(Table 2) Geochemistry of K-feldspars and associated plagioclase phenocrysts and rims at DSDP Legs 69, 52, 51 and 19

• Main Authors: Pertsev, Nikolay N, Boronikhin, V A
• Format: Dataset
• Language: English
• Published: PANGAEA 1983
• Subjects: 19-192A; 51-417; 52-418A; 69-504B; 69-505B; Albite; Aluminium oxide; Anorthite; Calcium oxide; Calculated; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Electron microprobe (EMP); Elevation of event; Event label; Glomar Challenger; Latitude of event; Leg19; Leg51; Leg52; Leg69; Longitude of event; Minerals; North Atlantic/CONT RISE; North Pacific/GRABEN; North Pacific/GUYOT; Orthoclase; Piece; Potassium oxide; Reference/source; Sample code/label; Sample ID; Silicon dioxide; Sodium oxide; Total; Pacific; North Atlantic
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.816468; https://doi.org/10.1594/PANGAEA.816468

Basalts from some holes of the Deep Sea Drilling Project contain secondary K-feldspar which forms pseudomorphs after calcic (>76% An) Plagioclase cores, whereas Plagioclase of rims and microlites (68-74% An) remains unaltered. In basalts of Hole 504B two such grains with relics of Plagioclase in the central parts of phenocysts were recovered. The composition of the Plagioclase rims and of non-replaced phenocrysts is An79-81; the composition of relics is An83. The An and Ab contents of the K-feldspar is higher than in K-feldspar from altered basalt in Hole 418A in the Atlantic Ocean near the Bermuda Rise. Replacement of plagioclases by K-feldspar evidently is caused by oxygen-rich nearbottom sea water penetrating into basalts. The temperature interval of K-feldspathization is probably in the range 30 to 80°C, more-calcic Plagioclase being replaced by K-feldspar at higher temperatures.