| Abstract: | Late Mesozoic and Cenozoic volcanic rocks in eastern Papua record a complex series of volcanotectonic events which reflect interaction between the Indo-Australian and Solomon sea plates. Basement formations of Upper Cretaceous and Eocene submarine basalt are comparable to those characteristic of sea floor spreading centers and are thought to have originated during volcanic activity associated with spreading in the Coral Sea basin. Arc-trench type andesitic volcanism was prominent during the late Cenozoic but shows no clear relationship to a subduction event. An alternative explanation links the development of thickened crust and consequent crust/mantle interaction with the generation of andesitic magmas. The tectonic environment of eastern Papua during the late Cenozoic was one of block faulting and uplift associated with crustal tension. The presence of Quaternary peralkaline rhyolites suggests that this environment is now being replaced by active rifting. |
