·Oxide gabbro interlayered with relatively thin monzodiorite bands forms cyclical units irregularly distributed throughout the EZ and consists of olivine and pyroxene with minor interstitial magnetite ilmenite and apatite Magnetite is the principal Fe Ti oxide mineral and varies in chemical composition and microtextures in different ore zones
·Popular models of chemical geodynamics use average composition of MORB as proxy for ocean crust Hofmann 1 988 but this use neglects the fact that MORB is only a compositional end member and
Gabbro rock is a type of intrusive basalt that differs from basalt in that it has variable mineral content Light and dark minerals stratification layered gabbro large quantities of olivine olivine gabbro or a high proportion of coarse plagioclase feldspar crystals löcogabbro Classification and Gabbros Composition
Based on petrographic studies the mafic igneous rocks comprise medium to coarse gabbro micro gabbro and hornblende gabbro The rocks mainly consist of plagioclase olivine clinopyroxene biotite amphibole and Fe Ti oxides The chemical composition of the minerals is similar to those of gabbroic rocks that were formed in a non orogenic
Igneous rocks can be divided into four categories based on their chemical composition felsic intermediate mafic and ultramafic The diagram of Bowen s reaction series shows that differences in chemical composition correspond to differences in the types of minerals within an igneous rock Igneous rock names are based in part on the
·Gabbro s durability and weather resistant properties make it valuable in construction and decorative stone applications often marketed under the trade name black granite Classification Igneous rock; Chemical Composition Primarily composed of plagioclase feldspar pyroxene and olivine with minor amounts of amphibole and magnetite
·The compositions of the lower gabbro cumulates and lavas and dykes can be broadly explained using a simple fractional crystallization model grey arrows of the bulk crustal composition but the
Chemical analyses of gabbroic rocks are given in Table 1 together with the rocks contain ≪54% SiO 2 which is an indication that they are have relatively high CaO and Al 2 O 3 values reflecting the high plagioclase content The main chemical difference between gabbro and norite is the higher CaO content of gabbro especially that which is in excess of the
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