Investigating the record of Permian climate change from argillaceous sedimentary rocks, Oman

摘要

A standard method for the analysis of carbon isotope composition of bulk organic matter (13C_bulk) in palaeoenvironmental and stratigraphic studies of sedimentary basins associated with hydrocarbons is suggested. This method includes the removal of interstitial hydrocarbon within the sediments, which is shown to have a negative effect on 13C. Using the method, a 13C_bulk trend (c. –21 to –24) was found within the Lower Permian Al Khlata and lower Gharif formations of Thuleilat-16 and -42 well sections, south Oman. Palaeontological and sedimentological evidence indicates considerable palaeoenvironmental change, from a cold climate lowland fern flora and upland primitive conifer flora low in the sequence, to a lowland cycad-like and upland glossopterid or other gymnospermous flora higher in the sequence. The lithologies range from glacial diamictite at the base to calcrete horizons and redbeds at the top. It is therefore likely that the 13C_bulk trend is related to palaeoenvironmental change.