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C316: Completeness and Representation of the Stratigraphic Sedimentary Record: Insights from Active Tidal Sedimentology, Geomorphology and Geochemistry (Lead Supervisor: Neil Davies, Earth Sciences)

Supervisors: Neil Davies (Earth Sciences) and Sasha Turchyn (Earth Sciences)

Importance of the area of research: 

There is an increasing recognition that the sedimentary stratigraphic record is permeated with gaps representing intervals of non-deposition, sediment bypass and erosion.  These gaps occur on a hierarchy of scales, from minutes or less (e.g., ripple migration) to hundreds of millions of years (e.g., cratonic cycling).  Whilst statistical modelling and stratigraphic analyses have been applied to good effect to understand the significance of these gaps from the ‘bottom-up’ perspective of the geological record, there have been fewer attempts to monitor ‘active’ gaps in modern sedimentary environments.  Using the Norfolk coast as a natural laboratory, this proposal seeks to monitor active geochemical processes, sedimentation, stasis, sediment bypass and erosion at selected staked points at timescales ranging from the instantaneous to annual.  This will be augmented with secondary data to translate these observations onto a decadal to thousands-year timescale, in order to offer a general ‘top-down’ understanding of gaps in the sedimentary record.

Project summary:

Our understanding of gaps in the sedimentary record – and the implications of these gaps for our interpretation of the record of ancient physical, chemical and biological signatures – has largely been approached from a theoretical stastical analysis of the stratigraphic record.  This project aims to improve our understanding by employing a fieldwork-based ‘present-to-past’ approach, identifying the levels of permanence or transience of various sedimentological and geochemical signatures of the Stiffkey Salt Marshes in Norfolk on temporal scales ranging from minutes to tens of thousands of years.

What the student will do:

The student will closely monitor the duration of permanence of, and the diurnal to seasonal variation in, different sedimentary signatures in the tidal environment, and attempt to understand any bias in their ‘preservation potential’.  These will include physical sedimentary and geomorphic elements, geochemical signatures (e.g., seasonal production of sedimentary pyrite with different sulphur isotope compositions) and the intensity and type of bioturbation.  For at least one year of the project, the student will make regular visits to north Norfolk in order to take measurements and samples over the course of full tidal and seasonal cycles (measurements on Sedimentation Rate Scales (SRS) 1-4 [Miall, 2015]).  The collection of this data over a calendar year will permit the observation of annual changes on SRS 5.  This original data will then be compared with secondary records (aerial photos, historic maps, core logs) available at Cambridge extending the study into timescales representing SRS 6-7.

Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.

References:

Miall, A.D., 2015, Updating uniformitarianism: stratigraphy as just a set of ‘frozen accidents’.  In: Smith, D.G., Bailey, R.J., Burgess, P.M., Fraser, A.J., (eds.), Strata and Time: Probing the Gaps in Our Understanding.  Geological Society, London, Special Publications, 404, http://dx.doi.org/10.1144/SP404.4

Allen, J.R.L., & Friend, P.F., 1976, Changes in intertidal dunes during two spring-neap cycles, Lifeboat Station Bank, Wells-next-the-Sea, Norfolk (England).  Sedimentology, 23, 329-346.

Andrews, J.E., et al., 2000, Sedimentary evolution of the north Norfolk barrier coastline in the context of Holocene sea-level change. Geological Society, London, Special Publications, v. 166, p. 219-251.

Follow this link to find out about applying for this project.

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