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First Report of Small Shelly Fossils from the Cambrian Miaolingian Limestones (Zhangxia and Hsuzhuang Formations) in Yiyang County, Henan Province of North China
oleh: Yazhou Hu, Lars E. Holmer, Yue Liang, Xiaolin Duan, Zhifei Zhang
Format: | Article |
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Diterbitkan: | MDPI AG 2021-10-01 |
Deskripsi
Small Shelly Fossils (SSFs) from the Cambrian are widely distributed and well known across different paleocontinents of the world. However, middle Cambrian SSFs from North China Platform have only rarely been documented until now. In this paper, we presented the first report on SSFs from bioclastic and oolitic limestones of the Zhangxia and Hsuzhuang formations of Henan province, North China. The carbonate-hosted fauna includes brachiopods (<i>Micromitra</i> sp., <i>M</i>. <i>modesta</i>, <i>Eoobolus</i> sp., and <i>Schizopholis</i> sp.), helcionellids (<i>Oelandiella</i><i>accordionata</i> and <i>O</i>. <i>aliciae</i>), hyolithids, <i>Hyolithellus</i> sp., <i>Chancelloria</i><i>eros</i>, sponge spicules, echinoderm ossicles, and chancelloriid sclerites. In terms of preservation, the brachiopod shell valves of <i>M</i>. <i>modesta</i> appeared to be homogeneous, consisting of tightly packed phosphate grains. <i>Eoobolus</i> sp. is composed of primary layer and secondary baculate, both of which consist of tightly compacted phosphate grains. <i>Schizopholis</i> sp. has multiple-lamellar phosphatized microstructures that distinctly differ from the other brachiopods recovered from the Longwanggou section. A similar multiple-lamellar microstructure was also revealed in conchs of <i>Hyolithellus</i>, with tightly compacted phosphate grains. The argillaceous shell of <i>Oelandiella</i><i>accordionata</i> and <i>O</i>. <i>aliciae</i>, and the calcitic inner molds of hyolith did not preserve any shell structure. The helcionellids <i>O</i>. <i>accordionata</i> and <i>O</i>. <i>aliciae</i> and the brachiopod <i>M</i>. <i>modesta</i> were reported for the first time from North China. The fauna is most similar to the middle Cambrian faunas of Australia, in the brachiopod and mollusk components; it is also similar in composition of brachiopods and mollusks to coeval faunas from South China. The new fauna of SSFs in the Yiyang Longwanggou Section indicated that the Hsuzhuang and Zhangxia formations are late Drumian to middle Guzhuangian in age, most likely correlating with the Murrawong Creek Formation of Australia.