Minor and Trace Element Geochemistry, Initial 87Sr/86Sr Ratios and Oxygen Isotopic Ratios of Leucite-Bearing Rocks
Holmes and Harwood (1937) studied the trace element geochemistry of leucite-bearing rocks of the Birunga volcanic province and found that these differ chemically from the granites and pegmatites in the abundance of Ti, Cl, P, Ba, and Sr and in the paucity of Li, B, and Be. They differ from basaltic rocks by their abundance of F, P, Ba, and Sr and presence of Zr. Higazy (1954) studied the trace element contents of the rocks of Birunga and Toro-Ankole and found that the notable chemical features of these rocks from the latter area are also the relative abundance of Sr, Ba, Rb, and Zr, which are uncommon in ultramafic rocks. They are high in Cr and Ni contents, except for the rocks poor in Mg, namely melilite leucitite and melilite-potash nephelinite. The other characteristic features include low Li content and relatively high La and Y (La > Y). Although the rocks of both areas have similar trace element contents, the Y content of the Birunga rocks is higher than the La content. The trace element contents of some of the leucite-bearing rocks are summarized in Tables 4.1 and 4.2 and Fig. 4.1.
KeywordsCrystallization Geochemistry Calcite Olivine Rutile
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