Alternating Fluvial and Lacustrine Sedimentation: Tectonic and Climatic Controls (Provence Basin, S. France, Upper Cretaceous/Palaeocene)
- M. Marzo and
- C. Puigdefábregas
Published Online: 14 APR 2009
Copyright © 1993 The International Association of Sedimentologists
How to Cite
Cojan, I. (1993) Alternating Fluvial and Lacustrine Sedimentation: Tectonic and Climatic Controls (Provence Basin, S. France, Upper Cretaceous/Palaeocene), in Alluvial Sedimentation (eds M. Marzo and C. Puigdefábregas), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303995.ch27
- Published Online: 14 APR 2009
- Published Print: 16 SEP 1993
Print ISBN: 9780632035458
Online ISBN: 9781444303995
- Alternating fluvial and lacustrine sedimentation;
- horizons of detrital sediments (quartz sand channel bodies, bars or sand sheet) developed in a braided system;
- Cretaceous chronostratigraphy;
- floodplain, lacustrine and proximal alluvial fan;
- Fluvial pattern reconstruction by measurements of current marks, dip of bed sets etc
The continental sediments that accumulated in Provence during the Upper Cretaceous/Palaeocene are organized in several similar sequences that evolve from fluvial to lacustrine facies. A first attempt to analyse the parameters governing such a sequential arrangement persisting during some 30–40 m.y. is based on a detailed analysis of the two best preserved sequences (Rognacian–Vitrollian).
The horizons of detrital sediments (quartz sand channel bodies, bars or sand sheet) developed in a braided system network which spread on a silty floodplain. Sediment supply was dominantly fine grained and water stage fluctuations were common. Sand bodies are the result of cumulative deposits of flood episodes; high stages are characterized by channel fill deposits, and low stage by build-up of sand bars and development of algal mats or oncolites. The lacustrine carbonate muds precipitated in shallow water depth lakes. Base level fluctuations controlled the sequential arrangement, and the carbonate muds were often subjected to subaerial exposure. Sediment supply was probably low as testified by the long periods of non-deposition, the intense bioturbation of the sediments, and the low detrital content of the lacustrine deposits.
The basin palaeogeography is governed by two fault systems: an E–W oriented one that defined the drainage pattern, and a NNE–SSW one that controlled the lateral variations of facies. The braided system was, from time to time, bound by locally derived conglomerates which accumulated along the E–W oriented fault system and are evidence of tectonic pulses. The subsidence rate was fairly low (some 300 m over approximately 15 m.y.) and suggests at least a local compressional deformation. Based on the lithofacies arrangement, a model involving thrust and strike-slip displacement along the E–W trending system may be suggested.
From the two analysed sequences, the lithofacies assemblages are governed by a combination of climatic influence controlling base level fluctuations as well as extensive pedogenesis, and of tectonic activity influencing sediment influxes as well as the evolution of depositional environments. Periods of tectonic quiescence and an average low rate of sediment influx allowed climatic influences on sediment to develop and be preserved. Such a balance, between braided fluvial and shallow lacustrine environments, was maintained over such a long period because the low rate of sediment influx roughly matched the subsidence rate. In this context, the environmental fluctuations linked with climatic or tectonic changes were only of limited amplitude.