The nature and tectonic setting of mélange deposits in Soknedal, near Støren, Central Norwegian Caledonides.

Abstract

A sedimentary m\u00E9lange occurs as a mega-lens just east of the disjunctive boundary between the Støren Nappe and the Gula Nappe within the Trondheim Nappe Complex in the Soknedal-Støren area. Packets, blocks and shreds of pervasively sheared Gula and Støren lithologies occur as fragments within a virtually undeformed siltstone-greywacke matrix. The lithology is considered to represent an oliostrome with matrix material chiefly derived from the volcanic and volcanoclastic units of the Hovin and Horg Groups, but also from the Støren and Gula Groups. Evidence points to deposition after obduction, folding, thrusting and graviatational sagging with small-scale renewed thrusting of the Støren Nappe. The petrology of the m\u00E9lange and the tectonic evolution of the adjacent nappe units suggest a late Silurian age for the olistostrome.