Whole rock and elements concentrations from IODP Hole 343-C0019E

The microstructures, mineralogy and chemistry of four representative samples collected from cores extracted from the Japan Trench during Integrated Ocean Drilling Project Expedition 343, the Japan Trench Fast Drilling Project (JFAST) have been studied using optical microscopy, TEM, SEM, XRF, XRD and microprobe analyses. The samples provide a transect from relatively undeformed marine sediments in the hanging wall, to the undeformed footwall material, crossing the thrust interface between the Pacific and North American plate, where the fault slipped during the March 2011 Tohoku-Oki earthquake. Our preliminary results suggest that the low strength of JFAST fault gouge material is caused by the high amount of clay minerals (~ 60% smectite, ~ 14 illite). Clay minerals in the décollement (gouge) sample are partly replaced by newly formed manganese oxide, which precipitated from hydrothermal fluids. Dauphine twins were found in quartz grains of the décollement sample suggesting local high stress possible during seismic loading. Other microstructures cannot be assigned unambiguously to co-seismic or a-seismic faulting processes. The observed scaly clay fabric is consistent with observations in many other plate-boundary fault zones. Significant grain size reduction was found in the fault (decollement) zone sample. But a change in lithology of the fault material cannot be ruled out. Microstructures typical for a-seismic deformation like dissolution-precipitation features (e.g. dissolved grain boundaries, mineral alteration) occur in all JFAST core samples, but more frequently in the décollement sample.

Swath sonar bathymetry during POLARSTERN cruise ANT-XIX/2 (PS61) with links to multibeam raw data files

Multibeam data were measured during R/V Polarstern cruise ANT-XIX/2 along track lines of about 6,100 NM total length along transits, survey profiles and during stationary work, mainly in the Weddell Sea. A multibeam survey was conducted in the eastern Weddell Sea at a potential earthquake area, located east of Fimbul Canyon. The tracks complemented data from former expeditions and extended the surveyed area to 60 by 80 NM. Data were achieved during the transit to the eastern Weddell Sea and by several wide spaced track lines at the continental margin east of Antarctic Peninsula. Between 66°30'S and 67°S a systematic survey of about 35 by 40 NM was carried out at a slump area. The multibeam sonar system Hydrosweep DS-2 was operated using 59 beams and 90° aperture angle. The refraction correction was achieved utilizing the system's own cross fan calibration. The quality of data might be reduced during bad weather periods or adverse sea ice conditions. The dataset contains raw data that are not processed and thus may contain errors and blunders in depth and position.