Die Gesteine der Inseln des zentralen Boknfjords. Beiträge zur Metamorphose und zum Aufbau der kambro-silurischen Gesteine des Stavanger-Gebietes III

Abstract

A metamorphic series of Cambro-Silurian sediments have been investigated in the Boknfjord area (SW-Norway) by mapping and petrographical studies. The lower division was found to be a weakly metamorphosed sequence of manifold interbedded layers of shales, sandstones, greywackes, arkoses, and pyroclastics. In the upper division metamorphosed basalts (amphibolites) and kindred pyroclastics are the most important rocks. The highest division of the series contains marbles mixed with basic pyroclastics and minor parts of clastics. In the Boknfjord section we have not the ideal case that the marginal parts of the geosynclinale region containing unmetamorphosed sediments have been preserved. But we can observe a gradually change of the Caledonian metamorphism succesively increasing from weakly metamorphosed sediments (quartz-albite-muscovite-chlorite-paragenesis) in the southeastern coast range into the highest facies (kyanite-almandine-muscovite-paragenesis) at the islands in the central parts of the Boknfjord basin. In accordance with our earlier papers (M\u00CFller & Wurm 1969 and 1970) we did not find any indication to the verification of Goldschmidt's hypothesis of the \"Injektions-Kontaktmetamorphose\" (1921) in the central Boknfjord area.