Melt and fluid inclusions and mineral thermobarometry of mantle xenoliths in Makhtesh Ramon, Israel

Spinel-bearing, garnet-free mantle xenoliths of dunite, wehrlite, lherzolite, and olivine websterite in alkaline basic-ultrabasic rocks of Makhtesh Ramon were studied. Mineral thermobarometry and melt- and fluid-inclusion microthermometry were used to evaluate the conditions of formation of mantle xenoliths. Liquidus temperatures in the range of 1200-1250 °C and solidus temperatures in the range of 1000-1100°C were obtained on the basis of melt inclusions and mineral geothermometric studies. The range of pressure during formation of the xenoliths, calculated on the basis of high-density CO₂ inclusions, is between 6 and 9.5 kbar. The P-T conditions of fonnation of the xenoliths suggest that strongly heated and highly attenuated crust existed before the intrusion of Early Cretaceous basic-ultrabasic alkaline magmas.