The structure and metamorphic petrology of the Eocambrian rocks of the Langstrand area, Soroy, northern Norway

• Main Author: Roberts, David
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 1965
• Subjects: Petrology; Langstrand; Norway; Northern Norway
• Online Access: https://repository.royalholloway.ac.uk/items/d008924b-7495-4eab-b283-56e75d9dd36b/1/

An investigation of the structures and metamorphic petrology of an area of Eocambrian rocks in Soroy, Northern Norway, forms the basis of this dissertation. The area is characterised by metasediments some of which enclose sheared lenticular bodies of metagabbro. Gneisses have been developed as products of granitisation.The stratigraphical order of the metasedimentary succession can be demonstrated by reference to sedimentary structures preserved in massive psammites. From this evidence, it is manifest that strata are Inverted over a large part of N.E. Sry, this inversion being attributed to the presence of early recumbent folds of considerable magnitude. In the surveyed area, major folds of a later, second deformation episode dominate the structural picture and refold the early structures. The second episode of folding was protracted and consists of two distinct phases. The main folding occurred early in this period while the later phase is characterised by a brittle deformation. Generally, second episode folds display monoclinic symmetry though in the south and west there is no uni-directional sense of fold overturning and the symmetry of movement is apparently orthorhombic. This difference of fold symmetry is clearly related to an orthogonal swing of strike direction. Textural studies of the metasediments in relation to the tectonic episodes allow a subdivision of the metamorphic history into a number of phases. A low grade metamorphism accompanied the early folding. The highest grade of regional metamorphism was established late in the static Interval separating the first and second deformation episodes. Coeval with this, a granitisation of the metasediments was effected which continued, in part, into the second episode of folding. Diaphthoretic phenomena characterise the later phase of brittle deformation.