Tectonic evolution of the Sierra Maestra Mountains, SE Cuba, during Tertiary times: From arc-continent collision to transform motion

Abstract

A structural study was carried out along the southern Sierra Maestra mountain range, SE Cuba. This was aimed to monitor the effects of Paleogene island arc formation and collision due to convergence of the Caribbean and North American plates and subsequent Neogene disruption of the arc by initiation of the North Caribbean Transform Fault. In the Sierra Maestra two different and unrelated volcanic arcs are exposed, one of Cretaceous age (pre-Maastrichtian) and the other of Paleogene age, the latter forming the main expression of the mountain range. The volcanic arcs are overlain by Middle–Upper Eocene siliciclastic, carbonate and terrigenous rocks. Six distinct phases of deformation were recognized in this area (D1–D6). The first phase (D1) is related to the intrusion of a set of extensive subparallel, N-trending subvertical basalt-andesite dikes which record mainly E–W extension and N–S shortening during the Late Paleocene to Middle Eocene. The final stage of collision of eastern Cuba (Caribbean plate) with the Bahamas Platform (North American plate) began in the Middle Eocene and coincided with cessation of magmatism in the Sierra Maestra. Following uplift in the Sierra Maestra, coarse clastic sediments were deposited along the northern edge with clast provenance from the uplifted, southerly located, areas. Between Late Middle Eocene and Early Oligocene, rocks of the Sierra Maestra were deformed by nearly east-west trending folds and north-vergent thrust faults (D2) in an overall antiformal structure. This deformation was linked to a shift in the stress regime of the Caribbean plate from mainly N–S to NE–SW compression. Subsequent shifting in plate motion caused the abandonment of the Nipe-Guacanayabo fault system in the Early Oligocene and initiation of a deformation front to the south where the Oriente fault is now located. Shortening structures within the Sierra Maestra were overprinted in the Oligocene to Early Miocene by widespread extensional structures (D3), represented mainly by normal faults with southward-directed displacement. These faults resulted from a major S-directed detachment system, probably associated with regional isostatic readjustment, and developed in a transtensional regime during initiation of the Oriente fault. During this period, the plate boundary jumped to the Oriente fault. This event was followed by transpressive and transtensive structures (D4–D6) due to further development of the sinistral E-trending Oriente transform wrench corridor (OTWC). These structures are consistent with oblique convergence in a wide zone of mainly left-lateral shear along an E–W-oriented transform fault, during a short period of dextral motion. Our new structural data provide evidence for a Middle Eocene to Early Miocene transition from regional NNE- to NE-directed compression to left-lateral transform deformation along the OTWC in the northern Caribbean realm.