Mount Woolnough: the submerged volcano, SE of Sydney, NSW

Abstract

Part of a larger investigation of the sea bed off Sydney was a study of the extinct submarine volcano Mount Woolnough. It is located approximately 41 km east of Kurnell, NSW, and protrudes 175 m above the sediment cover at depths of approximately −550 to −375 m. Volcanic rock, approximately 2.2 km in diameter, is exposed above the sediment sea floor and is much smaller than its magnetic expression (approximately 13 km in diameter). Samples dredged from Mount Woolnough were conglomerates with phosphatic nodules and volcanic fragments set in a fine foraminiferal sediment matrix. Zircons within the mafic fragments yielded a minimum age of 261 Ma.

悉尼外缘海床探研的部分内容是对已灭绝海底火山Woolnough山的研究。它位于新南威尔士州Kernell之东约41公里处，并在水下约550至375米深处从沉积物覆盖面突伸175米。直径大约2.2公里的火山岩出露在海底沉积物之上，并且比它的磁表达小得多（直径约13公里）。从Woolnough山捞获的样品是含有磷酸盐瘤和嵌有细粒含有孔虫沉积物的火山碎片。基性岩碎片中的锆石得出的最低年龄是261Ma。

KEY WORDS:

• Mount Woolnough
• submarine
• volcano
• Permian
• Cenozoic
• phosphatic nodules
• Kurnell

View correction statement:

Corrigendum

ACKNOWLEDGEMENTS

This research could not have been undertaken without the cooperation of Mr Roy Foster who provided his vessel MV Sieglinde for the marine surveys—and skippered it. We are grateful to Mr Ken Gibbons for invaluable assistance with the geophysical equipment. We thank various students and technical staff of the University of New South Wales, for manning Miniranger transmitters on land and for assisting at sea. The Royal Australian Navy are thanked for their cooperation by allowing us to dredge from HMAS Kimbla, which was achieved through the assistance of Ken Gibbons, Dr David Roots and Professor Pat Quilty (all then of Macquarie University). We are especially grateful to Professor Quilty for advice on aspects of the Mount Woolnough rocks and for providing the zircon dates. Dr M. V. Kitahara (Departamento de Ciências do Mar, Universidade Federal de São Paulo, Brazil) is thanked for identifying the coral. This study is part of an overall investigation of the continental shelf funded by the Australian Research Grant Scheme.