Stratigraphy and age-dating of the Kiriwina Formation,Woodlark Island, Papua New Guinea

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Australian Geosciences Council
The Upper-Pleistocene Kiriwina Formation (KFm) of Woodlark Island, Papua New Guinea, is a complex, largely transitional shallow marine to near-shore terrestrial sedimentary unit. This study provides the first detailed analysis of the KFm on any KFm hosting island of the Solomon Sea. Highly elevated Au contents (up to 10 ppm) occur within various sub-units. The KFm covers most of the island’s surface, has a thickness of 0–90m, and unconformably overlies the mid-Miocene Okiduse Volcanics that host carbonate-base metal-Au epithermal mineralization. The formation has undergone rapid horizontal and vertical changes in the sedimentary environment and style; individual units and subunits occur as repeated lenses of conglomerates, gritstones, beach sands, silts, lagoonal clays, and mixed clays/carbonates. The KFm is capped by porous and permeable shallow marine limestones, which in places have undergone karst development. Detailed mapping indicates previously unknown near-shore terrestrial subunits that may comprise a large part of the sequence. Andesitic fragments are widely dispersed throughout each member and subunit. The main clay in the Talpos Marine Clay Member is nontronite, an Fe-rich smectite. New C14 radiometric age-dating has determined the KFm to be 47,130–60,300 yrs BP at Kulumadau and > 70,000 yrs BP at Busai. These ages were used as a basis to determine an average uplift rate of 1.06m/1000 years.
Age estimation, Papua New Guinea, Pleistocene epoch, Aquatic ecosystems, Terrestrial ecosystems, Islands, Surface area, Caves, Clays, Smectite
McGeeney, D., Graham, I., Cohen, D., Spencer, L., Jacobsen, G., & Williams, A. (2012). Stratigraphy and age-dating of the Kiriwina Formation,Woodlark Island, Papua New Guinea. Paper presented to the 34th International Geological Congress 2012, "Unearthing our Past and Future - Resourcing Tomorrow". 5-10 August 2012 . Brisbane, Australia. (pp. 3507).