Tectonic focusing of voluminous basaltic eruptions in magma-deficient backarc rifts

Anderson M, Hannington M, Haase K, Schwarz-Schampera U, Augustin N, McConachy T, Allen K (2016)

Publication Language: English

Publication Status: Published

Publication Type: Journal article, Original article

Publication year: 2016

Journal

Earth and Planetary Science Letters Elsevier

Publisher: Elsevier

Book Volume: 440

Pages Range: 43-55

DOI: 10.1016/j.epsl.2016.02.002

Abstract

The Coriolis Troughs of the New Hebrides subduction zone are among the youngest backarc rifts in the world. They reach depths of >3 km, despite their small size (<100 km in length and only 25-45 km wide) and their proximity to the arc front (~50 km). The narrow, deep graben morphology is characteristic of magma-deficient arc rifts in the early stages of backarc extension, where the rate of extension and subsidence exceeds the magmatic input. Unexpectedly, the youngest graben, the Vate Trough, contains a centrally-located 1000-tall and 14-km wide shield volcano with a large, 5×8 km breached summit caldera. The Nifonea axial volcano has a volume of ~126 km, reflecting unusually high extrusion rates, given its young age (<3 Ma), and the summit caldera hosts the remnants of a large lava lake, the first described from a submarine backarc setting. Extensive diffuse hydrothermal venting and several clusters of black smoker chimneys, with the highest recorded fluid temperatures (368C) in the SW Pacific, occur on the youngest lava flows. Comparison with similar axial volcanoes on the mid-ocean ridges suggests that the 46×10 m of sheet flows in the caldera could have been erupted in <30 hours. The focusing of voluminous basaltic eruptions into an otherwise magma-deficient backarc has been linked to strong left-lateral transtension caused by clockwise rotation and segmentation of the southern portion of the arc after collision with d'Entrecasteaux ridge. This study shows that the upper plate stresses can result in dramatic variability in magma supply and hydrothermal activity at the earliest stages of arc rifting and could explain the wide range of melt compositions, volcanic styles and mineral deposit types found in nascent backarc rifts.

Authors with CRIS profile

Karsten Haase Lehrstuhl für Endogene Geodynamik (LEG)

Related research project(s)

Volcanism and hydrothermal venting in the Coriolis Basins, New Hebrides Island Arc (COVOLVE) June 1, 2013 - May 31, 2015

Involved external institutions

GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel DE Germany (DE) Bundesanstalt für Geowissenschaften und Rohstoffe (BGR) DE Germany (DE)

How to cite

APA:

Anderson, M., Hannington, M., Haase, K., Schwarz-Schampera, U., Augustin, N., McConachy, T., & Allen, K. (2016). Tectonic focusing of voluminous basaltic eruptions in magma-deficient backarc rifts. Earth and Planetary Science Letters, 440, 43-55. https://doi.org/10.1016/j.epsl.2016.02.002

MLA:

Anderson, Melissa, et al. "Tectonic focusing of voluminous basaltic eruptions in magma-deficient backarc rifts." Earth and Planetary Science Letters 440 (2016): 43-55.

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