3-D CT Core Imaging Laboratory
Learn more about the Rotating X-ray Computed Tomography (RXCT) system at the USGS Pacific Coastal and Marine Science Center in Santa Cruz, California.
The Geotek RXCT, a "rotating x-ray computed tomography" system, creates ultra high-resolution imagery of sediment cores. The system resides at the USGS Pacific Coastal and Marine Science Center in Santa Cruz, California. It requires the operator to take specialized training and hold X-ray radiation and safety certifications.
In medicine, radiologists use computed tomography (CT) scans to collect highly detailed images of your body. Similarly, the RXCT creates a complete 3-D image rendering of a sediment core by combining a series of X-ray images taken from different angles around it (thus, the "rotating" part of the name). The system then uses computer processing to create cross-sectional images (slices) of the core. Thus, a CT scan provides more detailed information than a simple 2-D X-ray image.
The images created by the RXCT allow scientists to look into the core at any area and at any angle, without having to carve into it. Looking at the structure and composition of cores in this fashion helps scientists determine the history of the location where the core was collected, such as the seafloor, a lake bed, or a marshy area. For example, if they find a sandy layer in an otherwise calm environment, like a coastal marsh which is normally just peat and mud, this may be evidence of a big wave event that carried sand from the beach and nearshore back into the marsh area. Further inspection of the CT image may reveal subtle sedimentary characteristics of the sandy deposit such as changes in grainsize, heavy mineral layers, and rip-up clasts that may help researchers determine whether deposition occurred during a tsunami or a storm.