Back into basement

My photo today shows the results of our drilling over the last half day in our attempts to get some more volcanic rocks close to the old seafloor spreading center in the southwestern South China Sea. As predicted we were able to start drilling the volcanic basement here quite soon after drilling through a relatively thin sequence of sedimentary rock, including some volcanic breccias, which had been derived from a local and relatively young seamount volcano. This however was not our primary objective, but instead to date the end of the seafloor spreading. As you can see in this photograph we did not get a great deal of rock despite investing a lot of time in this because the drilling was very slow, reflecting the very hard character of the rock itself. However, we do not give up so easily and will continue to try to get some more material overnight by taking half-length cores which tends to improve our recovery. The most important thing is that the material is fresh and that we have sufficient to allow radiometric dating and some basic geochemistry after the cruise. Some tough decisions will have to be made over the next couple of days in terms of how to use the last remaining operational days of our cruise in order to maximize the scientific benefits of the drilling. In the meantime we are hoping that the high winds which are now affecting the northern part of the sea start to slacken because this is the final destination for Expedition 349.

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