Sazhi Fm
Type Locality and Naming
The type section is located by the Sazhi Highway of the Langdai Country 24 km to the south by west of the Liuzhi County Town, Guizhou Province. It was named by Xiao Weimin et al., in 1986.
Lithology and Thickness
It is divisible into two parts. Lower part, known as the Fengwo Member, is composed of interbeds of light-grey thick-bedded dolomitized bioclastic micrite and silty claystones, yielding Fusulinida fossils, with a thickness of 60.8 m. The basal part of the formation is composed of medium-, and thick-bedded weakly-dolomitized bioclastic micrite. In the standard locality the amount of clastic rocks is great, and the Fusulinida is represented essentially by the Pseudofusulina kueichowensis, P. kraffti and Schwagerina guembeli, etc.; southerly the clastic rocks are decreasing in amount, with the Fusulinida fossils being predominant, and in association with corals represented by Kepingophyllum and Protomichelinia. The facies grades westwardly into the dolomitized limestone, yielding Fusulinida represented by Pamirina and Staffella. Upper part, known as the Sanchalu Member, is composed of dark-grey and grey-black, medium- and thin-bedded, carbonaceous and clayey limestones, intercalated with black shale and thick-bedded dolomitized micritic bio-limestone, with a thickness of 234.2 m, rich in Fusulinida represented by Misellina termieri, Darvasites parva and Chalaroschwagerina vulgaris; and coral represented by Wentzellophyllum simplex. The facies of the Upper part of the formation changes westwardly to quartz-sandstone intercalated with limestone, with the top part of the formation containing thin-bedded coal seams, yielding such Fusulinida as Darvasites and Pseudofusulina. Total thickness of the formation is 294.9 m.
Relationships and Distribution
Lower contact
Conformable contact with the shale, intercalated with sandstone at the top of the underlying Longyin Fm
Upper contact
Conformable contact with the overlying Qixia Fm
Regional extent
Distributed in the areas of Shuicheng, Liuzhi, Panan, Pu’an and Qinglong in the southern part of Guizhou Province, as well as from the Sazhi County extending southward to the Zhewang area of the Ceheng County and the Ke’ao area of the Ziyun County, Guizhou Province, with a thickness of 100-150 m; westward to the Huagong of the Qinglong County its thickness is of 445 m, which used to be known as the Huagong Fm. Still further west, there occurs a sharp vertical stepped change in its lithology; southwesterly till the area of the Panxian-Pu’an Counties the formation is 120-m thick.
GeoJSON
Fossils
Fengwo Member has Fusulinida of Pseudofusulina kueichowensis, P. kraffti, Schwagerina guembeli, Pamirina and Staffella, and Corals represented by Kepingophyllum and Protomichelinia (see Lithology section).
Sanchalu Member has Fusulinida represented by Misellina termieri, Darvasites parva, Chalaroschwagerina vulgaris, and Pseudofusulina; and Coral represented by Wentzellophyllum simplex.
Age
Depositional setting
It is interpreted as shallow-sea carbonate-platform and slope-facies deposits.
Additional Information