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- Miocene-Pliocene volcanic edifices of Gran Canaria can be reconstructed by morphometry.
- Paleosurfaces (planÃ¨zes and quasi planar surfaces) are a useful tool in reconstruction.
- Fataga and Roque Nublo volcanoes had at least 900Â km3 original volume each.
Original volcanic edifices of two successive stages of Gran Canaria are reconstructed using a geomorphometric analysis of existent or restored paleosurfaces. In the reconstruction, surface fitting was applied preferably to planÃ¨zes (i.e. triangular facets of original volcano flanks) and quasi-planar surfaces, QPS (those occurring on planÃ¨zes, or scattered, slightly eroded portions derived from original cone surfaces) with the help of red relief image map (RRIM) analysis. Out of the long-lasting, Mid-Miocene to Holocene subaerial evolution of the island, the Late Miocene Fataga volcano and the subsequent, Pliocene Roque Nublo volcanoes were the largest and highest. The eruptive center of Fataga, a composite edifice (12.2-8.8Â Ma) that may have grown up excentrically with respect to the previous Tejeda caldera, is well-defined by both two planÃ¨zes (named Veneguera-Mogán and Fataga-Tirajana) and QPS remnants. Its calculated original volume, â¤Â 1000Â km3, is close to the largest stratovolcanoes on Earth. However, its â¥Â 3300Â m elevation, obtained by exponential fit, may have been significantly lower due to the complex architecture of the summit region, e.g. a caldera responsible for ignimbrite eruptions. Roque Nublo, a 3.7-2.9Â Ma stratovolcanic cone, which was superimposed upon the Fataga rocks â¥Â 3Â km west of the Fataga center, has left no considerable paleosurfaces behind due to heavy postvolcanic erosion. Yet, its remnant formations preserved in a radial pattern unambiguously define its center. Moreover, surface fitting of the outcropping rocks can be corrected taking the erosion rate for the past 3Â Ma into account. Such a corrected surface fit points to a regular-shaped, â¥Â 3000Â m-high cone with a 25Â km radius and ca. 940Â km3 original volume, also comparable with the dimensions of the largest terrestrial stratovolcanoes.
Journal: Geomorphology - Volume 253, 15 January 2016, Pages 123-134