Immiscible separation of metalliferous Fe/Ti-oxide melts from fractionating alkali basalt: P-T-f (sub O2) conditions and two-liquid elemental partitioning

Article Abstract:

Analyses of igneous xenoliths containing high-iron-oxide melt (HIM) indicated that they resulted from crystal fractionation in a deep-crustal chamber of alkali basalt magma. HIM represented a primary magmatic phase. These findings were observed in globules of oxide melts dominated by iron and titanium. Fluid inclusion and mineral composition data showed immiscible separation of the HIM at magmatic temperatures. The HIM separation occurred during clinopyroxene accumulation in an alkali trachybasalt and continued during crystallization of amphibole and K-feldspar.

Analysis, Basalt, Iron oxides, Magmatism, Rocks, Igneous, Inclusions, Xenoliths

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Carbon isotope fractionation between calcite, graphite and CO2: an experimental study

Article Abstract:

An analysis of carbon isotopes is presented. Experiments were done to determine the partitioning of stable carbon isotopes between calcite, graphite and CO2 under temperature ranges from 500 to 1200 degrees celsius and 1 to 15 kbar pressure levels. It is shown that the achievement of similar fractionationresults by different isotopic directions yielded carbon isotope equilibrium. Inaddition, the application of a derivative fractionation curve on metacarbonatesgenerates metamorphic temperatures higher than those established by earlier research.

Carbon dioxide, Isotopes, Graphite, Fractionation, Fractional distillation, Calcite

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Oxygen isotope heterogeneity of the mantle deduced from global 18O systematics of basalts from different geotectonic settings

Article Abstract:

Oxygen isotope data of the earth's Neogene volcanic rocks has a variation plus 2.9% to plus 11.4%. The analysis of data indicates heterogeneity in the earth's mantle for oxygen isotope concentration and these have contributed to basalt petrogenesis. These results are same as that from isotope ratio variation of O-, Sr-, Nd-, and Pb-, implying a common process responsible for the origin of upper mantle.

Earth, Geology, Stratigraphic, Stratigraphy, Geology, Structural, Structural geology, Mantle (Geology), Neogene period

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