Production of multi-décollement folding by pressure release in the formation of a microbreccia at Lough Doon, Donegal, eire
✍ Scribed by M. T. Holder
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 867 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0072-1050
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✦ Synopsis
An unusual matrix-supported microbreccia of Caledonian age is described from the Dalradian rocks of Donegal. Field and textural relationships indicate that the breccia formed 'in situ' by a non-dilational mechanism during regional deformation. The presence of breccia veins of low competancy during this deformation caused multi-dtcollement folds to be formed adjacent to the breccias. A cyclical mechanism of formation of these breccias is proposed in which fluctuations in the overpressuring of pore fluids escaping from an adjacent crystallizing appinite mass caused periodic excursions from ductile to brittle deformation during the regional folding.