Majiaoling Fm
Type Locality and Naming
The type section is located from Heli to Beisi, Laibin County, Guangxi. And it was named by Zhang Wenyou and Chen Jiatian in 1938. Zhang Wenyou and Chen Jiatian (1938) divided the Lower Triassic from Heli to Beisi in Laibin County, Guangxi from bottom to top, into "Nanhong Shale", "Majiaoling Limestone" and "Beisi Limestone". Zhao Jinke et al. (1962) collectively referred to the combination of "Nanhong Shale" and "Majiaoling Limestone" as the Majiaoling Fm, which represented the entire Early Triassic deposits in central Guangxi. Lowermost formation in Luolou Gr.
Synonym:
Lithology and Thickness
It is thin-bedded limestone, argillaceous limestone, and banded limestone, partially intercalated with dolomite, oolitic limestone, and mudstone, with gray fine sandstone and sandy shale intercalated with green shale at the bottom. Its thickness is 302 m.
Relationships and Distribution
Lower contact
It is conformable in contact to the siliceous limestone of the underlying Upper Permian Dalong Fm
Upper contact
It is conformable in contact to the overlying Beisi Fm with the bottom shale.
Regional extent
The thickness is thinner in western and southwestern Guangxi, 59 to 166 m and 10 to 150 m respectively; in Longan, Pingguo, Kaiming, Shanglin, Laibin to Longzhou, the thickness is 300 to 700 m; in Longan Minyang. The thickest area of Wuming Chengxiang is 701 to 749 m. In some areas of Pingguo, Chongzuo and Fusui, this group contains intermediate-acid tuff lava.
GeoJSON
Fossils
From Bottom to upper part of this formation, it can be divided into 5 Bivalve assemblages: (1) Towapteria scythica assemblage, (2) Pseudocannonica assemblage, (3) C. stachei assemblage, (4) C. aurita assemblage, (5) Bakevella subpannonica assemblage. According to the distribution of Conodonts, it is divided into 5 zones: (1) Hindeodus minutus peak zone, (2) Hindeodus parvus peak zone, (3) Isarcicella isarcica range zone, (4) Neogondolella carinata range zone, (5) Pachycladina erronera range zone; see also ammonoid Ophiceras sp., Prionolobus sp. etc.
Age
Depositional setting
Shallow marine platform.
Additional Information