Las Cañas plutonic complex: Geodynamic implications during the Famatinian magmatism in northeast of Sierra de San Luis, Argentina

PAGANO, SEBASTIAN; MOROSINI AUGUSTO; OROZCO BRIAN; ENRIQUEZ ELIEL

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2019 vol. 93 p. 313 - 347

0895-9811

Las Cañas Plutonic Complex (LCPC) is a small representative of the Famatinian Ordovician plutonism(470.4 ± 8.1 Ma) located in the northeastern sector of Sierra Grande de San Luis, Argentina. The LCPC wasemplaced into a metasedimentary sequence, which reached their metamorphic climax under high-temperature/low-pressure conditions (∼680 ± 37 °C and 550 ± 120 MPa). The bodies of the LCPC are zoned by rocks ofdifferent compositions that represent ultrabasic, basic, intermediate and acidic trends (hornblendites, gabbros,tonalites, and granodiorites). Their petrological, mineralogical and geochemical characteristics indicate thatmultiple processes formed them, mainly crystal fractionation of magnesian, calc-alkaline and metaluminousmagmas (typical of arc), but also different assimilation degrees of crustal melts from the fusion of metawackesinvolving AFC processes. Fieldwork (structural and petrological data), the geochemical characteristics of rocks[eg. Low Sr/Y and (Gd/Yb)C-N], and thermobarometric results, indicate a relatively shallow fractionalization forthe LCPC, which is in line with a pre-collisional arc stage linked to an extensive retro-arc setting for theFamatinian orogeny in Sierra de San Luis.