Molecular Organic Geochemistry of Langshan Formation in Selincuo Sag, Coqen Basin, Central Tibet, China

Key words: 
• biomarker

Abstract: Coqen Basin is the second largest marine basin in Tibet Plateau. Carbonate rocks of the Lower Cretaceous Langshan Formation is one of the most important hydrocarbon source rocks. Although having good conditions for petroleum preservation, Selincuo Sag has been got little petroleum study so far. A comprehensive study on biomarker of the extracts of sediments from the Langshan Formation at Xiongmei area by GC and GCMS, indicated that marine algae was main contribution to formation of its organic matters together with a few higher plants input. The organic matters were formed under anoxic environment having a little high salinity, and experienced high maturing and biodegradation ranked 12. Therefore, according to other organic geochemistry data, sedimentary and structural condition, carbonate rocks of the Langshan Formation have good source rocks potential considering weathering and should be of great importance to petroleum exploration.