LATE PALEOCENE TO EARLY EOCENE KARSTIC CLAY DEPOSIT OF NORTHERN BELIZE, CENTRAL AMERICA

Lower Cenozoic Red Bank group crops out in several areas of northern Belize comprising mainly of clay with traces of carbonate and evaporite beds. Previous studies characterized this clay unit as relatively thin, and widespread across most of northern Belize. However, recent research integrating petrographic and cartographic methods revealed that the Red Bank group is a complex stratigraphic unit with depositional history linked to global events (i.e. sea‐level high‐stand). Well log correlation of the Spanish Lookout and Never Delay oil fields suggests that the Red Bank unconformably overlies the Upper Cretaceous Barton Creek limestone. The nature of the basal stratigraphic contact is a NW trending, fault bounded karst. The Red Bank clay fills the caverns and the channels karstic Barton Creek limestone.

Although previously reported as Miocene, presented study identified the chronostratigraphic position of the group as late Paleocene to early Eocene and thus encompassing the PETM (Paleocene‐Eocene Thermal Maximum) global climatic event and significant high and low sea level stands. Low sea‐level stand is correlated with the karst development in the underlying limestone; whereas high sea‐level stand is interpreted to occur with the transgressive sedimentation of the Red Bank clays based on the mineralogy and nannofossil content. The Red Bank’s nannofossils indicate that the clay and the karst development occurred during a period of regression in sea level ca. 58-60 Ma allowing for exposure to atmospheric and meteoric water, facilitating dissolution of the faulted limestone, formation of the karst and channel system as well as the deposition of the clay beds. X-ray diffraction analyses indicate that components of the clay were generated by the weathering of metamorphic rocks emphasizing a terrestrial influx of sediments. The distinguished nannofossil content, mineralogical composition and the chronostratigraphic constraints indicates that both clays within the karstic and the channel systems have similar sediment source with deposition occurring in a relatively low-energy environment. In addition to better description and understanding of the Lower Cenozoic Red Bank group of northern Belize, this study also helps enhance hydrocarbon exploration within the underlying strata of Belize’s Corozal Basin.