Almandine megacrysts from Yingfengling Cenozoic basalt in Leizhou Peninsula and their parental magma origin |
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Authors: | Jinhai Yu S Y O’Reilly |
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Institution: | (1) National Key Laboratory of Metallogenic Mechanism of Endogenetic Deposits, Department of Earth Sciences, Nanjing University, 210093 Nanjing, China;(2) National Key Center of GEMOC, Department of Earth and Planetary Sciences, Macquarie University, 109 North Ryde, NSW, Australia |
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Abstract: | The garnet megacrysts from Yingfengling basalts are characterized by high FeO (>20%), CaO (7.02% –8.16%) and low MgO (5.88%–10.87%).
Significant composition variations are observed in these megacrysts, of which Ni, V, Sc, Co, and HREE are positively correlated
with their Mg#, and Zr, Hf, Ga, Y, Sr, Nb, Zn and LREE-MREE are negatively correlated with Mg#. Megacryst parent magma is a highly evolved residual melt with strongl depletion in Ti, Sr, Hf, Nb and HREE. This parental
magma was generated by more than 60% of crystallization fractionation of clinopyroxene, garnet, plagioclase and ilmenite from
quartz tholeiitic magma. It has not erupted to the surface, but stayed at the upper mantle and formed the megacrystic cumulate.
Megacrysts and their host basalt are in disequilibrium. |
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Keywords: | almandine megacryst geochemistry LAM-ICPMS Leizhou Peninsula |
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