Description:

Continental dryland systems is a broad term applied to environments within prevailing arid and semi-arid conditions in which combinations of aeolian, fluvial and evaporite material can deposit and accumulate. Overall dryland continental systems are highly sensitive to environmental and climatic and changes. Dryland systems are often the first to respond to such changes even when relatively modest in magnitude. The impact of such changes upon the aeolian and fluvial sedimentation and halite accumulation can be highly variable on both temporal and spatial scales. For instance, relative increases in humidity within upwind regions, can lead to immediate (geological instantaneous) reductions in sediment supply for aeolian transport, by raising the energy required to entrain sediments that are wet relative to dry.

The prolonging of such conditions can drastically alter sedimentation within the dryland systems where aeolian bedforms accumulate. Such bedforms are likely to undergo re-shaping and possible erosion as the aeolian system responds to new sediment flux conditions. By comparison the response of fluvial sedimentation to increases in humidity, and thus more discharge, is often a more gradual process. Fluvial input into drylands systems is often short-lived and sporadic, a result of the prevailing arid and semi-arid conditions in dryland settings. However, increasing discharge often leads to progressive increases in the size and frequency of fluvial elements within dryland systems over time. This upward ‘wettening’ increase in fluvial facies types can impact the aeolian system in a manner previously mentioned and lead to a sudden termination of any aeolian sedimentation in favour deposition exclusively by fluvial processes. Such environmental switches in depositional character are readily seen in core examples from the North Sea, or even at outcrop scale in the Sherwood Sandstone Group of the West Midlands to name but a few.

Whilst evaporite accumulation in drylands settings is driven by the heightened rates of evaporation and concentration of ions, the governing forces in the growth of the deposits is driven not by process sedimentology as the with the aeolian and fluvial systems, but is instead driven by fundamentally by chemical processes. This creates complexity when trying to understand how such evaporite deposits interact with the clastic sedimentary deposits within which are intimately genetically associated with. This continental dryland systems workshop is being convened at the National Geological Repository at the British Geological Survey (BGS) headquarters in Keyworth, Nottingham.

The workshop will present a number of wells from both onshore and offshore settings across the UK and the North Sea, exploring the preserved sedimentological expression of a variety of dryland systems across the Permo-Triassic. The workshop will explicitly include the potential impacts to fluid flow resulting from the variable architectures and interactions identified between aeolian, fluvial and evaporite deposits and processes, as such it likely to be of interest to persons involved within hydrocarbon, water and contaminant sectors.

Please note that this workshop takes place offsite. Transport from and to ExCeL London will be provided.