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Historic models for the origins of the Montagne Noire dome

This summary is adapted from Van Den Driessche & Brun (1991-2) (drawings drawn by Paul Proudman after Van Den Driessche & Brun (1991-2) )

1, Diapiric uplift (A&B) (Schuilling, 1960). The large contrast between the high temperature low pressure high metamorphic grades of the migmatites of the interior and the low grades of the nappes outside supports this view.     2, Wrenching and diapirism (C) (Arthaud, 1970).The dominant theme of this model is the large shear zones. There are axial trending lineations and upright foliation in the south.   The causes of diapiric uplift are thought to be either shear heating or the thickening of the crust during the earlier thrusting.         An apparent shortening is due to the intersection between the early regional foliation and a superimposed upright cleavage.

Lineation directions are variously parallel or perpendicular to structural movement during uplift.       3, The compressive anticline models (D&E) (Arthaud, et al 1966) This anticline results from NS shortening parallel to the bulk Variscan shortening.   4, Metamorphic core complex models (F) (Van Den Driessche & Brun, (1989) etc. the similarity between the strain patterns seen in the Montagne Noire and the Basin and Range province is striking. Ductile normal faults are induced by the influence of gravity on the thickened crust. Some propose that the ENE - WSW dome axis is controlled by symmetrical earlier Variscan faults. Others see asymmetry due to detachment on the Northern margin.

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This page is maintained by Paul Proudman, Geology, School of Biology and Molecular Sciences, Oxford Brookes University, Gipsy Lane Campus, Headington, Oxford, OX3 OBP UK

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Last Modified: 25 June 03