The influence of hurricanes upon the quiet depositional conditions in the Lower Emsian La Vid shales of Colle (NW Spain)

The author supposes that the fossil content of thin carbonate units in the Upper La Vid shales (Lower Devonian) of Colle was influenced by heavy storms like hurricanes. Apart from microplankton (Cramer, 1964) no fossils are found in the shales. Together with the very well developed fissility of the shales this points to abiotic conditions, probably caused by the lack of oxygen in the deposition area. Alterations, e.g. by storms, of the water circulation pattern in the basin destroyed this situation, and a pioneer fauna was able to develop. Sometimes storm debris, probably deposited by hurricanes, served as a substrate for larvae which settled in the area. Little by little the former situation of lack of oxygen returned and the communities died.