Fractionation by compositional magma splitting: An example from Cerro Munro, Argentina

The Paleocene-Eocene Cerro Munro pluton, to the east of North Patagonian Batholith (NPB), is a tonalitic intrusion emplaced as shallow, small, sub-circular tonalite-granodiorite body hosting abundant co-magmatic mafic microgranular enclaves (MME). Besides, intrusive crosscut by radial porphyritic dikes and has been related andesitic, dacitic rhyolitic dikes, lava flows ignimbrites cropping out at neighboring areas. Magmatic contacts between MME host tonalites, together with their common geochemical features, suggest derivation from parental magma, although short-range mineralogical differences point an early crystallization (chilled margins) sidewalls ascent conduits or shallow reservoirs. established thermal gradient advance solidification front were responsible for presence subsystems and, in continuous process, promoted water saturation second boiling that finally account segregation rich highly differentiated residual liquid. Hbl-Pl cumulate textures observed tonalites enclaves, well incompatible element-enriched melts record results this in-situ differentiation process. UPb zircon ages obtained (57.1 ± 1.4 Ma), (55.4 0.6 Ma) (54.1 0.7 constrain age around 54 Ma final consolidation magma expelled melts. This coincides deposition volcanic volcanoclastic deposits north which suggests fractionation process led extrusion segregated melts, favored extension, uplift exhumation active rift tectonic setting.