Abstract

The deltaic Sabaneta and marine Palmarito formations represent a late Carboniferous (?) and early Permian (?) sedimentation cycle in the Mucuchach basin of middle Ordovician origin in western Venezuela. The basin subsidence and intermittent rim uptilt developed a hinge zone separating the middle Ordovician to late Carboniferous deposition of the coarsely clastic shelf facies of the Caparo formation from the fine-grained trough facies of the Mucuchach formation. The Devonian and Carboniferous strata of the Caparo formation were then eroded from the hinge zone before Sabaneta deposition began. Significantly, the Sabaneta formation is thickest along the trough side of the hinge zone. The Sabaneta formation has a lower member of coarse deltaic stream-channel sandstone and conglomerate, and an upper member of more silty deltaic sandstone. The Palmarito formation has a lower clastic member, and an upper limestone member. The structural response of the Caparo-Mucuchach and Sabaneta-Palmarito series to the Andean orogeny that transformed the rocks of the Mucuchach basin into the Merida Andes differed. The older rocks, more homogeneous, thicker, more plastic, and more deeply buried, are characterized by a regular series of wide synclines and narrow, steeply-overthrust anticlines. The younger Sabaneta and Palmarito rocks deformed asymmetrically, with much local imbrication.

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