We present results of experiments on mixtures of olivine tholeiite and mantle harzburgite, at 5 kb and 1050-1150°C, under conditions of controlled hydrogen fugacity. The basalt end-member was Kilauea 1921 olivine tholeiite + 3 wt.% H2O, and the harzburgite end-member was a mixture of olivine and orthopyroxene mineral separates made from a mantle-derived lherzolite xenolith. The experiments on m...

the pyroxene composition of basaltic rocks from the coloured series and exotic blocks in the neyriz area are discussed. comparison has been made with equivalent rocks from oman. the clinopyroxene compositions are in cognation with trace and rare-earth element analyses which definately confirm the occurrence of three different trends in basic lavas: i-depleted tholeiite, 2-transitional basalt, 3...

Liquidus phase relationships determined on the join CaAIzSi20 8 (anorthi te)-MgzSiO 4 (forsteri te)-SiO 2 (quartz) at 10 kbar show that increasing pressure causes the forsterite and anorthite primary phase fields to shrink and the spinel, enstatite and silica fields to expand. The boundary line between the enstatite and forsterite fields and that between the enstatite and quartz fields both mov...

The research area is Bualemo Village, Kwandang District, North Gorontalo Regency. With coordinates 0˚ 47' 10" - 48' 40" Latitude and 122˚ 55' 0" 57' 5" East Longitude with an of about 10 km2. This study aims to determine the petrogenesis andesite rocks tectonic setting in area. method used this a mapping geological conditions site X-ray fluorescence (XRF) geochemical analysis chemical content r...

The pyroxene composition of basaltic rocks from the Coloured Series and Exotic blocks in the Neyriz area are discussed. Comparison has been made with equivalent rocks from Oman. The clinopyroxene compositions are in cognation with trace and rare-earth element analyses which definately confirm the occurrence of three different trends in basic lavas: I-Depleted tholeiite, 2-Transitional basal...

BECAUSE OCEANIC ISLANDS in general have an underlying volcanic platform which can be expected to include a primary feeder pipe containing recrystallized magma , the gravity field observed will reflect both the topographic mass effect of the platform rising from the sea floor and a contribution from the feeder pipe presumably having a filling of denser material. Certainly the early study of Oahu...

Microprobe analyses of Ca-rich pyroxenes crystallized in the melting ranges of a magnesian alkali basalt, a transitional basalt, an olivine tholeiite, a tholeiitic andesite, and an augite leucitite at pressures between 8 and 45 kb show complex variation. Ca-poor pyroxene precipitated only from the alkali basalt at pressures between 14 and 18 kb. Pyroxene falling near the Di-Hed join in the pyro...

This paper presents results of modelling reaction between peridotite and fractionating tholeiitic basalt in simple and complex silicate systems. Reactions are outlined in appropriate binary and ternary silicate systems. In these simple systems, the result of reactions between 'basalt' and 'peridotite' may be treated as a combination of Fe-Mg exchange and mass transfer reactions at constant Fe/M...