Compositional variations in calciturbidites and calcidebrites in response to sea-level fluctuations (Exuma Sound, Bahamas)

Abstract

The compositional variation of Pleistocene carbonate gravity deposits from the Exuma Sound Basin, Bahamas, was determined. Two types of gravity deposit were present in the cores of ODP Leg 101, Site 632A, i.e., calciturbidites and calcidebrites. In analogy with earlier studies, the compositional variations in the calciturbidites could be linked to different sources on the carbonate margin, i.e., platform interior, platform edge, and platform slope. Calciturbidites deposited during interglacial, sealevel highstands show a dominance of non-skeletal grains, largely derived from the platform interior, while calciturbidites of glacial, sea-level lowstands, show a dominance of skeletal platform-edge to platform-slope-derived grains. Thus, the calciturbidite composition can be used to reconstruct the position of absolute sea level. In addition, the mud content of the calciturbidites increased after Marine Isotope Stage 11. In contrast, the composition of the calcidebrites remained unaltered through time and showed a clear dominance of platform-edge-derived sediments during varying sea-level positions. The Bahamian carbonate platform is located in a tectonically stable passive-margin setting and the gravity-flow deposits were laid down in an environment exclusively controlled by eustatic sea-level fluctuations. This study shows that all types of gravity-induced carbonate deposits, calciturbidites, and calcidebrites, were deposited in response to global eustatic sea-level variations. The sediment composition could be linked directly to sediment input from specific facies realms along the carbonate platform margin. Hence, sediment composition analysis is a strong tool that may be used to discriminate between gravity-induced deposition triggered by eustatic sea-level changes and that related to tectonic events, when analyzing resedimentation processes in sedimentary basins.

Facies, geometry and growth phases of the Valdorria carbonate platform (Pennsylvanian, northern Spain)

“…The fine-grained, laminated deposits of lithofacies 'bPG' would represent high-density and low-density turbidity current deposits (Bouma, 1962;Middleton & Hampton, 1973;Lowe, 1982;Mutti, 1992). Similar deposits have been linked to slope collapse events and/or to outer platform washing from normal exportation or storm events, as described by other authors (Bahamonde et al, 1997a(Bahamonde et al, , 2000B abek et al, 2007;Playton, 2008;Reijmer et al, 2012).…”

“…The apparent lack of coeval isolated carbonate platform field outcrop analogues, exhibiting laterally and vertically traceable facies belts at a kilometre scale, led to the use of land‐attached or non‐coeval isolated platforms for comparison. Thus, analogies are either made to well‐studied Palaeozoic high relief, flat‐top and steep slope platforms, such as the Devonian Great Barrier Reef of the Canning Basin (Playford, ; Playford et al ., , ; George et al ., ; Copp, ; Webb, ; Stephens & Sumner, ; Kerans & Harris, ; Chow et al ., ; among others), the Carboniferous Sierra del Cuera of northern Spain (Bahamonde et al ., ,b, , ; Della Porta et al ., ,b, , , , ; Kenter et al ., ; Della Porta, ; Verwer et al ., ), the Palaeozoic platforms of the Bolshoi Karatau (Cook et al ., ) and the Permian Capitan System of the USA (Borer & Harris, ; Kirkland et al ., ; Tinker, ; Hunt & Fitchen, ; Osleger & Tinker, ; publications in Saller et al ., ; Hunt et al ., ; Playton, ; Standen et al ., ; Van der Kooij et al ., ; among others), or to late Cainozoic isolated platforms, such as the Bahamas Islands (Mullins, ; Eberli & Ginsburg, ; Wilber et al ., ; publications in Ginsburg, ; Rankey, ; Harris et al ., ; Reijmer et al ., ). Among the cited examples, and in certain areas such as foreland basins and tilted blocks, the tectonic influence makes it difficult to discriminate among the factors controlling the sedimentary rock record (e.g.…”

Type and evolution of carbonate platforms in Jixian Period Mesoproterozoic: southwestern margin of Ordos Basin

“…The impacts of tectonism on carbonate platform Sea-level fluctuations can influence the type of carbonate platform and characteristics of gravity flow deposits (Read 1985;Reijmer et al 2012;Phelps et al 2014). Many studies have been focused on the sea-level changes of the Jixian Period of Mesoproterozoic at the eastern North China plate, but few studies try to address the problem from the southern margin of the North China plate.…”

Glacio‐eustasy and δ13C across the Mississippian–Pennsylvanian boundary in the eastern Paleo‐Tethys Ocean (South China): Implications for mid‐Carboniferous major glaciation

“…Laminated wackestones to packstones are interpreted as distal turbidites deposited in moderate‐ to low‐energy conditions. Normally‐graded beds were deposited from turbidity currents, interpreted as A–C portions of the Bouma sequence (Korn, ; Reijmer, Palmieri, & Groen, ). Slump beds formed by slumping and deformation of sedimentary strata, which are often triggered by earthquakes and relatively sea‐level changes (Alsop & Marco, ; Hilbrecht, ).…”