Journal article

Multiple-reaction geobarometry for olivine-bearing igneous rocks

Luca Ziberna, Eleanor CR Green, Jon D Blundy



Efforts to map the vertical distribution of mafic and ultramafic igneous rocks in the Earth's crust and uppermost mantle have long been hampered by the lack of precise geobarometers for the appropriate mineral assemblages. The average P (avP) method (Powell and Holland 1994) is a multiple-reaction approach that uses a least-squares minimization to average the pressures derived from individual mineral equilibria, taking into account both their uncertainties and correlations. We applied average P to a carefully selected database of published phase-equilibrium experiments in dry to H2O-saturated, andesitic to basaltic and peridotitic systems at P = 0.6-9.3 kbar, T = 940-1240 °C, with log fO2 fr..

View full abstract


Awarded by NERC

Awarded by Natural Environment Research Council

Funding Acknowledgements

We thank Roger Powell for helpful discussions, especially his insight into and debugging of the average P algorithm. Susanne Skora provided many useful suggestions in the original formulation of this project and, together with Richard Arculus and Richard Brooker, assisted in collection of the Dominica xenoliths. John Schumacher and Lena Melekhova are thanked for the useful discussions. Francesco Narduzzi is thanked for the valuable comments on preliminary versions of the manuscript. Silvio Mollo and Alexey Ariskin are thanked for their helpful and constructive reviews, and Renat Almeev for his editorial handling. This project was funded by NERC grant NE/K014978/1.