Bathymetry and topographic lineation in the Cook Islands

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Abstract
Palmerston, Aitutaki, Manuae, Atiu, Takutea, Mitiaro and Mauke, and Eclipse Seamount, within the Southern Cook Island Group, form a linear volcanic chain with WNW trend. Rarotonga and Mangaia belong to a separate linear system composed dominantly of seamounts. Concave slopes around the islands are geologically complex, consisting of the original volcanic slopes, reef talus deposits, and fans of slumped debris. Around the base of each volcano are archipelagic aprons, probably of sedimentary origin. Parasitic cones and laccolith intrusions occur along fractures ringing the bases of the volcanoes. Crustal warping due to subsidence of the Aitutaki-Mauke group of volcanoes has resulted in formation of “moat and arch” structures. The fissured crest of the arch surrounding the group is diversified by clusters of small volcanoes and the larger cones of Rarotonga and Mangaia. Development of this group is probably related to evolution of the Darwin Rise. Niue Island is part of an extensive, non-linear volcanic province with obscure origin. Manihiki rises from a NNE-trending fault scarp forming the eastern edge of the Manihiki Plateau, possibly an upstanding remnant of the crest of the Darwin Rise.