GEOLOGICAL HISTORY OF THE MORVAN

VARISCAN OROGENY

Part 3

The Hercynian Belt at the end of the Variscan Orogeny

Note: the intrusions of Carboniferous granites and the Carboniferous and Permian basins are non represented on these two diagram-blocks.

Neovarisque 2

In the Arverno-vosgian zone (Z. A-V.) the orogenic front progress southward, each of the 3 stages being marked by the boundaries of the tectonic nappes successively overthrusted during Devonian (j D: Brévenne)), then Visean (j V: Rouergue) and at last Namuro-Westphalian (j NW: Montagne Noire).

The Saxothuringian zone (Z. S-T.) comprises the Mid-German Crystalline Rise (zone cristalline) to the North and two tectonic units of Ordovician to Carboniferous formations (o.c.) to the South, enclosing a more metamorphic unit, leptyno-amphibolic (L.A.) having probable tectonic roots in the Moldanubian zone (Z.M.) .

In the southern part of the Rhenohercynian zone (Z. R-H.) , the Phyllitic zone (Z.P.) composed of metamorphic rocks with relics of high pressure minerals associations is interpreted as the trace of the subduction zone active between 380 et 350 Ma and the Rheic Ocean suture [REF], [REF].


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