Late Quaternary palaeoceanography of the western Woodlark Basin (Solomon Sea) and Manus Basin (Bismarck Sea), Papua New Guinea, from planktic foraminifera and radiocarbon dating
Foraminiferal assemblages and radiocarbon dates from three cores collected in the western Woodlark Basin and one from the Manus Basin have provided information on late Quaternary sedimentation rates and characteristics of water masses. In the western Woodlark Basin, where turbidites and slumps are present, sedimentation rates vary from a few tens of cm/1000 year to 140 cm/1000 year, with background rates decreasing eastwards from New Guinea from 7 cm/1000 year to 3.7 cm/1000 year. In the Manus Basin during the past 16,000 years the sedimentation rate was 15.5 cm/1000 year. In the western Woodlark Basin the lysocline has deepened by at least 900 m over the past 23,500 years. It was above 2680 m before 23,500 years ago; at 3145 m about 13,000 years ago and is now at 3500 m. During the past 30,000 years variations in the mean annual temperatures of surface waters in the western Woodlark Basin were about 3 °C, and about 4.5 °C in the Manus Basin. There were cool intervals at 19,500 and 13,000 years ago. A poorly developed early Holocene warm interval 10,000 − 8500 years ago was followed by a cooler interval with a minimum 8000 years ago. The Holocene climatic optimum occurred 5000 years ago with temperatures higher than at present.