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

Recent work on Permo-Carboniferous successions spanning diamictites and post-glacial sediments in East Africa and Australia has shown that they record elements of postglacial change associated with climatic amelioration, and that these can be related to some modern postglacial climate change processes (Wopfner & Diekmann 1996; Wopfner 1999). It has long been known that deposits of the Permo-Carboniferous glaciation also extended to Oman in the Arabian Peninsula in the form of the Al Khlata Formation. This formation is present in the subsurface in much of the southern part of Oman south of the Oman Mountains and extends northwestward beneath the Rub 'al Khali into Saudi Arabia (Fig. 1; Braakman et al. 1982; Levell et al. 1988; Al-Belushi et al. 1996). The distribution of climatesensitive lithologies within the overlying (informal) Lower Gharif member of the Gharif Formation indicates that postglacial climate change must have occurred in Oman (Wopfner & Diekmann 1996; Wopfner 1999). Much of the Al Khlata Formation is composed of glacigenic diamictites (Fig. 2). These are succeeded by the Rahab member, which is considered to be a postglacial lacustrine unit (Hughes Clarke 1988; Levell et al. 1988; Wopfner 1999). The lowest Lower Gharif member sedimentary rocks are sandstones and mudstones of probable fluvial origin, but above these is a restricted marine interval marked by the acritarch Ulanisphaeridiuin omanensis, which is termed the 'maximum flooding shale' (Guit et al. 1995) and represents a possible postglacial eustatic flooding event (Sharland et al. 2001; Stephenson & Osterloff 2002). Above the 'maximum flooding shale', in the subsurface, are beds correlative with the Haushi Limestone, which crops out in north-central Oman (Guit et al. 1995; Sharland et al. 2001). Angiolini et al. (2003) described faunal evidence for warming within the Haushi Limestone and between the exposed Rahab member and Haushi Limestone. Climate change continued into Middle Gharif member times, as that unit contains common calcrete horizons and redbeds (Guit et al. 1995).