Lingshui Fm

Hainan-offshore SW. The naming section is located in Ying 9 well in an offshore area, 83 km east of Sanya City, Hainan Island. Named by Hu Pingzhong, Su Houxi et al. of the South China Sea Branch, China National Offshore Oil Corp. in 1981.

Lying above granite and below the Sanya Formation, the Lingshui Formation takes the 2115–2697 m of Ying 9 well as the stratotype. Lower part of the formation consists predominantly of light gray siltstone and pebbly sandstone with thin-bedded black gray shale; the base is light gray and purplish gray micrite with grayish black sandy shale. Middle part is alternating beds of black shale, light gray, pebbly and lime quartz sandstone, siltstone and sandy conglomerate. Upper part is alternating beds of dark gray and blackish gray mudstone-shale and light gray sandy conglomerate and sandstone, with a thickness of 582 m. The total thickness ranges from 0 to 1697 m. In the seismic profile, the formation corresponds with the reflector group between reflection boundaries T₆–T₉.

In this formation there are only the benthic foraminifera Gaudryina hayasakai, Triloculina sp. and Asterigerina sp. etc.; the calcareous nannofossils include zone NP25 fossils such as Sphenolithus ciperoensis and Helicosphaera recta; sporopollen is represented by the Pinuspollenites-Gothanipollis-Rutaceoipollis assemblage. The organic limestone in the lower part contains detritus of corals, sponges, bryozoans, echinoderms and bivalves etc.

This formation belongs to littoral-bay deposits.