Polyphase deformation in Oscar II Land, central western Svalbard

Abstract

Pre-Carboniferous rocks in central western Svalbard can be divided into two rock packages that have experienced three phases of deformation. The lower package includes upper Proterozoic sediments, the upper package is of upper Ordovician to lower Silurian age. Pre-upper Ordovician (Caledonian) deformation is characterized by north-south fold-axes, and is recorded in the lower package only. Following the Ordovician, east-west fold axes developed in the upper package but only locally in the lower. The third phase, probably Tertiary in age, produced easterly directed thrusting, and refolding about sub-horizontal, north-south fold axes in both packages. This complex structural history has resulted in tectonic thickening of the rock sequences by refolding and thrusting which has not been recognized by previous workers.