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Title: The origin and interaction of diagenetic fluids in the Derbyshire-East Midland Shelf
Author: Bingham, G. C.
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1991
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The late Dinantian carbonate sediments of the Derbyshire-East Midland Shelf reflect a progression from the shallow, near surface environment through the early burial to the late burial environment. The shallow, near surface environment shows strong contrasts between the Platform margin and the Shelf interior. The Platform margin displays thick, isopachous layers of fibrous marine cement, that reflect a high energy marine hydraulic regime. Marine cements decrease in thickness towards the bottom of the palaeoslope where energy conditions are reduced, and also decrease towards the top of the palaeoslope, where meteoric fluids have replaced marine during exposure events. Meteoric cements on the Platform margin are concentrated towards the top of the palaeoslope, where they reflect precipitation in both the the vadose and phreatic environments. A complex intergrowth of marine and meteoric cements at the top of the palaeoslope reflects the repeated replacement of pore fluids during oscillations in late Dinantian sea level. The shelf interior shows only rare, thin marine cement layers which reflects the action of inhibitory factors in a low energy marine environment. Meteoric cement is more common and displays a non-luminescent, bright to dull luminescent subzonation, reflecting precipitation in oxidising to reducing fluids. A shelf-wide comparison of meteoric cement development suggests the centre of the shelf was buried more rapidly than the eastern or western edges. The early burial environment in the platform margin is characterised by an assemblage of dolomite, quartz and luminescent subzoned calcite. This is followed by pore-occlusion which is shelf-wide in distribution. Stable isotope and trace element geochemistry suggest a fluid origin from meteoric recharge in the east, which is complicated towards the margins by the introduction of hot, basinal brines, derived from the compaction of early Dinantian muds. The late burial environment is characterised by veining and the precipitation of calcite, fluorite and hydrocarbon. These are preceded and interrupted by dissolution and neomorphism. Late burial fluids are also basin derived and record a sequence of organic and clay diagenesis, in late Brig-antian/early Namurian shales. Late burial fluid introduction took place between the late Namurian and early Permian.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available