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Despite considerable research into the characterisation of the architectural elements of submarine fans, few studies have attempted the full integration of ichnology and sedimentology. In this thesis, a quantitative analysis of trace fossils from the Early-Middle Eocene deep-marine clastic systems, Ainsa-Jaca basin, Spanish Pyrenees, shows that trace fossils are powerful discriminators of deep-marine fan and related environments. Sixteen fan and related environments have been recognised in the Ainsa-Jaca basin, from upper-slope gully to distal basin-floor. In the more laterally confined and channel-dominated Ainsa basin, there is a trend of increasing bioturbation intensity and trace-fossil diversity away from channel-axis to off-axis environments. In the more unconfined and distal Jaca basin, there is a trend of increasing trace-fossil diversity and number of pre-depositional trace fossils including graphoglyptids from the channel-lobe transition to the fan-fringe. The trace-fossil assemblages of the Ainsa-Jaca basin are characteristic of a number of subichnofacies of the Nereites ichnofacies. In the distal Jaca basin, the Paleodictyon subichnofacies occurs in the lobe-fringe and fan-fringe, whereas the distal basin-floor has a trace-fossil assemblage typical of the Paleodictyon subichnofacies, but with a high proportion of post-depositional fodinichnia. Trace-fossil assemblages of proximal basin, axial, environments are characteristic of the Ophiomorpha rudis subichnofacies, whilst proximal off-axis environments, have a mixed Paleodictyon-Ophiomorpha rudis subichnofacies trace-fossil assemblage. In core, a detailed ichnofabric study of the proximal Ainsa channel system shows a clear trend of increasing bioturbation intensity and trace-fossil diversity from channel axis to levee-overbank. Spectral analysis of bioturbation intensity in thin-bedded turbidites deposited in overbank and interfan environments from one of the wells (A6), suggests, for the first time from a siliciclastic turbidite succession at a tectonically active plate margin, a strong cyclicity interpreted to reflect the -41 k.yr and -112 k.yr. Milankovitch frequencies. It is, therefore, proposed that global climate change acted as the principal environmental driver in controlling changes in bottom-water conditions within the deep-marine Ainsa basin.

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This thesis uses forward modelling to investigate the formation of intercratonic basins upon accretionary crust. It began from the hypothesis that accretionary crust forms with a near normal thickness crust, but a thin lithosphere inherited from the terranes that compose it. After the accretion process has ceased the lithosphere stabilises and begins to cool, causing it to grow thicker and this in turn drives subsidence of the accretionary crust. A 1-D finite difference computer code was developed to model conductive heat flow through a column of cooling lithosphere and asthenosphere. To test the hypothesis, the subsidence produced by the modelling of this process was compared to the observed subsidence from backstripping numerous basins situated on accretionary crust The model produced a good fit to the subsidence in a detailed case study of two of the Palaeozoic basins in North Africa. The study was then extended to test the applicability of to accretionary crust globally. It found that while using measured values of the crust and lithospheric thickness for each region the model produced subsidence curves that matched the observed subsidence in each basin. It makes a more coherent argument for the formation of these basins that is able to explain a wider variety of features than other proposed subsidence mechanisms such as slow stretching or dynamic topography. These results suggest that such subsidence is an inherent property of accretionary crust which could influence the evolution of the continental crust over long time periods. The model was used to investigate the subsidence of the West Siberian Basin and found the subsidence patterns to be consistent with the decay of a plume head which thinned the lithosphere. This subsidence patterns indicate the plume material thinned the lithosphere over an area of 2.5 million km2 resulting in uplift before it cooled and subsided.

The geomorphology of the upper reaches of the River Wear Valley has been based on Individual assessments of the complex topography of the area. Evaluation of the superficial deposits as a method of understanding the area, has so far been limited to subjective assessment. In this study a technique recently developed in sedimentary petrology is applied to samples of the suite of deposits existing in Upper Weardale. Two samples are considered, one, a purposive sample chosen to "represent" the deposits of the region for an initial evaluation of the technique, the other sample, a random sample, to permit general conclusions about the nature of the deposits existing in that area. Analysis of the particle-size distribution of the sediments obtained in each sample gives a basis for conclusions about the representative nature of both purposive and random samples. Factor Analysis of the particle-size data gives similar results for each body of data and the Factor analyses of all data as a single unit demonstrates an equal consistency. Consideration of the nature of the four factors produced in this way leads to their tentative identification as the products of glacial action, water-washing processes, rock decomposition and gelifluction. This tentative identification is reinforced by the statistically significant trend surface patterns which emerge from further data analysis. In the final section all other evidence is considered together with the results obtained from data analysis. The conclusions about the geomorphological history are compatible with the evidence considered by previous workers, although the conclusion that the whole area was over-ridden by ice is a departure from the commonly-held view. Conclusions of a methodological nature concerning the wider application of these techniques to complex suites of deposits are also formulated.

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No description available.