Extended-range optical televiewer imaging of the NEEM deep ice borehole, Greenland

The North Greenland Eemian (NEEM) Ice Drilling Project borehole reached the base of the ice sheet in August 2010, hitting the bed at a depth of 2438 m beneath the surface. The NEEM core is therefore one of the longest ever drilled, and it is hoped that it will provide a high-resolution record of past climate extending through the last (Eemian) interglacial period.

Additional complementary information relating to the core and the physical makeup of the local ice sheet can be provided by viewing the borehole that has been left following the removal of the core. An advanced technique for such logging (optical televiewing; OPTV) has recently been developed by Robertson Geologging Ltd (RGL) for use in the mining industry. OPTV has many advantages over previous (directional) borehole video technology in that it provides a geometrically accurate image of the entire borehole wall (i.e., 360 degrees around the borehole and along its full length) at a very high resolution (less than 1 mm per pixel). The applicant has, over the past three years, worked with RGL to adapt this equipment for use in ice and applied it to several test sites on glaciers and ice sheets. The results of these pilot studies have completely transformed the information that can be recovered from ice boreholes - including identifying different ice types, identifying different layers and structural generations, identifying and characterizing bubble and debris inclusions held within the borehole wall and, not least, providing orientated virtual images of the core removed from the borehole (by 'rolling' and inverting the image of the borehole wall).

Despite the potential of OPTV to revolutionize ice drilling research, the technique is currently restricted to use at depths of less than 1000 m by issues relating to the pressure rating of the sonde itself and signal communications along an extended length of relatively lightweight (and therefore transportable) cable. The former issue has now been resolved, and RGL is currently in the late stages of solving the signal-processing challenges and will have an extended-range OPTV system (EOPTV) developed by the end of 2011 (see Letter of Support). This small-grant application is to apply this new EOPTV system to the full (~2.5 km) length of the NEEM deep borehole, both to evaluate the performance of the new system and to address several specific science questions (listed under Objectives).

I. Who will benefit from this research?

Our research output will benefit four user groups (defined for this purpose by NERC as 'wider than (our) immediate professional circle carrying out similar research'):

(1) Broader scientific community
(2) Commercial private sector
(3) Public audiences
(4) School pupils

II. How will they benefit from this research?

Each of these groups will benefit from different aspects of the research programme and we will engage with them in slightly different ways (presented in more detail in the attached Pathways to Impact). These benefits may be summarized as follows:

(1) Broader scientific community

All borehole-based geophysicists will be interested in the results from this particular application to ice. Ice is, after all, a mineral that is in many ways similar to all other minerals. We will present and publish in at least one non-glaciological journal to engage with this community.

Image analysis software developers will be interested in the unprecedented length and richness of the ice borehole logs we will produce. We will make these logs available through presentations at conference sessions concerned with image analysis and geoscience software development, as well as online (below).

(2) Commercial private sector

This research is to be carried out in direct collaboration with a commercial PLC with broad and longstanding involvement in the oil and mineral exploration industry. Results from this research will be used by RGL to showcase their hardware and to test this new generation of EOPTV instrumentation.

The results of this research will be used by AU Knowledge Economy Skills Scholarship (KESS) student Mr Terry Malone as part of his PhD programme - based on applying 3D image analysis techniques developed for medical use to the automated interpretation of virtual OPTV logs.

(3) Public audiences

Detailed images, still and moving, of the pre-Eemian ice-bed interface of the Greenland Ice Sheet will undoubtedly be of fascination to the general public, and these images will be distributed to news and magazine channels as part of a broader educational pack distributed through the NEEM and AU press offices.

We will also mount images and video around the theme of 'Life at a deep ice coring site' on the internationally-renowned 'Glaciers online' internet image database (http://www.swisseduc.ch/glaciers/), a well as on a project website hosted at AU.

(4) School pupils

The Pathways to Impact plan includes provision to interact closely with school pupils, with the intention of improving their environmental awareness (present in curricula at a variety of levels). This interaction will take the form of a web blog with a 'Question of the day' facility. Following the fieldwork BH will engage with school and broader science talks aimed at young people - including at the national (Cenedlaethol) and youth (Urdd) Eisteddfodau.