NEOTECTÓNICA DE LA REGIÓN CENTRAL DE COSTA RICA: FRONTERA OESTE DE LA MICROPLACA DE PANAMÁ

Abstract

Neotectonic, seismicity and seismotectonic data allow to define the Central Costa Rica Deformed Belt(CDCCR) as a wide and diffuse recent fault system located between the Caribbean plate and the Panama microplate, transverse to the central region of Costa Rica, and located between the Middle America Trench (Pacific side) and the NorthPanama Deformed Belt (Caribbean side). In the central pacific forearc, the fault system combines sinistral strike slip andnormal slip. In the inner arc there is: 1) An external thrust fault system, with a predominantly WNW trend, and 2) An innerfault system including northwest dextral strike slip faults and east-northeast to northeast sinistral strike slip faults. In thebackarc, the fault system joins the North Panama Deformed Belt, which shows an external northwest thrust and fold sys-tem and an inner northwest fault system combining dextral strike slip and reverse faulting.The neotectonic faults which define the CDCCR are related to the collision of the Cocos Ridge with southern Costa Rica.The tectonic indentation caused by this collision produces the tectonic displacement to the east and north of the Panama microplate relative to the Caribbean Plate. This tectonic process produces normal slip combined with sinistral strike slipfaulting in the western pacific rear side of the diffuse limit, causing the development of marine basins transverse to theforearc. On the other hand, in the leading side of the limit, an external thrust and fold system has been developed betweenthe inner arc and the backarc. The predominantly strike slip faulting located inside the inner arc allows translational as wellas rotational movements between the diverse tectonic blocks of the plate boundary zone.