Quanyagou Gr
Type Locality and Naming
The Qinghai Petroleum Administration erected the Quanyagou Group in the report on the Mesozoic strata of the Qaidam basin (unpublished). The type locality for the designation is at Quanyagou on the western margin of the Qaidam basin of Qinghai. The reference section is at Quanyagou of the Mangya Town of the west Qaidam basin.
Lithology and Thickness
The Quanyagou Group is mainly represented by a set of tangerine sandstone and is represented by brown red sandstone, siltstone and brown gray sandy conglomerate and its lower part is built up by gray white conglomerate with tangerine and yellow gray sandy mudstone, bearing ostracods and sporopollen grains. It is 852.01 m thick.
Relationships and Distribution
Lower contact
Its base is a disconformity marked by tangerine and yellow gray sandy mudstone with abundant Cretaceous faunas is distinguished from the Hongshuigou Fm marked by dark brown sandstone.
Upper contact
Its top is an unconformity bounded by the appearance of gray and gray yellow sandy conglomerate interbedded with sandy mudstone under the Lulehe Fm (or, the higher Ganchaigou Fm).
Regional extent
The present group occurs in the Qaidam basin, which varies considerably both in lithology and thickness. In the Quanyagou area it is quite coarse in lithology and 852.61 m thick. In the Lenghu area, only the lower part of the formation is composed of sandy mudstone with a thickness of 55 m. In the Lulehe area, it is mainly represented by tangerine and purple gray sandy conglomerate, with a thickness of 571.4 m. In the Kushuiquan and Dahonggou areas, it becomes fine in lithology and there appear multiple layers of dark brown and blue gray mudstone, except tangerine and gray white sandy conglomerate, with a thickness of 1173 m.
GeoJSON
Fossils
This formation yields ostracods Latonia onerusa, Darwinula sp., D. contracta, Timiriasevia sp., Clinocypris sp.; sporopollen grains Cicatricosisporites sp., Cyathidites minor. In Dahonggou and Ruoshuiquan it contains ostracods Cypridea unicostata, Cypridea vitmensiis, Rhinocypris cirrita, D. jungarica sp., Theriosynoecum sp.; estherias Dachaidanestheria loxoquadrata; Charophytes Mesochara stipitata, Minchechara xiaoxiensis; sporopollen grains Toroisporis, Iygodiumsporites, Cicatricosisporites.
Age
Depositional setting
It belongs to piedmont-diluvial-fluvial deposition.
Additional Information