Evidence for multiple ice centres during the late Palaeozoic ice age in Oman: outcrop sedimentology and provenance of the Late Carboniferous–Early Permian Al Khlata Formation

Abstract

This paper proposes a model for glaciation in Oman during the late Palaeozoic ice age (LPIA) based on sedimentological and provenance analyses of the Late Carboniferous-Early Permian Al Khlata Formation, exposed in the Huqf, Oman. The results demonstrate a complex pattern of glaciation across Oman, not fully recognized in previous models. Striated glacial pavements provide evidence for two phases of ice advance: a phase of ice sheet advance towards the NE, and a second and probably younger phase where an ice centre localized on the Huqf High flowed towards the SW. The stratigraphy is constrained by previous palynological studies and is subdivided into three units, from oldest to youngest: 'early' AKP5, 'late' AKP5 and AKP5/P1. 'Early' AKP5 palaeogeography is characterized by ice-contact glacial lacustrine and deltaic sedimentary environments along the western margin of the Huqf High. Meltwater discharge flowed into the lake from ice margins located to the east, upon the Huqf High, recorded by progradational delta and fan complexes. 'Late' AKP5 palaeogeography is characterized by pro-glacial fluvialdeltaic outwash braidplains that record high-magnitude meltwater discharge from an ice margin located to the SW of the study area. The youngest undifferentiated AKP5/P1 palaeogeography is characterized by re-establishment of ice-contact glaciolacustrine conditions. The late Palaeozoic ice age (LPIA) in Arabia has been the subject of numerous studies over the last 50

Al Khlata glacial deposits in the Oman Mountains and their implications

“…More recent publications on the outcropping and subsurface Al Khlata include those of AlBelushi et al (1996), Hartmann et al (2000), Osterloff et al (2004), Heward & Al-Ja'aidi (2005), Martin et al (2008Martin et al ( , 2012, Penney et al (2008Penney et al ( , 2011, Stephenson et al (2008) and Forbes et al (2010). Much unpublished work lies in oil industry well files and reports.…”

“…The bulk of the evidence from subsurface cores and surface outcrops indicates that the Al Khlata was deposited by meltwaters in lakes, often adjacent to melting ice (Osterloff et al 2004;Martin et al 2012). The ice originated from highlands in the SW and advanced repeatedly towards the NE (Heward & Al Ja'adi 2005;Seldon et al 2010).…”

“…The ice originated from highlands in the SW and advanced repeatedly towards the NE (Heward & Al Ja'adi 2005;Seldon et al 2010). There is no conclusive evidence from subglacial features or provenance studies that ice advanced towards the SW at any stage, despite the models of Al-Belushi et al (1996) and Martin et al (2012). Palynological interpretations imply that deposition occurred at various times during Late Carboniferous-Early Permian time (Table 1, MoscovianSakmarian, c. 30 Ma).…”

“…Boulders within the Al Khlata, which can achieve a size of several metres, are either locally sourced sedimentary rocks or further-travelled erratics of granite, volcanic rocks or low-grade metamorphic rocks (Martin et al 2012). Many Al Khlata boulders and cobbles are quite well rounded, suggesting repeated cycles of transport by ice and water.…”

“…The outcrops and unweathered shallow-cored sections were dated as P5 and P1 (e.g. Besems & Schuurman 1987;Heward & Al-Ja'aidi 2005;Penney et al 2008;Martin et al 2012). The boulder spreads at Qarn Sahmah are undated but probably represent a raft of P5 based on comparison to the nearby Qarn Sahmah North-1 well (Heward & Al-Rawahi 2008).…”