Palaeolandscape Reconstruction of the South-Western Massif Central (France)
- Médard Thiry and
- Régine Simon-Coinçon
Published Online: 14 APR 2009
Copyright © 1999 The International Association of Sedimentologists
Palaeoweathering, Palaeosurfaces and Related Continental Deposits
How to Cite
Simon-Coinçon, R. (1995) Palaeolandscape Reconstruction of the South-Western Massif Central (France), in Palaeoweathering, Palaeosurfaces and Related Continental Deposits (eds M. Thiry and R. Simon-Coinçon), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304190.ch9
- Published Online: 14 APR 2009
- Published Print: 26 MAY 1995
Print ISBN: 9780632053117
Online ISBN: 9781444304190
- Continental uplands, enduring operation of long and complex subaerial processes;
- Palaeolandforms, surviving morphogenetic systems;
- ‘post-Hercynian’ peneplain;
- Carboniferous continental sediments, providing earliest indications of landscape development;
- tectonic rejuvenation, occurring in Early Jurassic;
- post-Hercynian palaeosurface, representing complex patchwork of landforms;
- south-western Massif Central, constituting ‘hinge’ zone
In subsiding areas, successive sequences of deposits progressively bury and protect each other. The sedimentary record in such areas is influenced fundamentally by the nature of the surrounding source regions, which control the lithological characteristics of the sedimentary infill. Continental uplands, on the other hand, enduring the operation of long and complex subaerial processes throughout changing tectonic and climatic environments, may keep only faint vestiges of these former imprints, making accurate geomorphological interpretation problematical. Clues for unravelling the geomorphological evolution of continents were sought by using usual tools of geomorphology (geometrical relationship between the landforms, weathering mantles, erosional processes), complemented by the results of mineralogical and geochemical studies.
The south-western Massif Central and its margins provide good case studies for palaeolandscape reconstruction. Its evolutionary history begins with the last uplift of the Hercynian range, at about 290 Ma and ends with the general inundation of the region 20 Ma. Landscape change beyond this time is not considered in this paper. Several periods have left distinctive traces in the modern landscape.
For example, albitization and dolomitization mark facets of ‘the post-Hercynian surface’ and are the characteristic products of peculiar geochemical environments. In the same way, calcretes mark an aridification of climates and seal the contemporary Tertiary palaeolandscapes. The typical weathered mantles of crystalline basement appear ubiquitous and are not so reliable for palaeolandscape reconstruction because they may have evolved through various palaeoenvironments.
Palaeolandforms can survive through a variety of morphogenetic systems and may be partly or totally inherited within younger landscapes. It is obvious that the major part of a landscape is polygenetic, having been submitted to successive degradational and rejuvenation events. Successive marine or lacustrine transgressions may seal and preserve the earlier landforms and palaeoweathered profiles. When exhumed, these palaeolandforms may be integrated in more recent landscapes and will profoundly affect their evolution.