The stratigraphy and structure of the Whithorn area of Wigtownshire, Scotland

Publisher Website
Google Scholar
Abstract
Synopsis: The rocks of the Whithorn area comprise two groups of Silurian strata: the Riccarton Beds, of Wenlock age, and the Hawick Rocks. The boundary between these groups is reinterpreted as a strike fault with major southward downthrow. Five fold movements have been recognised in the area. The first two comprise N.E.-S.W. folds and are responsible for the major monoclinal structure of the area. Folds of the third movement have E-W axial planes and steep plunges, and are considered contemporaneous with members of the Caledonian dyke suite. Fourth generation folds have low-angle axial planes, and are associated with late thrusts and mineralisation (probably Hercynian). The latest folds, dextral kink bands with N-S modal trend, are believed to post-date a Tertiary dyke series. Early thrusts are associated with the first folds, and a conjugate set of wrench faults with the second folds. It is suggested that strike faults originated as dip-slip fractures before or during the second fold movement, and were later reactivated by strike- and oblique-slip movement. The structural history of the area is found to be comparable with those of other parts of the southern Caledonian fold belt, especially the Silurian areas.