Permian deglaciation in Oman

Figure 1. Palaeoenvironmental change in flora and stable isotopes through the Permian deglaciation in Oman. Click to download.

Investigations of the palaeontology, sedimentology and stable-isotopic record of Palaeozoic sedimentary successions in Oman are providing valuable insight into past postglacial climatic variability. The research has been carried out as a collaboration between BGS and the Natural History museum, NERC Isotope Geosciences Laboratory, University of Leicester and Petroleum Development Oman.

The past is the key to the present

Carboniferous-Permian strata in East Africa and Australia show evidence of climate amelioration following glaciation. These observations can be used to inform modern processes in post-glacial climate change. It has long been known that deposits of the Permo-Carboniferous glaciation also extended to Oman in the Arabian Peninsula. The Permian Al Khlata Formation is such a deposit which is present in the subsurface to the south of the Oman Mountains and extends north-westward into Saudi Arabia. The occurrence of climate-sensitive sediments within the overlying Gharif Formation indicates that postglacial climate change must have occurred in Oman.

Evidence from stable isotopes, palaeontology and sedimentology

A δ13Cbulk trend (approximately -21 to -24 ‰) was found from well sections within the Lower Permian Al Khlata and lower Gharif formations in southern Oman. Palaeontological and sedimentological evidence indicate that considerable palaeoenvironmental change took place through the sedimentary succession. Cold-climate lowland fern flora with upland primitive conifer flora are observed in the lower part of the sequence, while lowland cycad-like with upland glossopterid or other gymnospermous flora occur in higher horizons. The lithologies range from glacial diamictite at the base to calcrete horizons and redbeds at the top. It is therefore likely that the δ13Cbulk trend is related to palaeoenvironmental change, and perhaps to postglacial global warming.

Further information

Selden, P A, Huys, R, Stephenson, M H, Heward A P and Taylor, P N. 2010. Crustaceans from a bitumen clast in Carboniferous glacial diamictite of Oman extend the fossil record of copepods. Nature Communications, 1, Article no. 50.

Stephenson, M H, Leng, M J, Vane, C H, Osterloff, P L and Arrowsmith C. 2005. Investigating the record of Permian climate change from argillaceous sediments, Oman. Journal of the Geological Society, London, 162, 1—11.

Stephenson, M H amd Osterloff, P L. 2002. Palynology of the deglaciation sequence represented by the Lower Permian Rahab and Lower Gharif members, Oman. AASP Contribution Series No. 40. 1—2.

Contact

Please contact Prof Mike Stephenson for further information