Coralline-algal assemblages of a Burdigalian platform slope: implications for carbonate platform reconstruction (northern Sardinia,western Mediterranean Sea) |
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Authors: | Merle-Friederike Benisek Christian Betzler Gabriela Marcano Maria Mutti |
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Institution: | 1.Department Geowissenschaften,Universit?t Hamburg,Hamburg,Germany;2.Institut für Geowissenschaften,Universit?t Potsdam,Golm,Germany;3.StatoilHydro ASA,Stavanger,Norway |
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Abstract: | The rhodolithic slope deposits of a Burdigalian carbonate platform in Sardinia near Sedini were analyzed to reconstruct facies
and palaeobathymetry. There is a distinct red-algal growth zonation along the platform slope. The clinoform rollover area
consists of coralline-algal bindstones, which downslope change into a zone where rhodoliths are locally fused by progressive
encrustation. Mid-slope rhodoliths are moderately branched, and downslope rhodoliths have fruticose protuberances, resulting
in branching rhodolith growth patterns. There is a sharp change from the rhodolitic rudstones to the basinal, bivalve-dominated
rudstones at the clinoform bottomsets. Red-algal genera identified include Sporolithon, Lithophyllum, Spongites, Hydrolithon, Mesophyllum, Lithoporella, Neogoniolithon, and other mastophoroids and melobesioids. Genera and subfamilies show a zonation along the clinoforms, allowing palaeobathymetric
estimates. The clinoform rollovers formed at a water depth of around 40 m and the bottomsets around 60 m. Results from geometrical
reconstruction show that coral reefs in the inner platform formed at water depths of around 20 m. Therefore, the Sedini carbonate
platform is an example of a reef-bearing platform in which the edge or the platform-interior reefs do not build up to sea
level. |
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Keywords: | Miocene carbonate platforms Carbonate platform architecture Coralline algae Transitional carbonates |
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