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1. Data report: in situ elastic properties of hydrothermally altered volcanic rocks, IODP Expedition 376, Brothers volcano, Kermadec arc

   https://doi.org/10.14379/iodp.proc.376.201.2022  

   Adam, L.; Massiot, C. (August 2022, Proceedings of the International Ocean Discovery Program)

   Cores and downhole measurements recovered during International Ocean Discovery Program (IODP) Expedition 376 to Brothers volcano in the Kermadec arc provided unprecedented in situ data in an active submarine arc caldera with extensive hydrothermal alteration. Pressure (P)-wave velocities were measured on the R/V JOIDES Resolution at atmospheric pressures and saturated with seawater. To complement these shipboard measurements, seven new samples were selected representing various primary lithologic and alteration mineralogic compositions in the three deepest holes (U1527C, U1528D, and U1530A) for further shore-based laboratory testing. P- and shear (S)-wave velocities and porosity were measured on seven samples at atmospheric pressure and dry conditions. In addition, P- and S-wave velocities of two of these samples were measured under effective pressure dry and brine saturated. Such data aids in situ porosity, saturation, and pressure sensitivity elastic data interpretation from downhole measurements acquired in Hole U1530A. The clear waveforms obtained and overall similarities to measurements from the nearest shipboard samples ensure that the results are reliable at atmospheric pressures. All shore-based samples have higher porosity than shipboard samples. This difference could be explained by gas- versus water-connected porosity. The two saturated samples measured at effective pressures of the borehole sample depths show that P-wave speeds are 13%–20% higher than the ship atmospheric pressure measurements. The pressure dependence of wave speeds also enables the qualitative interpretation of pore shapes for these submarine, hydrothermally altered rocks. 

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2. Data report: permeability, porosity, and frictional strength of core samples from IODP Expedition 366 in the Mariana forearc

   https://doi.org/10.14379/iodp.proc.366.202.2019  

   Morrow, C.A; Moore, D.E.; Lockner, D.A.; Bekins, B.A. (June 2019, Proceedings of the International Ocean Discovery Program)

   null (Ed.)

   Core samples from International Ocean Discovery Program (IODP) Expedition 366 were tested in the laboratory to determine permeability, porosity, density, and frictional strength and their relation to mineralogy as part of an effort to understand hydromechanical processes at convergent plate margins. Seven samples were tested from a depth range of 19.6 to 197.9 m below seafloor. The samples were derived from three serpentinite mud volcanoes in the Mariana forearc region that formed where slab-derived fluids and materials ascend along faults. The physical characteristics mirror compositional differences between predominantly serpentine-rich and saponite-rich samples. Permeability values ranged from 10−17 to 10−19 m2, low enough to facilitate the formation of high fluid pressures that have been observed in the Mariana and other subduction megathrust environments. Porosity ranged from 0.37 to 0.51 and density ranged from 1.66 to 2.01 g/cm3. Serpentine-rich samples have coefficients of friction of 0.2–0.4, consistent with crustal serpentinite from a variety of fault zones, whereas saponite-rich samples have friction values less than 0.2, consistent with saponite fault gouge from the San Andreas Fault Observatory at Depth (SAFOD) drill hole in California (USA). 

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3. Expedition 358 methods

   https://doi.org/10.14379/iodp.proc.358.102.2020  

   Hirose, T; Ikari, M; Kanagawa, K; Kimura, G; Kinoshita, M; Kitajima, H; Saffer, D; Tobin, H; Yamaguchi, A; Eguchi, N; et al (July 2020, Proceedings of the International Ocean Discovery Program Expedition reports)

   This chapter documents the methods used for shipboard measurements and analyses during International Ocean Discovery Program (IODP) Expedition 358. We conducted riser drilling from 2887.3 to 3262.5 meters below seafloor (mbsf) at Site C0002 (see Table T1 in the Expedition 358 summary chapter [Tobin et al., 2020a]) as a continuation of riser drilling in Hole C0002F begun during Integrated Ocean Drilling Program Expedition 326 (Expedition 326 Scientists, 2011) and deepened during Integrated Ocean Drilling Program Expeditions 338 and 348 (Strasser et al., 2014b; Tobin et al., 2015b). Please note that the top of Hole C0002Q begins from the top of the window cut into the Hole C0002P casing. Previous Integrated Ocean Drilling Program work at Site C0002 included logging and coring during Integrated Ocean Drilling Program Expeditions 314 (logging while drilling [LWD]), 315 (riserless coring), 332 (LWD and long-term monitoring observatory installation), 338 (riser drilling and riserless coring), and 348 (riser drilling) (Expedition 314 Scientists, 2009; Expedition 315 Scientists, 2009b; Expedition 332 Scientists, 2011; Strasser et al., 2014b; Tobin et al., 2015b). Riserless contingency drilling was also conducted at Site C0024 (LWD and coring) near the deformation front of the Nankai accretionary prism off the Kii Peninsula and at Site C0025 (coring only) in the Kumano fore-arc basin. Riser operations began with connection of the riser to the Hole C0002F wellhead, sidetrack drilling out the cement shoes from 2798 to 2966 mbsf to establish a new hole, and then running a cement bond log to check the integrity of the Hole C0002P casing-formation bonding. A new sidetrack was established parallel to previous Hole C0002P drilling and designated as Hole C0002Q to distinguish it from the overlapping interval in Hole C0002P. Several new kick offs were established (Holes C0002R–C0002T) in attempts to overcome problems drilling to the target depth and then, in the end, to collect core samples. During riser operations, we collected drilling mud, mud gas, cuttings, downhole logs, core samples, and drilling parameters (including mud flow rate, weight on bit [WOB], torque on bit, and downhole pressure, among others). Gas from drilling mud was analyzed in near–real time in a special mud-gas monitoring laboratory (MGML) and was sampled for further postcruise research. Continuous LWD data were transmitted on board and displayed in real time for QC and for initial assessment of borehole environment and formation properties. Recorded-mode LWD data provided higher spatial sampling of downhole parameters and conditions. Cuttings were sampled for standard shipboard analyses and shore-based research. Small-diameter rotary core barrel (SD-RCB; 8½ inch) coring in Hole C0002T provided only minimal core. Riserless coring at Sites C0024 and C0025 with a 10⅝ inch rotary core barrel (RCB) and hydraulic piston coring system (HPCS)/extended punch coring system (EPCS)/extended shoe coring system (ESCS) bottom-hole assembly (BHA) provided most of the core used for standard shipboard and shore-based research. 

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4. Data report: electrical resistivity of sediments from Site U1480, IODP Expedition 362, Sumatra subduction zone

   https://doi.org/10.14379/iodp.proc.362.205.2021  

   Hamahashi, M. (March 2021, Proceedings of the International Ocean Discovery Program)

   null (Ed.)

   Electrical resistivity of sediments was analyzed using samples recovered during International Ocean Discovery Program (IODP) Expedition 362, during which the input materials of the north Sumatran subduction zone were drilled to investigate the material properties linked to shallow seismogenic slip. Electrical resistivity is a valuable indicator for sediment consolidation, pore/grain structures, and distribution of fluid, which can affect the mechanical properties of the forearc wedge. Sediments were recovered from the seafloor to 1415.35 meters below seafloor (mbsf) at Site U1480 and from 1149.7 to 1500 mbsf at Site U1481. They consist of thick sequences of the Bengal-Nicobar Fan (Lithologic Units I–II) underlain by a thin pelagic/igneous sequence (Units III–V). In this study, electrical resistivity was measured on 35 sediment samples from Site U1480 with an Agilent 4294A component analyzer using the bridge method with a two-terminal circuit. Measured resistivity values range from 0.20 to 7.45 Ωm and generally increase with depth. Sample measurements are consistent with the downhole resistivity logs acquired during Expedition 362. Formation factor was calculated from sediment and seawater resistivities, and Archie’s coefficients (cementation [m] and tortuosity [b]) were examined from the relationship between formation factor and porosity. When plotting the sample resistivity in this study together with resistivity logs and shipboard porosity from Sites U1480 and U1481, a contrast in Archie’s coefficients are inferred between the Bengal-Nicobar Fan and pelagic sediments, where the former (m = 3.4–3.8) is characterized by higher m values compared to the latter (m = 2.2). These coefficients show differences in consolidation trend in the input sediments, providing improved equations to estimate porosity from resistivity logs. 

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5. Grain size and mineral variability of glacial marine sediments

   https://doi.org/10.2110/jsr.2022.044  

   Andrews, John T.; Roth, Wendy J.; Jennings, Anne E. (January 2023, Journal of Sedimentary Research)

   ABSTRACT Glacial marine sediment deposition varies both spatially and temporally, but nearly all studies evaluate down-core (∼ time) variations in sediment variables with little consideration for across core variability, or even the consistency of a data set over distance scales of 1 to 1000 m. Grain size and quantitative X-ray diffraction (qXRD) methods require only ≤ 1 g of sediment and thus analyses assume that the identification of coarse sand (i.e., ice-rafted debris) and sediment mineral composition are representative of the depth intervals. This assumption was tested for grain size and mineral weight % on core MD99-2317, off East Greenland. Samples were taken from two sections of the core that had contrasting coarse-sand content. A total of fourteen samples were taken consisting of seven (vertical) and two (horizontal) samples, with five replicates per sample for qXRD analyses and ∼ 10 to 20 replicates for grain size. They had an average dry weight of 10.5 ± 0.5 g and are compared with two previous sets of sediment samples that averaged 54.1 ± 18.9 g and 20.77 ± 5.8 g dry weight. The results indicated some significant differences between the pairs of samples for grain-size parameters (mean sortable silt, and median grain size) but little difference in the estimates of mineral weight percentages. Out of 84 paired mineral and grain-size comparisons only 17 were significantly different at p = < 0.05 in the post-hoc Scheffe test, all of which were linked to grain-size attributes. 

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