Meishan Fm
Type Locality and Naming
Hainan-offshore SW. The named section is located at No.6 Ying drill in the sea 69 km southwest of Sanya, Hainan. The Nanhai Petroleum Branch of China National Petroleum Corporation Hu Pingzhong and Su Houxi named it in 1987.
Lithology and Thickness
The Meishan Formation is located between the Sanya Fm and the Huangliu Fm. It is a set of neritic clastic rocks and carbonate rocks. Taking the 1532 to 1768 m drill section of No.6 Ying drill as the type interval, then it has a a thickness of 236 m. In that reference site, it can be divided into upper and lower sections: the Lower section is dominated by gray-white reef limestone, reef dolomite, and gray-white quartz sand and conglomerate; Upper section is dominated by light gray foraminiferous sandy limestone, chalky sandstone and gray-white pebbly quartz sandstone with intercalation of marl. Elsewhere, the Lower part is foraminiferous limestone, dolomite with glutenite. Middle part is chalky sand and mudstone. Upper part is composed of gravelly coarse sandstone and fine sandstone. The thickness of this group varies greatly. The drilling thickness is about 100-450m. According to seismic data, its maximum thickness can reach 2000 m.
Relationships and Distribution
Lower contact
This group has a conformity contact with the underlying Miocene Sanya Fm.
Upper contact
This group is in disconformity contact with the overlying Miocene Huangliu Fm.
Regional extent
This group is distributed in the Yinggehai Basin and Qiongdongnan Basin. The upper part is often missing. The lithology of this group is mainly reef limestone and sandstone in the west of Qiongdongnan Basin, and thick mudstone and sandstone in the eastern part of the basin. The eastern part of the Yinggehai Basin is also mudstone intercalated with sandstone; the Miocene in the Hanoi depression in the northwest of the basin is still dominated by mudstone intercalated with sandstone, but the middle part is composed of mudstone and limestone and is divided into three sections.
GeoJSON
Fossils
The Meishan Formation is rich in foraminifera fossils. The plankton one mainly includes Orbulina suturalis, Cassigerinella chipolensis, Globorotalia siakensis, etc., belonging to the N9-N15 zone. The benthos one includes Nephrolepidina verbeeki, N. sumatrensis, Miogypsina polymorpha, Miolepidocyclina burdigalpeus, Cycloc Posteidae, Austintrillina howchini, etc., belonging to foraminifera zone Te5-Tf1-2, the late Early to Middle Miocene. Calcareous nannofossils include Helicosphaera euphratis, Discoaster variabilis, D.hamatus, Sphenolithus moriformis, Cyclicargolithus floridanus, etc., which correspond to the NN4-NN9 zone; the pollen is the combination of Dicolpopollis kockelii-Polypodiisporites usmensis.
Age
Depositional setting
Shallow ocean
Additional Information