Publication Date:
2019
Description:
Abstract
Geophysical data acquisition in oceanic domains is challenging, implying measurements with low and/or non‐homogeneous spatial resolution. The evolution of satellite gravimetry and altimetry techniques allows testing 3D density models of the lithosphere, taking advantage of the high spatial resolution and homogeneous coverage of satellites. However, it is not trivial to discretise the source of the gravity field at different depths. Here, we propose a new method for inferring tectonic boundaries at the crustal level. As a novelty, instead of modelling the gravity anomalies and assuming a flat Earth approximation, we model the Vertical Gravity Gradients (VGG) in spherical coordinates, which are especially sensitive to density contrasts in the upper layers of the Earth. To validate the methodology, the complex oceanic domain of the Caribbean region is studied, which includes different crustal domains with a tectonic history since Late Jurassic time. After defining a lithospheric starting model constrained by up‐to‐date geophysical datasets, we tested several a‐priory density distributions and selected the model with the minimum misfits with respect to the VGG calculated from the EIGEN‐6C4 dataset. Additionally, the density of the crystalline crust was inferred by inverting the VGG field. Our methodology enabled us not only to refine, confirm and/or propose tectonic boundaries in the study area, but also to identify a new anomalous buoyant body, located in the South Lesser Antilles subduction zone, and high density bodies along the Greater, Lesser and Leeward Antilles forearcs.
Electronic ISSN:
1525-2027
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
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