Geocronología U-Pb SHRIMP y geoquímica de una adakita Mesoproterozoica en el bloque San Rafael (Mendoza, Argentina): contexto geotectónico

GALINDO, C.; CASQUET , C.; BALDO, E.G.; PANKHURST, R.J.; RAPELA, C.W.; FANNING, C.M.; DAHLQUIST, J.A.

San Miguel de Tucumán

Congreso; XX Congreso geológico Argentino; 2017

Asociación Geológica Argentina

U-Pb SHRIMP geochronology and geochemistry of a Mesoproterozoic adakite from the Bloque San Rafael, Mendoza, Argentina: Geotectonic context. In the Ponón Trehue area, within the Mesoproterozoic of San Rafael blo- ck, an Adakite orthogneis with a Na2O / K2O = 5.3 ratio, an Eu positive anomaly (Eu/Eu * = 1.83), low Content in REE (ΣREE = 34.9 ppm) and a marked fractionation ([La / Yb] N = 16.1) was recognized. It also shows low con - tent in the HREE and a Sr/Y ratio = 87.8. Isotopically it corresponds to a juvenile magmatic rock, ( 87Sr / 86Sr1,2Ga = 0,7031 and Nd = +4.44) with a model age Nd TDM = 1260 Ma and a crystallization age of 1208.8 ± 8.8 Ma (207Pb/206Pb SHRIMP age in zircon). This magmatism would represent a period of subduction and accretion of ocea- nic terrane temporarily correlated with the beginning of the Shawinigan orogenesis (1220 - 1200 Ma), of the Gren - ville orogenic cycle and culminating with the formation of the Rodinia supercontinent.