Home Multi-Country Search About Admin Login
Cenozoic
Cretaceous
Jurassic
Triassic
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
Neoproterozoic
Mesoproterozoic

Search by
Select Region(s) to search
Hold Ctrl (Windows/Linux) or Command (Mac) to select multiple
Cigang Formation

Cigang Fm

Period: 
Triassic

Age Interval: 
Early Triassic (TJ73b, TJ75b)


Province: 
Sichuan

Type Locality and Naming

The type section is located in Guxuecigang, Rongde Town, Sichuan Province, which was named by the third regional geological group of Sichuan Geological Survey in 1972. It was cited publicly by Sichuan Geological Survey and Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences in 1982 for the first time.

Synonym:


Lithology and Thickness

The Cigang Fm is consisted of interbedded oolitic limestone and purple red, greyish green sandy slate, and has been divided into three parts. Lower part is dominated by light grey thick limestone, with oolite, basalt and muddy conglomerate. Middle part consists of grey banded slate, metamorphic feldspathic quartz sandstone, oolitic and conglomerated limestone with few greyish green conglomerated basalts. Upper part is characterized by dark grey oolitic, pisolitic limestone and greyish green, purple red banded slate. Thickness is more than 611 m.


Lithology Pattern: 
Oolitic limestone


Relationships and Distribution

Lower contact

The conglomerate in the basal Cigang Fm lies unconformable in contact on the Permian strata.

Upper contact

Regional extent

Mainly distributed between Batangnala Mountain to Zhongza, Rongde Guxue in Sichuan Province with varied thickness ranging from 202-1234 m. Originally, the definition of Cigang Fm represents the early Triassic marine sediments distributed in Baiyu and Yidun of Sichuan Province. Considering the oolitic limestone and bioclastic limestone dominated Lower Triassic sequences in Rongdeguxuecigang, which were distinctly different to the sandstone and clay dominated in the Muli, distribution of this formation was reduced by Chengdu Institute of Geology and Mineral Resources, Chinese Academy of Geological Sciences and regional geological team of Bureau of Geology and Mineral Resources of Sichuan Province in 1992, representing the early Triassic sediments distributed restrictively around the Batanglana Mountain-Zhongza-Derongguxue in Sichuan Province.


GeoJSON

null

Fossils

Ammonoids: Ophiceras zone, Owenites zone and Procarnites-Procladiscites zone ; Bivalves: Claraia stachei, C. wangi and C. aurita


Age 

A Lingmaigou Fm was established by the third regional geological group of Sichuan Geological Survey in 1977, based on the stratotype of Lingmaigou in Tongba, representing the deposits formed during Induan of Early Triassic, consequently, the Cigang Fm was constrained within the Late Early Triassic. [However, as used in this Lexicon, the Cigang Fm does not overlie the Lingmaigou Fm, therefore also seems to include the Induan.]

Age Span: 

    Beginning stage: 
Induan

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
251.90

    Ending stage: 
Olenekian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
246.70

Depositional setting

Shallow marine facies


Depositional pattern:  


Additional Information


Compiler:  

Zhang Shunxin, Guo Wenwei and Tong Jinnan.