Neogene Ridge subduction and slab window in the Northern Andean block - Tectonic implications
Abstract
One of the major components of the Neogene geological configuration in the northern Andes remains inconclusive given the complex nature of the tectonic plate evolution history during the Cenozoic in North-Western South-America. This element is a slab window [1], an ideal setting for geochemically unique magmatism (alkaline, adakite-like and garnet-bearing rocks) and elevated uplift rates in the forearc and arc regions [2,3], which have been described in the area [4, 5, 6]. Among the many aspects that are still to be understood about the tectonic implications of this slab window, the fundamental feature to decipher is the geometry of the slab window and its tectonic evolution.
Here, we use meta-analysis to present a geodynamic model that spans from 15 to 8 Ma. This attempt allows us to integrate new and available geochemical data from igneous rocks along with U/Pb ages in zircon of both igneous and detrital rocks, to interpret the geochemical patterns along the Central and Western Colombian cordilleras through middle to late Miocene, which document geochronological and geochemical consistent spatiotemporal variations along the latitudinal axis. Therefore, we have proposed a tectonic evolution model associated with extension following the subduction of a spreading ridge (i.e., Sandra Ridge) under the Nazca Plate Slab, which enhanced the aperture of a slab window. Our approach also allows us to synthesize the forearc magmatic record using the ridge-trench intersection, ridge subduction, and slab window formation as the main causes of magmatism [7]. Furthermore, this analysis also explores the possible development of the slab window under the Panamá-Chocó Block collision scenario. [1] Hoyos et al. (Submitted), [2] Cai et al. (2018) Journal of Asian Earth Sciences. [3] Windley and Xiao, (2018) Gondwana Research. [4] Bissig et al. (2017) Economic Geology. [5] Weber et al . (2018) SGC (in press) [6] Jaramillo et al. (2019) Lithos. [7] Madsen et al. (2006) Geosphere.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T41I0236H
- Keywords:
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- 7230 Seismicity and tectonics;
- SEISMOLOGY;
- 8158 Plate motions: present and recent;
- TECTONOPHYSICS;
- 8170 Subduction zone processes;
- TECTONOPHYSICS;
- 8488 Volcanic hazards and risks;
- VOLCANOLOGY