Vitor Abreu1, Ricardo Rodrigues Savini2, Carlos Azalgara2, André Tonetto Picarelli3, Grosso Santiago2, Eduardo Vallejo3
(1) Exxon-Mobil, Houston, TX
(2) Perez Companc de Venezuela SA, Caracas, Venezuela
(3) Perez Companc de Venezuela SA, Caracas N/A, Venezuela
ABSTRACT: Sequence Stratigraphic Evolution of the Miocene of the Eastern Venezuela Basin: Interplay of Eustatic Cycles and Foredeep Tectonics
This work focuses on the sequence stratigraphic evolution of the foredeep phase in the Eastern Venezuela Basin. A 2nd-order Transgressive/Regressive cycle is defined in the basin, encompassing most of the Miocene, from the base of the Merecure Formation to the base of the Las Piedras Formation. This 2nd-order cycle is marked at the base by an erosional surface (foredeep unconformity), which coincides with the base of the Merecure Formation. The Oligocene/early Miocene Merecure Formation overlies presumably Paleogene and Cretaceous sedimentary rocks.
The Merecure Formation is represented in wells by blocky sand packages of fluvial to shallow marine sediments, representing the Lowstand Systems Tract (LST) of the 2nd-order cycle. The Transgressive Systems Tract (TST) of this cycle is formed mostly by the Oficina Formation, which is mostly represented by shallow marine deposits. A 2nd-order Maximum Flooding Surface (MFS) is present close to the boundary of the Oficina and Freites formations. The sand content of the second order LST and TST (Merecure and Oficina formations) is markedly higher than the one of the HST (Freitas Formation), indicating that the accommodation space created during the transgressive phase of the foredeep cycle was not completely infilled during highstand (starved basin).
Eleven 3rd-order sequences were defined in the Merecure and Oficina formations. Seismic attribute maps, for every system tract of the 3rd-order cycles, illustrate the evolution of the depositional systems in the basin.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado