性，有待进一步的研究。%Graptolites with clear morphology and pore⁃filling amorphous bitumen are abundant in the Lower Silurian Longmaxi shales from the southeastern Sichuan Basin. It is very necessary to distinguish them exactly for thermal maturity research in this area. Reflectance measurements of the Longmaxi shales from several boreholes have re⁃vealed that graptolite reflectance has a better consistency on regional distribution than bitumen reflectance. Grapto⁃lite reflectance is more than 3.0%, which is a little bit higher than bitumen reflectance, and gradually increases from southwest to northeast. The equivalent vitrinite reflectance based on graptolite reflectance is more than 2.0%, indicating that the Longmaxi shales from the southeastern Sichuan Basin are over⁃mature. However, the correlation between graptolite reflectance and equivalent vitrinite reflectance is uncertain yet, and needs further study.
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