Geochemical Characteristics Of The Middle-Upper Cambrian Limestones In South China

Based on the theory and method of organic geochemistry,the thesis analyzed the geochemical characteristics of the limestone in Xiangxibei area.The Cambrian rocks were analyzed to research TOC,the organic matter type by the measurements of TOC,vitrinite reflectance,Rock-Eval Pyrolysis,kerogen isotope and elemental analysis.By using fraction compositions,GC,GC-MS and isotopic composition,the basic geochemical data of the limestones are obtained.Consequently,the geochemical characteristics are studied.The biomarkers indicate that the organic matter of the limestones of the Huaqiao formation form the Paibi section and Luo Yixi section have the higher maturity,and have entered the high mature stage,which is the same with the sample in older strata.The study on the parameters of pristane to phytane ratio indicates that the Huaqiao formation was deposited in a reducing environment of relatively normal salinity,which suggesting that the sedimentary environment from Paibian stage,Guzhang stage to Drumian stage was steadily reducing.The biological source of the Huaqiao formation in Paibian stage were prokaryotic bacteria and algae.The biological source of the Huaqiao formation in Guzhang stage werer eukaryotic algae and reducing bacteria.The biological source of the Huaqiao formation in Drumian stage were low prokaryotic bacteria and algae.On the whole,the biological source of the Huaqiao formation in Paibian stage,Guzhang stage to Drumian stage were aquatic organisms...