Measuring the properties of the last interglacial: reflections on a research internship

Posted by ga16 at Aug 18, 2014 03:05 PM |
Matthew Hewitson graduated this summer with a first-class degree in Applied and Environmental Geology from the University of Leicester. Immediately after graduation he completed an internship with the department’s Geophysics, Rock Physics & Borehole Group working at a local SME, Geotek, in Daventry. Here he describes the project, his role and the experience he gained.
Measuring the properties of the last interglacial: reflections on a research internship

Matthew working inside the shipping container at Geotek

Earlier this summer I was working at Geotek, in Northamptonshire working on sediment cores collected by the British Geological Survey (BGS) from Lake Windermere. The sediments are lacustrine muds and silts from the Holocene representing an interglacial period.

Geotek 2
Examples of the split cores studied varying from dark grey to orange and pink muds
The different cores collected capture deposits in different sub basins.

In the first week I got to grips with some of Leicester’s equipment kept at Geotek within a 20’ shipping container. This included a MSCL (Multi-Sensor Core Logger), used to measure the magnetic susceptibility, gamma density, P-wave velocity and electrical resistivity of cores. The metre-long cores collected are pushed through each of the sensors, which can be done almost straight away during a project before the cores are sampled and stored.

Geotek 3
The collection of the 20ft shipping container for transport to Southampton

One of my first tasks was to describe the lithology and features of the Holocene sediment split cores (sliced in half lengthways). During the initial project, brief descriptions of lithological units were identified to correlate each of the cores together. I created new descriptions noting features like banding and colour to match with the original units identified. Additionally, I highlighted the quality of the fill including features like organic material, cracks and joints, which could affect geophysical measurements taken later.

 In the second week I began taking my own measurements on an MSCL-XYZ using the split cores. I collected spectral Natural Gamma Radiation (NGR) measurements of 40K, 232Th and 238U at selected points along the cores’ length. The descriptions made earlier were used to choose at least one point within each lithological unit, avoiding problematic areas. Up to 6 sections were loaded onto the trays of the MSCL-XYZ at one time, the machine was then programmed to lower the sensor over the cores to count natural gamma rays for an hour at each point.

 During the second week I also readied the shipping container for an upcoming project offshore Ireland (BRITICE-CHRONO) that the Group at Leicester are also working on. This involved removing the MSCL’s sensors and packing up other equipment, checking the inventory and strapping items down to prevent damage during transport. At the end of the week the shipping container was lifted onto a trailer for transport to Southampton for loading onto the RRS James Cook for the BRITICE-CHRONO cruise.

The work I undertook at Geotek gave me valuable experience using industry standard equipment and software within the field of geophysics applied to sedimentology. It also gave me the opportunity to apply the analytical skills I have acquired throughout my degree for generating data for a BGS-University of Leicester research project.

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