Polyphasic Tertiary Tectonics of the interior range in the Central Part of the Western Caribbean chain, Guarico state, Northern Venezuela.

Abstract

The southern -non metamorphic- belt of the Western Caribbean Chain is composed of the superposition of several tectonic units with an upper Cretaceous-Palaeocene content. The whole –called 'Piemontine Nappe'- was detached from an Albian and pre-Albian substratum and suffered two major compressive tectonic phases with southward displacements. The first phase Lower Middle Eocene- produced the allochthony of the previously tectonized Villa de Cura Nappe, which was strongly shortened. During the Oligocene (?) -Miocene period, a wide subsiding furrow appeared along the southern margin of the palaeorelief formed before in relation with a NNW-SSE distension. The second tangential phase -Middle-Upper Miocene- produced a partial overthrusting of the Piemontine Nappe on the Miocene terrains and a new shortening of the latter. An earlier phase may have affected the northern part of the Piemontine dominion in the lower Senonian. This hypothesis and the preceding conclusions are in opposition with the theory -generally held- of a displacement of the Villa de Cura Nappe as due to a continuous sliding occurring during Maastrichtian and Palaeocene time and followed by a continuous sliding of the Piemontine Nappe from Upper Eocene to Miocene time. The hypothesis of tectonisation by gravity sliding is discussed and discarded.