Early Tertiary Coarse Sediment Distribution Across the Central Range of Trinidad

Hasley Vincent
Department of Earth Sciences, Dalhousie University Halifax, Nova Scotia
[email protected]

     Early Tertiary coarse clastics are among the least understood sediments in the Trinidadian stratigraphy with a variety of stratigraphic definitions, ages, source terrains and depositional environments, largely due to sparse outcrops and structural complexity. The majority of studies on these sediments are paleontology-oriented and only a few have attempted to deduce the related sedimentary processes. Even among those, there are differences in interpretations.
     In this study, lithofacies and lithofacies associations are described based on physical and biogenic sedimentary structures, sand-body geometries, sediment stacking patterns and detrital mineralogy. These form the basis for interpreting the relative role of shallow and deep water processes, and the provenance of each coarse clastic interval. Preliminary results suggest that re-sedimentation processes may have been underestimated in the past as there is overwhelming evidence for sediment gravity flows relative to shallow water processes.
     These results have several implications for the Trinidad stratigraphy and paleogeography. Interpretations of falling sea level based solely on faunal evidence should be re-evaluated in light of the sedimentary processes that were active during deposition, as large amounts of shallow water fauna were displaced onto slope environments. Limestone and conglomeratic beds may prove to be insignificant events related to gravity flows and not represent significant changes in base level, as currently interpreted.

AAPG Search and Discovery Article #90070 © 2007 AAPG Foundation Grants in Aid