Dafeng Fm
Type Locality and Naming
Nanxiong Basin. In 1981 Zhang Xianqiu erected the Dafeng member of the Nanxiong Fm in the report on the study of the Dafeng section of Nanxiong. The section for the designation is in Dafeng of Nanxiong, Guangdong. The Nanxiong Fm represents the macroclastic rocks over the granite of early Yanshanian stage and under the Zhutian member, which was assigned to Late Cretaceous. In 1993 the Guangxi Bureau of Geology and Mineral Resources recalled it the Dafeng Formation and remained its age.
Synonym: It is, however, called as the lower member of the Sanshui Fm in central Guangdong.
Lithology and Thickness
The Dafeng Formation is mainly represented by purple red conglomerate, sandy conglomerate with sandstone, siltstone and silty mudstone. Its basal part consisting of purple red conglomerate and sandy conglomerate intercalated with brown red clayey siltstone and thin mudstone bands. It is differentiated from the granite of early Yanshanian (=mid-Jurassic) age. It has a thickness of 233 m.
Relationships and Distribution
Lower contact
The Dafeng Formation lies unconformably over the underlying strata
Upper contact
Its top is bounded by the basal part of the Zhutian Fm, which is built up by brown red silty mudstone interbedded with siltstone, thin-bedded clayey limestone and sandy conglomerate. The Dafeng Formation continues with the overlying strata.
Regional extent
The formation occurs in the Shaoguan and Huaiji areas of northern Guangdong. It does not vary considerably in lithology and becomes thinner from west to east, varying from 1969.6 m in the west and 223.7 m in the east. In the Changba area of the Danxia basin, the paleomagnetic determination indicates that the Dafeng Formation has normal polarity.
GeoJSON
Fossils
In Lechang and Qujiang, it yields ostracods such as the Cypridea-Talicypridea assemblage.
Age
Depositional setting
It is built up by lacustrine sediments
Additional Information