Wanggong Fm

Northernmost Taiwan. The naming section is located at Wanggong Village ~24 km at the seaside southwest of Changhua County, Taiwan. Named by Ji Wenrong in 1983.

Mainly variegated pyroclastic rocks, sandstone and shale, occasionally with limestone. It is overlain by the early Miocene strata and underlain by the pre-Tertiary. The thickness is >1046 m. The formation is divided into three parts: Lower part, dominantly green pyroclastic rocks and tuffaceous shale, with black calcareous shale and light green sandstone, ~755 m thick; Middle part, chiefly variegated pyroclastic rocks, occasionally with light green calcareous shale, ~250 m thick; Upper part, dominantly light greenish gray calcareous shale, pyroclastic rocks and limestone, with sandstone and tuffaceous shale, ~260 m thick. The thickness of the formation is highly varied and the bottom is not penetrated. According to seismic and well electric log data, the thickness increases toward the northwest and the thickness of the Paleocene reaches 2900 m in the CDA-2 well in the sea area west of Wanggong.

It contains calcareous nannofossils and foraminifera. The Wanggong No. 1 well yields the nannofossils Heliolithus kleinpelli, Discoaster mohleri and Fasciculithus tonii and the foraminifera Globorotalia pseudomenardii, G. verlascoensis etc. In the Tiexi No. 1 well the nannofossil Fasciculithus tympaniformis is found at 1910 m. The above-mentioned calcareous nannofossil assemblage belongs to zones NP5–NP8 and the foraminifera assemblage to zone P4.

The Wanggong Formation was deposited in a relatively unstable neritic environment and is represented by poorly sorted sandstone containing significant amount of pyroclastic material.