INVESTIGADORES
LARROVERE mariano Alexis
artículos
Título:
Mafic rocks of the Ordovician Famatinian magmatic arc (NW Argentina): New insights into the mantle contribution
Autor/es:
ALASINO, PABLO H.; CASQUET, CÉSAR; PANKHURST, ROBERT J.; RAPELA, CARLOS W.; DAHLQUIST, JUAN A.; GALINDO, CARMEN; LARROVERE, MARIANO A.; RECIO, CLEMENTE; PATERSON, SCOTT R.; COLOMBO, FERNANDO; BALDO, EDGARDO G.
Revista:
GEOLOGICAL SOCIETY OF AMERICA BULLETIN
Editorial:
GEOLOGICAL SOC AMER, INC
Referencias:
Lugar: Boulder; Año: 2016 vol. 128 p. 1105 - 1120
ISSN:
0016-7606
Resumen:
We studied the petrogenesis of mafic igneousrocks in the Famatinian arc in thewestern Sierra Famatina (NW Argentina),an Early Ordovician middle-crustal sectionin the proto-Andean margin of Gondwana.Mafic rock types consist of amphibolite,metagabbro, and gabbro, as well as pod- anddike-like bodies of gabbro to diorite composition.Field relations together with geochemicaland isotopic data for the mafic rocks of thewestern Sierra de Famatina (at 29°S) definetwo contrasting suites, which can be correlatedwith similar assemblages noted in otherparts of the orogen. Amphibolite, metagabbro,and gabbro bodies are mostly the oldestintrusive rocks (older than 480 Ma), with thehost tonalite and post-tonalite mafic dikesbeing slightly younger. The older mafic suiteis tholeiitic to calc-alkaline and isotopicallyevolved, except for most of the amphibolitesamples. The younger suite is calc-alkaline,typically displaying subduction-related geochemicalsignatures, and it is isotopicallymore juvenile. Whole-rock chemical compositionand isotopic analyses are compatiblewith a progressive mixing of differentisotopic reservoirs. Pyroxenite (±garnet) waslikely the dominant source of the older gabbroicmagmas, whereas peridotite dominatedin the source of the younger suite, implyingthat the mafic magma experienced a progressiveshift toward more juvenile compositionsthough time (over 20 m.y.). Pyroxenitederivedmelts could have been generated bylithospheric foundering followed by upwellingof primitive melts by adiabatic decompressionof mantle wedge peridotite.