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Articles |
ák Event in the Devonian terrestrial environment and its implications for understanding land–sea interactions
1 School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Waterfront Campus, European Way, Southampton SO14 3ZH, UK (e-mail: jeam{at}noc.soton.ac.uk)
2 School of Human and Environmental Science, The University of Reading, Whiteknights, PO Box 217, Reading RG6 6AH, UK
3 The Park, Hillside Road, Stromness, Orkney, KW16 3AH, Scotland
4 Institute of Geology, Tallinn University of Technology, Estonia Avenue 7, 10143 Tallinn, Estonia
5 Vilnius University, 21 Ciurlionio, LT-2009 Vilnius, Lithuania
The Ka
ák Event is a late Eifelian (Mid-Devonian) episode of marine dysoxia/anoxia with associated extinctions. It has been widely recognized in the shelf seas that surrounded the Old Red Sandstone continent. It was contemporary with the lacustrine Orcadian Basin in Scotland. This basin contains the distinctive Achanarras lake horizon that contains a rich and diverse fish fauna. The Achanarras lake was wide and deep and would have been filled by rainfall from a monsoon system at an insolation maximum. Faunal elements within the lake are in common with the Kernav
Member in Estonia and this level can be conodont dated as late Eifelian eiflius or ensensis Zone. Therefore the group of lacustrine flooding climatic events that occur at and above the Achanarras level can be correlated with the marine Kaák Event (sensu lato) and both can be regarded as having a common climatic cause and driven by an insolation maximum. A reconstruction of the Orcadian Basin drainage system and a water balance model based on the calcium flux within the lake shows that a very significant volume of water would have been seasonally discharged to the Rheic Ocean and would have caused an additional environmental effect.
