Ages of the Cape Hoskins volcanoes, New Britain, Papua New Guinea

Abstract

Ages of eleven volcanoes in the Cape Hoskins area are based on potassium-argon determinations on lava samples, on carbon-14 dates of charcoal from buried soil horizons, on relationships of the volcanoes to one another, and on comparison of the erosional states of the volcanoes with one another and with Hydrographers volcano, east Papua. The three oldest volcanoes, Ko, Husa, and Kapberg, are in a residual erosional stage and are probably similar in age. Ko was active about 900 000-800 000 years ago. Except for the active Pago volcano, the other volcanoes are in the planeze erosional stage. Of these Busui is overlapped by Oto, dated at about 190 000 years, and Mululus, dated at about 100 000 to 70 000 years, is overlapped by Mataleloch. Lolo, a little eroded cone that may be very late Pleistocene or Holocene, is overlapped by Witori, which has a central caldera formed about 2600 years ago. Pago, inside this caldera, last erupted in 1914-18 and may have begun its activity less than 350 years ago. The remaining volcano, Buru, is probably slightly younger than Witori, which it intersects. Pumiceous tephra layers mantle much of the area; some probably came from Witori and Buru, but the youngest layers, several metres thick, were deposited 350 to 2000 years ago and may be derived from volcanoes elsewhere.