Hydrocarbon source rock potential and paleoecological studies of the Surma sediments of Manipur region, India: Insights from palynology and organic geochemistry

Abstract

The palynological assemblages, organic content, Rock-Eval analysis and stable isotope ratios of three outcrop sections were studied of the Miocene Surma Group in Indo-Myanmar Range to characterize the lithology, and assess kerogen types. The well-preserved palynological assemblages from the ATF, AAN and AAS sections indicate a tropical-subtropical climate with humid conditions. The δ13C values of the organic matter in these sections ranges from −19.92 to −26.08 ‰, indicative of C3 vegetation. Among these sections, our data indicates ATF has the driest and AAN wettest climate. Results from Rock-Eval analysis suggests that all the rock samples have poor organic richness (TOC < 0.5 %) and poor hydrocarbon generation potential (S2 < 0.5 mgHC/g). The organic matter of these samples is mixture of Type III and Type IV. The Tmax and Productive Index values support the results of visual kerogen analysis suggesting immature with mature and contaminant zones. The Surma sediments are poor source of gaseous hydrocarbons based on the results of this work.