Phase Relations in Spinel Lherzolite KLB-1 According to Results of Thermodynamic Modeling up to 30 GPa: Peculiarities of Mineral Assemblages and Geodynamic Effects

Abstract The composition of spinel lherzolite xenolith KLB-1 from the Kilbourne Hole volcanic crater, United States, which is close to Earth’s primitive mantle, was used for thermodynamic modeling phase relations in Na 2 O–CaO–FeO–MgO–Al O 3 –SiO system (NCFMAS) using Perple_X software package temperature range 900–2000 °C and pressures 0.0001–30 GPa. calculated diagram good agreement with published data on reveals peculiarities mantle mineral assemblages at P–T parameters experimental are insufficient or absent. results showed that assemblage garnet wehrlite (garnet + olivine clinopyroxene), least common type peridotite surface, prevails upper since Archean. Mineral clinopyroxene orthopyroxene), a variety peridotites most widely found formed lithospheric because its temperatures lower than those convecting mantle. Thermodynamic ringwoodite-free field (located bottom transition zone), crosscut by Archean adiabats geotherms hottest Phanerozoic plumes. This area causes change, negative positive, slope boundary between zone. A positive should have stimulated ascend plumes through Conversely, this has plumes, rising as result, either slow down stop.