This book deals with the geological record and the evolution of ideas concerning the Variscan orogenic belt in France and neighboring regions.
Volume 1 is based on a general introduction concerning the imprint of the Variscan period on the geology of France, as well as on the particularities of the study of this ancient orogen. A history of the concepts applied to the Variscan belt is proposed in order to consider this orogen in the history of Earth Sciences. A paleogeodynamic analysis of the Variscan cycle sets the general framework for the evolution of the orogen, which is then tackled through the prism of the magmatic, metamorphic and tectonic record of the early phases (from Cambrian to Lower Carboniferous).
Volume 2 proposes an analysis of the late evolution of the Variscan orogenic belt, reflecting its dismantling in a high-temperature context during the Upper Carboniferous and Permian. The sedimentary archives are described, as well as the questions raised by the specificities of this ancient orogen.
Table of Contents
Preface ix
Yoann DENÈLE and Julien BERGER
Introduction xi
Yoann DENÈLE and Julien BERGER
List of Figures xxiii
Chapter 1 High-Temperature Metamorphism and Syn- to Late-Orogenic Magmatism 1
Arnaud VILLAROS, Oscar LAURENT, Simon COUZINIE and Jean-François MOYEN
1.1 Introduction 1
1.2 High-temperature/low- to medium-pressure metamorphism and partial melting of the Variscan crust 5
1.2.1 Evolution of high-temperature metamorphism 5
1.2.2 Petrology of high-temperature metamorphism 7
1.3 Late-orogenic magmatism 13
1.3.1 Two mica peraluminous leucogranites (MPG) 13
1.3.2 Biotite and cordierite peraluminous granites (CPG) 14
1.3.3 K-rich calc-alkaline granitoids (KCG) - durbachites, vaugnerites 16
1.3.4 Synchronous orogenic volcanism of HT metamorphism 17
1.3.5 Overview 18
1.4 Causes and geodynamic implications of crustal melting 19
1.4.1 Synchronous crustal melting episode of the Variscan collision 19
1.4.2 Melting associated with orogenic extension 19
1.4.3 High-temperature melting and the formation of domes 20
1.4.4 Synthesis of HT metamorphic evolution 22
1.4.5 Outlook 23
1.5 References 24
Chapter 2 Late-Orogenic Structural Reorganization of the Variscan Belt during the Upper Carboniferous 35
Yoann DENÈLE and Bryan COCHELIN
2.1 Introduction 35
2.2 Major structures of the Variscan belt of Western Europe 38
2.3 Ibero-Armorican Arc 43
2.3.1 Formation of a major orocline in the upper Carboniferous 43
2.3.2 Structure and evolution of the Armorican domain 46
2.3.3 The Armorican shear zones 49
2.3.4 A simple shear model in a horizontal plane at the scale of the Central Armorican domain 53
2.4 Late orogenic deformation in the internal domain 56
2.4.1 South Armorican domain: thinning and longitudinal stretching of a previously thickened domain 56
2.4.2 The Carboniferous syn-tectonic plutons of the French Massif Central: interaction between strike-slip shear zone and longitudinal extension 65
2.4.3 The Velay dome and the Pilat detachment: transverse extension in the hinterland 74
2.5 Late-orogenic deformation in the southern foreland domain 77
2.5.1 The Montagne Noire migmatite-cored gneiss dome 77
2.5.2 The Variscan segment of the Pyrenees 85
2.6 Summary and discussion on the restructuring of the Variscan belt in the Carboniferous 93
2.7 Conclusion 99
2.8 References 99
Chapter 3 Sedimentary Basins and Evolution of Reliefs Associated with the Variscan Cycle in France and Adjacent Countries 121
Markus ARETZ, Élise NARDIN, Frédéric CHRISTOPHOUL, Julien DENAYER
3.1 Introduction 121
3.2 Foreland basins along the Southern Laurussian Margin 122
3.2.1 The Ardenne and the Boulonnais 123
3.2.2 Rhenish Massif 138
3.3 Basins in the Inner Variscan zone 146
3.3.1 Armorican Massif Basins 147
3.3.2 Northern Vosges 152
3.4 Regions of the Gondwanan Margin and Foreland Basin 152
3.4.1 Middle Vosges and Southern Vosges 153
3.4.2 Morvan 154
3.4.3 Montagne Noire: reference for the Peri-Gondwanan Foreland Basin 154
3.4.4 The Pyrenees 162
3.5 Post-orogenic stage: Stephanian-Permian basins 169
3.5.1 Stratigraphy 171
3.5.2 Geodynamic and structural context 172
3.5.3 General sedimentological trends in Stephanian-Permian basins 177
3.6 Conclusion 179
3.7 References 181
Conclusion 203
Yoann DENÈLE and Julien BERGER
List of Authors 215
Index 217
Summary of Volume 1 219
