Unusual Ti, Fe, Mn and Ba silicates in alkaline granites from Mardan, Northern Pakistan
Abstract
The Shewa-Shahbazgarhi complex is a late Paleozoic intrusion covering 80 km2 area. It consists predominantly of silicic rocks (riebeckite + aegirine gneiss, aegirine-riebeckite porphyry, porphyritic microgranite and local quartz monozonite) that have been intruded locally by metadolerite. One variety of the granitic rocks contains unusual barium-, titanium- and manganese-bearing phases resembling bafertisite from Mongolia. The mineral occurs in trace amount as fibers (up to 0.75 mm in length) in feldspar, biotite and rarely groundmass. It is faintly pleochroic from pale yellow to golden yellow. The mineral may be a product of hydrothermal process or autometasomatism related to residual fluids in the granitic magma.
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