Mamani Et Al., 2008A)
Published online September 25, 2009; doi:10.1130/B26538.1 Geochemical variations in igneous rocks of the Central Andean orocline (13°S to 18°S): Tracing crustal thickening and magma generation through time and space Mirian Mamani1,†, Gerhard Wörner1, and Thierry Sempere2 1Abteilung Geochemie, Geowissenschaftlichen Zentrum der Universität Göttingen, Goldschmidtstrasse 1, D-37077 Göttingen, Germany 2Institut de Recherche pour le Développement and Université de Toulouse Paul Sabatier (SVT-OMP), Laboratoire Mécanismes de Transfert en Géologie, 14 avenue Edouard Belin, F-31400 Toulouse, France ABSTRACT data set to the geological record of uplift and Peru, Bolivia , northern Chile, and northwestern crustal thickening, we observe a correlation Argen tina, covering an area of ~1,300,000 km2. Compositional variations of Central between the composition of magmatic rocks Its width, between the subduction trench and the Andean subduction-related igneous rocks re- and the progression of Andean orogeny. In sub-Andean front, is locally >850 km, and its fl ect the plate-tectonic evolution of this active particular, our results support the interpreta- crustal thickness reaches values >70 km, par- continental margin through time and space. tion that major crustal thickening and uplift ticularly along the main magmatic arc (James, In order to address the effect on magmatism were initiated in the mid-Oligocene (30 Ma) 1971a, 1971b; Kono et al., 1989; Beck et al., of changing subduction geometry and crustal and that crustal thickness has kept increasing 1996; Yuan et al., 2002). The Central Andean evolution of the upper continental plate dur- until present day. Our data do not support de- orocline thus appears to be an extreme case of ing the Andean orogeny, we compiled more lamination as a general cause for major late crustal thickening among the various arc oro- than 1500 major- and trace-element data Miocene uplift in the Central Andes and in- gens of the Pacifi c Ocean margins.
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