Petrologic Conclusions

  • Alok Krishna Gupta
Part of the Springer Geology book series (SPRINGERGEOL)


Silica-deficient potassic rocks are characterized by high K2O content (>3), high K2O/Na2O ratio (>1) and low Si2O/K2O ratio (<15). They have high LREE concentration, sometimes 1,000–1,400 higher than that of chondrites. The LILE/HREE ratios are usually low, but 87Sr/86Sr ratios are usually high (0.707–0.730). The εNd content of these rocks is usually negative compared to average basaltic rocks. If we exclude some exceptional cases, these rocks are relatively young (<25–30 Ma) in the evolutionary history of the earth.


Lithospheric Mantle Mantle Plume Field Volcanism Continental Rift SiO2 System 
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© Springer India 2015

Authors and Affiliations

  1. 1.Mineralogy & PetrologyUniversity of AllahabadAllahabadIndia

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