Tuesday, 24 October 2017

Corinth Active Rift Development: the expedition begins

IODP Expedition 381
View 3: second petrophysics blog from the ship

So the time has come, the boat is fuelled, the labs are fully prepared and we are all ready to depart from the port in Corinth to our first site in the gulf. Very soon I will be bobbing up and down on the Gulf of Corinth as we drill into the seabed below us in an attempt to discover how it would’ve looked to witness the gulf appear over the past 5 million years (more on the expedition aims here).

Sunrise on the day of departure

The offshore team has now expanded as we have been joined by a subgroup of the scientists from the science party involved in this project. 9 of the 31 total. These scientists will be assisting with running the labs offshore and completing some of the initial analysis and sampling. The job is not a too privileged position though since the cores won’t be split until they reach the Onshore Science Party (OSP) in Bremen, Germany, during January of 2018. Since there is a little delay between recovery and full analysis of the cores, all of the ephemeral properties of the sediments (those that degrade in quality with time) and essential sampling (drilling mud, pore water, microbiology etc.) will be completed with the help of these 9 scientists on the vessel within the first hours of recovery. As one would expect, the doubling of the team size has affected the group dynamic on board the vessel. However the thing to remember about these 9 new team members is that they are all heavily invested in the science and will be completing research using the data produced by this project, each with their individual spins and focuses. This aspect defines the change. All 9 are all so passionate about the work and excited to be here. It’s infectious.
The Fugro Synergy at port in Corinth

Owing to all this, my next two months will be very different from the usual 9-5 office job. So what will I be doing for this time? I will be working on the opposite 12 hour shift to my work partner to ensure 24 hour continual operation of the Multi-SensorCore Logger . The Multi Sensor Core Logger (or MSCL) is an apparatus that measures ephemeral physical properties of rock and sediment cores, now I know that sounds boring when I explain it like that in full but bear with me. The Geotek™ system that I will be using is a fully automated track system where the cores themselves are moved through stationary sensors rather than there being moving sensors or probes. The process is almost fully automatic and generates masses of data at a great resolution. It really is very cool piece of kit.

MSCL lab

This will not the first time that I have used one, personally I have used this system before as well as using similar systems on other projects such as the Geotek XYZ system during the onshore phase of IODP expedition 357: Atlantis Massif; and using EPC’s bespoke MSCL: Fast-track for training during the Petrophysics Summer School 2016  and Petrophysics Summer School 2017.  


So what does the MSCL do exactly and what is my (and my scientist partner’s) job as the operator? Well to be perfectly honest it is fairly simple to understand and operate if you have a basic understanding of material properties.  The 5 properties that it measures in order are density, p-wave velocity, electrical resistivity, magnetic susceptibility and natural gamma radiation. Density is fairly self-explanatory. The MSCL though records electron density which is almost exactly the same as bulk density for the suite of elements that make up rock-forming minerals. P-wave velocity describes the speed with which an acoustic pulse (or sound wave) travels through a material, the electrical resistivity of a material is the inverse of its electrical conductivity and natural gamma radiation simply describes the natural gamma radiation output of the rock or sediment. Magnetic susceptibility on the other hand is bit less straightforward. It is most simply described as the degree by which a rock can be magnetised by an external magnetic field and in sedimentology it is most widely used to infer clay proportions in sand through the recognition of iron content.


My job as operator of the MSCL is to ensure that it is running and continually logging core for the full 12 hours of my shift, with my partner taking care of the other half of the day. This is important because the logger can complete measurements on 3 metres of core in just over 1 hour and therefore only keeps up with everything else if it is operating 24/7. It’s a busy task but we have air conditioning, speakers and a coffee machine in the container to make sure that we are comfortable and sufficiently caffeinated.


If all goes to plan this expedition will recover over 1500 m of core from the Gulf of Corinth. And that’s a busy MSCL (and busy operator!).


Where I will be working for the next couple of months is just the one of the many labs on Main Street. There are also labs for curation, geochemistry and a combined science office for microscopy, visual core description, palaeontology and core-log-seismic integration. But for more info on those labs keep an eye on the Expedition 381 blog over the coming months.



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