Qiaoyuan Fm

It was named by the No. 205 Party of the Coalfield Administration of Guangdong Province in 1969, and was first cited publicly by the Scientific Research Institute of Coal Industry of Xi’an in 1973. The naming section is located in the vicinity of Qiaoyuan Village of Longguiyu region, Qujiang County, Guangdong Province, with its reference section being situated in the Lianhe region to the Shanglongshui area of Huidong County.

Synonym: （桥源组）

Its basal part is composed of feldspar-quartz sandstones, gradating upwards into a rhythmic layering of fine-grained feldspar-quartz sandstones, siltstones and mudstones; with its upper part being intercalated commonly with carbonaceous shales, locally with coal seams; and with its top part being composed mainly of gritstones. It is of 2300 m in thickness.

It yields bivalve fossils as represented by the Lilingella cuneata-Hunanella shiliabaensis assemblage, and spinicaudatan fossils as represented by Asiolimnadiopsis spp. As for the plant fossils, they are found to occur essentially in the section extending from the Lianhe region to the Shanglongshui region of Huidong County, important genera and species of which comprise Coniopteris hymenophylloides, Dictyophyllum sp., Clathropteris sp., Phlebopteris cf. brauni, Cladophlebis cf. denticulate. It yields also spore-pollen fossils. In the Zhoule region, east of Lechang County, the formation yields occasionally bivalves of marine origin such as Pleuromya oblonga, Nuculana sp., Solemya aff. hoahuyhensis and Isognomon sp.

The formation represents fluvial-lacustrine coal-bearing clastic deposits of inland basins. In the Zhoule region, the formation belongs to continental-marine alternating deposits of regressive sequence.