The geology and petrology of the ennerdale granophyre, its metamorphic aureole and associated mineralization

The Ennerdale Granophyre occurs in the Lake District between Buttermere and Wasdale. It is a stock shaped, composite intrusion which was emplaced at the close of the Caledonian earth movements. The country rocks of the granophyre are the Borrowdale Volcanic Series and the Skiddaw Slates. The oldest rocks in the Ennerdale Granophyre are a series of dioritic rocks which have been largely metasomatised by the later granophyre magma into a series of granodioritic hybrids. Eighty percent of the outcrop of the Ennerdale Granophyre is occupied by a fine grained granophyre, the Main Granophyre. The youngest rocks associated with the granophyre are a series of fine aplitic microgranites and rhyolitic felsites. Metamorphism by the granophyre has been very slight. The main changes in the Skiddaw Slates are a change in colour and an increase in hardness, but the slates in places in Ennerdale have been soda-metasomatised. Macroscopic changes in the Borrowdale Volcanic Series are negligible, but there have been important mineralogical changes within a narrow aeureole adjacent to the granophyre.