Yuetan Fm

It was named by the Regional Survey Team of the No. 332 Geological Party under the Geological Bureau of the Metallurgical Industry of Anhui Province in 1971, and was first cited publicly by the Compiling Group for the Regional Stratigraphic Chart of Anhui Province in 1978. The naming section is located in the vicinity of the Yuetan Pond of Xiuning County, Anhui Province, with its reference section being situated at the Wangcun Village of Xiuning County.

Synonym: （月潭组）

The formation is composed largely of grey and grey-white siltstones and quartz-sandstones, intercalated with phyllitic silty mudstones. The base is a 0.4 m-thick layer of conglomerates, with a total thickness of the strata of about 21 m. The strata of the formation developed well in the area of the Wangcun Village, where the lower part of the formation is composed of a rhythmic unit constituted with grey and grey-black siltstones, shales, carbonaceous shales, coal beds or coal seams, intercalated occasionally with lithic sandstones and lenticular quartzitic conglomerates, with sandstones being possessed of cross-beddings, and with its basal part with a 0.5 m-thick layer of conglomerates serving as a boundary between it and the underlying strata, while its upper part representing a rhythmic unit composed of grey-green sandstones and siltstones, intercalated with coal seams or coal beds, with a thickness of 79-140 m, yielding the above-mentioned animal and plant fossils.

It yields plant fossils belongs to the Todites princeps-Ptilophyllum assemblage, important members of which comprise Todites princeps, Coniopteris hymenophylloides, Cladophlebis denticulata, Ptilophyllum pectin, Otozamites bengalensis, O. hsiangchiensis, Anomozamites cf. inconstans and Pterophyllum nathorsti. It is yielded also bivalve fossils as represented by Tutuella rotunda, Pseudocardinia carinata.

The formation is suggested as fluvial-lacustrine deposits, locally to swamped deposits.