Day 9 (23Jun) - Part 2

23 June 2008

Location: 48° 57' N - 33°58' W

Wind : ~17 knots

Water temperature : 14°C

Processing Samples and Data Collection

Bonjour chers collègues!

Today we are still traveling North from the two sampling locations near the Azores islands. This transit period will last 72 hours. Last night and this morning we were experiencing strong winds, and it was very challenging to walk around the ship. Some people were unable to sleep due to the motion, and those who get sea sick are trying to find effective ways to control their nausea.

Selecting the coring site at the Charlie-Gibbs fracture zone

Saturday and Sunday we completed processing the Casq and Calypso cores we collected in the Azores. There are many steps involved in this process-some can be completed here in the laboratory, and others must be completed in the laboratories of the participating institutions after the mission.

The Casq core is usually launched before the Calypso core. When the Casq core is brought on deck we must remove the cover, and then smooth the surface of the sediment with spatulas. We must be careful to smooth the sediment only horizontally and not vertically, or else we will mix sediments from different time periods and contaminate the sample! Then, we place three rows of plastic tubes in the core, flip the core, and remove the tubes with sediment. These samples must all be carefully labeled and packaged for many different types of analysis.

The Calypso core is a steel round metal tube with a thick plastic lining. The crew removes the plastic lining from the metallic tube and places it on the desk for us on metal stands. We then carefully cut the core into 1.5 meter sections. These samples are split into a "working" side and an "archival" side. For all types of cores we must be very careful to label the continuous length of the sediment properly, or else we will not obtain accurate information about the organisms that are present during each geological time period, and we will not be able to successfully reconstruct climate or circulation conditions.

On the ship several qualities of the sediment are described using the visual core description form that includes the summary of stratigraphy, bed thickness, lithology and sedimentary structures,

texture, fossil content and coring disturbances. Sometimes the scientists even taste the sediment in order to describe its texture.

On board the Marion Dufresne there is also the Multi Sensor Track (MST). This is a group of instruments, located in a special container, dedicated to the first measurements of physical properties of sediment cores. These measured properties are P-wave travel time, core diameter and temperature, Gamma ray attenuation and low field magnetic susceptibility. The sediment cores are also scanned and photographed and the visual core proprieties are quantified using a spectrometer.

Machinery cables

These measurements are all critical in order to achieve the goals of the AMOCINT project.

Last night we celebrated four birthdays that have taken place in the last three days. Transit periods are a good time to do this!

Thank you for following our journey, and have a wonderful week!

Your fellow teachers at sea