Search results for "Crustal contamination"
showing 2 items of 2 documents
Petrological and noble gas features of Lascar and Lastarria volcanoes (Chile): Inferences on plumbing systems and mantle characteristics
2020
Lascar (5592 m a.s.l.) and Lastarria (5697 m a.s.l.) are Chilean active stratovolcanoes located in the Central Volcanic Zone (CVZ; 16°S to 28°S) that have developed on top of a 71 km thick continental crust. Independently of the similarities in their Plinian/Vulcanian eruptive styles, their complex magmatic feeding structures and the origins of their magmatic fluids still necessitate constraints in order to improve the reliability of geochemical monitoring. Here we investigate the petrography, bulk-rock chemistry, and mineral chemistry in products from the 1986–1993 explosive eruptive cycle at Lascar and from several Holocene eruptive sequences at Lastarria. These data are integrated with m…
Bimodal sill emplacement from an inhomogeneous source: a case study of olivine-gabbronorite and diabase with Ni-Cu sulphides in a sill within Permian…
2009
A small outcrop of mafic rocks, located between the Permian-Triassic sediments of the Cenozoic tectonic unit of the Maghrebian chain in Western Sicily, is an olistolith made up of olivine gabbronorite within diabase. Textures, microprobe analyses, and major and trace element geochemistry confirm the co-genetic nature of the various rocks: the gabbronorite is the result of olivine and orthopyroxene accumulation, with interstitial clinopyroxene and plagioclase, in a framework of a gabbrodioritic diabase. At least two stages of magmatic crystallisation during ascent in the continental crust are described, on the basis of reconstructed conditions of T, P and XH2O. The primitive magma was recons…