Abstract
The composition of carbonate, sulphate, halide and other phases trapped as fluid inclusions in apatite crystals in ijolite and urtite from sub-volcanic complexes in East Africa have been determined using the electron micro-probe. The bulk composition of these inclusions is alkali-rich and closely comparable to the natrocarbonatite lava from the active volcano of Oldoinyo Lengai in N. Tanzania. The inclusions are interpreted as having been originally immiscible alkali carbonate-rich droplets within a nephelinitic melt. The evidence suggests that magma of the composition of natrocarbonatite lava is that most likely for the parent magma during carbonatite petrogenesis.
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Le Bas, M.J., Aspden, J.A. The comparability of carbonatitic fluid inclusions in ijolites with natrocarbonatite lava. Bull Volcanol 44, 429–438 (1981). https://doi.org/10.1007/BF02600574
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DOI: https://doi.org/10.1007/BF02600574