Biogeographical analysis of Late Silurian brachiopod faunas, chiefly from Asia and Australia

Abstract

Shallow water benthic marine invertebrates (such as brachiopods from Benthic Assemblages [BA] 1–3) have usually played a much more important role than deeper ones (BA 4–5 or even deeper) in evaluating biogeographical provincialism in geological history. The Silurian brachiopod Retziella Fauna, characterized by the common presence of Retziella in association with various provincial taxa and many common North Silurian Realm genera, is known from southwest Tienshan, North China, South China, North Vietnam, and East Australia. It is possibly also present in North Korea, the central Pamirs, Afghanistan, and New Zealand. The coeval Tuvaella Fauna occurs only in the southern marginal belt of the Siberian Plate. Synecologically, both faunas inhabited a normal, shallow‐water, level‐bottom environment, usually with a low‐diversity community (commonly 3–8 genera); assignment to BA 2–3 is indicated. Their mutual exclusiveness is of biogeographical significance: subdivisions of the Uralian‐Cordilleran Region can be based on them, with the Tuvaella Fauna being included in a redefined Mongolo‐Okhotsk Province. A Sino‐Australian Province is established and defined herein for the area occupied by the Retziella Fauna during the Ludlow‐Pridoli and probably the Wenlock. Two subdivisions of the province can be recognized, a Sino‐Central‐Asian Subprovince and an Australian Subprovince, based on different endemic brachiopods and separate geographical positions. The presence of a number of more cosmopolitan genera in both the tropical‐subtropical Sino‐Australian and subtropical‐temperate Mongolo‐Okhotsk Provinces during the Late Silurian testifies to oceanic surface current circulation patterns adequate for the distribution of planktic larvae capable of long‐distance dispersal while maintaining reproductive communication. This contrasts with the dispersal potential of endemic components of the newly defined Silurian biogeographical units. □ Late Silurian, Brachiopoda, Retziella, Fauna, Tuvaella Fauna, Synecology, Biogeography, Asia, Australia

Tectonic Evolution and Paleoposition of the Baoshan and Lincang Blocks of West Yunnan During the Paleozoic

“…During Middle-Late Ordovician times, the SIB had rifted from the northern margin of East Gondwana and the Changning-Menglian Proto-Tethys Ocean had formed at least since the Middle Ordovician (Figure 9b), such as the presence of~470 Ma oceanic cumulate gabbros in the CMSZ (Wang, Luo, et al, 2016;Wang, Wang, Pan, et al, 2013). However, considering the fact that these continental blocks have Sino-Australian province faunas in the Early Paleozoic (Metcalfe, 2013;Rong et al, 1995), it is likely that they were not far away from the northern Australian Gondwana and remained in the same latitude range at that time. In this respect, a narrow Changning-Menglian Proto-Tethys Ocean can most likely account for their similar province faunas in the Early Paleozoic.…”

Silurian‐Devonian Lithospheric Thinning and Thermally Softening Along the Northern Margin of the Tarim Craton: Geological Mapping, Petro‐Structural Analysis and Geochronological Constraints

“…As a consequence, these authors suggested that the two main units were connected at least during Ordovician‐Silurian time (Figure 17a). This assertion is further supported by (a) similarities of Ordovician‐Silurian conodont and brachiopod species found in the CTS, STS and northern Tarim regions (Rong et al., 1995; Z. H. Wang et al., 2007b) and (b) absence of older than Silurian ophiolites between the CTS and NE Tarim. In these regards, a Tarim‐CTS connection during, at least, early Paleozoic time can be established.…”

Early – Middle Paleozoic geology of the Sea of Japan Continent – Ocean Transitional Zone (review). Pt 2.

“…развитыми в Северной Японии в горах Китаками (свита Каваути). Однако там встречаются другие брахиоподы [39], принадлежащие, вероятно, Сино-Австралийской провинции [38]: Skenidioides kitakamiensis Tachib., Aegiria sugiyamai Tachib., Salopina onukii Tachib., Atrypina kitakamiensis Tachib., Endospirifer nipponicus Tachib.…”