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Unravelling the Influence of Tectonics on Sediment Distribution and the Changing Clinoform Geometry of the Orinoco River Delta’s Late Miocene deposits, the Cruse Formation, Trinidad

Southeast Caribbean Research Symposium Presentation
AAPG Distinguished Lecture

Author(s): Ariana Osman (presenter), Ryan Ramsook, The University of the West Indies; Ron J. Steel, Cornel Olariu, The University of Texas at Austin; Si Chen; China University of Geosciences

The continuous eastward migration of the Caribbean plate altered paleo-drainage directions since the middle Eocene, diverting the once north flowing mighty Orinoco to its current west-east trajectory across eastern Venezuela and Trinidad. In the late Miocene, the Cruse Formation marks the arrival of the delta on Trinidad, depositing a clastic wedge of >2500 ft which accreted eastwards by shallow to deepwater clinoform increments driven mainly by a huge sediment flux and glacio-eustatic climate cycles (ca. 100 ky), but modulated by Caribbean tectonics. In this study, 58 well logs and outcrop data were integrated to construct a 3D picture for 15 continental-margin clinoforms (C10-C24) to unravel the impact of tectonics on the sedimentation trends observed for the Cruse. The clinoforms have an average height of 550 m, continental slope of 2.5˚ tapering to 1˚, and a distance from shelf-edge to near-base of slope of >10 km, and can be grouped into three developmental phases: 1) C10-C13 have a flat shelf-edge trajectory, suggesting a high supply of sediment during periods of repeated icehouse rise and fall of eustatic sea-level, with fall outpacing subsidence rates. These topset sands are interpreted to have a strong fluvial regime that may have been influenced by the development of NE-SW directed growing thrusts, creating an embayed paleo-Columbus Channel area protected from strong wave energy; 2) C14-20 has an aggradational pattern with a rising shelf-edge trajectory, possibly resulting from increased tectonic induced subsidence as the Caribbean plate migrated eastwards post the culmination of collision in the Middle Miocene; 3) C21-24 show strong margin progradation, similar to C10-13, but, their topsets have a much stronger wave influence as the delta prograded past the subtle thrusts.


Ariana Osman, The University of the West Indies

Ariana earned a BSc from Western, Canada and a MSc from the University of Texas at Austin.

With 3 years of experience in the industry, she currently is PhD student at the University of the West Indies, Trinidad, where she researches and teaches courses in Sedimentology, Stratigraphy and Petroleum Geology. Previously, she has worked at BP Trinidad and Tobago, and Leibniz University Hannover.

Ariana is a member of AAPG, SEPM, IAS and GSA.

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