Somerville, David (2020) Fluvial and alluvial system response to rift basin evolution. PhD thesis, University of Leeds.
Abstract
The accumulated stratigraphy of alluvial and fluvial successions constitutes a significant
proportion of the fill of many continental rift basins. Subsurface studies commonly fail to
adequately account for sedimentological complexity, and field-based and remote sensing
studies typically focus on a single scale of observation. Detailed analyses of alluvial and fluvial
sedimentary successions across multiple scales are required to examine the roles played by
extrinsic and intrinsic depositional controls, and to determine response to ongoing basin
evolution.
Three studies have been undertaken to improve understanding of alluvial fan and fluvial
system response to rift evolution. First, three modern-day tilt-block crests from active rifts
are analysed through the measurement of their developed catchment and associated fan
system morphometrics. Comparisons are made of systems sourced over the footwall slope
and those sourced over the hangingwall dipslope. Moreover, comparisons are made of each
rift setting and their climatic regimes. The importance of system scale is examined: as
catchment size decreases, so fan size decreases, though at a markedly reduced rate. Alluvial
fan systems are especially important in smaller rift zones.
Second, a 600 m-thick conglomerate-dominated alluvial synrift succession from the Gulf of
Corinth, Greece, is analysed through interpretations of facies elements and architectural
elements within the context of a spatially and temporally complex framework of rift basin
evolution. The system developed as an alluvial fan sourced externally from the rift over the
hangingwall dipslope. Rift sedimentation led to overfilled basin conditions, which
transitioned rapidly to underfilled conditions following the onset of intrabasinal faulting,
which induced rapid subsidence. Results demonstrate the importance of rift evolution as a
control on the distribution of depositional environments.
Third, 1,531 conglomerate clasts from eight conglomerate lithofacies of a single synrift
succession are examined in terms of their qualitative (roundness, composition, shape) and
directional (axis lengths, dips, orientations) characteristics. Comparisons between facies
enable detailed reconstructions of formative depositional process.
The results are integrated to develop a suite of models that improve our understanding of the
links between basin-scale dynamics and resultant synrift alluvial stratigraphy, notably
allowing for enhanced subsurface prediction of their character.
Metadata
Supervisors: | Mountney, Nigel P. and Colombera, Luca and Collier, Richard E. L. |
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Related URLs: | |
Keywords: | alluvial fan, rift, conglomerate, fluvial, drainage, debris flow |
Awarding institution: | University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Earth Sciences (Leeds) The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Institute of Geological Sciences (Leeds) |
Academic unit: | Institute of Applied Geosciences |
Identification Number/EthosID: | uk.bl.ethos.832475 |
Depositing User: | Dr David James Philip Somerville |
Date Deposited: | 18 Jun 2021 09:24 |
Last Modified: | 11 Apr 2022 09:53 |
Open Archives Initiative ID (OAI ID): | oai:etheses.whiterose.ac.uk:29003 |
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