Pleistocene development and facies of southern Belize shelf and barrier reef
Final Report Abstract
The Belize barrier and atoll reefs represent the largest reef structure in the Atlantic Ocean. The southern shelf of Belize is a classic location of a modern mixed carbonate-siliciclastic system. Whereas the knowledge of the Holocene deposits in the area is extensive, data on the Pleistocene system is fragmentary. Open questions include the nature of the reef bases (carbonate versus siliciclastics), ages of the deposits including the initiation of the adjacent barrier reef, and the response of the mixed system to sea-level fluctuations. The results indicate that reefs on the Belize shelf were initiated both on carbonates and siliciclastics. Reefs at the shelf margin were established on carbonate deposits. The Belize Barrier Reef proper is probably significantly older than 400 kyrs (marine isotope stage 11) as seen in the occurrence of low-energy, lagoonal sediments on the shelf during the early Pleistocene. In general, sea-level highstands lead to the dominance of carbonates, and sea-level lowstands resulted in the abundance of siliciclastics on the Belize shelf. Using the record of Pleistocene sea-level variation, it is possible to develop a model of Pleistocene sedimentation on the Belize shelf and barrier reef. Early Pleistocene (older than 1 million years) and late Pleistocene (younger than 400 kyrs) carbonates were deposited during times of high sea-level highstands, and siliciclastics predominated over carbonates during the period of lower sea-level highstands in the middle Pleistocene (400-1.000 kyrs BP). It was a negative surprise that no Pleistocene corals could be retrieved that were suited for U-series dating, as described above.
Publications
- (2008): Late Quaternary deposits on the southern Belize shelf: how does the mixed carbonate-siliciclastic succession record Pleistocene sea-level variation?- 11th International Coral Reef Symposium, Fort Lauderdale, Abstract volume, page 3
Gischler, E., Ginsburg, R.N. & Prasad, R.
- (2008): Late Quaternary mixed carbonatesiliciclastic sequences on the central-southern Belize shelf, Central America.- Schriftenreihe der deutschen Gesellschaft für Geowissenschaften, 58: page 113 (SEPM-IAS 26th Meeting, Bochum)
Gischler, E., Ginsburg, R.N. & Prasad, R.
