The ECORD Science Operator is testing a new piece of equipment during the onshore science party of IODP Expedition 389. We always photograph all cores with a high-resolution camera, similar to the one many of us have used at some point. This time, we also take images with a hyperspectral camera that records infrared light reflected off the core surface. This technique is non-destructive and should give us a first indication of the minerals that make-up the core.
Just like any camera, a hyperspectral camera records reflected light, but it does so in the infrared range. Instead of just recording one colour per pixel, it records a full spectrum. Each mineral has its own characteristic spectrum that acts like a fingerprint and helps us to identify it. That way we can map the mineralogical composition of the core at its surface. Two carbonate minerals, calcite and aragonite, are especially important to the scientists of IODP Expedition 389. To the naked eye, there are indistinguishable, but their hyperspectral fingerprint should set them apart.
Why are the scientists interested in calcite and aragonite specifically? Co-chief Jody Webster explains: “Hawai’i’s corals have had a really complicated life (and death) story, where their skeletons may have been subjected to mineral changes. One of these mineralogical changes is the transition from aragonite to calcite. To decipher a coral’s history, we first need to find its pristine well-preserved parts that have not yet transformed into calcite. This exciting new tool may help us identify the aragonite without us having to destroy the core.”
Most of the core sections have been scanned with the TheiaX-operated hyperspectral scanner and the scientists have been excitedly pouring over the preliminary results – which are very promising.
Blog of IODP Expedition 389: Hawaiian Drowned Reefs 