Pingdong Fm
Type Locality and Naming
Pingdong Formation originally refers to the lower strata (red bed) of the "100 Wanshan Group" named by Chen Gang et al. (1960) in Guangxi, which is a set of red bed strata between the lithic sandstone of the Permian Fulong'ao Fm and the underlying Indosinian granite porphyry, and the age is designated as Triassic. Liu Zhengkun (1961) of Guangxi Petroleum Survey Team changed this set of red beds to Late Triassic. From 1972 to 1974, the petroleum survey team in Guangxi and the survey team in Guangxi area divided the Shiwandashan Gr into Pingdong Fm and Fulong'ao Fm from bottom to top. The base of the determined Pingdong Fm still contains unstable volcanic rocks.
Synonym: Pingdong Gr
Lithology and Thickness
It is mainly composed of light grayish green, purplish red sandstone, siltstone, pebbled sandstone and mudstone. The thickness is generally 210 to 3114 m.
Relationships and Distribution
Lower contact
At the bottom, the unconformable contact is between acidic lava and underlying Indosinian-age granite porphyry. Regionally, the next older unit is the Hekou Fm of Middle Triassic
Upper contact
At the top, the conformable contact is between acidic lava and the pebbled lithic sandstone at the bottom of Fulong'ao Fm
Regional extent
The lithology of this formation is stable and only distributed in Zhongba, Banba, Fulongao and Gonggong of Shangsi County in Fangcheng County. The thickness is generally 210 to 3114 m.
GeoJSON
Fossils
Only the lower part contains bivalves Posidonia sp., Isognomon abruta, Modiolus sp., Plagiostoma sp., Bakeveloides subquadratus, B. radiatus and leaf limbs fossils Euestheria yipinglangensis, Bulbilimnadia sp.
Age
Depositional setting
The sedimentary environment is Marine and continental interclastic sedimentary rock.
Additional Information