Early Carboniferous brachiopod fauna from the Altai Mountains, northern Xinjiang, Central Asia: Systematics, and palaeobiogeographic and palaeogeographical implications

Abstract

A diverse brachiopod fauna, comprising 37 species in 35 genera, is described from the Hongshanzui Formation of the Chinese Altai Mountains area, northern Xinjiang, north‐western China. A new speciesXinjiangiproductus?junggarensissp. nov. is erected. Faunal correlation constrains the Altai brachiopod fauna and its bearing formation as Tournaisian (Early Carboniferous) in age. The Altai brachiopod fauna is dominated by the Siberian elements that are also very common in the Kuznetsk Basin, Siberia, implying the same palaeobiogeographic province. In contrast, it shares much fewer species with the coeval assemblages reported from the Junggar terranes, suggesting a different palaeobiogeographic province from the latter. Moreover, the Altai fauna appears with high similarities to the coeval faunas reported from the Baoshan Block of western Yunnan, south‐western China, and, to a lesser context, resembles coeval faunas documented from north‐eastern Japan, North American mid‐continent, and Australia. In contrast, it shares very few elements with those reported from the Qaidam Basin, Tarim Basin, and South China. The rather high faunal affinity between the Altai area and Kuznetsk Basin indicates that these two regions were likely apart closely to one another during the Tournaisian, implying that the Altai area may have accreted to the Siberian Craton prior to the Tournaisian. The low faunal affinity between the western Junggar and Altai areas reveals that they both did not belong to the same palaeobiogeographic province, and the western Junggar terrane did not accrete to the Altaids, at least in the Tournaisian.