GEOLOGY OF THE CARACAS REGION, VENEZUELA

Abstract

The Caracas region is made up of metamorphic rocks which were originally sediments, plus some metamorphosed igneous rocks such as serpentinites and amphibolites. The original sediments, largely if not entirely of Cretaceous age, consisted of sandstones and conglomerates at the base that graded upward into limestones and limey shales. Basaltic rocks were extruded prior to any major deformation, and probably contemporaneously with the deposition of some of the sediments. Some volcanic tuffs were probably deposited in the upper part of the sedimentary succession. In the Late Cretaceous northern Venezuela was deformed, together with a large portion of the Caribbean region, resulting in the downbuckling of the earth9s crust. During this deformation ultramafic rocks were intruded along the axial region of the downbuckle. Continued deformation, probably accompanied by remelting of the crust at depth, rise of the isogeotherms, and migration of solutions into the sedimentary succession, produced the regional metamorphism. The sediments were changed into gneisses, schists, and marbles, and the basaltic rocks into amphibolites. Further deformation of the region was characterized by thrust faulting followed by normal and transcurrent faulting, and accompanied by folding and regional uplift.