Sancha Fm
Type Locality and Naming
The type section lies at Qinggangwan, Sancha, 8 km northeast of Shandan, Gansu. It was named by Liu Hongchou et al. in 1980.
Lithology and Thickness
Claystone and Sandstone. Littoral facies clastic deposits, consisting of dark-gray slate and metamorphic sandstone, occasionally intercalated with thin-bedded limestone, and with gray quartz-rich sandy conglomerate at bottom. The slate contains abundant fossil plants, and the limestone contains crinoid stems. Thickness >56.6 m. At Daqingyangkou of Jianshan (19 km northwest of the Jiling Railway Station), it is composed of gray-brown and gray-purple sandstone intercalated with black shale, thin coal seams and limestone lenses. Exposed thickness 81 m.
Relationships and Distribution
Lower contact
Underlain by granite intrusion; but regionally, there is also the middle-Lower Carboniferous unit of the Nanwading Fm.
Upper contact
Conformable contact with the overlying Jianshan Fm
Regional extent
Distributed along Sancha of Shandan County and Daqingyangkou of Jianshan on the south slope of Longshou Mt., while exposed only at Zangbutai, etc. on the north slope.
GeoJSON
Fossils
Yielding the Plant Mesocalamites-Rhodeopteridium assemblage, including M. cf. cisttiformis, M. ramifer, Rhodeopteridium cf. chinghaiensis, Sphenopteris emarginotus, Eleutherophyllum mirabile, Neuropteris gigantea, N. cardiopteroides, Linopteris brongniartii, L. cf. intricata, Asterophyllites longifolius, etc., in which Linopteris and Neuropteris are the most abundant.
Age
Depositional setting
It is interpreted as a littoral facies
Additional Information