Lithospheric and Slab Configurations From Receiver Function Imaging in Northwestern South America, Colombia

Mojica Boada, Manuel Jose; Poveda, Esteban und Tary, Jean Baptiste (2022): Lithospheric and Slab Configurations From Receiver Function Imaging in Northwestern South America, Colombia. In: JGR / Solid Earth, Bd. 127, Nr. 12, e2022JB024475

Abstract

The northwestern corner of South America presents a highly complex geodynamical setting including the convergence between South America, Nazca, and Caribbean plates;which also entails heterogeneity and complexity in the lithospheric structure. Here, we present depth-migrated common-conversion point (CCP) teleseismic receiver function profiles carried out using seismological data between 2011 and 2020 from the Colombian Geological Service, combined with some stations of observatories and international networks. These profiles provide better constraints on the lateral interpretation of the main lithospheric discontinuities in this region. We provide an updated crustal thickness map displaying some differences from previous studies, especially in the northernmost part of the cordilleran system. Our results also show some intracrustal features such as the regional detachment surface beneath the Eastern Cordillera and the presence of deep melt reservoirs under the Central Cordillera and the Paipa-Iza complex in the Eastern Cordillera. We also discuss the lithospheric thickness and the potential existence of a highly hydrated and serpentinized mantle wedge under the forearc over the slab segment south of the Caldas tear. Furthermore, the CCP profiles further support the subduction system segmentation under northwestern South America, with at least five slab segments, two of them overlapping between similar to 5.5 and similar to 8 degrees N, three belonging to the Nazca plate, and two having a Caribbean origin. The Bucaramanga nest appears to be linked to the interaction between the two northmost slab segments, while the Cauca cluster might be related to a slab dehydration process of a highly fractured zone. Plain Language Summary The Colombian tectonic configuration is highly complex with the convergence of three major tectonic plates. Despite extensive recent studies in this region, some of the important tectonic features are still under discussion. In this study, we present cross-section images of the lithospheric and upper mantle structure beneath Colombia, carrying out an analysis of teleseismic wave conversions corresponding to data collected between 2011 and 2020 by the Colombian Geological Service, volcanological and seismological observatories, and international stations. The results show that the crust is thinner than estimated in previous studies in the northernmost part of the Colombian cordillera system, and provide some material on intracrustal features and lithospheric thickness. Moreover, our images support other studies on the subduction system in this area, showing the presence of five slab segments on the Pacific side subducting beneath Colombia, including an overlapping segment between similar to 5.5 and similar to 8 degrees N. The two densest seismic clusters, the Bucaramanga nest and the Cauca cluster, seem to be linked to the interaction of two plates at depth and the dehydration of a fractured slab zone, respectively.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Geowissenschaften > Department für Geo- und Umweltwissenschaften
• Themengebiete: 500 Naturwissenschaften und Mathematik > 550 Geowissenschaften, Geologie
• ISSN: 2169-9313
• Sprache: Englisch