A new diapiric model for kimberlite genesis takes into account recent interpretations of peridotiteCO2-H20 melting relationships. A minor thermal perturbation at depth might trigger release of reduced vapors with major components C-H-O. Where these volatile components cross the estimated solidus boundary near 260 km, partial melting occurs, the density inversion causes diapiric uprise along adi...

Whole-rock major and trace element and O, Sr, Nd and Pb isotopic data are reported for 3.0–0.89 Ma lamproites from the Leucite Hills, Wyoming, USA. The two main groups of lamproites, madupitic lamproites and phlogopite lamproites, are geochemically distinct and cannot be related to one another by either fractional crystallization or crustal contamination. It seems likely that the geochemical di...

Rare ultrahigh-temperature–(near)ultrahigh-pressure (UHT–near-UHP) crustal xenoliths erupted at 11 Ma in the Pamir Mountains, southeastern Tajikistan, preserve a compositional and thermal record at mantle depths of crustal material subducted beneath the largest collisional orogen on Earth. A combination of oxygen-isotope thermometry, major-element thermobarometry and pseudosection analysis reve...

Typically, 40Ar/39Ar dating of phlogopites from deep-seated xenoliths kimberlite pipes produces estimates that suggest much older ages than those when these were intruded. High-pressure (3 GPa) laboratory experiments enabled the authors to explore behaviour argon in phlogopite structure under conditions correspond mantle, at temperatures (from 700 1000 °С), far exceeding closure temperature K/A...