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Neogene uplift of central eastern Patagonia: Dynamic response to active spreading ridge subduction?
Author(s) -
Guillaume Benjamin,
Martinod Joseph,
Husson Laurent,
Roddaz Martin,
Riquelme Rodrigo
Publication year - 2009
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/2008tc002324
Subject(s) - geology , subduction , triple junction , neogene , trench , paleontology , subsidence , ridge , fluvial , late miocene , slab window , convergent boundary , structural basin , geomorphology , seismology , tectonics , oceanic crust , geophysics , chemistry , organic chemistry , layer (electronics)
The Chile Triple Junction (CTJ) episodically migrated northward during the past 14 Ma from 54°S to its present‐day position at 46°30′S, as different almost trench‐parallel spreading segments entered in subduction. This migration resulted in the opening of an asthenospheric window below Patagonia, inducing a disturbance in the regional mantle convection. On the overriding plate, the middle Miocene time corresponds to a major change in the central Patagonian basin dynamics, with a transition from subsidence to generalized uplift. The detailed mapping and the morphological study of post‐middle Miocene terraces evidence regional‐scale trench‐parallel tilt histories that differ depending on latitude. South of 46°30′S, the slopes of the fluvial terraces indicate a change from northward to southward tilt during late Miocene. Terraces younger than the early Pliocene do not show any trench‐parallel tilt. North of 46°30′S, in contrast, only northward tilt, active until the Pleistocene, is recorded. We use a semianalytical model of dynamic topography which suggests that the northward migration of the Chile Triple Junction should be accompanied by a dynamic uplift of the central Patagonian basin. Uplift would cause both north directed and south directed tilt, north and south of the triple junction, respectively, with values of ∼0.1–0.2% 500 km east of the trench. Tilt measured in the southeastern part of the central Patagonian basin (∼0.1%) is comparable to values predicted using the semianalytical model. The dynamic topography associated to the Chile ridge subduction may have exerted a major control on the Neogene dynamics of Patagonia.