Metamorphic- tectonic implications under a compression dynamic in Cangre Belt, western of Cuba

Abstract

The Cangre Belt is located in western Cuba, where it belongs to the Mesozoic basement of the Island. The belt contains three tectonic units: Pino Solo, Mestanza and Cerro de Cabras, each one overthrusted upon the Alturas de Pizarras del Sur unit of the Guaniguanico terrane. This tectono-metamorphic scenario contrasts with the remaining parts of the terrane. The conclusions arrived in this paper are supported by cartographic, petrographic, and structural data, collected during decades, that also includes mineral chemistry content in the micas from the siliciclasts. The clockwise rotation of the main compressive stress σ₁ developed with singular time-spatial consequences that allow to discriminate several deformational periods (P) from NW 330°–340° up to NE 20°–30° during P1 compression and the development of tectonic transport (P2 and P4). The sinistral Pinar fault (P3) conditioned the birth and tectonic style of the belt from a small change in its trend, provoking transpression in some sector and the development of a positive flower structure (extrusive orogen) and its definite configuration during the last deformation period (P4). In these tectonic conditions occurs some metamorphic processes: mc-very low degree metamorphism, related to cleavage, developed during all periods, mt-transpressive metamorphism of low degree, progressive related to mid pressure-high part (P4 with the highest P/T gradients) and me-metamorphism by tectonic extrusion, of low degree, retrograde with mid pressure-middle part (P4). The juxtaposed emplacement of the extrusive sequences conditioned their metamorphic heterogeneities.