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
Bajiaoting Formation

Bajiaoting Fm

Period: 
Paleogene

Age Interval: 
Early Eocene to early Middle Eocene, (31)


Province: 
East China Sea

Type Locality and Naming

Basins offshore NE Zhejiang. The naming section is located at 29º08′18"N and 124º56′03"E, in well Pinghu No.2 in the Xihu depression of the shelf basin of the East China Sea. Named by the Shanghai Marine Geological Party, former Ministry of Geology and Mineral Resources in 1988.


Lithology and Thickness

The Bajiaoting Formation consists of volcanic rocks with clastic rocks encountered by three wells drilled in the Pinghu area. The strata in the 3697.5–4105 m interval of Pinghu No. 2 well are taken as the stratotype section, with an apparent thickness of 407.5 m. It is made up mainly of volcanic rocks with clastic rocks. Volcanic rocks are chiefly greenish gray and dark gray lithic-vitric ignimbrite, altered andesite, dacitic tuff and tuff etc.; sedimentary rocks are grayish green mudstone, grayish white sandstone and sandy conglomerate, the base being not penetrated. Its thickness is 395.7 m for Pingxi No. 1 well and 140.64 m for Pinghu No. 3 well.


Lithology Pattern: 
Volcanics


Relationships and Distribution

Lower contact

Upper contact

The Bajiaoting Formation underlies the Pinghu Fm.

Regional extent

This formation is only encountered by the three wells in the Pinghu area.


GeoJSON

null

Fossils

Mudstone intercalated in volcanic rocks in Pinghu No. 2 well and Pingxi No. 1 well contain the foraminifera Elphidium eocenica and Cibicidoides hilgardi and the Dinophyceae Impletosphaeridium and Lingulodinium, and in addition the Sporopollen assemblage Alnipollenites – Taxodiaceaepollenites - Gothanipollis is also found therein.


Age 

Its age was previously considered to be Eocene (Zheng et al., 1999). Recent study assign this formation to Early Eocene to early Middle Eocene (National Commission on Stratigraphy of China, 2018). According to isotope dating of volcanic rocks and microfossils found in clastic rocks, its age is determined to be Eocene. The K-Ar ages of volcanic rocks in various wells are 56.6±1.4 Ma for Pinghu No. 2 well, 53.1±1.6 Ma for Pinghu No. 3 well and 42.5–45.9 Ma for Pingxi No. 1 well.Top age is uncertain, and may range from late Ypresian to upper Lutetian.

Age Span: 

    Beginning stage: 
Ypresian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
56.00

    Ending stage: 
Lutetian

    Fraction up in the ending stage: 
0.25

    Ending date (Ma):  
46.31

Depositional setting

The Bajiaoting Formation belongs to a volcanic extrusive rock series and is the product of subaqueous intermittent volcanic eruption due to faulting. In the seismic sections it is generally manifested by irregular chaotic seismic reflection waves and thinning of the wedge-shaped structure toward the west. Its top is limited by the T30 wave set and the contact plane is displayed as strong reflection.


Depositional pattern:  

Additional Information


Compiler:  

Tao Deng, Yuanqing Wang, Qian Li, et al.