Magnetic, structural and sedimentological analysis of glacial sediments: insights from modern, quaternary and neoproterozoic environments

Fleming, Edward James (2014). Magnetic, structural and sedimentological analysis of glacial sediments: insights from modern, quaternary and neoproterozoic environments. University of Birmingham. Ph.D.

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Abstract

Glacial sediments, particularly diamicts, can be ambiguous to interpret. Fabric analyses, such as anisotropy of magnetic susceptibility (AMS), have been shown to provide specific information on the formation and subsequent deformation of glacial sediments. In this thesis, detailed investigations utilising the AMS technique have been combined with traditional sedimentological and structural techniques, to help resolve a number of current problems in glacial geology. At the same time, limitations of such uses of AMS have been established. In the modern environment (Tunabreen, Svalbard), magnetic lineations develop parallel to glacier flow and reveal dynamic behaviour during past surges. In a Quaternary glaciotectonite (Bacton Green Till Member, Norfolk, UK), AMS fabric develop in response to glacial deformation and reveal strain vectors that can be related to ice flow from contrasting directions. Finally in Neoproterozoic diamictites (Wilsonbreen Formation, Svalbard), despite local tectonic overprinting and diagenetic change, AMS can be used to reveal a dominant ice-flow to direction to the north. In combination with other sedimentological techniques, this has allowed the identification of glaciotectonic features and an ice-marginal, terrestrial and subaqueous model is proposed. These results support the use of AMS as a fast, objective and accurate technique that can facilitate the interpretation of cryptic glacial sediments.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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