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Title: Structure and kinematics of large submarine mass wasting deposits
Author: Bull, Suzanne
ISNI:       0000 0004 2748 0657
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2009
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This thesis uses a combination of industrially acquired seismic reflection data, along with supplementary bathymetry and geotechnical borehole data, to investigate the architecture, structural elements and evolution of submarine mass wasting deposits. The primary study area is the mid-continental margin of Norway and the Levant margin, east-Mediterranean Sea serves as a secondary study area. The principal aim is to gain an improved understanding of the evolution of submarine mass wasting deposits and the processes involved. To this end this thesis consists of three core research chapters which present the results of investigations into the mechanism responsible for the formation of a non-typical example of a submarine mass wasting deposit, the spectrum of geological features that can be found associated with submarine mass wasting deposits, and an example of a frontally confined submarine mass wasting deposit. In the first core chapter, an example of a non-typical submarine mass wasting deposit from the Norwegian continental margin was investigated using three- dimensional (3D) seismic data. The mass wasting deposit, informally named the 'South Voring Slide' (SVS) was found to differ from previously documented examples in that it showed significant thinning and volume loss which could not be accounted for by the transfer of material downslope over a basal shear surface. Analysis of the deformation and geometry of the SVS suggests that it developed due to the mobilisation of an approximately 40 m thick interval at the lower part of the SVS, and its removal from beneath a thin overburden which subsequently underwent extensional fragmentation. Submarine mass wasting deposits exhibit many different types of kinematic indicators from which information relating to the dynamic emplacement of the event can be deduced. The second core research chapter presents a classification scheme and comprehensive compilation of all of the various kinematic indicator types, fully illustrated using best examples taken from the 3D seismic database available from the Norwegian and Levant margins. For each kinematic indicator, a definition and seismic recognition criteria are presented along with discussion and worked examples of the kinematic information which they provide. It was shown that the application of 3D seismic data to the study of submarine mass wasting deposits can yield much information pertaining to the direction and magnitude of transport, mode of emplacement, dominant mass wasting process and rheology. In particular, it was shown that 3D seismic data allows swift and confident evaluation of the direction of translation, and in many cases also allows the degree of translation of the displaced material to be constrained. The final core research chapter documents and describes an example of a large frontally confined submarine mass wasting deposit from the Norwegian margin. The mass wasting deposit, informally named the 'Confined Storegga Slide (CSS)', is unique in that it detaches along a deep-seated basal horizon at a depth of 640 m below the seabed and exhibits spectacular contractional deformation in its distal region. Using a combination of 2D and 3D seismic data and bathymetry data, it has been possible to fully delimit the extent of the CSS, which has a section length of 135 km and involves some 1,227 km3 of material. The results of this study show that the CSS developed as part of the large, multi-phase Holocene Storegga Slide, and demonstrates how subsequent phases Storegga Slide development induced later deformation and volumetric changes which have not previously been recognised.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available