Esquema de tres interfaces con compensación isostática local en el margen continental Argentino
A. Carolina Pedraza De Marchi, Marta E. Ghidella and Claudia Tocho
Journal name: Geociencias Aplicadas Latinoamericanas
Issue: Vol 3, No 1, March 2016 pp. 1 - 13
Info: Article, PDF ( 4.1Mb )
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In the present paper, we investigate the Airy type isostatic compensation scheme for three interfaces: water-sediments, sediments-crust and crust-mantle, using forward modelling to calculate the isostatic anomaly with different approximations of Parker’s expression in the Argentine continental margin. The isostatic anomaly is estimated as the residue between the observed free air anomaly and the calculated free air anomaly through the sum of the contributions from the tree interfaces. After that, we perform the inversion of the isostatic anomaly in order to find the deflection of the Moho necessary to compensate it (or minimize it) using one term of Parker’s expression in the inversion, as an experiment to test the numerical methods. The Moho here considered is obtained from knowing the depth of the basement and crustal thickness. Another way to estimate the crust-mantle interface (Moho) is by the inversion with the iterative method of Parker-Oldenburg (Parker, 1973; Oldenburg, 1974), which allows inverting the Bouguer anomaly with more than one term. With the Moho thus obtained, a free-air gravity anomaly can be calculated, which reproduces the observed anomaly quite well. Even considering that the experiment constitutes a schematic model just to test the numerical methods involved, from the comparison with the only available digitized refraction profile in the study area, we find that the large wavelength of the inverted Moho is reproduced fairly well by the modeled Moho for both methods. However, the iterative method yields smoother surfaces, possibly more realistic surfaces given the roughness that the other estimates present.