Harnessing the potential of CT scanning to identify cryptotephra in sediment cores: a controlled experiment.

Volcanic ash (tephra) is a powerful geochronological tool, called tephrochronology, as rapid widespread deposition in multiple environments allows for correlation of geological archives across vast areas. It can thus help to understand the Earth’s climate system through time and space, and thanks to analytical advances in the past decades it is now possible to detect invisible (crypto) tephra deposits across thousands of kilometers from its original volcanic source. At present, lab-work related to tephrochronology is both time-consuming and labor-intensive, involving multiple steps to both identify and extract the tephra before it can be analyzed. To overcome these obstacles, we introduce the usage of Computed Tomography (CT) as a tool to identify cryptotephra horizons in sediment cores. The results are promising and show that CT scanning combined with different processing-tools can be used to 1) locate invisible ash horizons in both minerogenic, ice and organic cores, as well as 2) visualize the structure of the horizons. Potentially saving researchers a lot of time and further improve the tephrochronological research. The results also highlight the partial volume effect that needs to be accounted for when applying CT scanning on other sediment cores, also outside of tephrochronology.Masteroppgave i geovitenskapGEOV399MAMN-GEO