The role of diagenetic carbonate concretions in the preservation of the original sedimentary record |
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| Authors: | A El Albani D Vachard W Kuhnt & J Thurow |
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| Institution: | Laboratoire de Géobiologie, Universitéde Poitiers, UMR-CNRS 6046, UFR SFA, 40, Avenue du Recteur Pineau F-86022, Poitiers Cedex France (E-mail:;)Laboratoire de Paléontologie, Universitéde Lille 1, Villeneuve d'Ascq Cedex, F-59655, France;Geologisch-Palaeontologisches Institut, Universität zu Kiel, Olshausenstr. 40, 24118 Kiel, Germany;Department of Geological Sciences, University College London, Gower Street, WC1E 6BT, UK |
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| Abstract: | The Upper Cretaceous organic rich limestones and marls of the Tarfaya basin of southwest Morocco contain numerous calcite concretions, which formed during early diagenesis. Relative textural similarities are observed both in the concretions and in the host sediments. However, the biological content of the concretions is considerably higher than in the host marls and limestones. Evidence for fossil dissolution in the host marls, and the absence of concretions in some fossil-rich zones, suggest that the difference in fossil abundance between the concretions and host rock is a function of dissolution, rather than preferential precipitation in fossil-rich areas. Consequently, the carbonate concretions appear to represent the 'memory' of the sediment and allow quantification of the original biological components and are potential tools for estimating the original biological material deposited in the soft sediments. |
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| Keywords: | Biogenic material carbonate concretions Cretaceous early diagenesis preservation sedimentary record |
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