Geochemistry of Lavas from Taal Volcano, Southwestern Luzon, Philippines: Evidence for Multiple Magma Supply Systems and Mantle Source Heterogeneity   总被引：4，自引：1，他引：4  

MIKLIUS  ASTA; FLOWER  MARTIN F. J.; HUIJSMANS  JOEP P. P.; MUKASA  SAMUEL B.; CASTILLO  PATERNO 《Journal of Petrology》1991,32(3):593-627

Taal Volcano is a highly active center in the southwest Luzonvolcanic field. Recent eruptions are confined to Volcano Island,a plexus of cinder cones and tuff rings surrounding a centralcrater, occupying (and post-dating) a massive volcano-tectonicdepression resulting from multiple phases of collapse. Taallava series can be distinguished from each other by differencesin major and trace element trends and trace element ratios,indicating multiple magmatic systems associated with discretecenters in time and space. On Volcano Island, contemporaneous lava series range from typicallycalc-alkaline to iron-enriched. Major and trace element variationin these series can be modelled by fractionation of similarassemblages, with early fractionation of titano-magnetite inless iron-enriched series. However, phase compositional andpetrographic evidence of mineral-liquid disequilibrium suggeststhat magma mixing played an important role in the evolutionof these series. We interpret this to mean that mixing occurredalong a line of descent defined by fractional crystallization,with mixing occurring over larger compositional intervals inthe less iron-enriched series, consistent with numerical modelling. Between-series incompatible element ratio differences are notexplicable through differential partial melting of a homogeneoussource (also confirmed by variation in Pb isotopic ratios),suggesting a supply system from discrete melt zones in heterogeneousmantle.  相似文献   

Kilauea East Rift Zone Magmatism: an Episode 54 Perspective   总被引：1，自引：0，他引：1  

THORNBER  CARL R.; HELIKER  CHRISTINA; SHERROD  DAVID R.; KAUAHIKAUA  JAMES P.; MIKLIUS  ASTA; OKUBO  PAUL G.; TRUSDELL  FRANK A.; BUDAHN  JAMES R.; RIDLEY  W. IAN; MEEKER  GREGORY P. 《Journal of Petrology》2003,44(9):1525-1559

On January 29–30, 1997, prolonged steady-state effusionof lava from Pu'u'O'o was briefly disrupted by shallow extensionbeneath Napau Crater, 1–4 km uprift of the active Kilaueavent. A 23-h-long eruption (episode 54) ensued from fissuresthat were overlapping or en echelon with eruptive fissures formedduring episode 1 in 1983 and those of earlier rift zone eruptionsin 1963 and 1968. Combined geophysical and petrologic data forthe 1994–1999 eruptive interval, including episode 54,reveal a variety of shallow magmatic conditions that persistin association with prolonged rift zone eruption. Near-ventlava samples document a significant range in composition, temperatureand crystallinity of pre-eruptive magma. As supported by phenocryst–liquidrelations and Kilauea mineral thermometers established herein,the rift zone extension that led to episode 54 resulted in mixtureof near-cotectic magma with discrete magma bodies cooled to  相似文献