On the isostatic state of the eastern Alps and the central Andes; A statistical comparison
Hans-Jürgen Götze, Bruno Meurers, Sabine Schmidt, Peter Steinhauser, 1991. "On the isostatic state of the eastern Alps and the central Andes; A statistical comparison", Andean Magmatism and Its Tectonic Setting, Russell S. Harmon, Carlos W. Rapela
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The gravity field of the eastern Alps and the central Andes was investigated with regard to the isostatic state and the tectonic evolution of these young orogens. Bouguer and isostatic anomalies were correlated with mean topographic heights. Statistical analysis and theoretical modeling were applied in order to determine the degree to which quantitative conclusions could be drawn. Additionally the balance of topographic surplus and deficit masses was estimated for both areas under investigation.
A significant correlation between Bouguer anomalies and mean topographic heights is observed, which qualitatively indicates more or less isostatic equilibrium, while the mean isostatic anomalies are slightly positive and larger in the Andes than in the Alps. This agrees well with results from mass budget estimations, which show gravimetric mass deficits being 10 percent smaller than the topographic load for both mountain ranges. Therefore, an undercompensation effect of the Alpine and Andean crust can be concluded. On a regional scale this is in contrast to the observed positive vertical movements, because subsidence should be expected.
Therefore, the isostatic states and the vertical movement patterns can be considered to be effects of plate tectonic forces due, respectively, to the collision of the Eurasian and African plates (eastern Alps) and the subduction of the Nazca plate under the South American continent (central Andes).