Sequence stratigraphic framework of the Miocene Oficina Formation, Orinoco Oil Belt of Venezuela: Integrating multiple datasets for the recognition of third-order depositional sequences

Posted on 2017-12-05 in Events
Dec 8, 2017

Please join us for the graduate student seminar this Friday December 8 at 3:30 pm in rm 155 Geology presented by Euridice Solorzano, PhD Candidate:

Sequence stratigraphic framework of the Miocene Oficina Formation, Orinoco Oil Belt of Venezuela: Integrating multiple datasets for the recognition of third-order depositional sequences

The middle Miocene Oficina Formation (15.97-12.7 Ma) in the Orinoco Oil Belt comprises a single 2nd-order sequence, which is divided into two third-order sequences (DS1-2), based on the integration of sedimentologic, stratigraphic, ichnologic and biostratigraphic datasets using well logs and core. DS1 is bounded by sequence boundaries U-1 (15.97 Ma) and U-2 (13.82 Ma) and includes maximum flooding surface MFS-1 (14.91 Ma). It consists of thick lowstand systems tract (LST) and transgressive systems tract (TST) strata, and a thin highstand systems tract (HST) package. DS1 is associated with incised-valley systems formed during a relative sea-level fall. These valleys consist of fluvial braided channels, swamps, paleosols, floodplains and the Scoyenia Ichnofacies. The fluvial valleys were replaced by estuaries during the Langhian transgression. The estuarine valley-fill displays a retrogradational stacking pattern, comprising meandering estuarine channels, tidal flats, estuarine sandbars, paleosols, and swamps. The Glossifungites, Teredolites, Scoyenia, Skolithos, and depauperate Cruziana Ichnofacies have been identified. Based on regional mapping of the Glossifungites Ichnofacies, DS1 was subdivided into three fourth-order sequences. DS2 is bounded by U-2 (13.82 Ma) and U-3 (12.7 Ma), and includes MFS-2 (13.53 Ma). It consists of a thin TST and a thick HST. It was essentially developed during the Serravallian sea-level highstand, and is constituted by lower delta plain deposits, displaying a progradational stacking pattern. These deposits consist of distributary channels, interdistributary bays, floodplains, and the Scoyenia Ichnofacies. Third-order sequences closely match with the middle Miocene third-order global eustatic curve and define the facies architecture at reservoir scale.