Core Flow

After the cores arrive on deck (as described in Dave’s drilling blog), they are greeted by a squad of expectant Scientists. Offshore, we measure ephemeral properties from whole cores and samples taken from the core catchers, and store the cores in refrigerated containers called “reefers”. These data will help inform the sampling plan when the cores are split at the Bremen Core Repository early next year.

The first samples are taken on the curation table, located on the drilling deck. After the cores have been cut into sections, the Geochemists take samples from the cleanly cut ends for later measurement of methane concentration. We also have a handheld penetrometer device which is used to give an idea of the stiffness of the material.

The core then starts its journey down the street of containerised laboratories on the back deck. First stop is the curation container. Here, core measurements are taken and recorded – what was the drilled length, what was the length of recovered core, date, time and unique core section number. Samples from the core catchers are also taken to be analysed for microfossils and sedimentology. Further samples are taken on some cores to extract pore water When extracted the water is taken to the Geochemistry container for preliminary measurements (of pH, alkalinity, salinity and ammonium) and preservation for future use.

The next stop is the Multi Sensor Core Logger (MSCL) container. Here physical properties of the whole round cores are measured through the plastic liners. The cores are placed on a track and run through sensors to measure density, p-wave velocity, electrical resistivity, magnetic susceptibility and natural gamma radiation. We can use these data, alongside the other preliminary measurements, to understand how environments change as we move down and hole, and back in time.

IMG-20171024-WA0011

Finally the cores make it to the Science Office! In here the Sedimentologist on shift will examine both the core catcher samples and what they can see through the liners. Although the liners are clear, the view can be obscured by mud, and many features will not be visible until we get to Bremen next year and split the cores. The Micropaleontologists also sit in this space and use microscopes to identify microfossils which can give us an idea on the age of the sediments and the environment in which they formed. Also in this container are the Co-Chief Scientists, Lisa and Donna, who work on integrating existing data with our new cores and trying to understand the changes we see, using the various streams of evidence from all these measurements.

The cores finally come to rest in the reefers. At the end of the offshore phase of Expedition 381 they’ll travel on to the IODP Bremen Core Repository, MARUM Germany, to be met by the whole Science Party at the end of January, where the cores will be split and the detailed analyses undertaken.

Sophie Green

Images courtesy of CMiller@ECORD_IODP; SSauer@ECORD_IODP; DSmith@ECORD_IODP and ELeBer@ECORD_IODP

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