SPANISH HIGH-POTASSIUM MAGMAS AND EVIDENCE OF THEIR GENERATION DEPTH (AS INFERRED FROM THERMOBAROGEOCHEMICAL DATA)

Abstract

The ultrapotassic rocks of Spain have a number of features that relate them to diamond-bearing lamproites of Australia, although there also are some differences. Measurements of homogenization and resorption temperatures of daughter minerals in melt inclusions show that the subliquidus minerals here are olivine and chrome spine. Comparison of the Australian and Spanish lamproites shows that relatively shallow-depth processes were important in their formations. From our data, we conclude that high-potassium igneous rocks, geochemically similar to Spanish lamproites, have little diamond potential.