Tarava Seamounts

Linear chains of volcanoes in the Pacific have been attributed to deep mantle plumes,[5] but a number of such chains appear to correspond to short lasting volcanism, such as processes triggered by tension in the Pacific Plate.[1]

The South Pacific Superswell is a large structure in the southern Pacific Ocean, where there are many volcanoes and the seafloor is unusually shallow. Asthenospheric processes may be responsible for its existence.[3]

The Tarava Seamounts consist of eighteen separate edifices[4] which extend across six longitudes and four latitudes[3] over a length of 700 kilometres (430 mi),[6] 200 kilometres (120 mi) away from the Society Islands.[7] Aside from five large guyots which reach depths of 580 metres (1,900 ft) below sea level, the Tarava Seamounts consist of 4,000–4,500 metres (13,100–14,800 ft) high cones.[8] Among the named edifices are Arere (16°50′S 155°20′W), Fafa Piti (19°00′S 154°10′W), Honu (18°20′S 154°10′W), Orio'Mata (17°50′S 154°10′W), Otaha (18°40′S 152°50′W), Otu'eroa, Punu Taipu (19°15′S 151°30′W) and Ua'ao.[9]

The seamounts are considered to be of Eocene-Oligocene age.[10] Only two seamounts have been dated, both by potassium-argon dating: Fafa Piti has yielded ages of 43.5 ± 0.6 million years ago and Punu Taipu of 36.1 ± 0.5 million years ago.[3] Such ages are consistent with an age progressive volcanism caused by a hotspot, whose volcano-building activity was influenced by lithospheric anomalies,[11] considering that there is a discontinuity in the chain which would have formed about 43 million years ago[12] at the time of a major change in the motion of the Pacific Plate.[13] The hotspot in question may be the Foundation hotspot, the Pitcairn hotspot[14] or a now extinct third hotspot.[11] Alternatively, the formation of the Tuamotu Plateau may have induced tectonic stress that propagated towards the location of the future Tarava Seamounts.[10]