A late Cisuralian (early Permian) brachiopod fauna from the Taungnyo Group in the Zwekabin Range, eastern Myanmar and its biostratigraphic, paleobiogeographic, and tectonic implications

Abstract

The tectonic evolution of the Sibumasu Block during the Permian remains controversial, and Permian faunas and their paleobiogeographic affinities provide some insight into its paleogeographic and tectonic evolutionary histories. In this paper, a new brachiopod fauna dominated by Spinomartinia prolifica Waterhouse, 1981 is described from the uppermost part of the Taungnyo Group in the Zwekabin Range, eastern Myanmar. This brachiopod fauna includes 23 species and its age is well constrained as late Kungurian by the associated conodonts, i.e., Vjalovognathus nicolli Yuan et al., 2016 and Mesogondolella idahoensis (Youngquist, Hawley, and Miller, 1951), contrary to the late Sakmarian age given to the same brachiopod faunas previously reported from southern Thailand and Malaysia. Based on comprehensive comparisons of the Cisuralian brachiopod faunas and other data in different parts of the Sibumasu Block, we consider that they are better subdivided into two independent stratigraphic assemblages, i.e., the lower (earlier) Bandoproductus monticulus-Spirelytha petaliformis Assemblage of a Sakmarian to probably early Artinskian age, and the upper (younger) Spinomartinia prolifica-Retimarginifera alata Assemblage of a late Kungurian age. The former assemblage is a typical cold-water fauna, mainly composed of Gondwanan-type genera, e.g., Bandoproductus Jin and Sun, 1981, Spirelytha Fredericks, 1924, and Sulciplica Waterhouse, 1968. The latter assemblage is strongly characterized by an admixture of both Cathaysian and Gondwanan elements, as well as some genera restricted to the Cimmerian continents. Notably, the spatial distribution pattern of these two separate brachiopod assemblages varies distinctly. The Sakmarian cold-water brachiopod faunas have been found in association with glacial-marine diamictites throughout the Sibumasu Block including both the Irrawaddy and Sibuma blocks. In contrast, the Kungurian biogeographically mixed brachiopod faunas are only recorded in the Irrawaddy Block, unlike the Sibuma Block that contains a contemporaneous paleotropical Tethyan fusuline fauna. Thus, it appears likely that by the end of Cisuralian (early Permian), the Sibumasu Block comprised the Irrawaddy Block in the south with cool climatic conditions, and the Sibuma Block in the north with a temperate to warm-water environment, separated by the incipient Thai-Myanmar Mesotethys.

Cisuralian–Guadalupian brachiopod assemblages from the northern Tengchong Block in western Yunnan, China and their paleogeographical implications—a revisit

“…resembles the juvenile of Notothyris hexeris Waterhouse, 1981. In addition, the Elivina-Etherilosia Assemblage is comparable to the Bandoproductus monticulus-Spirelytha petaliformis Assemblage (named by Xu et al, 2021) of the Sibumasu Block (of Sakmarian–early Artinskian) in the age, including brachiopod faunas from the Nam Loong No. 1 Mine beds of western Malaysia (Shi and Waterhouse, 1991) and from the Khao Phra Formation, southern Thailand (Shi et al, 2002).…”

“…The Elivina-Etherilosia Assemblage is represented by several typical Gondwanan elements, e.g., Trigonotreta , Aperispirifer Waterhouse, 1968, and Elivina (Waterhouse, 1964, 1968; Shi et al, 1995; Shi and Archbold, 1998; Li et al, 2012; Xu et al, 2021). Etherilosia Archbold, 1993a was previously reported from the Cundlego and Callytharra formations, Carnarvon Basin, Western Australia (Prendergast, 1943; Coleman, 1957; Archbold, 1993a), and can be regarded as a Gondwanan genus.…”

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

“…The Qarari brachiopods do not show many affinities with the coeval faunas from the northern Gondwana margin and the Cimmerian and Cathaysian blocks, except from some relationships with the upper Kungurian fauna from Myanmar (Xu et al 2021).…”

“…5, suggests that the Qarari brachiopods are quite advanced in character for the late Kungurian. Brachiopod faunas of similar late Kungurian-early Roadian age from the northern Gondwana margin and peripheral blocks (Cimmerian and Cathaysian regions) are known mainly from Karakoram (Pakistan) (Angiolini 1995(Angiolini , 1996, the Irrawaddy Block, Myanmar (Xu et al 2021), South China (Shen 2018 and references therein), Western Australia (e.g. Archbold 1998;Archbold & Thomas 1986;Archbold & Skwarko 1998;Archbold et al 1993) and Eastern Australia (e.g.…”

“…differs from the species S. embrithes Cooper & Grant, 1976, S. clypeata Cooper & Grant, 1976, S. gravis Cooper & Grant, 1976, S. propria Cooper & Grant, 1976 from the Guadalupian Word Formation of West Texas because of their suboval to subtriangular outline, the lower number of sulcal ribs and the dorsal sulcus which occurs only posteriorly on the fold. S. modesta Waterhouse, 1981 from the Kungurian of Taungnyo Group, Myanmar and the Ko Yao Noi Formation, southern Thailand (Xu et al 2021) has a tranverse outline and no sulcus on the dorsal fold. S. saranae from the Cisuralian of Russia has a more elongate outline, a deeper "V" shaped sulcus and more numerous plicae.…”