## Abstract A RbβSr wholeβrock isochron study indicates that the entire Donegal granite suite was emplaced into orthotectonic Caledonian (Dalradian) rocks over a short interval during midβSilurian to earliestβDevonian times. The Thorr pluton, probably the earliest member of the suite, yields an age
The origin of banding in the Main Donegal Granite, N.W. Ireland
β Scribed by A. R. Berger
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 841 KB
- Volume
- 7
- Category
- Article
- ISSN
- 0072-1050
No coin nor oath required. For personal study only.
β¦ Synopsis
This Caledonian pluton exhibits a regular, sub-vertical banding in which layers of dark, relatively fine grained trondhjernite alternate with layers of light, coarse grained granite. The textures and the presence of cross-cutting bands of granite indicate that the light bands were derived by potash feldspathization of the trondhjemite. The geometry of the banding indicates that it formed during the "synplutonic" deformation of the pluton, largely in situ. The bands formed by segregation of alkalies into dilatant zones of movement produced during the deformation of partly consolidated magma.
π SIMILAR VOLUMES
## Abstract Seven phases of deformation are recognised in Dalradian metasediments within the NW aureole of the Main Donegal Granite. Major NW facing F2 folds (the Aghla Anticline and Errigal Syncline) refold an originally NW facing slaty cleavage, which is usually parallel to bedding. D3 structures
## Abstract A recent interpretation of the structural geology and chronology of the northwestern envelope of the Main Donegal Granite by Hutton (1977) is critically examined. Although many aspects of this analysis are sound, there remains serious doubt concerning Hutton's main conclusion that the
I thank Dr. Berger for his comments on an earlier paper of mine (Hutton 1977) and welcome this opportunity to clarify and expand on various aspects of that work. Berger (1980) has divided the Creeslough Formation in its type area into a lower 'calcareous' unit (occurring in the SE) and an upper pel
The crr.400Ma Caledonian Barnesmore complex, Donegal, includes a 1.5 km' area in the Main Granite (G2) in which pristine biotite monzogranite has undergone in sifu alteration to brick-red, two feldspar, chloritic syenite which is virtually quartz-free. The principal chemical changes involve major el
## Abstract The structural relationships of several intrusive sheets belonging to the extensive metadolerite suite of the Appin (lower) Dalradian rocks of the Creeslough area, northwest Donegal, Ireland have been examined. It is concluded that, relative to the regional chronology of deformation of