| Affiliation: | 1.GEOMAR Research Center for marine Geosciences, Wischhofstr. 1-3, 24148 Kiel, Germany,Germany;2.Geologisch–Pal?ontologisches Institut, Universit?t Hamburg and Department of Earth Sciences, University of Cambridge, Bundesstr. 55, 20146 Hamburg, Germany,Germany;3.Faculty of Earth Sciences, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands,The Netherlands;4.RSMAS-MGG, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA,USA |
| Abstract: | In this paper we show that the development of the sediment architecture at the leeward toe-of-slope of Great Bahama Bank (Ocean Drilling Project Leg 166, Bahama Transect) during the last 6 Ma is not only a response to sea-level fluctuations, but also to major paleo-oceanographic and climatic changes. A major sequence boundary close to the Miocene/Pliocene boundary (dated at 5.6-5.4 Ma) is interpreted to reflect a major sea-level drop that was followed by a sea-level rise, which led to the re-flooding of the Mediterranean Sea at the end of the Messinian and increasing sea-surface temperatures at Great Bahama Bank. Distinct erosional horizons occurred during the Pliocene (dated at 4.6 and 3.3-3.6 Ma) related to sea-level change and the intensification of the Gulf Stream when the emergence of the Isthmus of Panama reached a critical threshold. The Gulf Stream brings warm, saline and nutrient-poor waters to the Bahamas. Starting at the Early-Late Pliocene boundary at 3.6 Ma this paleo-oceanographic reorganization in combination with enhanced sea-level fluctuations associated with the Late Pliocene main intensification in Northern Hemisphere Glaciation (since 3.2 Ma) led to (1) a gradual change from a ramp-type to a flat-topped type morphology, and (2) a change from a skeletal to a non-skeletal-dominated sedimentary system (mainly peloidal). Increased sea-level fluctuations during the second half of the Pleistocene led to an intensified high stand-shedding depositional pattern within the surrounding basins. |
