The structure metamorphism, and stratigraphy of the skiddaw Slates, east of Crummock Water, Cumberland

Jeans, Peter J.F. (1974). The structure metamorphism, and stratigraphy of the skiddaw Slates, east of Crummock Water, Cumberland. University of Birmingham. Ph.D.

Preview

Jeans1974PhD.pdf
Text - Accepted Version
Available under License All rights reserved.
Download (27MB) | Preview

Abstract

The Skiddaw Slates succession of this area is 7,500’ thick, and is sub-divided into five lithological groups:-
Buttermere Slates
Whiteless Pike Slates
Mosser-Kirkstile Slates
Loweswater Flags
Hope Beck Slates
Intruded into these sediments are two distinct groups of basic igneous bodies. Those of the south are very tholeiitic in composition, whereas those of the north are more silica-rich and show close geochemical affinities to the northern - Eycott - outcrop of the Borrowdale Volcanic Group.
Both the sediments and the basic igneous rocks were subjected to very low (chlorite) grade regional metamorphism towards the end of the Silurian period.
In addition, the central part of the area suffered a low-grade contact metamorphism, generating ?cordierite, andalusite, and biotite in suitable lithologies and effecting an overall baking of the aureole rocks.
The aureole is the result of the postulated intrusion beneath the area of a granitic pluton; the granite is thought to be related to the Skiddaw and Eskdale Granites (dated radiometrically at 395 +/- 14 m.y.).
Four phases of deformation have been recognized within this area. F1 structures are represented by N - S striking overturned folds, with no cleavage, and are of pre-Borrowdale Volcanic age. F2 - F4 are end- Silurian events; F2 deformation produced ENE - WSW trending folds, with an associated fracture cleavage, and refolded the F1 folds into their present, generally steep-plunging, attitude. F3 folds, characterized by horizontal axial planes, are open warps with an associated fracture or crenulation cleavage; F4 folds are open structures, with NW - SE axial planes. These last two events, FJ and F4 are thought to be due, respectively, to vertical and axial compression consequent upon the flattening of the rocks induced by F2.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):