Chejiaba Fm

It was nominated by Jin Chuntai et al in 1992. The nominated section is located from Cautougou to Jiangjia of Chejiaba, in Xibei Town, Guangyuan City, Sichuan Province. The section from Majia to Longdongbei in Xuanhe town of Guangyuan City was assigned to be the type section for the redefined Chejiaba Fm (Tang et al., 2010). Coordinate: 105°57′21″E, 32°39′40″N. The late Silurian strata was subdivided previously into three formations, in ascending order, the Jintaiguan Fm, Chejiaba Fm and Zhongjianliang Fm by Jin et al. (1992). On the basis new lithostratigraphic and biostratigraphic data, these three formations are combined into the Chejiaba Fm by Rong and Chen (2003) and Tang et al. (2010).

Synonym: （车家坝组）

The formation is dominated by the interbedding of yellowish green, grey green silty mudstone and purple silty mudstone, intercalated with thin medium bedded gray, gray green calcareous siltstone, partially changes to thin bedded shelly micrite or silty limestone lenses. A layer of yellowish-brown medium-thick bedded coarse quartz sandstone usually containing the black calcareous conglomerate. It is 391-427.3 m in thickness in the Guangyuan area according to Tang et al. (2010).

The formation contains brachiopoda Retziella uniplicata, R. minor, Spirinella, Eoschizophoria, Conchidium, Atrypoidea, Striispirifer, Howellella, Protathyris, etc., and minor other fossils as well. The conodont Ozarkodina crispa previously reported from the Chejiaba Fm was re-identified as Ozarkodina snajdri by Tang et al. (2010).