Abstract
In this study, the oxygen isotope (δ18O) composition of pink to red gem-quality rubies from Paranesti, Greece was investigated using in-situ secondary ionization mass spectrometry (SIMS) and laser-fluorination techniques. Paranesti rubies have a narrow range of δ18O values between ~0 and +1‰ and represent one of only a few cases worldwide where δ18O signatures can be used to distinguish them from other localities. SIMS analyses from this study and previous work by the authors suggests that the rubies formed under metamorphic/metasomatic conditions involving deeply penetrating meteoric waters along major crustal structures associated with the Nestos Shear Zone. SIMS analyses also revealed slight variations in δ18O composition for two outcrops located just ~500 m apart: PAR-1 with a mean value of 1.0‰ ± 0.42‰ and PAR-5 with a mean value of 0.14‰ ± 0.24‰. This work adds to the growing use of in-situ methods to determine the origin of gem-quality corundum and re-confirms its usefulness in geographic “fingerprinting”.
Highlights
IntroductionOxygen consists of three naturally-occurring stable isotopes: O (99.76%), O (0.04%) and O (0.2%)
Two different oxygen isotopic analytical methods have been used in this study in order to verify the oxygen isotope valuesand of the rubies mechanically extracted pargasite host matrix carefully cleaned prior The to being sentwere for analysis
Based on the low δ18 O value and the local geology, it is most likely that the Paranesti rubies formed under metamorphic/metasomatic conditions involving deeply penetrating meteoric waters along major crustal structures related to the Nestos Shear Zone
Summary
Oxygen consists of three naturally-occurring stable isotopes: O (99.76%), O (0.04%) and O (0.2%). Δ18 O expressed as Vienna standard mean ocean water (VSMOW) in per mil is the standard for the oxygen isotopic composition which is a measure of the ratio of the stable isotopes oxygen-18 (18 O) and oxygen-16 (16 O). There are numerous applications of oxygen isotope geochemistry including paleoclimatology, urban forensics, geological genesis and many more [1,2,3]. Oxygen isotope fractionation is a function of the initial Rayleigh evaporation-precipitation cycle, temperature of the system and degree of water-rock interaction and great care must be taken when interpreting oxygen isotope values [4,5,6,7].
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