GOLD AND PALLADIUM IN THE BASALTOIDS OF T HE COSTA-RICA RIFT-ZONE (PACIFIC) AND COMPARATIVE-ANALYSIS OF GOLD CONTENT IN CENOZOIC BASALTS

Gold and palladium distribution in basalts and dolerites (diabases) re covered by Hole 504B (Ocean Drilling Project) at the depth above 1700 m have been studied. Basalts and diabases were found to have 1.5-5 fol d increase of Au and Pd content in comparison with basaltoids of young volcanic zones of oceanic ridges: 3.3 vs 2.1 ppb of Au and 10.8-29 vs 4.8 ppb of Pd. Secondary alterations of the rocks unlikely induced th e redistribution of Au and Pd. The substantial decrease of Au content in the diabase dykes of the lower part of Hole 504B (recovered at Leg 140) seem to be associated with leaching in the lower part of assumed hydrothermal cell (recycling model).