Lyell Collection
Journal of the Geological Society
Lyell Centre  |   Lyell Collection  |   Subscriptions   |   Geological Society  |   Email alerts  |   Online bookshop  |   Help

Keywords:
Author:
Advanced search>>
This Article
Right arrow Full Text (PDF)
Right arrow References
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by WARRAK, M.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation
Journal of the Geological Society; 1974; v. 130; issue.3; p. 229-245;
DOI: 10.1144/gsjgs.130.3.0229
© 1974 Geological Society of London

The petrography and origin of dedolomitized, veined or brecciated carbonate rocks, the ‘cornieules’, in the Fréjus region, French Alps

MOHAMMED WARRAK

Cornieules (or rauhwackes) are essentially dedolomitized, veined or brecciated carbonate rocks or marls with a characteristic porous to cellular appearance. In hand specimen, they can be divided into two types, those with a veined structure, and those showing a brecciated structure. In the Fréjus region and in most other areas both inside and outside the Alps, cornieules are restricted in occurrence to evaporitic sequences. They are frequently associated with gypsum or anhydrite, which suggests a genetic link between cornieule and evaporites. This was confirmed when a full petrographic investigation was carried out, first on a Triassic evaporite sequence and then on cornieules. Field and petrographic evidence has revealed that cornieules are formed from a starting material of gypsum and dolomite that had been fractured, veined and brecciated many times. The causes of fracturing were probably tectonic in the initial phases, and non-tectonic later. Due to the major post F4 metamorphism, the gypsum was replaced by calcite and the calcite was subsequently dolomitized. Dolomitization was accompanied by a 12–13% increase in porosity. When the rocks were brought near to the earth’s surface, chemically active sulphate-rich percolating solutions invaded the rocks, brought about dedolomitization and formed the cavernous structure of cornieule.




This article has been cited by other articles:


Home page
 Geological Society, London, Special PublicationsHome page
W. Alberto, F. Carraro, M. Giardino, and D. Tiranti
Genesis and evolution of 'pseudocarniole': preliminary observations from the Susa Valley (Western Alps)
Geological Society, London, Special Publications, 2007; 285: 155 - 168.
[Abstract] [Full Text] [PDF]

Home page
 Geological Society, London, Special PublicationsHome page
J. P. Platt, P. C. Cunningham, P. Weston, G. S. Lister, F. Peel, T. Baudin, and H. Dondey
Thrusting and backthrusting in the Brianconnais domain of the western Alps
Geological Society, London, Special Publications, 1989; 45: 135 - 152.
[Abstract] [PDF]

Home page
 Geological Society, London, Special PublicationsHome page
A. Beach
Some observations on the development of thrust faults in the Ultradauphinois Zone, French Alps
Geological Society, London, Special Publications, 1981; 9: 329 - 334.
[Abstract] [PDF]