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Slieve Gullion Ring - Slieve GullionArmagh
PHOTO TO BE ADDED Crag overlooking forest scenic drive, south-west of summit of Slieve Gullion, Co. Armagh.
Summary Full report
Site Type: Crag, Crags
Site Status: PASSI
District: Newry & Mourne District Council
Grid Reference: J020198
Rocks
Rock Age: Tertiary (Palaeogene)
Rock Name: Slieve Gullion Complex
Rock Type: Dolerite, Granite, Granophyre
Interest
Other interest: magma mixing, net veins, pipes, sill, Intrusion

Summary of site:

This account describes layer 10, one of 13 layers forming the central mass of Slieve Gullion. The context for this site is given in the Slieve Gullion Ring Overview, site1118.

Layer 10 is exposed south west of the summit of Slieve Gullion and is a dolerite (medium-grained, dark coloured rock of basaltic composition) injected horizontally into the local host rock, the much older Newry granodiorite. Narrow vertical pipes of granophyre, a type of granite, and mixed hybrids with dolerite terminate blindly in this layer and probably originate in veins and sheets below. Networks of veins permeate the dolerite and rounded pillow-like masses of dolerite can be seen in the cliff above the summit car park. This site shows that basic and acidic magmas co-existed, that the dolerite chilled against the cooler granophyre and the two rocks mixed in places to form hybrids. The blind pipes are unique to layer 10. The pillow-like masses are due to bulging on the interface between the two magmas. This site is an essential component of our overall understanding of the Slieve Gullion Ring complex and should be designated.


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