Relief variation and erosion of the Variscan belt: detrital geochronology of the Palaeozoic sediments from the Mauges Unit
(Armorican Massif, France)
Céline Ducassou
Marc Poujol
Gilles Ruffet
Olivier Bruguier
Michel Ballèvre
10.6084/m9.figshare.3453674
https://geolsoc.figshare.com/articles/dataset/Relief_variation_and_erosion_of_the_Variscan_belt_detrital_geochronology_of_the_Palaeozoic_sediments_from_the_Mauges_Unit___Armorican_Massif_France_/3453674
<p>The sediments of the Mauges Unit located in the internal zone provide an opportunity of studying the evolution of relief during
Palaeozoic time. U–Pb dating on zircon and <sup>39</sup>Ar/<sup>40</sup>Ar on white mica are used to constrain the age and nature of the sources. The first relief identified is marked by an Early
Devonian unconformity interpreted as the opening of a northern back-arc basin. Detrital minerals are first reworked from underlying
layers indicating a local supply. Magmatic zircons at <em>c.</em> 400 Ma then record the emergence of a magmatic arc. During the Middle Devonian, the gap in the sedimentary record is attributed
to an emersion followed by the disappearance of the relief during the Late Devonian. At the Devonian–Carboniferous boundary,
the main collision is followed by the onset of a relief. The continental sedimentation in the Ancenis Basin (late Tournaisian–Viséan)
is a coarsening-upwards megasequence indicating an increasing and/or approaching relief. The detrital minerals record the
progressive exhumation of Variscan metamorphic (mica at <em>c.</em> 350 Ma) and magmatic rocks (zircons at <em>c.</em> 390–340 Ma). The Serpukhovian–Bashkirian sedimentation records the erosion of a proximal metamorphic source (Champtoceaux
with micas at <em>c.</em> 350–340 Ma) showing a much shorter drainage system.
</p>
2016-06-21 11:36:12
detrital minerals record
Mauges Unit
mica
zircon
Devonian
relief
Geology