A 3-D lithospheric model of the Caribbean-South American plate boundary

Abstract

A 3-D structural model of the Caribbean-South American plate boundary was constructed by gravity modeling. The model was constrained by four wide-angle seismic refraction sections, Moho depth estimations from receiver functions, and additionally seismological hypocenters, surface geology, and geodynamic information. Density values were calculated from empirical velocitydensity functions, and mineralogical-chemical composition considering specific P/T conditions. We tested different structural models for Western and Eastern Venezuela. In the final model, the fit of the measured and modeled gravity fields for a long Caribbean slab in Western Venezuela was better than the fit obtained for a short one. This interpretation is consistent with the constraining data. The slab is interpreted to extend further to the south beneath Northern Colombia and culminates in the area of the seismic cluster of the Bucaramanga nest. The modeling estimates a slab dip angle under Maracaibo and Mérida Andes of 15°, which increases to 32°below 100 km depth. The dip direction of approx. N150°E ± 5 increases lightly eastward. In Eastern Venezuela, considering its short wavelength, lineaments analyzed from gravity data (by curvature methods and Euler deconvolution) seem to be related to shallow structures and density contrast in the Serranía del Interior and not from a deep detached slab beneath the continental crust. It is deduced from modeling results that this slab configuration has a very small influence on the gravity field. The slab was modeled according to the subduction-transform propagation model with purely westward subduction and a slab break off along a vertical dip-slip tear through the lithosphere.

New Bouguer Gravity Maps of Venezuela: Representation and Analysis of Free-Air and Bouguer Anomalies with Emphasis on Spectral Analyses and Elastic Thickness

“…Figure 8 show that there are significant differences among Moho values estimated with spectral analysis and Moho estimated with receiver function. On the other hand, Moho depth values in Figure 7 and closely match the values estimated by Schmitz et al [38] and also produces the best fits to the observed Bouguer gravity data [54]. According to Schmitz et al [38] the mismatch between seismic Moho and receiver function Moho is caused by the resolution of these technics.…”

“…This pronounced negative Bouguer gravity anomaly has been studied by several authors [3,[51][52][53][54]. The negative gravity anomaly is roughly parallel to the arc platform extension, but it does not extend west of Gulf of Paria.…”

3D object-oriented image analysis in 3D geophysical modelling: Analysing the central part of the East African Rift System

“…Subsequently the densities of these objects are calculated using one of the velocity-density relationships or through a trial and error approach. After that, the forward signal associated with these objects is compared with the measured gravity (e.g., Sanchez et al, 2011). A following step can be applying inversion approaches to reduce the misfit between the calculated and the measured gravity (e.g., Ebbing et al, 2001).…”

“…A following step can be applying inversion approaches to reduce the misfit between the calculated and the measured gravity (e.g., Ebbing et al, 2001). This gravity modelling object-based approach has been done without a standardized methodology on how to extract the subsurface structures from 3D subsurface data, and has traditionally mainly been based on the user experience or pre-existing data (e.g., Ebbing et al, 2001;Sanchez et al, 2011).…”

Crustal and upper mantle structure of Botswana

“…For a single geophysical technique, e.g., seismic reflection/refraction or tomography, the interpretation and the classification have been done without a standardized methodology and were often done based on contouring or expert interpretation of the 3D seismic velocity data cube and a priori information about the studied area (e.g., Ebbing et al (2001), Li (2010) and Sanchez et al (2011)). However, this can be sensitive to subjective choices that can often make the process unrepeatable.…”