کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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6435947 | 1637255 | 2012 | 7 صفحه PDF | دانلود رایگان |
The San Jorge porphyry copper deposit in Mendoza, Argentina in some parts contains breccia pipes that are strongly enriched with tourmaline of the dravite-schorl solid solution series with some quartz, muscovite, orthoclase, kaolinite, Cu sulfides and arsenopyrite. The overall composition of tourmaline is rather homogeneous with an intracrystalline variation of the Fe/Mg ratio reflected by its texture, its core-rim zonation of tourmaline and by the statistical variation of the Fe/Mg ratio. The depth-related intracrystalline changes are best interpreted as a hydrothermal collapse breccia which formed as a result of the reaction of primary hydrothermal B-Fe-enriched fluids with the country rocks enriched in Mg. The chemical composition attests to only small-scale interaction of tourmaline with silicate fragments within the tourmaline breccia itself. Tourmaline as one of the ultrastable heavy minerals in stream sediment offers a potential tool to discriminate between Cu-bearing and barren breccia pipes, using the Fe/Mg ratio of the boron silicate for distinction. Fertile breccias reveal a significantly better correlation between Fe and Mg than barren tourmaline breccias.
Journal: Ore Geology Reviews - Volume 48, October 2012, Pages 271-277