Upper Cisuralian-Lower Guadalupian Brachiopods From the Qarari Unit, Batain Plain, Northeast Oman: Systematics, Palaeoecology and Correlation

Abstract

Permian brachiopods from Oman are well-known as valuable tools for correlation and palaeobiogeographical and palaeoclimatic reconstructions. Here, we describe a new brachiopod fauna from the Qarari Unit of the allochthonous Batain Group in northeast Oman. Brachiopods were collected from four localities: Wadi Khawr al Jaramah (WKJ), Jebel Qarari (JQ1), Jebel X (JX3) and Shiya (SH11). The age of the fossiliferous localities is wellconstrained to the late Kungurian-early Roadian by conodonts and fusulines, in agreement with the age suggested by the brachiopod ranges.The brachiopod fauna consists of 339 specimens belonging to 68 species of 8 orders, among which five species are here identified as new. Based on the taphonomic attributes and the analysis of the brachiopod life-styles, the assemblages from the Qarari Unit are interpreted as life assemblages thriving on varied substrates, with limited post-mortem exposure on the sea floor and rapid burial at depths around the storm wave base.Based on the generally high biodiversity indices (Shannon-Wiener and Margalef indices), the Qarari brachiopod fauna can be considered a biodiversity hotspot, only comparable, in term of biodiversity, to the coeval faunas from West Texas and South China. However, palaeobiogeographical affinities of the Qarari brachiopods with these faunas are scanty, as well as the affinities with coeval faunas from the northern Gondwana margin and the Cimmerian and Cathaysian blocks, except for some similarities with the upper Kungurian brachiopods of Myanmar. This may be explained by the fact that the Qarari succession was deposited in the Madagascan arm of Neo-Tethys, and thus rather isolated from the main Gondwanan margin.

Redefinition of the Global Stratotype Section and Point (GSSP) and new Standard Auxiliary Boundary Stratotype (SABS) for the base of Wuchiapingian Stage (Lopingian Series, Permian) in South China

“…Therefore, this brachiopod fauna obviously indicates that the horizon is close to the latest Capitanian, which is fully comparable with that of the Penglaitan section (Shen and Shi, 2009). These are typical lower-middle Wuchiapingian taxa, which are found abundantly also in Tethyan sections (Angiolini and Carabelli, 2010;Ghaderi et al, 2014;Viaretti et al, 2022).…”

Isotopic time-series (δ13C and δ18O) obtained from the columnar layer of Permian brachiopod shells are a reliable archive of seasonal variations

“…Based on the correlation of the Tethyan stages with the ISC timescale (Angiolini et al, 2015), the unit is Kungurian-Roadian in age. Recent data, based on brachiopod assemblages from Wadi Khawr al Jaramah, suggest that the Qarari Unit straddles the Cisuralian-Guadalupian boundary (Viaretti et al, 2022). The Wadi Khawr al Jaramah outcrop consists of a weathered surface of a 450 m 2 of yellowish and highly fossiliferous marly limestones (Fortey and Heward, 2015).…”

“…The Wadi Khawr al Jaramah outcrop consists of a weathered surface of a 450 m 2 of yellowish and highly fossiliferous marly limestones (Fortey and Heward, 2015). The Qarari Unit has been interpreted to have been deposited at depths around the storm wave base (Leven and Heward, 2013;Viaretti et al, 2022).…”

“…At about 30 • of paleolatitudes, the specimens from Oman show a range of δ 18 O values between − 2.1 and − 1.2‰. In the late Kungurian, the Qarari Unit was deposited in settings around the storm wave base (Immenhauser et al, 1998;Viaretti et al, 2022). The temperature variation results in a range of ~3.8 • C, assuming a constant composition of δ 18 O sw .…”

“…Also, increasing evaporation during the summer could increase δ 18 O sw , resulting in an even smaller range of δ 18 O variation of the calcite. This is a reliable alternative to explain the narrow range of δ 18 O values of these specimens, considering that the depositional setting of the Qarari Unit (late Kungurian) was an isolated, relatively shallow basin (Viaretti et al, 2022), and thus probably subjected to evaporation.…”