Chris Beveridge is a Physical Properties Technician on Expedition 323. He has agreed to share some of his experiences and tell you a little bit more about what he does on board the JOIDES Resolution.
The Physical Properties Lab consists of all the ‘Tracks’, the Natural Gamma Radiation detector, Sediment strength tester, p-wave, thermo conductivity, and mass density (MAD).
The ‘Tracks’ consist of the Whole Round Multisensor Logger (Slow and Fast). We have two of these on the ship that are called the Slow and Fast track. Both of them do the same thing but with some slight differences. The Fast track consists of only 2 main data sensors and takes the information at a lower resolution (every 10 cm) where as the ‘Slow’ track takes 4 different readings and does so every 5 cm giving a much higher resolution. The 4 main readings that are taken are Gamma Ray attenuation (or GRA which measures the decrease in intensity of beam of gamma rays as a result of absorption of energy and of scattering out of the path of a detector), Magnetic susceptibility (MSL or the degree of magnetization of a material in response to an applied magnetic field), P-Wave velocity (or PWL. P-waves are type of elastic wave, also called seismic waves), and Noncontact resistivity (or NCR which measures the resistivity of slices of semi-conducting material). Each of these readings helps in the understanding of the composition of the core along with allowing the stratigraphic correlators know where we are in respect to other holes drilled at the same site. This is sort of like matching up finger prints from one hole to the next!
Technicians during the drilling:
Even when we have not started drilling the technicians know what to do and are ready to go when it begins. When drilling starts the techs that are on shift will prepare the catwalk and lab area for receiving core. When the words ‘Core on the Floor” or “Core on Deck” are heard all Core Lab Techs hastily move to the catwalk to assist in transporting the 10m core liner now full of sediment over to the cutting tables where it is split into 1.5 meter sections. Once the core is on the catwalk the Assistant Lab Officer (ALO) and the Curator will measure and cut the core into 7 sections. While this happens one of the technicians will take the core catcher (CC) (very bottom of the core) from the core tech and remove it from its cradle. Removing the CC is not always an easy task and sometimes requires some elbow grease. Core recovery rate depends on the depth of water that is being drilling in. On an average water depths around 100-1500m cores can come up on deck at a rate of every 15-29min. The greater the water depth the longer it takes for a core to get back to the deck.
In his next post Chris will explain more about the core catcher. Both its importance in the drilling process, and the importance of the core material it returns.