The environmental significance of algae in the mi Llandovery succession of the central Oslo Region

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Abstract
Girvanella, micritization phenomena and the dasycladacean Cylocrinites were found in the middle Llandovery succession of the central Oslo region. Both Girvanella and micritization phenomena occurred in carbonate-dominated sequences where sedimentary structures and associated faunas suggest depositional environments above normal wave base. In contrast, Cyclocrinites occurred in shale-dominated sequences where other evidence suggests quiet, deep-water environments. Cyclocrinites may not normally be preserved in situ in its life environment in relatively turbulent shallow waters. Preservation most commonly resulted from postmortem transport into low-energy muddy enviroments devoid of in situ algal activity. The resultant fossil was a flattened cast of this originally spherical alga.