The northern Kongsberg series and its western margin.

Abstract

In the Kongsberg Series a major fold interference pattern was established during the Svecofennian orogeny before westward thrusting over the Telemark block developed a margin of ultramylonite (preserved from Flesberg to lake Soneren): further north (to Ådal) this was cut out by a later mylonite. A subsequent, basic intrusive phase was associated with rifting, which was aborted by the onset of the Sveconorwegian (Grenvillian) Regeneration. Late reactivations of the whole margin caused brittle faulting and developed the so-called \"friction breccia\". The early regional structure and its relics could explain many features of the Kongsberg Series; in particular, the Modum area complex may represent Bamble Series rocks infolded into the Kongsberg series during the Svecofennian orogeny.