Contributions Series Nr. 40

Description

Abstract

A unique record of deglaciation following the Carboniferous-Permian Gondwanan glacial period is preserved in the oil­ bearing Lower Permian ‘Rahab’ and ‘Lower Charif members of Oman. A large-scale study of closely-sampled cored sections in wells across Oman has revealed a sequence of palaeoclimatic and palaeoecological changes which are associated with climatic amelioration. In the upland area, change occurred from a periglacial monosaccate-producing flora to a warmer climate bisaccate-producing flora. In the lowlands, a parallel change in lowland flora from a periglacial, typically Permo ­Carboniferous Gondwanan, fern flora to a warmer climate colpate-producing and lycopsid lowland flora occurred. A horizon, of the order of a few metres thick, marked by a new acritarch species, Ulanisphaeridium omanensis sp. nov., follows these changes and is believed to mark the first deglacial marine transgression of the succession. The horizon is present throughout Oman and is of value in marking the middle part of the Lower Charif member.

A palynostratigraphic scheme has been developed for the sequences, which is capable of resolving metre-scale changes and which represents an improvement on other Permian palynostratigraphic schemes. Many of the events on which this scheme is built are thought to be associated with large-scale climatic change. Therefore they are probably synchronous and of great significance for correlation across Gondwana.

This is primarily a stratigraphic study and so only taxa of immediate stratigraphic value are described and illustrated. Five taxa, Indotriradites apiculatus sp. nov. Cyclogranisporites rex sp. nov., Cyclogranisporites pox sp. nov., Lundbladispora gracilis sp. nov. and Ulanisphaeridium omanensis sp. nov., are described as new and one new combination is proposed.