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- Title
Macroscopically-Zoned Grandite from the Garnetite Skarn of Meka Presedla (Kopaonik Mountain, Serbia).
- Authors
TANČIĆ, Pavle; VULIĆ, Predrag; KAINDL, Reinhard; SARTORY, Bernhard; DIMITRIJEVIĆ, Radovan
- Abstract
The macroscopically-zoned grandite from the garnetite skarn of Meka Presedla (Kopaonik Mountain, Serbia) was studied with optical microscopy, electron microprobe analysis (EMPA), Fourier transform infra-red (FT-IR), and Raman methods. The EMPA results indicate that the main core-rim compositional variations (Ca2.93-2.97Mn0.05-0.06Mg0.00-0.01Al1.14-1.26Fe3+0.72-0.83 Ti0.00-0.02Si2.97-3.02O12) slightly differ along the zones, showing evidence for a quasi-cyclic alternation of the oscillatory zoning nature. Among this, considerable variation is observed only by the Al-Fe3+ substitutions in the octahedral site. The EMPA also indicate that the grandite zones compositionally vary, mostly within ±1 and ±2 mol% of the homogeneity level range, that is, Grs64±1Adr36±1Sps2 (A), Grs62±1Adr38±1Sps2 (B), Grs59±2Adr40±2Sps2 (C), Grs58±2Adr41±2Sps2 (D), and Grs58±1Adr41±1Sps2 (E). Therefore, the investigated garnet can be considered as relatively highly homogeneous. The majority of compositions lie within the narrow miscibility region of 0.58±2<XGrs<0.64±1, without gaps, and with only three outliers near the zone boundaries of approximately 0.38<XGrs<0.52. FT-IR and Raman bands are almost constant within the zones and adequate to the chemical compositions. All of the zones should be considered as anhydrous. From the results, formation temperatures between ∼600 and 720°C, and pressures of ∼2-3 kbars, are derived. Among five possible causes for the slightly optical anisotropy of grandite, three were reconsidered, and consequently rejected.
- Subjects
KOPAONIK Mountains (Serbia &; Kosovo); SERBIA; KOSOVO (Republic); ANISOTROPY; SKARN; MICROSCOPY; ELECTRON probe microanalysis; FOURIER transform infrared spectroscopy
- Publication
Acta Geologica Sinica (English Edition), 2012, Vol 86, Issue 2, p393
- ISSN
1000-9515
- Publication type
Article
- DOI
10.1111/j.1755-6724.2012.00668.x