Characterizations of organic matter in the Garau Formation (Early Cretaceous), in the South of Lorestan

The Garau Formation in Tang-e-Haft area of Lorestan province has a thickness of 703m. The lower boundary is with Gotnia evaporite Formation and its upper boundary is continuous with Sarvak Formation and it is mainly consist of alternation of limestone, shaly limestone, shale and marl. In this research, the shale and shaly limestone of this rock unit were sampled in a systematic method. The results of pyrolysis of the samples were drawn in geochemical diagrams and the following results were obtained: In the studied samples, the existing hydrocarbons are indigenous. 60 percent of available kerogen is from type III and 40 percent type II, which are able to produce gas and oil. Amount of Total Organic Carbon (TOC) is in the range of fair to very good and S2 values are low and according to high thickness of the shale layers, it has high ability to produce significant amounts of hydrocarbons. Also, the consideration to palynological slides identified 4 palynofacies. 75 percent of samples were placed within the range of palynofacies I and II (kerogen type III and probable hydrocarbon of gas) and 25 percent were placed within the range of palynofacies VI and IX (mostly type II kerogen and probable hydrocarbon of oil).