Curie point depth in Venezuela and the Eastern Caribbean

Abstract

We estimate the Curie point depth (CPD) variations of Venezuela (continental crust, South American plate) and the Eastern Caribbean (oceanic crust, Caribbean Plate) by using spectral analysis of the magnetic anomalies, extracted from the 2010 Enhanced Magnetic Model (EMM2010), available at the National Oceanic and Atmospheric Administration (NOAA). To test the reliability of the spectral content of this model, for a small region, we compare he CPD derived from the EMM2010 against the one from aeromagnetic data. We also compile heat flow data from previous studies to correlate them with the CPD lateral variations. The estimations show that the CPD in Venezuela and the Eastern Caribbean ranges between 54 and 17km. The mean depth value within the continental crust is around 38km. On the Guayana Shield, it has a mean value of 42km and reaches a maximum of 54km. As the Moho depth is at most 50km, the upper mantle beneath the craton is magnetized. Continental lateral variations appear to be linked to the isostatic state and age of the different provinces, and mark the limit between the Precambrian and the Paleozoic provinces. The Maracaibo Basin is revealed as a thermally stable one with a constant CPD, while the Eastern Venezuela Basin is thermally affected. Most of the Eastern Caribbean seems stable, with a large non-perturbed area with a mean CPD value of 23km. As the crustal thickness is at most 20km, the isotherm is located within the upper mantle. A CPD minimum located on the Lesser Antilles arc is concentrated in its northern part, and can be related to the subduction zone that is most active. Finally, a shallow area within the Eastern Caribbean corresponds to the thin crust region in the Venezuela Basin, although it might be linked to mantle dynamics.