RT Journal Article
T1 Top-down structures of mafic enclaves within the Valle Fértil magmatic complex (Early Ordovician, San Juan, Argentina)
A1 Castro Dorado, Antonio
A1 Otamendi, Juan E.
A1 Pinotti, Lucio P.
A1 D’Eramo, Fernando J.
A1 Vujovich, Graciela I.
A1 Tibaldi, Alina M.
AB Magmatic structures related to the mechanical interaction between mafic magmas and granitoids have beenstudied in the Valle Fértil calc-alkaline igneous complex, Argentina. Excepcional outcrops with vertical walls ofmore than 300 m high allow us the study of three-dimensional geometries of individual blobs of mafic magmaas well as the geometry of pipe-like structures in which mafic microgranular enclaves are concentrated in morethan 50 times the normal abundance in the granodiorite mass. The shape of enclaves and pipe-like structures areinterpreted as the ressult of top-to-down intrusions of a mafic magma into a granodiorite-tonalite mass. Thesesinking structures are the result of a reverselly stratified magma chamber with gabbros and diorites at the topand granodiorite-tonalite at the bottom. They may account for most of the structures found in microgranularenclaves and magma mingling zones that characterize calc-alkaline batholiths. Synplutonic intrusions from thetop is the only plausible mechanism to account for the observed structures. The model may be of general applicationto calc-alkaline batholiths characterized by the presence of mafic microgranular enclaves. An implicationof these reverselly stratified magma chambers is the presence of a petrological inversion which may be the consequenceof cold diapirs emplaced below the mantle wedge in a suprasubduction setting.
PB Institut de Ciències de la Terra "Jaume Almera"
SN 1695-6133
YR 2008
FD 2008-09
LK http://hdl.handle.net/10272/15848
UL http://hdl.handle.net/10272/15848
LA eng
NO Antonio 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: 10.1344/105.000000252
DS Repositorio Institucional de la Universidad de Huelva
RD 1 jun 2026