Spivack, Arthur J; Staudigel, Hubert (1994): Elemental data for composites from DSDP Sites 417A, 417D, and 418A. PANGAEA, https://doi.org/10.1594/PANGAEA.704818, Supplement to: Spivack, AJ; Staudigel, H (1994): Low-temperature alteration of the upper oceanic crust and the alkalinity budget of seawater. Chemical Geology, 115(3), 239-247, https://doi.org/10.1016/0009-2541(94)90189-9
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While the input of river-alkalinity into seawater is relatively well known, the complementary acidity production is poorly understood. Using the major-element budget of seafloor alteration of the upper 500 m of 120-Ma-old oceanic crust at DSDP/ODP Sites 417A, 417D and 418A in the central western Atlantic, we estimate the acidity flux associated with the low-temperature weathering of the upper oceanic crust. The acidity flux is calculated based on major-element fluxes and charge-balance considerations. The relevant chemical fluxes from seawater to the upper crust are 4.1+-0.1; 1.4+-1.4; 2.2+-0.6 and -12+-2 10**11 mol/yr for K, Mg, Na and silicate-Ca, respectively. The associated acidity flux is (3.5+-3)10**11 eq/y. Relative to continental weathering, these fluxes are significant for K and silicate-Ca, but are minor for Na, Mg and acidity. Thus, riverine fluxes of alkalinity are not significantly balanced by acidity fluxes from low-temperature upper ocean crust alteration.
Median Latitude: 25.085667 * Median Longitude: -68.048467 * South-bound Latitude: 25.035000 * West-bound Longitude: -68.057300 * North-bound Latitude: 25.111500 * East-bound Longitude: -68.041300
Date/Time Start: 1976-12-02T00:00:00 * Date/Time End: 1977-02-10T00:00:00
51-417A * Latitude: 25.110500 * Longitude: -68.041300 * Date/Time: 1976-12-02T00:00:00 * Elevation: -5468.0 m * Penetration: 417 m * Recovery: 250.4 m * Location: North Atlantic/CONT RISE * Campaign: Leg51 * Basis: Glomar Challenger * Device: Drilling/drill rig (DRILL) * Comment: 43 cores; 389.1 m cored; 27.8 m drilled; 64.4 % recovery
51-417D * Latitude: 25.111500 * Longitude: -68.046800 * Date/Time: 1976-12-02T00:00:00 * Elevation: -5482.0 m * Penetration: 532.5 m * Recovery: 202.6 m * Location: North Atlantic/CONT RISE * Campaign: Leg51 * Basis: Glomar Challenger * Device: Drilling/drill rig (DRILL) * Comment: 43 cores; 508.6 m cored; 30.4 m drilled; 39.8 % recovery
52-418A * Latitude: 25.035000 * Longitude: -68.057300 * Date/Time: 1977-02-10T00:00:00 * Elevation: -5511.0 m * Penetration: 570.5 m * Recovery: 205.5 m * Location: North Atlantic/CONT RISE * Campaign: Leg52 * Basis: Glomar Challenger * Device: Drilling/drill rig (DRILL) * Comment: 48 cores; 374 m cored; 0 m drilled; 54.9 % recovery