Castro Dorado, AntonioOtamendi, Juan E.Pinotti, Lucio P.D’Eramo, Fernando J.Vujovich, Graciela I.Tibaldi, Alina M.2019-01-312019-01-312008-09Antonio Castro Dorado, J. Otamendi, L. P. Pinotti, F. J. D'Eramo, R. Martino, G. Vujovich, A. Tibaldi, A. Viñao. Top-down structures of mafic enclaves within the Valle Fértil magmatic complex (Early Ordovician, San Juan, Argentina). Geologica acta: an international earth science journal, ISSN 1695-6133, Vol. 6, Nº. 3, 2008, págs. 217-229. DOI: 10.1344/105.0000002521695-6133http://hdl.handle.net/10272/15848Magmatic structures related to the mechanical interaction between mafic magmas and granitoids have been studied in the Valle Fértil calc-alkaline igneous complex, Argentina. Excepcional outcrops with vertical walls of more than 300 m high allow us the study of three-dimensional geometries of individual blobs of mafic magma as well as the geometry of pipe-like structures in which mafic microgranular enclaves are concentrated in more than 50 times the normal abundance in the granodiorite mass. The shape of enclaves and pipe-like structures are interpreted as the ressult of top-to-down intrusions of a mafic magma into a granodiorite-tonalite mass. These sinking structures are the result of a reverselly stratified magma chamber with gabbros and diorites at the top and granodiorite-tonalite at the bottom. They may account for most of the structures found in microgranular enclaves and magma mingling zones that characterize calc-alkaline batholiths. Synplutonic intrusions from the top is the only plausible mechanism to account for the observed structures. The model may be of general application to calc-alkaline batholiths characterized by the presence of mafic microgranular enclaves. An implication of these reverselly stratified magma chambers is the presence of a petrological inversion which may be the consequence of cold diapirs emplaced below the mantle wedge in a suprasubduction setting.engAtribución-NoComercial-SinDerivadas 3.0 Españahttp://creativecommons.org/licenses/by-nc-nd/3.0/es/EnclavesSynplutonic intrusionsCalc-alkaline batholithsArgentinaFamatinian beltjournal article10.1344/105.000000252open access