Description: Products of two mud volcanoes from the distal part of the Mediterranean Ridge accretionary complex have been investigated regarding their B, C, and O stable isotope signatures. The mud breccias have been divided into mud matrix, lithified clasts, biogenic deposits, and authigenic cements and crusts related to fluid flow and cementation. Isotope geochemistry is used to evaluate the depth of mobilization of each phase in the subduction zone. B contents and isotope ratios of the mud and mud clasts show a general trend of B enrichment and decreasing d11B values with increasing consolidation (i.e., depth). However, the majority of the clast and matrix samples relate to moderate depths of mobilization within the wedge (1-2 km below seafloor). The carbonate cements of most of these clasts as well as the authigenic crusts, however, provide evidence for a deep fluid influence, probably associated with the décollement at 5-6 km depth. This interpretation is supported by d13C ratios of the crust, which indicate precipitation of C from thermogenic methane, and by the d11B ratios of pore-water samples of mud-breccia drill cores. Clams (Vesicomya sp.) living adjacent to fluid vents have d11B and d18O values corresponding to brines known in the area, which acted as the parent solution for shell precipitation. Such brines are most likely Miocene pore waters trapped at deep levels within the backstop to the accretionary prism, probably prior to desiccation of the Mediterranean in the Messinian (6-5 Ma). Combining all results, deep fluid circulation and expulsion are identified as the main processes triggering mud liquefaction and extrusion, whereas brines contribute only locally. Given the high B contents, mud extrusion has to be considered a major backflux mechanism of B into the hydrosphere.

Description: Raw data acquired by position sensors on board RV MERIAN during expedition MSM119 were processed to receive a validated master track which can be used as reference of further expedition data. During MSM119 the motion reference unit Kongsberg SeaTex AS MRU-5 combined with Kongsberg SeaTex AS Seapath 320 and the GPS receivers Trimble SPS855 and SAAB R4 were used as navigation sensors. Data were downloaded from DAVIS SHIP data base (https://dship.bsh.de) with a resolution of 1 sec. Processing and evaluation of the data is outlined in the data processing report. Processed data are provided as a master track with 1 sec resolution derived from the position sensors' data selected by priority and a generalized track with a reduced set of the most significant positions of the master track.