Moore, George W; Gieskes, Joris M (1980): Interstitial water chemistry at DSDP Leg 57 Holes. PANGAEA, https://doi.org/10.1594/PANGAEA.823017, Supplement to: Moore, GW; Gieskes, JM (1980): Interaction between sediment and interstitial water near the Japan Trench, Leg 57, Deep Sea Drilling Project. In: Scientific Party, Initial Reports of the Deep Sea Drilling Project, 56/57 (eds.), Initial Reports of the Deep Sea Drilling Project (U.S. Govt. Printing Office), 56-57, 1269-1275, https://doi.org/10.2973/dsdp.proc.5657.158.1980
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Analyses of water samples taken by means of an in-hole sampler generally show good agreement with analyses of samples collected by routine shipboard squeezing techniques. At Sites 438 and 439, a decrease in salinity with depth is related to former freshwater flow from an aquifer that crops out at an anticline on a deep sea terrace between Japan and the top of the trench slope of the Japan Trench. This former subaerial recharge suggests significant late Cenozoic subsidence of the terrace, because it now lies at a water depth of 1500 meters. Samples from the trench slope at Site 440 have extremely high values of alkalinity and ammonia, presumably because of a favorable combination of high sedimentation rate and organic carbon content. Diagenetic conditions on the trench slope favor formation of the Fe-Mg carbonate mineral, ankerite; at Site 440 it first occurs at a depth below the sea floor of only 29 meters in late Pleistocene strata. Undissolved diatoms persist to relatively great depth at the sites of Leg 57 because of a low geothermal gradient caused by subduction. Secondary silica lepispheres first appear at 851 meters at the most landward and warmest site, Site 438, in strata 16 million years old with an ambient temperature of 31 °C.
Median Latitude: 40.172313 * Median Longitude: 143.619641 * South-bound Latitude: 39.735500 * West-bound Longitude: 143.231700 * North-bound Latitude: 40.630000 * East-bound Longitude: 144.076700
Date/Time Start: 1977-10-19T00:00:00 * Date/Time End: 1977-11-21T00:00:00
57-438 * Latitude: 40.629200 * Longitude: 143.231700 * Date/Time: 1977-10-19T00:00:00 * Elevation: -1552.0 m * Penetration: 109.5 m * Recovery: 82.1 m * Location: North Pacific/BASIN * Campaign: Leg57 * Basis: Glomar Challenger * Device: Drilling/drill rig (DRILL) * Comment: 10 cores; 90.5 m cored; 19 m drilled; 90.7 % recovery
57-438A * Latitude: 40.629800 * Longitude: 143.235800 * Date/Time: 1977-10-19T00:00:00 * Elevation: -1558.0 m * Penetration: 878 m * Recovery: 535.5 m * Location: North Pacific/BASIN * Campaign: Leg57 * Basis: Glomar Challenger * Device: Drilling/drill rig (DRILL) * Comment: 83 cores; 780.5 m cored; 0 m drilled; 68.6 % recovery
57-438B * Latitude: 40.630000 * Longitude: 143.246700 * Date/Time: 1977-10-19T00:00:00 * Elevation: -1564.0 m * Penetration: 1040.7 m * Recovery: 84.2 m * Location: North Pacific/BASIN * Campaign: Leg57 * Basis: Glomar Challenger * Device: Drilling/drill rig (DRILL) * Comment: 23 cores; 206.5 m cored; 0 m drilled; 40.8 % recovery