LARROVERE mariano Alexis
congresos y reuniones científicas
Evolución estructural del complejo ígneo Huaco, Sierra de Velasco, La Rioja
MACCHIOLI GRANDE, MARCOS; ALASINO, PABLO H.; ROCHER, SEBASTIÁN; LARROVERE, MARIANO A.; DAHLQUIST, JUAN A.; REINOSO CARBONELL, VIRGINIA
San Miguel de Tucumán
Congreso; XX Congreso Geológico Argentino; 2017
Structural evolution of the Huaco Igneous Complex, Sierra de Velasco, La Rioja. The Huaco Igneous Complex is one of several granitic massifs emplaced at shallow levels that outcrop in Sierras Pampeanas (NW Argentina). It comprises three plutonic units, named Huaco, Sanagasta and La Chinchilla, all of Early Carboniferous age. Huaco and Sanagasta units are porphyritic biotitic monzo to syenogranites, and intrude Ordovician-Silurian metamorphic rocks. La Chinchilla unit is a monzogranite that intrudes Huaco unit. The latter shows discordant relationships with host rock fabrics in sharp contacts in the north, as medium to shallow-dipping sheets, generating an interdigitated pattern. Host rock fabrics near the contact keep the NW-SE regional foliation. Conversely, the Sanagasta unit exhibits vertical contacts with the mylonites in the SW region, which occur as concordant anastomosed sheets. Moreover, in the SE of this unit, the host rock nearby the contact is locally deflected. Numerous blocks of mylonites appear in both units. La Chinchilla unit, in turn, shows sharp discordant relations with Huaco unit. The observed features allow us to propose a fragile emplacement mechanism for both Huaco and La Chinchilla units, developing a tabular geometry. Sanagasta unit, in contrast, reveals a fragile-ductile emplacement style which leads to a cylindrical body. This switch in the emplacement style is due to the Huaco unit intruding a relatively cold, immature crust and Sanagasta unit emplacing in a thermally mature crust. Later on, at the moment of the intrusion of La Chinchilla unit the system cools and the crust is immature again.