[M-IS32_30PO1] Drilling Earth Science

[MIS32-P02] Coring disturbances with the riser drilling system of the D/V Chikyu during IODP Exp. 337 off Shimokita, Japan

*Masafumi MURAYAMA¹, Sumito MORITA², Yasuhiro YAMADA³, Yusuke KUBO⁴, K-u HINRICHS⁵, Fumio INAGAKI⁶ (1.Center for Advanced Marine Core Research, Kochi University, Japan, 2.Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and T, 3.Depertment of Urban Management Engineering, Kyoto University, 4.CDEX, Japan Agency for Marine-Earth Science and Technology, 5.University of Bremen, Germany, 6.Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology)

Keywords:Coring disturbance, riser drilling, IODP, Exp. 337

Coring disturbances were observed using the riser drilling system of the D/V Chikyu during IODP Exp. 337 off Shimokita, Japan. Injections of drilling mud and fluid with high density and pressure used in riser drilling during Expedition 337 caused complications to visual core observations. Semiconsolidated materials were commonly observed in this Hole, and drilling mud often easily penetrated the semiconsolidated sandstones and siltstones, causing possible false lamination structure in the cores, which might be misinterpreted as natural sedimentary structure preserved in the cores. Here, we report various kind of coring disturbances which were observed on board with riser drilling system.