A Kungurian (Early Permian) Panthalassan brachiopod fauna from Hatahoko in the Mino Belt, central Japan

Abstract

Twelve brachiopod species are described from the Cisuralian (Early Permian) Kungurian horizon of a large limestone block in the Middle Jurassic accretionary complex at Hatahoko in the Mino Belt, central Japan. Most species of the Hatahoko fauna are known from the Kungurian to lowest Guadalupian (Middle Permian) of West Texas, U.S.A. The Kungurian age is also indicated by the associated conodonts in the same limestone block. The Hatahoko brachiopod fauna, as well as some other previously-reported Guadalupian brachiopod faunas, exhibits a very strong paleobiogeographical affinity with the faunas in West Texas, U.S.A. Therefore it can be interpreted as a fauna which inhabited reef-seamount complexes close to North America in the mid-equatorial region of the Panthalassa in the late Early Permian, rifted westwards thousands of kilometers, and finally accreted onto the Japanese Island when the Western Pacific Plate subducted beneath the Eurasian Plate during the Jurassic.

Permian lyttoniid brachiopod <i>Petasmaia</i> from Akasaka, Mino Belt, central Japan

“…Consequently, the Mino fauna came to be a mixture of the Tethyan and the West Texas elements, and lacking the Boreal elements. The present report of Petasmaia expansa from Akasaka strongly supports the palaeobiogeographical scheme proposed by Tazawa and Shen (2010) and Shen et al (2011).…”

“…Tazawa and his colleagues (Tazawa and Shen, 1997;Tazawa et al, 1998;Shen et al, 2011) noted that the Permian brachiopod faunas of the Hiyomo, Hatahoko and Akasaka areas of the Mino Belt indicate a close affinity with that of West Texas. Thus, Tazawa and Shen (2010) and Shen et al (2011) concluded that the Mino reef-seamounts (including the Akasaka Limestone) were located in the equatorial region of mid-Panthalassa between the Palaeotethys and North American Continent in the Early to Middle Permian.…”

“…Thus, Tazawa and Shen (2010) and Shen et al (2011) concluded that the Mino reef-seamounts (including the Akasaka Limestone) were located in the equatorial region of mid-Panthalassa between the Palaeotethys and North American Continent in the Early to Middle Permian. At that time, a warm-water current transported the West Texas fauna, excluding the Boreal elements, from east to west.…”

Permian Panthalassan brachiopods <i>Eolyttonia</i> and <i>Permophricodothyris</i> from Akasaka, central Japan

“…Therefore, the occurrence of Eolyttonia diabloensis and Permophricodothyris horii in the Akasaka Limestone very likely suggests that in the Permian, the Akasaka area was located in the mid-Panthalassan equatorial region between the Palaeotethys Ocean and the North American continent. This conclusion is consistent with the recent studies on Permian brachiopods of the Kuzu (Tazawa et al, 2010(Tazawa et al, , 2012b, Kiryu (Tazawa and Takakuwa, 2009;Tazawa et al, 2012a), Hatahoko (Shen et al, 2011), Hiyomo (Tazawa and Shen, 1997) and Akasaka (Tazawa et al, 1998;Tazawa and Ono, 2013) areas of the Mino Belt.…”

Palaeobiogeographical studies on the Palaeozoic brachiopods of Japan, and their tectonic significance: A review

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