Depositional Sequences and Relative Sea-Level Change in Jamaica Determined by Biostratigraphic Data

Abstract

Jamaica and its offshore basins are sparsely explored: only two wells have been drilled offshore and nine wells onshore, along with several shallow boreholes, and oil or gas shows have been seen in 10 of the 11 wells. Jamaica has a broad stratigraphic framework consisting of Cretaceous shales representing potential source rocks, and rudist limestones with reservoir potential. The Cretaceous succession is overlain by Palaeogene carbonate and siliciclastic units which have both source and reservoir potential. The Middle Eocene Litchfield Formation is recognised as the main Cenozoic source rock, with potential reservoirs in the overlying Chapelton Formation and younger rocks. This data-rich study comprises new analyses of over 800 outcrop and well/borehole samples. New biostratigraphic and sedimentological data have enabled revision and updating of the sequence stratigraphic framework of Jamaica and the tie of depositional cycles to third-order sequences.

Biostratigraphic analysis reveals several major unconformities. These are related to major tectonic (predominantly collisional) events that occurred during the assembly of the various terranes of the Nicaragua Rise. The environmental preferences of organisms identified during the biostratigraphic analyses permit the construction of a relative sea-level curve for the island of Jamaica. This curve reveals several newly identified transgressive-regressive (T-R) depositional cycles in the stratigraphy. Maximum transgressive and regressive inflections in the relative sea-level curve are associated with third-order sequences. Single T-R cycles are identified within the Early Cretaceous, Coniacian-Santonian and Campanian, two T-R cycles are identified in the Maastrichtian, a further single T-R cycle within the Paleocene to Early Eocene, three T-R cycles within the Middle Eocene age Yellow Limestone Group and a single transgressive sequence within the Late Eocene to Miocene age White Limestone Group. Transgressions and regressions that are recorded within the Yellow Limestone Group represent changes in relative sea-level of only several tens of metres. Application of this new relative sea-level curve has enhanced the identification of potential source, reservoir and seal units within the petroleum systems of Jamaica.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018