Fluid-rock interaction at the backstop to the Mediterranean Ridge Accretionary Complex South of Crete : R/V SONNE Cruise Report SO278 : Emden (Germany), 12.10.2020 - Emden (Germany), 01.12.2020 : FRINGE

The research cruise to the Eastern Mediterranean (GPF-18-2-40) originally planned on RV METEOR was relocated to RV SONNE (Fig. 1.2) due to the reduced number of scientists as part of the corona pandemic. The main objective of the Bremen Ocean Cluster expedition (DFG, EXC2077) was to investigate the interactions between the seabed and ocean water in Greek waters, whereby the plate tectonic constellation of a broad collision zone represents a special tectonic drive. A secondary goal was the sampling of the Sartori mud volcano, which is being processed in Italian waters as part of a separate DFG project and for which the GPF granted an additional permit for ship time (GPF 20-1_054). The expedition began on 12 October in Emden/Germany and ended on 01 December 2020, in Emden. Investigations on mud volcanoes were carried out divided into 3 working areas (Fig. 1.1, the Sartori mud volcano in the Calabrian arc, the so-called Cobblestone Area, the Olimpi mud volcano field including the United Nation Ridge). With the MARUM AUV SEAL (Fig. 1.3) 11 dives were successfully carried out to create high-resolution detailed maps of certain seafloor structures. A total of 38 gravity cores (Fig. 1.4), 30 multicorers (Fig. 1.5) and 4 minicorers were used for sampling sediments and 6 CTD stations for sampling methane in the water column. Furthermore, 10 profiles were carried out with the heat flow lance and 5 observation profiles with the on-board OFOS. In four different provinces, 16 mud volcanoes were examined, 10 of which are characterized by pore waters that show a distinct freshening, while three mud volcanoes, Napoli, Heraklion and Gelendzhik, are characterized by very high salt concentrations. The salt accumulations in these structures are derived from the Messinian salt deposits in the subbed, from which salty brines arise through subrosion, which interact in various ways with the mud volcanoes. The study areas were selected based on preliminary surveys and morphological structures and increased backscatter patterns from multibeam mapping carried out over 3580 nautical miles in Italian and Greek waters.32

X-ray fluorescence (XRF) data of sediment core GeoB24351-1, 50 kV run

X-Ray fluorescence (XRF) scans were carried out for core GeoB24351-1 (Gelendzhik MV; 0-284 cm) in 10 mm steps downcore on the split core surface of the archive half with the XRF Core Scanner III (AVAATECH Serial No. 12) at MARUM – Center for Marine Environmental Sciences in Bremen. To avoid contamination of the XRF measurement unit and the desiccation of the sediment, the split core was covered with a 4 µm thin SPEXCerti Ultralene1 foil. Reported data was acquired with a SGX Sensortech Silicon drift detector (Modul S SiriusD®D65133Be-INF with 133 eV X-ray resolution), a Topaz-X High-Resolution Digital MCA, and an Oxford Instruments 100 W Neptune X-Ray tube with rhodium (Rh) target material. Data were obtained during three runs at 50 kV (1st run), 30 kV (2nd run) and 10 kV (3rd run). Processing of raw data took place by the analysis of X-ray spectra by an iterative least square software package from Canberra Eurisys (WIN AXIL)

X-ray fluorescence (XRF) data of sediment core GeoB24351-1, 30 kV run

X-Ray fluorescence (XRF) scans were carried out for core GeoB24351-1 (Gelendzhik MV; 0-284 cm) in 10 mm steps downcore on the split core surface of the archive half with the XRF Core Scanner III (AVAATECH Serial No. 12) at MARUM – Center for Marine Environmental Sciences in Bremen. To avoid contamination of the XRF measurement unit and the desiccation of the sediment, the split core was covered with a 4 µm thin SPEXCerti Ultralene1 foil. Reported data was acquired with a SGX Sensortech Silicon drift detector (Modul S SiriusD®D65133Be-INF with 133 eV X-ray resolution), a Topaz-X High-Resolution Digital MCA, and an Oxford Instruments 100 W Neptune X-Ray tube with rhodium (Rh) target material. Data were obtained during three runs at 50 kV (1st run), 30 kV (2nd run) and 10 kV (3rd run). Processing of raw data took place by the analysis of X-ray spectra by an iterative least square software package from Canberra Eurisys (WIN AXIL)

X-ray fluorescence (XRF) data of sediment core GeoB24351-1, 10 kV run

X-Ray fluorescence (XRF) scans were carried out for core GeoB24351-1 (Gelendzhik MV; 0-284 cm) in 10 mm steps downcore on the split core surface of the archive half with the XRF Core Scanner III (AVAATECH Serial No. 12) at MARUM – Center for Marine Environmental Sciences in Bremen. To avoid contamination of the XRF measurement unit and the desiccation of the sediment, the split core was covered with a 4 µm thin SPEXCerti Ultralene1 foil. Reported data was acquired with a SGX Sensortech Silicon drift detector (Modul S SiriusD®D65133Be-INF with 133 eV X-ray resolution), a Topaz-X High-Resolution Digital MCA, and an Oxford Instruments 100 W Neptune X-Ray tube with rhodium (Rh) target material. Data were obtained during three runs at 50 kV (1st run), 30 kV (2nd run) and 10 kV (3rd run). Processing of raw data took place by the analysis of X-ray spectra by an iterative least square software package from Canberra Eurisys (WIN AXIL)

Sediment core description of GeoB24366-2 (MUC24) recovered during R/V Sonne expedition SO278 at Sartori MV in the Calabrian Arc, Mediterranean Sea

Sediment core GeoB24366-2 (MUC24) was collected during R/V Sonne expedition SO278 using a multi corer. The position is close to the Sartori Mud Volcano located in the Calabrian accretionary prism (Mediterranean Sea). To capture the sedimentary structure, the multi core was longitudinally split and the archive halve was photographed using a camera at a 300-dpi resolution. To investigate lithological changes in more detail, a macroscopic core description is prepared. The core description provides information regarding core length, exact position, water depth, number of core sections, core image, color, lithology, sedimentary structures and a descriptive text. Sediment color was determined qualitatively using Munsell soil color charts

Stable oxygen and hydrogen isotopic composition of pore water (δ18O; δD) of sediment core GeoB24310-1

The samples are retrieved from sediment core GeoB24310-1 (Napoli MV; 0-280 cm) in the Olimpi mud volcano field, located south of Crete at the Mediterranean Ridge accretionary complex. Hydrogen (δD) and oxygen (δ18O) isotopes were analysed in the sediment geochemistry laboratory at MARUM using a Picarro 2130i CRD System. Approximately 2 mL of the onboard extracted pore water was used per measurement. The results are an average of at least three injections, while a total of 9 injections of 7 µL each have been analysed per sample. Results are reported in delta notation (‰) relative to V-SMOW2 -SLAP2 with nominal standard (std) deviation of 0.03 for δ18O and 0.3 for δD. Actual std deviation is between 0.02 and 0.29 for δ18O and between 0.04 and 1.68 for δD

Sediment core description of GeoB24303-1 (GC02) recovered during R/V Sonne expedition SO278 at Sartori MV in the Calabrian Arc, Mediterranean Sea

Sediment core GeoB24303-1 (GC02) was collected during R/V Sonne expedition SO278 using a gravity corer. The position is close to the Sartori Mud Volcano located in the Calabrian accretionary prism (Mediterranean Sea). To capture the sedimentary structure, the gravity core was longitudinally split directly after recovery on board of cruise SO278 and the archive halve was photographed using the smartCIS1600 line scan technique of the MARUM GeoB Core repository at a 500-dpi resolution. To investigate lithological changes in more detail, a macroscopic core description is prepared. The core description provides information regarding core length, exact position, water depth, number of core sections, core image, color, lithology, sedimentary structures and a descriptive text. Sediment color was determined qualitatively using Munsell soil color charts

Stable oxygen and hydrogen isotopic composition of pore water (δ18O; δD) of sediment core GeoB24348-2

The samples are retrieved from sediment core GeoB24348-2 (Brine pool; 0-537 cm) in the Olimpi mud volcano field, located south of Crete at the Mediterranean Ridge accretionary complex. Hydrogen (δD) and oxygen (δ18O) isotopes were analysed in the sediment geochemistry laboratory at MARUM using a Picarro 2130i CRD System. Approximately 2 mL of the onboard extracted pore water was used per measurement. The results are an average of at least three injections, while a total of 9 injections of 7 µL each have been analysed per sample. Results are reported in delta notation (‰) relative to V-SMOW2 -SLAP2 with nominal standard (std) deviation of 0.03 for δ18O and 0.3 for δD. Actual std deviation is between 0.02 and 0.29 for δ18O and between 0.04 and 1.68 for δD

Stable oxygen and hydrogen isotopic composition of pore water (δ18O; δD) of sediment core GeoB24343-1

The samples are retrieved from sediment core GeoB24343-1 (Monza MV; 0-318 cm) in the Olimpi mud volcano field, located south of Crete at the Mediterranean Ridge accretionary complex. Hydrogen (δD) and oxygen (δ18O) isotopes were analysed in the sediment geochemistry laboratory at MARUM using a Picarro 2130i CRD System. Approximately 2 mL of the onboard extracted pore water was used per measurement. The results are an average of at least three injections, while a total of 9 injections of 7 µL each have been analysed per sample. Results are reported in delta notation (‰) relative to V-SMOW2 -SLAP2 with nominal standard (std) deviation of 0.03 for δ18O and 0.3 for δD. Actual std deviation is between 0.02 and 0.29 for δ18O and between 0.04 and 1.68 for δD

Sediment core description of GeoB24374-2 (MUC29) recovered during R/V Sonne expedition SO278 at Sartori MV in the Calabrian Arc, Mediterranean Sea

Sediment core GeoB24374-2 (MUC29) was collected during R/V Sonne expedition SO278 using a multi corer. The position is close to the Sartori Mud Volcano located in the Calabrian accretionary prism (Mediterranean Sea). To capture the sedimentary structure, the multi core was longitudinally split and the archive halve was photographed using a camera at a 300-dpi resolution. To investigate lithological changes in more detail, a macroscopic core description is prepared. The core description provides information regarding core length, exact position, water depth, number of core sections, core image, color, lithology, sedimentary structures and a descriptive text. Sediment color was determined qualitatively using Munsell soil color charts