Hi, all.
I have a set of cumulate rocks formed by the accumulation of plagioclase and biotite. The proportion of plagioclase is around 55%-60%. However, the whole-rock geochemical data show a strong negative Sr anomaly in the primitive mantle normalized trace element patterns. Any potential interpretations for such a chemical characteristic?
Thank you, guys.
Thank you for your answer. These rocks have Eu concentrations of 1.32-1.55 ppm and do not show an Eu anomaly. Because of the identification of monazite in thin sections and the relatively high Th concentrations, the lack of positive Eu anomaly might be ascribed to the accumulation of monazite. Except for the negative Sr anomaly, petrography characteristics and other geochemical data consistently support the accumulation of plagioclase in my samples.
As we all know, the positive Sr anomaly could be interpreted as the accumulation of plagioclase. Does plagioclase accumulation necessarily cause a positive Sr anomaly?
Dear Mr. Gu Daxiang
I think the depletions in Sr content are related to the crystallization of plagioclase and apatite minerals in early-stage magmatic phases, suggesting your samples have undergone significant plagioclase fractionation in their evolution. Also, I advised you to wait for the best answer to your question from experts.
Best Regards Mohamed Faisal
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