The West Shetland Shelf : a recent storm-dominated, biogenic carbonate system

• Main Author: Light, Janice Marissa
• Published: Royal Holloway, University of London 2004
• Subjects: 551.4686133
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407435

The West Shetland Shelf (WSS) is a region of biogenic sedimentation within the North East Atlantic Cold Water Carbonate Province (NEACP) as defined in this thesis. Sediments and benthos collected from four transects across the continental shelf and shelf edge, associated side scan sonar and echosounder records and underwater video recordings, have been analysed and synthesised to identify the WSS sedimentary facies. The calcareous macrofauna whose skeletal remains contribute to the sediments have been identified from sorted subsamples and a spreadsheet of some 260 taxa has been statistically analysed to assist in community and facies recognition. The calcareous macrofauna, the sites of carbonate production on the shelf, and the taphonomic processes which affect the condition and preservability of the sediments, have been identified and assessed. Because most non-tropical carbonate sediments are produced biologically, their character is controlled by the indigenous organisms. In this modern WSS setting, certain taxa and associations of taxa play important roles in the carbonate system and these are identified and classified as sedimentary facies. The shell gravels and calcareous sands are focused around southern Shetland, Foula and Fair Isle as Facies Association A. The Ditrupa sediments of the distal middle and outer shelf form two Facies Associations, B and C respectively, and the highly distinctive shelf edge sediments are Facies 17. Viewed from a faunal perspective three recurring communities have been described as biotas, on the basis of their taxonomic composition which has played a dominant role in WSS facies classification. These facies and biotas are recognised elsewhere in the NEACP. Globally, non-tropical shelf carbonates occur at latitudes> 30°. The WSS setting is compared and contrasted with its southern hemisphere counterparts in south Australia and New Zealand. The findings in this thesis are synthesised with the work of others whose studies have been focused in the study area, in order to define the WSS depositional environments and their controls.