Premium
The structure of the Skiddaw Slates in the Blencathra‐Mungrisdale area, Cumbria
Author(s) -
Roberts D. E.
Publication year - 1977
Publication title -
geological journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.721
H-Index - 54
eISSN - 1099-1034
pISSN - 0072-1050
DOI - 10.1002/gj.3350120104
Subject(s) - slates , geology , batholith , orogeny , crenulation , fold (higher order function) , tectonics , cleavage (geology) , geosyncline , bedding , diapir , geochemistry , volcanic rock , syncline , foliation (geology) , paleozoic , metamorphic rock , paleontology , volcano , mechanical engineering , fracture (geology) , biology , shear zone , horticulture , engineering
Four phases of deformation (D1‐D4) and a ubiquitous non‐tectonic bedding‐cleavage are described. D1 structures are gravity collapse folds without an associated cleavage, formed before the extrusion of the Borrowdale Volcanics. Pre‐Bala folds recognised in the Volcanics are not readily observable in the Slates on a small scale, but may be present on a wider aspect. D2‐D4 folds and cleavages are end‐Silurian structures, the result of the main closure of the Lake District Geosyncline during the Caledonian Orogeny. D2 is the result of crustal shortening and is closely related in time to the emplacement of the Skiddaw Granite; D3 resulted from vertical shortening in conjunction with the intrusion of the Lake District Batholith; and D4 resulted from post‐granite shortening of the existing fold axes. A correlation of the history of deformation with those of other areas is also suggested.