Comment on “The insular shelves of the Faial-Pico Ridge (Azores archipelago) : a morphological record of its evolution” by Quartau et al. - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Geochemistry, Geophysics, Geosystems Année : 2016

Comment on “The insular shelves of the Faial-Pico Ridge (Azores archipelago) : a morphological record of its evolution” by Quartau et al.

F.O. Marques
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A. Hildenbrand
T. Boulesteix
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Résumé

Several processes concur to shape an oceanic volcanic island, in particular the insular shelves, but the dominant process will be the one with the highest rate for a given period of time. Therefore, one has to estimate rates in order to conclude for the dominant process. We take advantage of the contrasting tectonic settings of two islands in the Azores, Pico (on the active diffuse Nubia-Eurasia plate boundary) and Santa Maria (on the oldest and inactive eastern end of the Azores Plateau), in order to estimate two main rates and their effects on shaping insular shelves: subsidence and wave erosion rates. We conclude that, for subsidence rates ≥ 1 mm/yr and lava flow dips ≤ 5º, as in Pico Island, the subsidence rate can dominate. Despite the likely dominant effect of island subsidence, Quartau et al. (2015) recognized its existence in Pico but did not estimate its magnitude or use the subsidence rate to discuss the wave erosion rates reported in the paper. Therefore, the wave erosion rates reported in Quartau et al. (2015) may be greatly overestimated by incorporating indiscriminately two rates, island subsidence and wave erosion. The effects of subsidence on shaping insular shelves as discussed here can potentially be applied to other subsiding islands mostly made of shield volcanoes, like the Big Island in Hawaii. This article is protected by copyright. All rights reserved.

Dates et versions

hal-01322658 , version 1 (27-05-2016)

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Citer

F.O. Marques, A. Hildenbrand, V. Zanon, T. Boulesteix. Comment on “The insular shelves of the Faial-Pico Ridge (Azores archipelago) : a morphological record of its evolution” by Quartau et al.. Geochemistry, Geophysics, Geosystems, 2016, 17 ((2):), pp.625-632 (IF 2,923). ⟨10.1002/2015GC006052⟩. ⟨hal-01322658⟩
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