Two early Carboniferous brachiopod species, Levitusia humerosa (Sowerby) and Grandispirifer mylkensis Yang, are described from Japan for the first time. These species, from the middle part of the Arisu Formation in the Okuhinotsuchi area, South Kitakami Belt, indicate an early Visean age. Therefore, the middle part of the Arisu Formation is correlated with the lower Visean. In terms of palaeobiogeography, occurrence of the two species suggests that South Kitakami was probably the eastern extension of the North China Province, and located near and to the east of North China (Sino-Korea) during the early Visean.
Introduction
This paper describes two early Carboniferous brachiopod species, Levitusia humerosa (Sowerby, 1822) and Grandispirifer mylkensis Yang, 1959, for the first time from Japan. The brachiopod fossils were collected from the middle part of the Arisu Formation in the Okuhinotsuchi area, South Kitakami Belt, northeastern Japan (Figure 1). In the South Kitakami Belt, the Arisu Formation occurs in the central part of the belt, i.e., in the Yokota, Shimoarisu and Okuhinotsuchi areas. The stratigraphy of the Arisu Formation has been studied previously (Minato, 1941; Minato et al., 1953, 1979; Onuki, 1956, 1969, 1981; Takeda, 1960; Saito, 1966, 1968; Tazawa and Katayama, 1979; Kawamura, 1985a, 1985b; Tazawa and Iryu, 2019). However, the age of the formation is still controversial, having been identified as late Tournaisian to early Visean (Minato et al., 1953), late Tournaisian (Minato and Kato, 1979), and early Visean (Tazawa, 1985; Kawamura and Kawamura, 1989; Tazawa and Iryu, 2019), owing to a paucity of fossil evidence. The occurrence of Levitusia humerosa and Grandispirifer mylkensis in the middle part of the Arisu Formation provides reliable evidence for the age of the formation. In terms of palaeobiogeography, the senior author (J. Tazawa) stated that South Kitakami was probably the eastern extension of the North China Province (of Yang, 1980, 1983) or the Tianshan–Jilin Province (of Yang, 1994) on the basis of brachiopods from the lower Carboniferous of the South Kitakami Belt (Tazawa, 2002, 2006, 2017, 2018; Tazawa and Iryu, 2019). The occurrence of the above two species from Okuhinotsuchi provides additional evidence for this hypothesis.
Stratigraphy and material
The Carboniferous rocks of the Okuhinotsuchi area are divided on the basis of lithology into the Shittakazawa, Arisu, Odaira, Onimaru and Nagaiwa formations, in ascending stratigraphic order. The Odaira Formation corresponds to the Karoyama Formation of Tazawa et al. (1981). According to unpublished data of the present authors, the Arisu Formation of the Okuhinotsuchi area can be subdivided into a lower part (dark green andesitic lapilli tuff, 157 m thick), a middle part (alternating shale and sandstone, intercalated with andesitic tuff, 343 m thick) and an upper part (black shale, 57 m thick), with a total thickness of 557 m (Figure 2). The brachiopod specimens described herein were collected by one of the authors (H. Kurita) from greenish-grey tuffaceous sandstone in the middle part of the Arisu Formation at three localities (KAR4, KAR6 and KAR11) in the Okuhinotsuchi area. The location, horizon, lithology and brachiopod species of each site are as follows:
KAR4: Upper Yasumotozawa Valley (39°09′54″N, 141°31′18″E), 1.1 km northwest of Shimokashi-wari, outcrop of greenish-grey medium-grained tuffaceous sandstone 114 m above the base of the middle part of the Arisu Formation, with Grandispirifer mylkensis.
KAR6: Upper Yasumotozawa Valley (39°10′26″N, 141°31′05″E), 2.9 km northwest of Shimokashi-wari, outcrop of greenish-grey coarse-grained tuffaceous sandstone 36 m above the base of the middle part of the Arisu Formation, with Grandispirifer mylkensis.
KAR11: Ridge (39°11′52″N, 141°30′53″E), 0.8 km north of Okuhinotsuchi, outcrop of greenish-grey, coarse-grained tuffaceous sandstone 150 m above the base of the middle part of the Arisu Formation, with Levitusia humerosa.
Figure 1.
Map showing the fossil localities KAR4, KAR6 and KAR11 in the Okuhinotsuchi area, South Kitakami Belt (using a digital topographic map of the Geospatial Information Authority of Japan).
Stratigraphic and palaeobiogeographic significance of Levitusia humerosa and Grandispirifer mylkensis
Levitusia humerosa is known from the lower Visean of northeastern Japan (this study), England (Sowerby, 1822; Davidson, 1861; Muir-Wood and Cooper, 1960; Brunton, 1979), Belgium (Muir-Wood and Cooper, 1960; Brunton, 1979), Germany (Paeckelmann, 1931), western Russia (Rotai, 1931; Garanj et al., 1975), central Russia (Rotai, 1941; Nalivkin and Fotieva, 1973; Nalivkin, 1979), Uzbekistan (Yanishevsky, 1918) and Kyrgyzstan (Galitskaya, 1977). Grandispirifer mylkensis has been reported from the upper Tournaisian to lower Visean of northeastern Japan (this study) and northwestern China (Yang, 1959, 1964; Yang et al., 1962; Zhang et al., 1983; Shi et al., 2016).
Figure 2.
Generalized columnar section of the Carboniferous succession in the Okuhinotsuchi area, South Kitakami Belt, showing the fossil horizons of localities KAR4, KAR6 and KAR11. Legend: 1, shale; 2, sandstone; 3, alternating sandstone and shale; 4, limestone of the Nagaiwa Formation; 5, limestone of the Onimaru Formation; 6, limestone of the Odaira, Arisu and Shittakazawa formations; 7, andesitic–basaltic tuff; 8, andesitic–basaltic lapilli tuff; 9, rhyolitic tuff; 10, conglomerate. “F” denotes a fault contact.
Thus, the age of the middle part of the Arisu Formation is identified as early Visean on the basis of the co-occurrence of Levitusia humerosa and Grandispirifer mylkensis; and the middle part of the Arisu Formation at Okuhinotsuchi is correlated with the lower Visean. This conclusion is consistent with the correlation and age determination by Tazawa and Iryu (2019), which is based on the brachiopod fauna from the middle part of the Arisu Formation at Shimoarisu, east of Okuhinotsuchi, in the South Kitakami Belt. In terms of palaeobiogeography, both species are known from central Asia (Uzbekistan, Kyrgyzstan and northwestern China), but are absent from South China (Yangtze). These data suggest that the South Kitakami region, including Okuhinotsuchi, was the eastern extension of the North China Province (of Yang, 1980, 1983) and located near and to the east of North China (Sino-Korea) in early Visean.
Systematic descriptions
(by J. Tazawa)
The specimens described below are registered and housed in the Tohoku University Museum, Sendai, Japan (prefix IGPS, numbers IGPS111742 to IGPS111744).
Order Productida Sarytcheva and Sokolskaya, 1959
Suborder Productidina Waagen, 1883
Superfamily Horridonioidea Muir-Wood and Cooper, 1960
Family Leioproductidae Muir-Wood and Cooper, 1960
Subfamily Levitusiinae Muir-Wood and Cooper, 1960
Genus Levitusia Muir-Wood and Cooper, 1960
Type species.—Productus humerosus Sowerby, 1822.
Levitusia humerosa (Sowerby, 1822)
Figure 3
Productus humerosus Sowerby, 1822, p. 21, fig. 322; Davidson, 1861, p. 147, pl. 36, figs. 1, 2; Yanishevsky, 1918, p. 38, pl. 3, figs. 1–5.
Productus sublaevis de Koninck. Davidson, 1861, p. 177, pl. 31, figs. 1, 2; pl. 32, fig. 1; pl. 51, figs. 1, 2; Rotai, 1931, p. 50, pl. 1, figs. 7, 8; pl. 2, figs. 1, 5.
Productus (Plicatifera) humerosus Sowerby. Paeckelmann, 1931, p. 120, pl. 6, fig. 5; pl. 7, figs. 1–4; pl. 8, figs. 1–3; pl. 11, fig. 1; Rotai, 1941, p. 96, pl. 17, figs. 3–6.
Productus (Plicatifera) humerosus var. longa Paeckelmann, 1931, p. 128, pl. 9, fig. 1.
Productus (Plicatifera) humerosus var. christiani de Koninck. Paeckelmann, 1931, p. 131, pl. 10, fig. 1; pl. 12, fig. 4; pl. 13, fig. 1.
Levitusia humerosa (Sowerby). Muir-Wood and Cooper, 1960, pl. 109, figs. 2–5; pl. 110, figs. 1–5; Nalivkin and Fotieva, 1973, p. 43, pl. 9, figs. 4, 5: Garanj et al., 1975, p. 181, pl. 78, fig. 2; pl. 80, fig. 5; Galitskaya, 1977, p. 123, pl. 12, figs. 4–7; pl. 38, fig. 1; Brunton, 1979, p. 7, pl. 1, figs. 1–6; pl. 2, figs. 1–5; pl. 4, figs. 1–4; Nalivkin, 1979, p. 59, pl. 18, fig. 6.
Levitusia christiani uralica Fotieva in Nalivkin and Fotieva, 1973, p. 44, pl. 10, figs. 1, 2.
Material.—One specimen from locality KAR11, external mould of a ventral valve, IGPS111744.
Description.—Shell large in size for genus, longer subrectangular in outline, widest slightly anterior to mid-length; length more than 45 mm, width more than 35 mm in the sole specimen (IGPS111744). Ventral valve strongly convex in lateral profile, roundly geniculated and followed by a long trail; sulcus broad and shallow on trail. External surface of ventral valve ornamented with irregular weak rugae on visceral portion and several strong longitudinal flutings on trail. Interior of the ventral valve not preserved.
Remarks.—This specimen is poorly preserved, but can be referred to Levitusia humerosa (Sowerby, 1822), redescribed by Brunton (1979, p. 7, pl. 1, figs. 1–6; pl. 2, figs. 1–5; pl. 4, figs. 1–4) on the type specimens from the lower Visean of Belgium and Staffordshire, England, in the large, strongly convex ventral valve, with long sulcated trail, and ornamented with irregular rugae on visceral portion and several strong longitudinal flutings on trail. Levitusia sublaevis (de Koninck, 1843), redescribed by Brunton (1979, p. 12, pl. 3, figs. 1–9; pl. 4, figs. 5, 6) from the lower Visean of Belgium and Lancashire, England, differs from L. humerosa in having weaker posterior rugation and a shallower ventral sulcus.
Distribution.—Lower Visean: northeastern Japan (Okuhinotsuchi in the South Kitakami Belt), UK (England), Belgium, Germany, western Russia (Donetz Basin), central Russia (western and southern Urals), Uzbekistan (Fergana) and Kyrgyzstan (northern Tian-Shan).
Figure 3.
Levitusia humerosa (Sowerby) from the Arisu Formation of Okuhinotsuchi; ventral (A1), anterior (A2) and lateral (A3, A4, A5) views of external latex cast of ventral valve, IGPS111744. Scale bars are 1 cm.
Order Spiriferida Waagen, 1883
Suborder Spiriferidina Waagen, 1883
Superfamily Spiriferoidea King, 1846
Family Spiriferidae King, 1846
Subfamily Spiriferinae King, 1846
Genus Grandispirifer Yang, 1959
Type species.—Grandispirifer mylkensis Yang, 1959.
Figure 4.
Grandispirifer mylkensis Yang from the Arisu Formation of Okuhinotsuchi. A, external latex cast (A1, A2, A3) and internal mould (A4) of ventral valve, IGPS111742, enlarged external latex cast of ventral valve (A3) showing very fine growth lines over the ventral valve; B, internal mould of ventral valve, IGPS111743. Scale bars are 1 cm, except for A3.
Grandispirifer mylkensis Yang, 1959
Figure 4
Grandispirifer mylkensis Yang, 1959, p. 113, 118, pl. 1, figs. 1, 2; pl. 2, figs. 1–3; Yang, 1964, p. 121, pl. 16, figs. 4, 5: pl. 17, figs. 1–3; text-figs. 18, 19; Zhang et al., 1983, p. 350, pl. 121, fig. 1; Shi et al., 2016, p. 586, figs. 4, 5A, B.
Spirifer subaequalis Hall. Yang et al., 1962, p. 99, pl. 39, figs. 2, 3.
Material.—Two specimens from localities KAR4 and KAR6: (1) external and internal moulds of a ventral valve, IGPS111742; and (2) internal mould of a ventral valve, IGPS111743.
Description.—Shell medium in size for genus, transversely semicircular in outline, with greatest width slightly anterior to hinge, cardinal extremities rounded; length 36 mm, width 77 mm in the better preserved specimen (IGPS111742). Ventral valve moderately convex in lateral profile, most convex at umbonal region; umbo small, incurved; sulcus narrow and shallow, weakly developed. External surface of ventral valve ornamented with numerous simple and nearly flat costae, numbering 7–8 in 10 mm at anterior margin of valve, and very fine concentric growth lines over valve. Ventral interior with a large, heart-shaped muscle field. Other internal structures not preserved.
Remarks.—These specimens are referred to Grandispirifer mylkensis Yang, 1959, from the lower Visean of Mt. Borohoro, Xinjiang, northwestern China, in the large, transverse ventral valve with weakly developed sulcus and rounded cardinal extremities. Shells described by Yang et al. (1962, p. 99, pl. 39, figs. 2, 3) as Spirifer subaequalis (Hall) from the Chengqianggou Formation of the southern Qilianshan, Qinghai, northwestern China, are considered to be conspecific with the present species. G. qaidamensis Lee, Shi and Chen in Shi et al. (2016, p. 586, figs. 5C, 6, 7), from the upper part of the Huaitoutala Formation of Qinghai, northwestern China, is readily distinguished from G. mylkensis by its strongly transverse outline.
Distribution.—Upper Tournaisian–lower Visean: northeastern Japan (Okuhinotsuchi and Yokota in the South Kitakami Belt) and northwestern China (Xinjiang and Qinghai).
Acknowledgements
Sincere thanks are due to two anonymous reviewers for their valuable comments and suggestions on the manuscript; and Yousuke Ibaraki (Fossa Magna Museum, Itoigawa) for his help in drawing figures.
