Fossil foraminiferal assemblages from Pleistocene seagrass-bank deposits of the southern Perth Basin, Western Australia, and their palaeotemperature implications

• Published in: Journal of the Royal Society of Western Australia Vol. 88; p. 177
• Main Author: Semeniuk, T A
• Format: Journal Article
• Language: English
• Published: Welshpool Royal Society of Western Australia 01.12.2005
• Subjects: Foraminifera; Marine; Pleistocene; ISW, Indian Ocean, Leeuwin Current; ISW, Australia, Western Australia; ISW, Indian Ocean, Perth Basin
• ISSN: 0035-922X

Fossil foraminifera were collected from three Pleistocene seagrass-bank deposits in the laterally contiguous Tims Thicket Limestone, Myalup Sand, and Kooallup Limestone in the southern Perth Basin, Western Australia. In total, 112 species of foraminifera were recorded. Tims Thicket Limestone and Kooallup Limestone had diverse assemblages (> 90 species) characterised by a Marginopora-Amphisorus-Cibicides assemblage. The limestone lens in the quartz-rich Myalup Sand had a moderately diverse assemblage (35 species) and was characterised by a Lamellodiscorbis-Rotorboides assemblage. Comparisons of the fossil assemblages with modern ecological assemblages from seagrass communities from a range of warm to cool climate settings along the Western Australian coast indicate that the limestone and siliciclastic formations formed in warm and cool water settings, respectively. Hence, these formations preserve a warm-cool-warm cycle of carbonate deposition in the late Quaternary, most likely linked to latitudinal shift in climate zones compounded by changing strength of the Leeuwin Current.