Chenming Fm

The type section of the Chenming Formation is the Chenming section. It is located on west bank of Tangwan River, north of the Chenming Village in Chenming Township, Nancha District, Yichun City, Heilongjiang Province (129°28’00” E, 46°59’00” N). It lies 2 km northwest of Chenming Town or about 22 km southeast of the seat of Nancha County and is measured by Sun Shu et al. in 1957. In the type section, the formation is over 897 m thick. The Chenming Formation was named by Sun (1963). The name is derived from Chenming Town, Nancha District, Yichun City, central Heilongjiang Province. The nomenclature of the Chenming Formation should owe to Sun Shu (1963) because he solely published the formation formally with descripting the type section, bed by bed, and discussing features of the formation in details. Zhang (2009) and Qu (1997) took either Hodak and Sun Shu (1963) or Jiang Chunchao and Sun Shu et al. in 1963 as nomenclatures of the formation respectively, but these assignments are exactly incorrect. All these authors are members of China-USSR joint Team of Integrated Expedition to the Geology of the Heilongjiang (Amur) River Valley in 1960s, but there is not any papers in their 1963 published book showing Jiang was involved in naming the formation. Indeed, Hodak and Sun (1963) published the formation’s name several pages earlier than Sun did in the book but they had just mentioned briefly the lithology and distribution of the formation, which are apparently based on the work of Sun (1963).

Synonym: （晨明组）

The Chenming Formation is a carbonate sequence. It mainly consists of greyish black, grey dolomitic limestone and bituminous limestone, which are usually thick-bedded, with interbeds of thin-bedded limestone, slate, phyllitic shale, and siltstone. Some limestone layers bear chert-bands. The carbonate rocks decrease upwards in section, whereas clastic rocks increase accordingly.

The lowest exposed bed of the formation yields taxon of micro-palaeoplant fossils Chlorellopsis and Protosphaeridium.