Gold and palladium in basaltoids of the Costa Rica rift zone (Pacific Ocean) and gold levels in Cenozoic basalts

The distribution of gold and palladium has been studied in basalts and dolerites (diabases) reached by oceanic borehole ODP 504B at a depth of over 1700 m. The basalts and diabases here have levels of these metals 1.5-5 times higher than those in analogous rocks from young volcanic zones in ocean ridges: 3.3 as against 2.1 ppb Au and 10.8-29 ppb Pd as against 4.8. Secondary alterations appear not to have produced appreciable gold and palladium redistribution. There is an appreciable reduction in the gold contents in the dike diabases in the lower part of the borehole succession, which is probably due to leaching in an inferred hydrothermal system. -Journal summary