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Showing 2 results for Nd-Sr Isotopes

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Volume 17, Issue 2 (7-2009)
Abstract

The Javaherdasht Basalts show compositional range from olivine basalts to quartz basaltic andesites. Petrographic studies indicate that the differentiation of clinopyroxene and olivine minerals has main role for lithologic variety of the basalts.The corosion golf, crenated margins and lack of the same colour in the clinopyroxene phenochrysts margins with matrix Pyroxene grains express a nonequilibrium and are petrographic features for crustal contamination of the basalts.The positive correlation CaO,CaO/Al2O3 and Cr with Mg# and CaO/Al2O3 with Sc and the negative correlation Al2O3 with Mg# are geochemical  characters for the differentiation of clinopyroxene and olivine in the magmatic evolution of the area.The high ratios of Ba/Zr and Pb/Nd and low ratio of Ce/Pb and positive correlation of SiO2 and Rb with 87Sr/86Sr and negative correlation of Nd-Sr isotopes display the contamination of these basalts with continental crust.


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Volume 25, Issue 1 (4-2017)
Abstract

The Qalaylan pluton of Late Jurassic age is composed of intermediate and felsic rocks that crop out in the northern Sanandaj-Sirjan Zone. A body is comprising alkaline, high K, Ferroan A1-type rocks with contrasting aspects; whiles, Nd-Sr primitive isotopic composition consistent with a mantle source. On the other hand, inherited zircon cores (with a range of 230 – 2700 Ma) and elevated Nd model ages (Avg. »670 Ma) indicate that the source of these rocks was not juvenile mantle-derived subduction related magma. Unusually large proportion of inherited zircons demonstrates that fast and non-equilibrium melting of pre-fertile crust with primitive isotopic signatures was the source of these rocks. Zoning and porphyritic texture of the body, oscillatory zoning of plagioclase grains and unusually amount of pre-magmatic zircons all are evidences of non-equilibrium condition as a result of fast cooling rate of parental magma of Qalaylan.



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