The Nova Monte Verde metamorphic core complex: Tectonic implications for the southern Amazonian Craton

摘要: Abstract The Nova Monte Verde metamorphic core complex is an arched structure located in the southern portion of Rio Negro-Juruena geochronological Province and part a belt rocks containing gneiss migmatite domes exhumed during Statherian extension rifted Ventuari-Tapajos crust. This bordered, both to north south, by felsic volcanic plutonic intensely foliated near becoming progressively undeformed as one moves away from core. U-Pb analyses zircon monazite migmatites exposed complex, coupled with detailed structural analysis, enlighten timing duration crystallization, indicating that extensional deformation exhumation core-complex were coeval. Analysis high melt fraction outcroping Bacaeri Farm suggest records history neosome formation spanning at least 37 Ma, indicated 206Pb/238U ages (1800-1763Ma) for new growth attributed migmatization. Monazite two samples yielded 1798 ± 29 Ma aluminous metatexite 1754 ± 11 Ma sillimanite-biotite metatexite. former interpreted peak main generation leucosomes, latter second phase partial melting or alternative, cooling complex. Crystallization was therefore coeval upper crustal ductile flow mid-crust, suggesting anatexis widespread over much mid-crust time (∼1800-1760Ma). Therefore, tectonic involved regional high-grade transtensional tectonics. following results are more compatible with, if not suggestive of, continental rift setting than traditionally accepted arc setting.