Relasjonen mellom senkaledonsk tektonikk og sedimentasjon ved Hornelens og Håsteinens devon.

Abstract

The Old Red in western Norway form very thick \"molasse\" deposits. The Håsteinen district is made up of coarse breccia with an estimated thickness of more than 1000 m and the Hornelen district has mainly sandstone with an estimated thickness of 20-25 000 m. The apparent enormous thickness of the latter series is difficult to reconcile with normal sedimentation in a vertically sinking basin. Reusch (1881) called attention to the regular eastern dip of the Devonian deposits, and suggested that the position might be primary, like the foreset of a delta deposit. However, the eastward dipping attitude of the Hornelen series cannot be primary because numerous mud-cracks and ripplemarks in the bedding surfaces reveal that the sediments were deposited in a state that was not far from horizontal. In this preliminary paper attention is called to major dislocation zones in the area between the Devonian deposits. These dislocation zones contain mylonitized rocks and often separate major geologic units. Most of them strike WSW-ENE and dip 35-60 degrees towards north, and it is believed that they represent normal faults with some strike-slip movement towards east.