Jiaowei Fm
Type Locality and Naming
Beibu Gulf region. The named section is located in Leiqiong No.1 drill, Yijiaowei, Xuwen County, Guangdong. Named in 1965 by the Fourth Census Exploration Team of the Ministry of Geology.
Lithology and Thickness
The formation is composed of interbedded gray, gray-green mudstone, silty mudstone and fine sandstone with varying thicknesses; the bottom is marked by sandstone as a boundary with the underlying suboceanic composition. The lithology can be divided into two sections: Lower section is green-gray siltstone, fine sandstone with mudstone; Upper section is gray-green mudstone, siltstone and sandstone. Mudstone has good diagenesis, with fine horizontal bedding, and sandstone has tiny interlaced layers. It contains charcoal chips, pyrite, sea green stone and insect traces.
Relationships and Distribution
Lower contact
Conformity contact with the underlying Miocene Xiayang Fm.
Upper contact
Conformity or pseudo- conformity contact with the overlying Dengloujiao Fm.
Regional extent
This Formation is mainly distributed in Beibu Gulf, Leizhou Peninsula and northern Hainan Island. The lithology and thickness vary greatly. Generally, it gradually becomes thinner and coarser toward the edge of each basin. For example, the rock in the center of the Qianweixinan depression and Qiongbei depression is thick and the lithology is finer. In the Maichen depression, the thickness of the Formation is 43 to 610m.
GeoJSON
Fossils
This group contains foraminifera, ostracod, gastropod, calcium nannofossils andpollen. Foraminifera mainly include Cassigerinella chipolensis, Orbulina suturalis, Globorotalia siakaensis and Uvigerina graciliformis, etc., belonging to the N14-N9 zone; the calcareous nannofossils include Discoaster hamatus, Cyclicargolithus floridanus, Catinaster coalitus, Helicosphaera minuta, belonging to NN9—NN5 zone; pollen is the combination of Polypodiisporites-Foveotriletes-Casuarinidites, and the ostracod is mainly represented by Spinileberis longicaudata.
Age
Depositional setting
Neritic deposits
Additional Information