Manbo Fm
Period:
Silurian
Age Interval:
mid Telychian-Sheinwoodian (S1-S2) (38b)
Province:
Yunnan
Type Locality and Naming
The formation was proposed by Zhang Yuanzhi(1996). The type section is the Manbo-Hulutian section, which is near the Manbo village, ca.5 km to the south of the Mojiang Xian, Yunnan Province(101°44', 23°22').
Synonym: (漫波组)
Lithology and Thickness
The formation, over 1694 m at the type section, consists of greyish green, greyish yellow fine grained quartz sandstone, siltstone and shale, with a few layers of micritic limestone.
Lithology Pattern:
Clayey sandstone
Relationships and Distribution
Lower contact
The base of the strata is unknown according to Zhang et al. (2014). Regionally, the next older unit is the Dapingzi Fm of earliest Silurian.
Upper contact
It probably conformably underlies the Shuiqing Fm
Regional extent
The formation is restricted in distribution. It is only outcropped sporadically in Manbo, Hulutian of Mojiang Xian and Songbilangzi, Dashuigou and Banpo of Lüchun Xian.
GeoJSON
null
Fossils
It bears graptolites Monograptus cf. Flemingii, Pristiograptus meneghiini, P. cf. Dubius and Monoclimacis vomerina in the type section (Zhang Yuanzhi, 1996).
Age
The formation was revised by Zhang et Lenz (1999) and Zhang et al.(2014). According to the graptolites reported by Zhang Yuanzhi (1996), the age of the formation belongs to Sheinwoodian. The graptolite fauna found in Kemen section, ca. 20 km to the north of the Mojiang Xian, suggesting a correspondence with the Monoclimacis crenulata Biozone, indicates that the formation is probably of Telychian to Sheinwoodian age (Zhang et al., 2014).
Age Span:
Beginning stage:
Telychian
Fraction up in beginning stage:
0
Beginning date (Ma):
438.59
Ending stage:
Sheinwoodian
Fraction up in the ending stage:
1
Ending date (Ma):
430.62
Depositional setting
Depositional pattern:
Additional Information
Compiler:
Wang Chuanshang and Wang Xiaofeng