Early Cainozoic stratigraphy and structure of the Gazelle Peninsula, east New Britain: An example of extensional tectonics in the New Britain arc-trench complex

Abstract

The Early Cainozoic geological history of the Gazelle Peninsula, east New Britain, Papua New Guinea, indicates that extensional tectonics have influenced sedimentation and volcanism in this part of the New Britain arc-trench complex since the earliest Miocene. Remapping of the Gazelle Peninsula has resulted in a significant revision of the Mio-Pliocene stratigraphy and structure: three new formations (Pali River Conglomerate, Bergberg Formation and Arabam Diorite) and six new structural units (Baining Mountain Horst and Graben Zone, Wide Bay Fault System, Nengmutka Caldera, Keravat Caldera, Sikut Caldera, and Warangoi Trend) are defined. Three formations (Yalam Limestone, Nengmutka Volcanics and Sinewit Formation) are redefined. The first obvious influence of the Baining Mountain Horstand Graben Zone, which runs centrally through the Gazelle Peninsiula, postdates an orogenic event at the Oligocene-Miocene boundary. By the mid-Miocene, emergent caldera centres were localized along this extensional zone, an...