SPATIOTEMPORAL DISTRIBUTION OF NEOTECTONIC ACTIVITY IN THE ARAYA-PARIA PENINSULA, VENEZUELA

The Araya-Paria Peninsula is a narrow E-W trending metamorphic hinterland exposed between the Caribbean and South American plates along the north coast of Venezuela. The mountain belt is thought to have experienced surface uplift primarily during Miocene oblique collision and is now located along the active dextral El Pilar plate boundary fault zone (EPFZ). We performed geomorphic analyses on 175 catchments and on the mountain fronts across the peninsula to characterize the spatiotemporal distribution of neotectonic activity in the Araya-Paria Peninsula. Geomorphic indices include the valley width-to-height ratio (V), catchment elongation (E), catchment asymmetry (A), and hypsometric indices (HI) at the catchment scale, and the mountain front sinuosity index for 17 regions (~10 km) along the north coast and the range’s southern flank. HI values (mean = 0.38) generally increase from west (HI = 0.12) to east (HI = 0.71) with the highest values concentrated along the northeast coast. The highest V values (max = 36) occur in catchments located in the south-central peninsula and coincide with a region where the mountain drainage pattern transitions from N-S to E-W. Catchment asymmetry ranges from nearly symmetric catchments in the south (A = 0.07) to highly asymmetric catchments along the north coast (A = 36). The observed variations of geomorphic indices were evaluated in light of lithologic erosivity indices and variations in vegetation and precipitation. In the eastern study area (Paria Peninsula), high HI values, a nonuniform direction of catchment asymmetry, and V-shaped valleys may indicate a significant control from resistant lithology and uniform south-dipping bedrock. In the south-central peninsula, planimetric mountain fronts (M < 1.5) and high V values (V > 4) are interpreted to be the result surface uplift due to active Caribbean-South American plate boundary tectonics. In the western study area (Araya Peninsula), generally low HI (< 0.4), highly sinuous (M > 2) mountain fronts, and regionally low relief (< 400 m), despite relatively resistant bedrock, suggest a highly denuded landscape weakly influenced by active tectonics. These results highlight the variation of Quaternary tectonism along the EPFZ and may reflect how deformation is partitioned by the eastward migration of the Caribbean plate.