The age and origin of the Pacific islands: a geological overview

Abstract

The Pacific Ocean evolved from the Panthalassic Ocean that was first formed ca 750 Ma with the rifting apart of Rodinia. By 160 Ma, the first ocean floor ascribed to the current Pacific plate was produced to the west of a spreading centre in the central Pacific, ultimately growing to become the largest oceanic plate on the Earth. The current Nazca, Cocos and Juan de Fuca (Gorda) plates were initially one plate, produced to the east of the original spreading centre before becoming split into three. The islands of the Pacific have originated as: linear chains of volcanic islands on the above plates either by mantle plume or propagating fracture origin, atolls, uplifted coralline reefs, fragments of continental crust, obducted portions of adjoining lithospheric plates and islands resulting from subduction along convergent plate margins. Out of the 11 linear volcanic chains identified, each is briefly described and its history summarized. The geology of 10 exemplar archipelagos ( Japan, Izu-Bonin, Palau, Solomons, Fiji, New Caledonia, New Zealand, Society, Galápagos and Hawaii) is then discussed in detail.

Out of the Neotropics: Late Cretaceous colonization of Australasia by American arthropods

“…The stratified model reconstructs the split between Neotropical and Indo-Pacific zalmoxids as the union of the Neotropics and Borneo (p r ¼ 0.32) or alternatively, the Neotropics alone (p r ¼ 0.30). Diversification of Zalmoxis in the Indo-Pacific is reconstructed as the union of Borneo and Australia (p r ¼ 0.29), the latter being the only terrane of the South Pacific clade (in the BEAST topology) that has consistently maintained suitable habitat for Opiliones since ca 81.7 Ma (while Gondwanan in origin, New Caledonia did not emerge in its present form until ca 37 Ma; [6,38] …”

“…One compelling biogeographic theatre that demonstrates the importance of transoceanic dispersal is the tropical South Pacific. The juxtaposition of a plethora of continental terranes and oceanic islands with diverse geological histories in this region has resulted in unique assemblages of biota found nowhere else in the world [5,6], with nearly all landmasses of the South Pacific categorized as biodiversity hotspots for conservation priority [7]. Biogeographic studies based on molecular phylogenies have implicated multiple source areas of South Pacific diversity, principally the Indo-Malay Archipelago, Australia, New Zealand, New Caledonia and the Neotropics (often via the Hawaiian Archipelago [4,8,9]).…”

Faunal breaks and species composition of Indo-Pacific corals: the role of plate tectonics, environment and habitat distribution

“…We identified geological clusters according to transitions in features indicative of different geological histories, which, if co-located with faunal breaks, would suggest that species distributions reflect long-term colonization, extinction or speciation processes. These geological clusters were defined by the extent of major tectonic plates [30] and mantle plume tracks [31 -33], which share a similar geological history ( [31,34,35]; electronic supplementary material, methods (e)). To account for the possibility that reefs on the same plate may have a different geological history due to the formation of more recent mantle plume tracks, we assigned an intermediate geological distance value to reflect similar ancient ( plate), but dissimilar recent (track), geological history.…”

New Guinea highland origin of a widespread arthropod supertramp

“…debilis (Tahiti) to 1 Myr, assuming the origin of the two Tahitian species R. intermedius and R. debilis on that large island, and dispersal-mediated allopatry (sensu Clark et al 2008) of R. schereri by dispersal to Bora Bora out of Tahiti. One Myr is the approximate age of Tahiti island (0.4-1.2 Myr, Guillou et al 2005;Neall & Trewick 2008), and obtained a mean rate of 0.019 substitutions per site per Myr, with a 95% confidence interval between 0.011 and 0.028. This rate is in agreement with the 0.0115 substitutions per site per Myr widely assumed for insect mtDNA (Brower 1994) that we here also used for alternative age estimations.…”