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Seeing through volcanic rocks, every mineral all at once

Olivia Barbee1,2, Florian Bachmann1, Jette Oddershede1, Håkon Wiik Ånes1, Ravi Purushottam1, Craig Chesner3, Jun Sun1, Stephen Hall2, Matthew Pankhurst4,5

  • Affiliations: 1Xnovo Technology, Køge, Denmark; 2Division of Solid Mechanics, Lund University, Lund, Sweden; 3Department of Geology and Geography, Eastern Illinois University, Charleston, IL, United States; 4Department of Earth Sciences, University of Geneva, Geneva, Switzerland; 5Gaiaxiom Pty Ltd, Korumburra, Australia

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 223

  • Programme No: 1.9.30

  • Theme 1 > Session 9

Abstract

Volcanic rocks are chemically and texturally complex products of subsurface magma systems that we cannot directly observe. Crystals within, however, provide us windows into how these systems work, but our interpretations of their records rely on how we access their interior features. Since thin section petrography was developed in the mid-19th century, it has remained a standard practice used by geologists to access and characterize rock interiors. Today, dissecting rocks is inherent to the majority of established techniques used to analyze rock and mineral chemistry, texture, and age. Although it leads to information loss, what is gained is valuable and contributes to our foundational understanding of volcanism. There may be more to learn, however, if we could gain access to crystals initially without dissection and in three-dimensions.  Crystal architectures are multi-dimensional, over time recording magmatic conditions and dynamics in their chemical structures, orientations and twinning, sizes, shapes, imperfections and inclusions. In recent decades, X-ray microtomography has paved a way to visualize and measure these characteristics in 3D. Here we develop a workflow combining state-of-the-art X-ray modalities and correlative tools that are poised to change the way we approach petrological research. Using lab-based, absorption and diffraction contrast tomography, we non-destructively map in 3D the physical attributes and crystallographic orientations of multiple mineral phases in a rhyolitic pumice. Visualizing and quantifying 3D spatial relationships between every mineral and every crystal all at once brings new opportunities to contextualize and target the most valuable features in down-stream, traditional 2D analyses.