Supervisors: Dr Sarah Davies (University of Leicester), Dr Joe Macquaker (Memorial University, Newfoundland), Dr Mike Norry (University of Leicester) and Dr Kevin Bohacs (URC, ExxonMobil, Houston).

Research

My PhD research investigates the fundamental controls on sedimentation and the preservation of organic matter in mudstone successions. Understanding these controls has significant implications for interpreting climate change signals preserved in these strata and for effectively exploring for unconventional shale gas plays and conventional source rocks, in particular identifying the temporal and spatial distribution of organic matter.

Key Objectives

• Describe the variability in mudstone character from Carboniferous (Pennsylvanian) successions using a multidisciplinary approach that includes field logging, optical, electron optical, whole rock geochemical methods.

• Interpret this variability in terms of fundamental physical, chemical and biological controls operating at and close to the sediment water interface.

• Investigate geochemical proxies as indicators of redox conditions during deposition that may correspond with enhanced organic matter deposition/preservation.

• Generate integrated high-resolution sequence stratigraphic models in order to determine the temporal and spatial processes that might lead to organic carbon enrichment in specific environments.

Thin section scan of the marine band with 3D preserved goniatites.

The analysis focuses on the fine-grained successions from the onshore UK Carboniferous stratigraphic record. Open shelf mudstones, dominated by water column organic productivity, and distal delta front successions, dominated by fine-grained siliciclastic inputs were deposited in a shallow epicontinental seaway that extended across the UK during the Carboniferous. The mudstones, other than thin organic-rich, fauna-rich mudstones (‘marine bands’), are little studied.

This research will contribute to a rapidly expanding area of sedimentological research (e.g. Schieber, 1999; Schieber, 2007; Macquaker, Keller and Davies 2010; Macquaker, Bentley and Bohacs 2010) that have revealed how fine-grained strata are not homogeneous but can contain very different proportions of material, at the millimetre and sub- millimetre scales, derived from clastic input, primary productivity and diagenetic processes.

A plate showing the 4 main lithofacies - Pelleted; Goniatite-Bearing; Bedded and Homogeneous Mudstones.

References

Macquaker, J.H.S., Bentley, S.J. and Bohacs, K.M. (2010) Wave-enhanced sediment-gravity flows and mud dispersal across continental shelves: Reappraising sediment transport processes operating in ancient mudstone successions. Geology, 38, 947-950

Macquaker, J.H.S., Keller, M.A. and Davies, S.J. (2010) Algal blooms and “marine snow”: mechanisms that enhance preservation of organic carbon in ancient fine-grained sediments. Journal of Sedimentary Research, 80, 934-942

Schieber, J. (1999) Distribution and deposition of mudstone facies in the Upper Devonian Sonyea Group of New York. Journal of Sedimentary Research, 69, 909-925

Schieber, J., Southard, J. and Thaisen, K. (2007) Accretion of mudstone beds from migrating floccule ripples. Science, 318, 1760-1764