Largest CT core scan completed at the BGS Core Scanning Facility

The Core Scanning Facility (CSF) at BGS has successfully completed the largest computed tomography (CT) core scanning project at this facility to date. Approximately 400 m of core from the International Ocean Discovery Program (IODP) Expedition 389: Hawai’ian Drowned Reefs project was scanned through the rotating X-ray CT (RXCT) core scanner to produce a three-dimensional X-ray image of the core.

IODP is an international marine research programme that explores Earth’s history and structure that has been recorded in sea-floor sediments and rocks, and monitors sub-seafloor environments. Expedition 389 focuses on the submerged fossil reefs off the coast of Hawai’i where changes in sea level and global climate are preserved in a greatly expanded and near-continuous fossil coral record covering the last half a million years.

The core samples from the expedition were transported in large, refrigerated containers and kept at 4°C. A coordinated operation involving BGS’s estates, goods-in and Core Store teams, in addition to a telehandler and forklifts, were deployed on arrival to unload the core and move the stillages prior to being scanned.

The CSF staff and 21 volunteers worked 24/7, covering two shifts over the course of a two month-period. The team successfully delivered a unique dataset that will be used for years to come. Core was scanned at a resolution of 93 µm for high-priority core and 186 µm for the rest. The priority order was set out by the offshore science party and was based on core condition and scientific importance.

Seeing the core scanner run non-stop for 516 hours without any downtime is truly astonishing. This highlights the importance of regular maintenance activities and functionality and safety tests of the machinery we host at BGS.

Magret Damaschke, BGS Core Scanning Facility Manager.

CT produces large amounts of data (both raw and reconstructed), with terabytes of data being generated every couple of days. Data management was therefore at the forefront of core-scanning workflows. This helped the team to avoid overloading transfer and archiving of data drives, which could result in bottlenecks when handling such a large dataset.

This CT dataset provides the scientists with a three-dimensional X-ray image of the core. The resultant CT imagery was used by the IODP’s onshore science party in Bremen to gain detailed insight into the inner structure of the core collected during the Hawai’ian Drowned Reefs expedition. It provided the opportunity to make an informed decision where to split the core to preserve coral structures and growth patterns for future scientific analysis. In addition, CT scans can be used to generate downhole radiodensity profiles to identify potential lithological or facies changes. Specialised CT image segmentation tools allow coral species and populations to be characterised, as well as basalt porosity analysis to be performed.

The onshore science party found the CT data to be incredibly useful during sampling and commented that the images were far more informative and detailed than anticipated. Post-sampling, scientists have already discovered more coral species ‘hiding’ within the cores, which were not visible during core description.

Dr Hannah Grant, BGS Marine Geoscientist and expedition project manager.

Many thanks again for all your team’s hard work with the X389 samples. The CT scan data is already proving to be incredibly valuable. One of my colleagues just sent me an image of a particular coral genus that is not supposed to be in Hawai’i! It only revealed itself after examination of the CT scan data.

Jody Webster, co-chief scientist on IODP Expedition 389.