Analysis of Geochemical Feature and Sediment Environment for Hydrocarbon  Source Rocks of Cambrian in West Hunan-Hubei Area

Key words: 
• west Hunan-Hubei /
• Cambrian /
• source rock /
• trace element /
• palaeo-environment

Abstract: Based on the analysis of TOC, trace elements of 3 typical Cambrian stratigraphic sections from platform-slope-basin in west Hunan-Hubei area. V/(V+Ni), U/Th, Ni/Co indicated Cambrian sediment turn from strong reducing environment to oxidized environment, and with a few oxidation-deoxidation sediment periodicity in slope zone. After normalized by NASC, δEu with positive anomaly and δCe with negative anomaly, and the abnormal degree showed a deeper-water from platform-slope-basin, as a whole regression after transgression in Cambrian. The environment of source rock in the bottom of Niutitang Formation was productive, strong reducing, and transgressive; the high TOC shale probably has relationship with reductive, nutritive elements-rich hydrothermal  fluid  flow, which upwelled along deep fracture during the transition from Sinian to Cambrian, and also with episodicity upwelling.