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oai:docta.ucm.es:20.500.14352/235752025-09-15T13:28:56Zcom_20.500.14352_14col_20.500.14352_15
Docta Complutense author Alasino, P.H author Casquet Martín, César author Pankhurst, R.J. author Rapela, C.W. author Galindo Francisco, María Del Carmen author Dahlquist, J.A author Larrovere, M.A. author Recio, C. author Paterson, S.R. author Colombo, F. author Baldo, E.G. 2023-06-18T05:54:41Z 2023-06-18T05:54:41Z 2016 0016-7606 10.1130/B31417.1 https://hdl.handle.net/20.500.14352/23575 https://doi.org/10.1130/B31417.1 https://pubs.geoscienceworld.org/journals We studied the petrogenesis of mafic igneous rocks in the Famatinian arc in the western Sierra Famatina (NW Argentina), an Early Ordovician middle-crustal section in the proto-Andean margin of Gondwana. Mafic rock types consist of amphibolite, metagabbro, and gabbro, as well as pod- and dike-like bodies of gabbro to diorite composition. Field relations together with geochemical and isotopic data for the mafic rocks of the western Sierra de Famatina (at 29°S) define two contrasting suites, which can be correlated with similar assemblages noted in other parts of the orogen. Amphibolite, metagabbro, and gabbro bodies are mostly the oldest intrusive rocks (older than 480 Ma), with the host tonalite and post-tonalite mafic dikes being slightly ounger. The older mafic suite is tholeiitic to calc-alkaline and isotopically evolved, except for most of the amphibolite samples. The younger suite is calc-alkaline, typically displaying subduction-related geochemical signatures, and it is isotopically more juvenile. Whole-rock chemical composition and isotopic analyses are compatible with a progressive mixing of different isotopic reservoirs. Pyroxenite (±garnet) was likely the dominant source of the older gabbroic magmas, whereas peridotite dominated in the source of the younger suite, implying that the mafic magma experienced a progressive shift toward more juvenile compositions though time (over 20 m.y.). Pyroxenitederived melts could have been generated by lithospheric foundering followed by upwelling of primitive melts by adiabatic decompression of mantle wedge peridotite. eng Mafic rocks of the Ordovician Famatinian magmatic arc (NW Argentina): New insights into the mantle contribution journal article URL https://docta.ucm.es/bitstreams/13d74fca-acd4-4e9a-b6b3-7bfd20ec9603/download File MD5 194fc9c3de31f4b7c550f56445b62465 3101673 application/pdf Mafic rocks of the Ordovician Famatinian.pdf URL https://docta.ucm.es/bitstreams/f41d85b8-4f47-4008-806e-cbbcb105bc9e/download File MD5 61c7a02d4e52a0acaafa689a219f8ca3 94933 text/plain Mafic rocks of the Ordovician Famatinian.pdf.txt