Low grade (greenschist facies) metamorphism in southern Prins Karls Forland, Svalbard

Abstract

The pre-Carboniferous miogeosynclinal sedimentary and volcanic sequences of south-central Prins Karls Forland belong to a suite of rocks known as the Forland Complex. During early Palaeozoic diastrophism the Complex of Prins Karls Forland experienced predeformational, low grade metamorphism. A knowledge of the stratigraphy and structure of the region, together with an analysis of metamorphic mineral assemblages and reactions enable the conditions of metamorphism to be determined within certain limits. It is found that temperatures during metamorphism were between 400°C and 500°C, and pressures were about 6 kb. These conditions provide an estimate of palaeogeothermal gradient, consistent with observed mineralogies, of 18 to 21°C.km?1. In addition, compositional variations within mineral phases are found to be largely dependent upon bulk-rock chemistry, and are of limited use in determining grade changes.