Trenching and 14C dating of the postglacial Stuoragurra Fault Complex in Finnmark, Northern Norway, and geohazard implications

Abstract

The Stuoragurra Fault Complex (SFC) constitutes the Norwegian part of the larger Lapland Province of postglacial faults in northern Fennoscandia. The 90 km long SFC consists of two separate fault systems: the Máze Fault (revised) System in the southwestern area and the Iešjávri Fault System to the northeast. The distance between the fault systems is 12 km. The faults dip at an angle of 30–75° to the SE. Here we present data from trenching of different fault sections. The trenching reveals deformed overburden in all 11 sites and inclusions of peat and organic bearing soil in the deformed and partly overrun loose deposits on the footwall in most of the sites. Radiocarbon dating of macro remains of plants located in buried and severely deformed sediment horizons indicates late Holocene ages for the (final) formation of the different fault segments, more specifically that the faulting at Fitnajohka and Máze in the Máze Fault System formed during earthquakes younger than c. 470-500 years ago.