Mont Chenaillet
| Mont Chenaillet | ||
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 The ophiolite from Mont Chenaillet - southwest ridge |
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| height | 2650 m | |
| location | Hautes-Alpes , France | |
| Mountains | Massif du Queyras , Cottian Alps | |
| Dominance | 7 km → Mont Chaberton | |
| Notch height | 1850 m ↓ Col de Montgenèvre | |
| Coordinates | 44 ° 54 '8 " N , 6 ° 44' 25" E | |
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| Normal way | From Montgenèvre | |
The 2650 meter high Mont Chenaillet is a peak in the French western Alps . It is located in the department of Hautes-Alpes ( Region Provence-Alpes-Côte d'Azur ) and is part of the Massif du Queyras the Cottian Alps . The Italian border runs not far to the east.
geography
The Mont Chenaillet, often just Le Chenaillet , can be reached from Montgenèvre in the north via the 2519 meter high Collet Vert (or Colletto Verde ). The geological nature trail starting at the Chalmettes lift station also leads over the southwest ridge to the summit. Another access is from Cervières via the southern flank.
The summit of Mont Chenaillet sends out three ridge systems . It is not located directly on the main Alpine ridge , but is offset a little to the southwest. Rather, the latter runs over the neighboring summit of the Grand Charvia (2648 meters), which is almost 1000 meters further northeast, and follows the French-Italian state border.
The southwest ridge of Mont Chenaillet leads to the 2,459 meter high Sommet des Anges , the saddle on the Cabane des Douaniers is at 2,297 meters. The northeast ridge to Grand Charvia saddles in the 2522 meter high Col du Chenaillet . The north-north-west ridge slopes down quite steadily to the Chalmettes station at a little over 2200 meters .
Hydrography
On the southwest side of Mont Chenaillet, the Durance rises in several source streams that later join together and drain the Replat du Gondran to the north. The source of the Dora Riparia (referred to here as Doire ) is on the northeast flank of the summit. In the south runs the valley of the Cerveyrette , a left tributary of the Durance.
geology
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The specialty of Mont Chenaillet lies in its geological structure . On the mountain there are pillow lavas , gabbros and serpentinites . These rocks are the remains of an autopsied oceanic crust that slipped onto the European continental margin during the course of the Alpine orogenesis . The Mont Chenaillet thus represents an alpine ophiolite complex - part of the western alpine ophiolite , WAO for short . Its age is estimated at 165 to 153 million years and should therefore come from the Callovian / Kimmeridgian period.
The summit is made up of dark pillow lavas that were likely to have emerged on or near a mid-ocean ridge , recognizable by their chemical composition (MORB signature). At the southwest ridge towards Replat du Gondran the pillow lava above gabbros, the rare passages of dolerite have. The contact between pillow lavas and gabbros is tectonic in nature and follows an undersea detachment . The gabbros are in turn underlain by serpentinites - former hydrothermally modified peridotites . The bed of the serpentinites forms the main thrust horizon on which the oceanic rocks of the Chenaillet ophiolite had slid westward towards the Sommet des Anges over under chalk sediments of the Queyras ophiolite .
On the northeast ridge near the Col du Souréou, ophicalcite breccias appear , consisting of serpentinite fragments in a calcareous matrix. They can be alternately stored with basaltic effusions or covered with under chalk sediments. The ophicalcites are believed to be of hydrothermal origin and associated with submarine faults that caused hot solutions to swell.
Petrologically, the ophiolite belongs to the LOT type ( Lherzolithic ophiolite type), which currently arises on slowly spreading mid-ocean ridges (such as in the Atlantic ). This type is characterized by a very low rate of melting of the underlying earth mantle - recognizable by the very rare presence of conveyor tunnels in the gabbros.
history
Due to its high alpine location along the watershed, Mont Chenaillet formed part of the French defense system in Briançonnais . Already under Louis XIV. The eastern border of France - starting with the strongholds of Vauban up to the Maginot Line - was fortified more and more. Nevertheless, on June 23, 1940, the Italian offensive succeeded in temporarily breaking through and taking the defensive line. This was repeated again in 1944 by a German-Italian battalion, despite the resistance of French troops reinforced by Moroccan units. Shrapnel from this period can still be found scattered across the ground.
literature
- Jacques Debelmas among others: Alpes du Dauphiné . In: Guides géologiques régionaux . Masson, 1983, ISBN 2-225-78276-8 .
Individual evidence
- ↑ Gianreto Manatschal and O. Müntener: A type sequence across an ancient magma-poor ocean-continent transition: The Example of the western Alpine Tethys ophiolites . In: Tectonophysics . tape 473 , 2009, p. 4-19 .
