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Poster communications

SEDIMENTOLOGY AND SEQUENCE STRATIGRAPHY ANALYSIS OF FLUVIAL AND AEOLIAN SYSTEMS WITHIN TERRESTRIAL AND NEARSHORE ENVIRONMENTS: NOVEL INSIGHT AND CLIMATE IMPLICATION

Abstract : Stratigraphic correlations are often considered as impossible in thick accumulations of fluvial deposits where arid conditions are often underestimated. In fact, most of the time, aeolian deposits in arid environments dominated by ephemeral alluvial fan or braided river are poorly preserved and particular attention should be paid to any sedimentological marker of aridity, such as wind-worn stones (ventifacts), sand-drift surfaces and aeolian sheets. Only detailed study of alluvial plain facies and ephemeral streams provide indications of climatic conditions within the sedimentary basin, whereas fluvial system only reflects climatic conditions of the upstream erosional catchment. Moreover, in such context the deposition of conglomerate of alluvial fan system could correspond to a peak of aridity without an increase in tectonic activity. Conversely, the sedimentary record of aeolian deposits, often considered as preserved in arid desert basin, can occur under semi-arid and even humid climates, and from near the Equator to the Arctic Circle. Ventifacts are climate-sensitive sedimentary features that provide evidence for long periods without any vegetation in terrestrial environment under hot or cold climate. Therefore, they can allow recognizing desert conditions, even where no aeolian dune deposits are preserved. Moreover, the well-preserved widespread paleoregs seem to mark major stratigraphic discontinuity above a geomorphic surface remained a long time without vegetation as a result of a very dry climate, hot or cold. Detailed sedimentological study and the recognition of bounding surfaces of regional extend (sanddrift surface, palaeosols, flooding surface...) allow for the identification of stratigraphic cycles, permit correlation within time and space and precise the climate conditions. Moreover, these detailed sedimentological and stratigraphic analyses highlight the influence of climate or tectonic change on sediment facies and depositional environments. Applied to various Permian and Triassic continental sections in Europe and USA and Jurassic– Cretaceous sections in China, this methodology allows to define fluvial and aeolian interaction processes through time and space, to discuss the allogenic vs autogenic controls and the preserved sediment record within terrestrial and nearshore environments. The recognition of sand-drift surface and maximum flooding episode at the scale of genetic unit, provide a valuable tool for stratigraphic correlation within continental environments devoid of any biostratigraphic markers. Moreover, such results allow to discuss the climate condition of the basin.
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Poster communications
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Contributor : Isabelle Dubigeon <>
Submitted on : Tuesday, February 27, 2018 - 8:44:35 AM
Last modification on : Friday, May 29, 2020 - 2:44:02 PM

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  • HAL Id : insu-01717997, version 1

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Sylvie Bourquin, Marie Olivier, Guy Désaubliaux, Marc Durand, Marc Jolivet. SEDIMENTOLOGY AND SEQUENCE STRATIGRAPHY ANALYSIS OF FLUVIAL AND AEOLIAN SYSTEMS WITHIN TERRESTRIAL AND NEARSHORE ENVIRONMENTS: NOVEL INSIGHT AND CLIMATE IMPLICATION. International Meeting of Sedimentology 2017, Oct 2017, Toulouse, France. pp.125, 2017, Abstract book. ⟨insu-01717997⟩

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