Lianhuashan Fm
Type Locality and Naming
The type section is located at Lianhuashan (hill) southeast of Donglong Town (used name Shangdongshilong) in Guigang County, Guanxi; but the exposure is not complete with covers in the upper parts. The selectstratotype is at south slope of Xiayiling Hill, Liujing Town of Hengxian County, east Nanning City (108o52’E-22o52’N). It was named by Chu T.H. (=Zhu Tinggu) in 1928.
Lithology and Thickness
Siltstone. The original description in the naming section is as follows: thick-bedded hard quartz sandstone (mistaken as quartzite) intercalated with few thin shale with a several-meter-thick conglomerate at the base. The quartz sandstone is coarse-grained, mainly red color, occasionally white in color and the shale is grayish and red. Upward, the shale increased and sandstone reduced both in number and thickness, and the color of shale are in yellow, gray, and red, intercalated thin-bedded or irregular limestone. The alternation of limestone, sandstone and shale occurs in the uppermost part with brown coal beds. The thickness is more than 800 m. The Lianhuashan Fm was divided into three members:
Lower - Lingli Member, about 109 m thick, is dominated by gray-white fine- to medium-grained quartz sandstone with small cross bedding and purplish-red siltstone and clayey fine sandstone with a 20-30 cm thick quartz conglomerate at the base.
Middle - Hengxian Member, 136.8 m thick, consists of purplish-red clayey siltstone and fine-grained sandstone with more manganese concretions at bottom. Some silty dolomite, bioclastic dolomitic limestone, nodular argillaceous limestone and mudstone are occurred in the upper.
Upper - Liukankou Member, 134.5 m thick, includes two parts; the upper part consists of purplish-red thin-bedded clayey siltstone and fine sandstone, intercalated with yellow-green mudstone bearing muscovite debris. The lower part consists of purplish-red calcareous mudstone with yellow silty mudstone and dolomitic limestone. It is about less than 400 m in total thickness.
[Figure: Outcrops of Lianhuashan Formation at type locality of Xiayiling Hill in Liujing. A- basal conglomerate beds, unconformable contact with the underlying Cambrian rocks. B, D - purple sandstone and siltstone of the Liuhankou Mbr. C- Siltstone with sandy dolomite of Hengxian Mbr]
Relationships and Distribution
Lower contact
The formation is unconformable onto the underlying Cambrian strata of gray green sandstone with light metamorphosed sericite mudstone.
Upper contact
This formation has a conformable contact to the overlying Nagaoling Fm. Their difference is only based on the rock color, the former is purple red and the latter green in color
Regional extent
The formation is widely distributed in the west flank of Dayaoshan Mts in central Guangxi and around Damingshan Mts. in south Guangxi. In the north and northeast Guangxi and to Hunan Province its lateral equivalent is represented by the deposits of much younger age, for which some other lithologic names were given.
GeoJSON
Fossils
Middle - Hengxian Member, contains Bivalves Leiodysodonta guangxiensis, L. henxianensis, L. elliptica, Dysodonta angulate; Ostracods Beyrichia sp., Leperditia sp. Healdianella sp. Fish: Yunnanolepis sp. Lianhuashanolepis liukingensis; Brachiopods Lingula sp. and small sized spiriferids.
Upper - Liukankou Member yields Bivalves Dysodonta angulata, Leiodysodonta
guangxiensis, L. levis, Goniophora sp. etc. Ostracods Beyrichia sp., Leperditia sp. etc. Fish Asiaspis expansa, Asiacanthus suni, A. kaoi; and trace fossils of burrows.
Age
Depositional setting
It is interpreted as a backshore and lagoonshore depositional environment.
Additional Information