Calcareous turbidity current emplacement as an initiation mechanism for substrate brecciation and deformation
Published:January 01, 2005
B. Savary, 2005. "Calcareous turbidity current emplacement as an initiation mechanism for substrate brecciation and deformation", Submarine Slope Systems: Processes and Products, David M. Hodgson, Stephen S. Flint
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The Barremian-Aptian Baronnies syncline, located in SE France, provides the opportunity to study a calcareous turbidite lobe with intercalated breccias and slumps. These features are formed in-situ by the emplacement of turbidity currents that distorted the underlying semi-consolidated substrate. The brecciation occurs in three stages. The first stage is represented by the penetration of calcarenitic sediment into the underlying unlithified calcisiltic sediment due to the hydraulic pressure of an overriding turbidity current. In the next stage, a pseudo-breccia forms where the brecciated clasts are still attached to the substrate. Finally, these breccia clasts are separated entirely from the seabed and locally entrained into the flow. In addition, the penetration of the flow into the underlying semi-consolidated sediment can induce destabilization, down slope movement and folding. Similar Tithonian-aged (Late Jurassic) breccias have been interpreted previously as in-situ wave-induced features in this region; however, this study testifies that this deformation is not diagnostic of storms but can also be induced by turbidity current deposition.
The mechanisms that induce brecciation have to be identified correctly in order to consider them within a sequence stratigraphic context. Calcareous turbidites and their associated breccias, however, are not strongly diagnostic of relative sea-level.
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Submarine Slope Systems: Processes and Products
Submarine slopes provide the critical link between shallow-water and deep-water sedimentary environments. They accumulate a sensitive record of sediment supply, accommodation creation/destruction, and tectonic processes during basin filling. There is a complex stratigraphic response to the interplay between parameters that control the evolution of submarine slope systems, e.g. slope gradient, topographic complexity, sediment flux and calibre, base-level change,tectonic setting, and post-depositional sediment remobilization processes. The increased understanding of submarine slope system has been driven partly by the discovery of large hydrocarbon fields in morphologically complex slope settings, such as the Gulf of Mexico and offshore West Africa, and has led to detailed case studies and improved generic models for their evolution. This volume brings together research papers from modern, outcrop and subsurface settings to highlight these recent advances in understanding of the stratigraphic evolution of submarine slope systems.