The Oslo Graben was formed during a geologic rifting event in Permian time. The rift formation was accompanied by volcanic activity and associated Rhomb porphyry lava flows. It is located in the area around the Norwegian capital Oslo. It is often referred to as the Oslo Rift. USGS image In geology, a rift is a place where the Earths crust and lithosphere are being pulled apart. ... The Permian is a geologic period that extends from about 280 to 248 million years before the present (mya). ... This article is about volcanoes in geology. ... Rhomb porphyry from the Oslo rift area in Norway Rhomb porphyry is a volcanic rock with gray-white large porphyritic rhomb shaped phenocrysts enbedded in a very fine grained red-brown matrix. ... County Oslo NO-03 Landscape Viken Municipality NO-0301 Administrative centre Oslo Mayor (2004) Per Ditlev-Simonsen (H) Official language form Neutral Area - Total - Land - Percentage Ranked 224 454 km² 426 km² 0. ... The Oslo Graben was formed during a geologic rifting event in Permian time. ...
The lava production was high when the rhomb porphyry lavas were deposited. The lavas reflect a period of abundant earthquake-related movements, when strong forces tore the crust apart.
In the Vestfold district, one lava flow was deposited on average every 250 000 years. Here occurs a 3000 metre thick sequence of mainly volcanic material. In the Oslo area, lavas were deposited on average every 800 000 years. Only a few plant remains have been found between these lavas. Vestfold is a county in Norway, bordering Buskerud and Telemark. ... County Oslo NO-03 Landscape Viken Municipality NO-0301 Administrative centre Oslo Mayor (2004) Per Ditlev-Simonsen (H) Official language form Neutral Area - Total - Land - Percentage Ranked 224 454 km² 426 km² 0. ...
In particular, the OsloGraben and the northern North Sea rift initiated in close areas of northern Europe.
The OsloGraben evolved in the cold and stable Precambrian lithosphere of Fennoscandia, whereas the northern North Sea rift took birth in freshly reworked Caledonian lithosphere.
Consequently, we suggest that rifting in the northern North Sea began as early as regional extension was effective (i.e., Late Carboniferous–Early Permian) and does not postdate the OsloGraben as it is commonly assumed.
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