The sedimentary and stratigraphic record of external and internal factors affecting deep-water sedimentary systems

Abstract

Deep-water sedimentary systems are the products of, and may record, the interaction of a range of external and internal factors. External factors, i.e., climate, eustasy, and tectonics, act to control sediment supply and accommodation space, while internal factors, such as flow dynamics and bedform deposition, act to control sediment distribution and character. The expression of the interplay between external and internal forces acting on deep-water sedimentary systems is archived in the stratigraphic record, however, deconvolving these in time and space remains challenging. This study aims to enhance our understanding of the influence of external and internal factors on deep-water systems through a multi-scalar and multi-method approach. Outcrop data from the Eocene-Oligocene Alpine foreland and Cretaceous Greater Caucasus are compared with subsurface data from the Paleocene-Eocene North Sea Central Graben, with the results of these studies compared to simplified physical models of the topographic configurations of these basins. Key insights derived from this study include: 1) onlap patterns in deep-water systems are controlled by a predictable interplay between external and internal factors, with 'external' onlap trends produced by progradation which is partially masked by 'internal' onlap trends produced by the character and evolution of the flows in space and time; 2) the isotopic record of deep-water systems can be used to assess the dominant external control on deposition within a basin and Earth's surface conditions during deposition; 3) deep-water deposition in the Alpine foreland was enhanced by increased aridity and lowered eustatic sea-levels associated with the Eocene-Oligocene climate transition and hinterland tectonism; 4) enhanced burial of organic carbon in deep-water systems during greenhouse-icehouse transitions may provide a positive feedback for cooling during these transitions; 5) far afield tectonic perturbations are recorded within the stratigraphy of deep-water basins, and can be used to reconstruct the timing of tectonic events; 6) deposition in deep-water systems affected by tectonic perturbations may initially be characterised by large-scale mass-transport, with progradation of submarine fans affected by the topography of this early mass-transport-dominated period; 7) deep-water systems characterised by contemporaneous carbonate and siliciclastic deposition have facies, facies associations and stacking patterns that differ from purely siliciclastic systems; 8) the orientation of basin floor topography, with respect to the sediment delivery system, exerts a fundamental control on the distribution and geometry of turbidity current deposits, and as a result controls the stratigraphic record of confined deep-water systems.

Date of Award	1 Aug 2020
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Mads Huuse (Supervisor)