Longyangxia Gr

The type section is located at Longyangxia, Guide County, Qinghai. And the reference section is located at Heishuihe, Wulanchaka. It was named by Chen Qingxuan and Li Yulong in 1956. In 1987, Rao Rongbiao and others renamed the Longyangxia Group and divided into two subgroups, the upper and lower subgroups.

Synonym:

It is dominated by a set of sandy mud volcanic flysch deposits rich in intermediate-basic- intermediate-acid lava and pyroclastic rocks. Lower Subgroup is divided into 4 lithological parts from bottom to top: (1) Conglomerate Member, composed of conglomerate, glutenite (= gravel-rich) and gravelly coarse sandstone; (2) Volcanic Member, composed of intermediate-basic lava breccia and breccia lava. Pyroxene andesite composition; (3) Conglomerate Member, composed of conglomerate, glutenite, and feldspar sandstone; (4) Volcanic Member, mainly composed of interbedded middle-basic volcanic lava and lava tuff; the total thickness is about 2500 m. Upper Subgroup is divided into two lithological parts from bottom to top: (1) Sandstone intercalated limestone Member, composed of conglomerate, feldspar quartz sandstone, siltstone, slate intercalated with thin limestone, and three sedimentary rhythms; (2) Limestone and limestone Sandstone interbedded Member are dominated by limestone and marble in the lower part and sandstone and slate in the upper part; the total thickness is more than 8000 m.

Lower subgroup yielded ammonoids: Lytophiceras sp., Inyoites sp. and Dieneroceras sp. and bivalves: Claraia sp.; Upper subgroup yielded ammonoids: Procarnites kokeni, Pseudoflemingites sp., Eophyllites sp., Dieneroceras sp., Subvishnuites sp., Xenoceltites sp., Tirolites sp., Pseudosageceras sp., Arnautoceltites arnauticus and bivalves: Eumorphotis sp., Posidonia cf. kedahensis.

This group is a marine volcano-sedimentary rock sequence.