Cretaceous to Neogene tectonic control on sedimentation : Maracaibo Basin, Venezuela




Lugo Lobo, Jairo Miguel, 1955-

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The Maracaibo basin records a complex tectonic and depositional history. Compilation of seismic and well data allows me to distinguish six tectonostratigraphic episodes. The first episode is characterized by Jurassic rifting along north-northeast-trending half-grabens filled with continental red beds and volcanics rocks. The second episode is characterized by the deposition of shallow to deep marine carbonates and clastic rocks in which subsidence rates increase away from the northwest-trending Mérida arch, a mid-Late Paleozoic northwest-trending range anchored to the Guayana Shield. The third episode is distinguished by oblique collision of south-southwest-verging Caribbean terranes toward the continental platform. As collision evolved, the tectonically carried crustal flexure and associated turbiditic basin migrated south-southeastward. Evidences from geohistory analysis shows the shift of the axis of subsidence in that direction. During this episode six unconformity-bounded deltaic wedges marked an equal number of regressive stages caused by thrust propagation above the flysch basin. Seismic clinoform orientations and sandstone composition document the regional northern provenance for such paralic wedges in the northeastern portion of the basin. The fourth episode developed from Late Eocene to Middle Miocene in which transpressive tectonism reactivated the structural weaknesses developed in the earlier rift. Left-lateral north-northeast-trending strike-slip faults and related en echelon secondary structures were built in two main active phases: one during Late Eocene and the other in Middle Miocene time. The reactivation of the main Icotea and Pueblo Viejo faults influenced the distribution of intrabasinal restraining bends, pull-apart basins, and associated sediment infill. The fifth episode is characterized by diachronous orogeny that began with Oligocene uplift along the Sierra de Perijá and continued southeastward toward the Mérida Andes. These uplifts created a closed depositional basin and converted the depositional environment from marine to continental. The six episode is characterized by compression evidenced by north-striking east-vergent reverse fault in the Sierra de Perijá