The Pebidian Supergroup is interbedded basic lavas and acid tuffs, is cut by the St David's Granophyre.
12.
Granophyre may also form as the uppermost stratigraphic layer resulting from melting of upper-middle crustal rocks by a meteorite impact.
13.
The components here are called Fort Regent / Elizabeth Castle Granophyre, Dicq Granite, Longueville Granite, and La Roque Granite.
14.
The Granophyre is dated at 560 + /-1Ma and is thought to be related to the volcanic events in the area.
15.
The Ercall Granophyre is overlain by shallow dipping Cambrian rocks ( in relation to the steeply dipping Uriconian volcanics ) which contain Atdabanian fossils.
16.
These cooled to form very hard granophyre and felsite rocks in fact two'rink dykes'or the " outer " and " inner " rings.
17.
This leads to suggest that the area was affected by ( Uriconian ) volcanism and associated events between 570-550Ma including the intrusion of the Ercall Granophyre.
18.
On Orval and Ard Nev the weathered basalt and granophyre has been sorted by frost heaving into circles 50 centimetres in diameter and weathering on Barkeval has produced unusual rock sculptures.
19.
The SIC is believed to be a stratified impact melt sheet composed from the base up of sublayer norite, mafic norite, felsic norite, quartz gabbro, and granophyre.
20.
The texture should not be confused with myrmekite or granophyre, in which quartz forms club-shaped, curved or vermiform threads intergrown with plagioclase feldspar and alkali feldspar, respectively.
