The Hf isotope composition of cratonic mantle: LAM-MC-ICPMS analysis of zircon megacrysts in kimberlites

羟氨苄青霉素引起大疱性类天疱疮样疹

A-type granites and related rocks: Evolution of a concept, problems and prospects

Oxygen thermobarometry measurements on spinel peridotite rocks indicate that the oxygen fugacity at the top of the upper mantle falls within ±2 log units of the fayalite-magnetite-quartz (FMQ) oxygen buffer. Measurements on garnet peridotites from cratonic lithosphere reveal a general decrease in fo2 with depth, which appears to result principally from the effect of pressure on the controlling Fe3+/Fe2+ equilibria. Modeling of experimental data indicates that at approximately 8 GPa, mantle fo2 will be 5 log units below FMQ and at a level where Ni-Fe metal becomes stable. Fe-Ni alloy and an Fe2O3-garnet component will be formed as a result of the disproportionation of FeO, which is experimentally demonstrated through observations of high Fe3+/ΣFe ratios in minerals in equilibrium with metallic Fe. In the lower mantle, the favorable coupled substitution of Al and Fe3+ into (Fe,Mg)SiO3 perovskite results in very high perovskite Fe3+/ΣFe ratios in equilibrium with metallic Fe. As a result, the lower mantle sh...

The Redox State of Earth's Mantle

The deep carbon cycle and melting in Earth's interior

The origin of cratonic diamonds — Constraints from mineral inclusions

Frequent inclusions of ferropericlase, some coexisting with phases of MgSiO3, CaSiO3 and SiO2 composition, suggest that a large proportion of diamonds from Guinea are derived from the lower mantle. Low aluminium contents in MgSiO3 inclusions indicate derivation from the uppermost lower mantle, where Al solubility in perovskite is low. Trace element analyses (SIMS) of CaSiO3 inclusions reveal extreme degrees of LREE (200–2000 times chondritic) and Sr enrichment (70–1000 times chondritic) together with negative and positive Eu anomalies. This implies a highly enriched lower mantle source, possibly a product of a subducted oceanic slab. A number of phases that are only stable in the upper mantle are found to coexist with lower mantle phases and thereby indicate retrograde equilibration during slow exhumation within a rising plume or convection cell. In one case, however, an inclusion paragenesis of ferropericlase and olivine can be shown to have formed within the upper mantle, indicating that the occurrence of ferropericlase inclusions alone is an unreliable indicator of lower mantle origin.

Kankan diamonds (Guinea) II: lower mantle inclusion parageneses

Metasomatic processes in lherzolitic and harzburgitic domains of diamondiferous lithospheric mantle: REE in garnets from xenoliths and inclusions in diamonds

https://www.geol.umd.edu/%7Emcdonoug/Lithium%20Group/Stachel%20et%20al%20lithos.pdf

Thomas Stachel

Papers

The origin of cratonic diamonds — Constraints from mineral inclusions

Kankan diamonds (Guinea) II: lower mantle inclusion parageneses

Metasomatic processes in lherzolitic and harzburgitic domains of diamondiferous lithospheric mantle: REE in garnets from xenoliths and inclusions in diamonds

The trace element composition of silicate inclusions in diamonds: a review

Diamond formation — Where, when and how?