Mengyueling Fm

The type section of the formation is Mengyueling section, situated between Mengyueling and Xuexionling ridges in Honghua, Jiyang, Sanya, Hainan Province, about 13 km northeast of the seat of Sanya City (109°31’58”E, 18°21’41”N). The Mengyueling Formation was firstly published by Ge et al. (1983). The name is derived from Mengyueling Ridge at Honghua Village in Jiyang District, Sanya City, southern Hainan Province. The formation’s name was originally appeared in a 1977 manuscript by Mu Enzhi and others from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, and was subsequently raised in rank as Mengyueling Group by Ge et al. (1983). Finally, Chen (1997) returned it to formation rank.

Synonym: （孟月岭组）

The Mengyueling Formation is a fine-grained clastic sequence. The formation is roughly divided into three parts; Lower part consists of silty claystone, intercalated or alternated with muddy siltstone; Middle part consists of medium- to find-grained quartzose sandstone, alternated with muddy siltstone or silty claystone and intercalated with dolomite, and phosphoric chert; Upper part consists of silty claystone, muddy siltstone, intercalated with dolomite. In the type section, the formation is incomplete as its basal part and base are unknown. The exposed portion is over 717.0 m thick.

Because of influence by magmatic instruction, the Mengyueling Formation had undergone contact metamorphism in part, resulting rock alteration into quartzose tremolite-diopside hornstone, tremolite-albite-hornstone or sericitic knotted slate.