Metamorphism, deformation, and geochronology of Cretaceous blueschists, Villa de Cura Belt, Venezuela

[摘要] The Villa de Cura belt, one of several allochthonous belts comprising the Caribbean Mountain System of northern Venezuela, contains island arc volcanic and volcaniclastic rocks, metacherts, and mafic rocks metamorphosed to blueschist facies. It consists of four east-west trending metamorphic zones. The prograde pressure-temperature (P-T) path for the northern three zones indicates high P-low T metamorphism, with a similar retrograde P-T path. The southernmost zone formed at similar P, but higher T, and underwent a counter-clockwise P-T path. Ductile D$sb1$ structures in the Villa de Cura belt indicate that the belt formed in a right-oblique subduction zone to the west of its present location. $sp{40}$Ar/$sp{39}$A, data (97 to 78 Ma) suggest that exhumation occurred in the late Cretaceous. D$sb2$ structures are related to SSE emplacement of the belt onto South America.

[发布机构] Rice University