TRANSPRESSION AND STRAIN PARTITIONING IN THE CARIBBEAN ISLAND-ARC: FABRIC DEVELOPMENT, KINEMATICS AND AR-AR AGES OF SYNTECTONIC EMPLACEMENT OF THE LOMA DE CABRERA BATHOLITH, DOMINICAN REPUBLIC

Abstract

An integrative structural and geochronologic study of the Loma de Cabrera batholith (LCB, Cordillera Central, Dominican Republic) and its country rocks reveals the interplay of deformation, metamorphism and plutonism produced in the Caribbean island-arc during Late Cretaceous oblique convergence. The results emphasize the interference between three contemporaneous strain fields: (1) a northern and southern domains produced by (<95 ma) arc-perpendicular ne- and sw-vergent folding thrusting, respectively; (2) arc-parallel sinistral strike-slip shearing along the la meseta shear zone (lmsz), active during 88-74 ma interval; (3) adjacent syn-kinematic emplacement of lcb (90-74 ma; 40Ar/39Ar in hornblende) during sinistral transpressional shearing. Comparison of the structural data with strain models of oblique plate convergence suggest that the LMSZ is a preserved ductile signature of strike-slip partitioning within a sinistral transpressional intra-oceanic subduction zone. In the LCB, microstructural data indicate that the magmatic to high-temperature solid-state deformation initially occurred over a wider band of heterogeneously distributed shear deformation, and was partitioned in narrow bands of mid- to low-temperature deformation connected with the LMSZ during the cooling of the batholith. Field and geochronologic studies also suggest that shortening across the southern domain took place concurrently with sinistral strike-slip movement along the crustal-scale La Guácara and Macutico fault zones, also consistent with a transpressional setting for the Late Cretaceous Caribbean magmatic arc. Shear and fault zones were variably reactivated during Upper Eocene-Oligocene thrusting and Miocene to Recent uplift of the Cordillera Central. © 2006 Elsevier Ltd. All rights reserved.