Waluba Fm

In 1975, the Nanjing Institute of Geology and Paleontology of the Chinese Academy of Sciences named the “Walu eighth member of the Weichuan Formation”. The named section is located in Waluba village, Weishan County, Yunnan Province. The reference section is located near Sanhe Cave, Waigu Village, Ma'Anshan Township, Weishan County.

Synonym: In 1974, the First District Team of Yunnan Geological Bureau named Sanhedong Fm, which was divided into lower limestone member and upper black shale member. In 1975, Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences and other units named Waluba Member of the Weishan Fm, which is basically the same as the upper black shale member. The section was revised by Yunnan Geology and Mineral Bureau (1990) as the Waluba Fm, and its age was determined in Norian, Late Triassic.

Mainly gray-black thin siltstone and mud (shale) rock. Gray, dark gray, black shales at lower part, coal and silty bearing locally; upper part is gray-black thick layer siltstone with fine sandstone and shale, shale sometimes contains coal. It’s common to find irregular, parallel asymmetric ripples in sandstone and siltstone. The lower boundary takes the black shale first appearances as the sign. The top boundary is marked by disconformity. The thickness is 200 ~ 275 m.

Bivalves: Halobia pluriradiata, H. yunnanensis, H. spectabilis, H. sp., Burmesia sp., Indopecten sp., Costatoria sp. and Prolaria sp. etc.; Ammonoids: Tibetites aff. perrinsmithi, Paratibetites yunnanensis, P. aff. adolphi, Cyrtopleurites sp., Cladiscites sp., etc., also found a small amount of gastropods and plant fossils.

This group is a nearshore shallow water deposit with a relatively limited distribution.