Magmatic Conditions and Magma Ascent as Indicated by Hornblende Phase Equilibria and Reactions in the 1995-2002 Soufriere Hills Magma   总被引：3，自引：0，他引：3  

RUTHERFORD  MALCOLM J.; DEVINE  JOSEPH D. 《Journal of Petrology》2003,44(8):1433-1453

A study of amphiboles and associated minerals in samples ofSoufrière Hills andesite erupted from 1995 to 2002 showssignificant compositional variations within hornblende phenocrysts,a separate set of small pargasitic crystals in the groundmass,and two types of reaction rims on the phenocrysts. The compositionof the amphiboles and coexisting phases defines the thermalhistory of the erupting magma. As many as seven zones (<200µm wide) in the hornblende phenocrysts begin with a sharpincrease in Mg and Si, and then change gradually to a more Fe-and Al-rich hornblende, a transition that is consistent witha temperature rise. Analyses of the hornblende phenocrysts andassociated Fe–Ti oxides verify previous conclusions thatthe pre-eruption magma was at 130 MPa and 830 ± 10°C,but was variably heated before eruption. The heating occurredwithin  相似文献   

Magma Storage Region Processes Inferred from Geochemistry of Fe-Ti Oxides in Andesitic Magma, Soufriere Hills Volcano, Montserrat, W.I.     

DEVINE  J. D.; RUTHERFORD  M. J.; NORTON  G. E.; YOUNG  S. R. 《Journal of Petrology》2003,44(8):1375-1400

Analyses of Fe–Ti oxides help constrain models of magmastorage region processes for the Soufrière Hills Volcano,Montserrat (W.I.), and provide clear evidence of the natureof transient heating events in the magma storage region. Toconstrain timescales of magma heating and remobilization, theTiO₂ zoning patterns in a time series of natural titanomagnetiteswere compared with those produced in controlled phase equilibriumexperiments on the andesite. Most samples of andesite eruptedfrom 1995 to 2002 contain titanomagnetite crystals with uniformcore compositions (TiO₂  相似文献