This study presents the first field evidence of emplacement of a huge stratovolcano within contractional tectonics, in spite of the widely accepted idea that volcanism can develop only in extensional or transcurrent tectonic settings. El Reventador volcano ( Ecuador) started to grow 0.32 Ma BP and is still active. During pre-El Reventador times, its substratum has been affected by N-S- to NNE-striking reverse faults. During late Pleistocene-Holocene, some reverse faults with the same orientations were still active, locally with a component of right-lateral strike-slip motions. Seismicity shows widespread events with intensity up to 6.9 Mw and compression. Some of these faults cut the volcano creating differential uplift along N-S- to NNE-trending tectonic blocks. Hypocenter swarms and field data indicate east-vergent basal thrusting under the volcano and N-S- trending ault-propagation folds to the east. A model for magma migration in this setting is proposed, suggesting that similar cases of volcanism within a dominantly contractional tectonic regime may be more frequent than previously thought.
Tibaldi, A. (2005). Volcanism in compressional tectonic settings: Is it possible?. GEOPHYSICAL RESEARCH LETTERS, 32(6), 1-4 [10.1029/2004GL021798].
Volcanism in compressional tectonic settings: Is it possible?
TIBALDI, ALESSANDRO
2005
Abstract
This study presents the first field evidence of emplacement of a huge stratovolcano within contractional tectonics, in spite of the widely accepted idea that volcanism can develop only in extensional or transcurrent tectonic settings. El Reventador volcano ( Ecuador) started to grow 0.32 Ma BP and is still active. During pre-El Reventador times, its substratum has been affected by N-S- to NNE-striking reverse faults. During late Pleistocene-Holocene, some reverse faults with the same orientations were still active, locally with a component of right-lateral strike-slip motions. Seismicity shows widespread events with intensity up to 6.9 Mw and compression. Some of these faults cut the volcano creating differential uplift along N-S- to NNE-trending tectonic blocks. Hypocenter swarms and field data indicate east-vergent basal thrusting under the volcano and N-S- trending ault-propagation folds to the east. A model for magma migration in this setting is proposed, suggesting that similar cases of volcanism within a dominantly contractional tectonic regime may be more frequent than previously thought.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.