Three Types of Apatite in Norilsk Sulfide Ores
- Authors: Serova A.A.1, Spiridonov E.M.1
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Affiliations:
- Faculty of Geology
- Issue: Vol 56, No 5 (2018)
- Pages: 474-483
- Section: Short Communications
- URL: https://journals.rcsi.science/0016-7029/article/view/155944
- DOI: https://doi.org/10.1134/S0016702918050075
- ID: 155944
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Abstract
Apatite is a concentrator of F and Cl, which play a significant role in the formation of minerals of platinum-group elements of pneumatolitic origin. There are three apatite generations in Norilsk magmatic sulfide ores. Apatite I occurs in sulfide bodies and rims of fluid alteration above sulfide droplets in disseminated ores. Its composition evolved from hydroxyl-chlorapatite to chlorapatite. Apatite I associates with Tiрbiotite, titanomagnetite, ilmenite with baddeleyite lamellae, anhydrite, Ti-poor kaersutite, Cl-bearing hastingsite and edenite, djerfisherite, bartonite, and minerals of the Pt and Au groups. Apatite I contains up to 2.3 wt % lanthanides, primarily Ce, La, and Nd. Apatite I is overgrown and replaced by apatite II, the composition of which evolved from hydroxyl-chlor-fluorapatite to fluorapatite. Apatite II often occurs also as individual crystals in massive sulfides and contains up to 0.9 wt % lanthanides. The pneumatolitic chlorapatite and fluorapatite contain ~0.5 wt % SiO2. The composition of apatite indicates discrete evolution of fluids released during the crystallization of Norilsk sulfide melts: from water–chloride to chloride at the first state, and from water–chlorite–fluoride to essentially fluoride at the second stage. The lanthanides released during the replacement of chlorapatite I by fluorapatite II were probably incorporated in pneumatolitic zoned orthite-(Ce). In the areas affected by prehnite–pumpellyite metamorphism, apatite I and apatite II within metamorphosed sulfide ores are partly or completely replaced by apatite III, which varies in composition from hydroxyl-chlorapatite to hydroxylapatite poor in fluorine and lanthanides. The lanthanides released during the replacement of apatite I and II by metamorphic hydroxylapatite III were probably incorporated in metamorphic unzoned orthite-(Ce).
About the authors
A. A. Serova
Faculty of Geology
Author for correspondence.
Email: almashkina@mail.ru
Russian Federation, Moscow, 119991
E. M. Spiridonov
Faculty of Geology
Email: almashkina@mail.ru
Russian Federation, Moscow, 119991
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