A Comparative Analysis of Seismological and Gravimetric Crustal Thicknesses below the Andean Region with Flat Subduction of the Nazca Plate
Figure 4
Crustal model where the gravimetric effect adjusts to the Bouguer anomaly. This model considers an upper crust with a density 2.7 g/cm3, a lower crust with the density of 2.9 g/cm3, the upper mantle with a density 3.3 g/cm3 and incorporates the inhomogeneities interpreted by Gimenez et al. [13]: the most occidental structure represents the suture zone between the Chilean and Cuyania Terranes. The Bermejo Basin is located in the central zone, with a density-contrast of 0.3 g/cm3, and with a depth of approximately 10 km. The incorporation of a dense positive mass below the Valley Fertil range, with a density contrast of 0.47 g/cm3, justifies the positive anomaly in Valley Fertil. This also represents the suture zone between the Cuyania and Pampean Terranes [13]. The sediments of the Bermejo basin, wedged below the Valley Fertil range, justify the strong gradient in the Bouguer anomaly which exists between both structures. Finally, at the base of the crust, within the Cuyania region, the layer of high density or eclogitized crust is seen in the model.
