Temperature measurements at IODP 337 Expedition, off Shimokita, NE Japan.

Tuesday, 16 December 2014
Yasuhiro Yamada1, Yoshinori Sanada2, Kyaw Moe3, Yusuke Kubo2 and Fumio Inagaki2, (1)Kyoto University, Kyoto, Japan, (2)JAMSTEC Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan, (3)CDEX, Yokohama, Japan
Precise estimation of underground temperature is a challenging issue, since direct measurements require drill holes that disturb the original underground environment. During IODP 337 expedition, we have obtained in-situ temperature datasets for several times by using geophysical logging tools. A common procedure to estimate the undisturbed maximum underground temperature is by approximating that the ‘build-up’ pattern of measured values in the borehole should reach to the equilibrium temperature. At the Shimokita site, this was 63.7 oC at a depth of 2466 m. We have much more measurement dataset and all of these were used to analyze detailed in-site temperatures at various depths. The result shows a non-linear temperature profile to the depth and this may be reflected by the thermal properties of the surrounding rocks.