Dunmoor Hill

I trace samples of dioritic ‘Marginal’ rock between NT 97475 17206 and NT 96914 17281 to see whether there is any significant change in mafic content approaching the junction with the andesite.
I found no evidence, at least on Dunmoor Hill, for increasing mafic content towards the perimeter of the pluton. There are however local variations which are consistent with the principle of local fractionation bands within the Marginal.