Study on relationship between graptolite and shale gas origin of Longmaxi Formation in southern Sichuan

For an in- depth understanding on biogenetic mechanism of shale gas and the relevance between graptolite creatures and hydrocarbon derived from shale, a combination of taphonomy and micro- fabric analysis was used for graptolite fossils contained in Longmaxi Formation in southern Sichuan from view of fossils conservati ve characteristics ,micro- structure, components as well as surrounding rock.Graptolites as only presented macro fossil type,its taphonomic behaviors were marked by a diso rdered superimposition or centralized accumulation. Fossil diversity was not high in single layer with varied abundance. It could be considered as parent material for gas hy drocarbon source, because the observation and analysis of hard part of graptolites by SEM and EBSD showed that C was the unique element in residues component of har dware of graptolites,especially in axis and the walls of thecae. In contrast,the surrounding rock were composed mainly by clay minerals,and there were rarely organic const itute elements. The recovery results of shale sampleDs organic matter abundance was nearly the same as oil immersion. Therefore,it must be some relationships between graptolites and the formation of shale gas in study area.