Late Quaternary formation and infilling of basins in the upper Kaugel valley, Papua New Guinea highlands

The Kaugel valley basins are representative of at least 20 basins that are present in the Papua New Guinea highlands. They were formed during the late Quaternary when lavas from Giluwe volcano dammed the Kaugel River. This occurred at least three times, giving rise to five lakes that occupied parts of the Kaugel valley in succession. The earliest lake, Lake Winjaka, filled with finely laminated clays and diatomite more than 100 m thick. Lake Kapena, the second lake, filled with deltaic sediments ranging from fine clays in bottomset locations to gravel around the margins. Following the final lava eruptions from Giluwe to affect the Kaugel valley, lakes Tambul, Alkena and Bonga were formed. These filled with a range of deposits including deltaic gravels, subaqueous mudflow deposits, graded beds, fine silts and clays, and organic detritus. Tephras erupted from highland volcanoes (and to a lesser extent from Bismarck Sea volcanoes) contributed much of the materials that make up the sediments in the basins. Lake Kutubu and the Kandep-Marient basins provide modern analogues to the Kaugel valley basins.