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The Response of Mediterranean River Basins to Pleistocene Glaciation
[Thesis]. Manchester, UK: The University of Manchester; 2012.
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Abstract
Fluvial morphosedimentary records surrounding the Orjen massif, western Montenegro, have been studied to investigate the response of Mediterranean river systems to Pleistocene glaciation. A range of depositional contexts, across 12 sites, have been analysed, including: terraced alluvial valley fills, poljes and alluvial fans. These sites include both ice marginal contexts and more distal locations. It can be argued that these settings are broadly representative of the depositional environments found within glaciated upland catchments across the Mediterranean, and especially those in limestone landscapes. The timing of fluvial activity has been constrained using detailed stratigraphical analysis, 35 U-series dates, calcite micromorphology, and soil profile analysis. The fluvial record is fragmentary but is in good agreement with the Pleistocene glacial history of the Orjen massif, developed by Hughes et al. (2010).Two main phases of Pleistocene fluvial sedimentation have been identified in the morphosedimentary record. The most extensive phase of fluvialaggradation is correlated to MIS 12 (Kotorska-Sušica Member) and is characterised by the infilling of large depocentres beyond the maximum MIS 12 ice margins. These deposits dominate the fluvial record. The next recorded phase of fluvial deposition is correlated to MIS 6 (Krivošije Member) and contains only limited evidence of fluvial activity. No morphosedimentary evidence for fluvial deposition in MIS 5d-2 has yet been observed in the study area. An analysis of published studies shows that the Pleistocene glacial and fluvial archives are highly fragmentary across the Mediterranean basin. The limestone karst terrain of Mount Orjen has exerted an important influence on sediment delivery and the meltwater pathways draining the Orjen ice cap over successive glacial cycles. Evidence suggests that, since MIS 12, sediment supply to the fluvial system has declined in accord with the decreasing magnitude of glaciation and subterranean karst flows havebecome increasingly dominant over surface flows. As ice volume and extent decreased in the cold stages following MIS 12, the Pleistocene glacial and surface fluvial systems became progressively decoupled. Two types of surface meltwater routes operated during MIS 12: Type 1 – steep sided limestone bedrock gorges; and Type 2 - alluvial channels draining directly from the ice margin. These contrasting pathways are associated with distinctive sedimentological signatures both at the macro-scale and within the fine (<63µm) matrix fraction This study provides one of the first attempts to directly correlate Pleistocene glacial and fluvial records – and to consider the process interactions – in a range of depositional contexts at the landscape scale.
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A supplementary data disc containing Appendices D and E have been submitted with the hard copy. These appendices contain all raw sedimentological data used within the thesis.