Cuijiagou Fm
Period:
Silurian
Age Interval:
Telychian, (45)
Province:
Shaanxi
Type Locality and Naming
It was nominated by Yu Changmin, Chen Xu et al in middle-late 1960s, and then quoted and published by the Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences in 1974. The type section is at Cuijiagou, Ningqiang Xian in southern Shaanxi Province.
Synonym: 崔家沟组
Lithology and Thickness
The formation, 447m in thickness, is dominated by dark grey and yellow green shale, siliceous slaty shale and mudstone.
Lithology Pattern:
Sandy claystone
Relationships and Distribution
Lower contact
Regionally, the next older unit is the Longmaxi Fm of early Silurian
Upper contact
Conformable below the Wangjiawan Fm
Regional extent
The distribution of the formation, as known so far, is restricted in the border area between Sichuan and Shaanxi provinces.
GeoJSON
null
Fossils
The graptolite fossils are found in the formation, such as Streptograptus nodifer, S. extenuatus, Spirograptus minor, etc., equivalent to Spirograptus turriculatus-Monograptus crispus zone. In comparison with the underlying condensed deposition of the Longmaxi Fm, the Cuijiagou Fm is more than 20 times thicker than the Longmaxi Fm, which reflects a rapid accumulation within a rather short time interval.
Age
Schematic strat column shows as early Telychian
Age Span:
Beginning stage:
Telychian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
438.59
Ending stage:
Telychian
Fraction up in the ending stage:
0.25
Ending date (Ma):
437.18
Depositional setting
Depositional pattern:
Additional Information
Compiler:
From Geological Formation Names of China (1866-2000); Springer Publ.