Transpression, displacement partitioning, and exhumation in the eastern Caribbean / South American plate boundary zone

Abstract

The Caribbean/South American plate boundary zone in northeastern Venezuela is a transpressive orogenic belt consisting from north to south of a nascent subduction zone (South Caribbean deformed belt), a volcanic arc (Leeward Antilles arc), a “hinterland” with high‐pressure (P)/low temperature (T) metamorphic rocks (Cordillera de la Costa belt), and a southern nonmetamorphic, foreland fold and thrust belt (Serranía del Interior). The geometry, style, and orientation of mid‐Cretaceous to Tertiary synmetamorphic deformation structures (D1) in the hinterland are compatible with formation in a right‐oblique subduction or collision zone in which displacement partitioning has occurred. Late Oligocene to Recent right‐oblique convergence resulted in the emplacement of the arc and hinterland on the passive South American margin and the formation of the foreland fold and thrust belt (D2); the displacements between the Caribbean and South American plates are partitioned as well. Both D1 and D2 deformations are diachronous: they are older in the west and younger in the east and related to the eastward passage of the Caribbean plate with respect to South America. The ascent, decompression, and exhumation of the high‐P/low‐T metamorphic rocks occurred in two stages: the first in the Cretaceous by arc‐parallel extension (D1) and the second in Neogene time by thrusting (D2) and subsequent erosion.