Staudigel, Hubert; Frey, Frederick A; Hart, Stanley R (1979): Chemical composition and isotope ratios of basalts from DSDP Sites 417 and 418, West Atlantic Ocean. PANGAEA, https://doi.org/10.1594/PANGAEA.667438, Supplement to: Staudigel, H et al. (1979): Incompatible trace-element geochemistry and 87/86Sr in basalts and corresponding glasses and palagonites. In: Donnelly, T, Francheteau, J., Bryan, W., Robinson, P., Flower, M., Salisbury, M., et al. (eds.), Initial Reports of the Deep Sea Drilling Project, Washington (U.S. Government Print Office), 51,52,53, 1137-1144, https://doi.org/10.2973/dsdp.proc.515253.138.1980
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Basalts from Sites 417 and 418 are relatively depleted in light REE compared to a chondritic REE distribution. In the least altered samples, K, Rb, Cs, and Sr and Ba concentrations are lower than in average mid-ocean ridge basalt (MORB). Thus, the source rock for these basalts must have been highly depleted in incompatible elements. However, 87/86Sr ratios in these basalts, even in microscopically fresh glass, are high (> 0.7030). These ratios, compared to normal MORB, are largely an effect of low-temperature alteration. Sr isotope exchange with sea water is postulated for basaltic glass (87/86Sr = 0.70301) with low incompatible-element abundances, but we cannot eliminate the possibility that these relatively high 87/86Sr ratios are primary. By studying closely associated glass-palagonite-crystalline rock samples, we can identify two types of alteration processes: (1) palagonite formation which causes loss of REE elements, without changing their distribution, and decreasing K/Rb and K/Cs with increasing K content; and (2) glass-sea water exchange which is apparently a diffusioncontrolled process, causing increasing K/Rb and K/Cs with increasing K content but not affecting REE.
Median Latitude: 25.060500 * Median Longitude: -68.053800 * South-bound Latitude: 25.035000 * West-bound Longitude: -68.057300 * North-bound Latitude: 25.111500 * East-bound Longitude: -68.046800
Date/Time Start: 1976-12-02T00:00:00 * Date/Time End: 1977-03-15T00:00:00
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
52-417D * Latitude: 25.111500 * Longitude: -68.046800 * Date/Time: 1976-12-30T00:00:00 * Elevation: -5482.0 m * Penetration: 708 m * Recovery: 532 m * Campaign: Leg52 * Basis: Glomar Challenger * Device: Drilling/drill rig (DRILL)
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