همایش بین المللی گوهرشناسی و کانیهای صنعتی

صفحه اصلی / دومین همایش بین المللی گوهرشناسی و کانیهای صنعتی

The Formation and Chemical composition, genesis and exploration implication of garnet in Serpentinites of Takab (Iran)

نویسندگان :

Morteza Razmara¹ Arian Almasi²

1- دانشگاه فردوسی مشهد 2- دانشگاه فردوسی مشهد

کلمات کلیدی :

Takab،demantoid garnet،inclusions

چکیده :

Gem-quality transparent to semi-transparent garnet crystals from serpentinized lherzolite and harzburgites from Takab area, were explorated. The measured density ranged from 3.82 to 3.84 g·cm−3. Raman spectrum of demantoid showed 3 spectral regions containing relatively strong bands: I—352–371 cm−1, II—816–874 cm−1, and III—493–516 cm−1. Garnet in the study area belongs to the grossular–andradite solid solution series and comprises 4 types: :1) Garnet andradite in the serpentinite zones, 2) Garnet andradite in the contact skarn, 3) Oscillatory-zoned Garnet andradite in proximal skarn, 4) Garnet andradite in distal skarn. This study focuses on garnets sourced from Takab, Iran, using standard and advanced gemological methods as well as chemical analyses, XRD, energy dispersive X-ray fluorescence (EDXRF) and Raman spectroscopy. The results show that the content of Cr and V in most samples is high, with some samples containing a Cr2O3 content up to 0.032%. The high Cr content sets Takab garnet apart from demantoid of the skarn type found in Kerman regions. This suggests that Cr is the primary chromogenic element of Takab demantoid, but the role of vanadium cannot be ignored. The high pressure mineral assemblage (amphibolite, garnet-amphibolite, kyanite-garnet-amphibolite, hornblendite and epidote-amphibolite), indicated that the studied garnet from serpentinite was formed through high pressure metamorphism, during the subduction zone serpentinization.