Roger Higgs¹, James Pindell²

(1) Geoclastica Ltd Sedimentology Consulting, Oxford, England
(2) Tectonic Analysis Ltd, West Sussex, England

ABSTRACT: Cenozoic Composite-Basin Tectonics and Sedimentation, Venezuela-Trinidad Oil Province

Throughout Paleogene time, Proto-Caribbean ocean lithosphere was subducted slowly (amagmatically) under the northern South America Cretaceous passive margin. Subduction uplifted an E-W continental-margin ridge (?Costa, Araya/Paria, Northern Range), north of a marine trough running eastward from Central Venezuela (Guárico) to Trinidad. The trough received turbidites and olistostromes, named (W to E): Guárico-Cajones Formations; eroded in E Serranía; Chaudiere-Pierre-Fernando. South of the trough was a shelf: Cautaro; Caratas-Jabillos-Areo; predicted under Orinoco pro-delta. The trough was shorter-lived in Guárico (Paleocene-Middle Eocene) than in Trinidad (Paleocene-Middle Miocene) because it was overrun from the west by transpressively obducted nappes of the Caribbean Plate's accretionary wedge, including meta-ophiolites (Villa de Cura). The nappes drove an oblique, peripheral foreland basin (PFB), comprising a NE-opening marine gulf (paired trough and wide shelf) which migrated east, merged into, and diachronously superceded the E-W Guárico-Trinidad marginal trough. The PFB trough received turbidites and olistostromes from both flanks (ophiolitic olistoliths from the allochthon; sedimentary olistoliths from the autochthon). These deposits young eastward, reflecting trough migration: Matatere (Paleocene-Lr Eocene); Guache (Lr-M Eocene); Garrapata-Tememure (U Eocene-Lr Oligocene); Chapapotal-Herrera (M Miocene). Immediately SE are corresponding E-younging shelf deposits: Guasare-Misoa-Paují; Gobernador-Pagüey; Pascua-Roblecito; Merecure-Oficina-Freites; sub-Orinoco. These shelf deposits are succeeded by 'overfilled-stage' alluvial-plain deposits, which also young eastward (eroded at sub-Rosa unconformity; Chaguaramas-Naricual; eroded sub-Pica).

Overprinting the PFB are unconformities and basins caused by (1) Maracaibo-Guajira-Orchila Block escape and possible clockwise rotation (20-0Ma), and (2) Caribbean-S America transcurrence since Late Miocene time.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado