Mineralogy and geochemistry of multi genesis Garnetsin Anjir Khajeh Garnet schists, (outheast Iran) with constraining to micro Raman spectroscopy

The Anjir Khajeh area is located in the southern part of Sanandaj-Sirjan metamorphic belt in northwest of Golgohar iron mine. The rock units of the region include metabasites, metasediments, igneous and sedimentary rocks. Metasedimentary rocks containing mica-schist, garnet schist, and garnet staurolite schist, having metamorphosed into greenschist facies and amphibolite facies. Garnet mineral is the most abundant porphyroblasts in metasedimentary rocks which is present in the form of  amorphous to semi-amorphous with the large to medium sizes. Electron Microprobe results show the solid dissolution evidences of garnets with the highest frequency in almandine type. Based on petro-fabric analysis, three generations of garnets are identified that have different chemical and Raman spectral characteristics too. These three generations include Almandine rich, Grossular rich and Pyrope rich  garnets that have been analyzed and classified based on petrography, mineral chemistry and Raman spectroscopy. Almandine rich type with higher Iron content and lowest peak wavenumber under 320 cm-1, Grossular rich type with relatively lower Fe and higher Ca content and highest peak wavenumber between moderate frequencies of 400 to 650 cm-1 and Pyrope rich type with higher Mg and lower Fe content and highest peak wavenumber more than 800 cm-1 can be seen. The petrogenetic investigations of the Anjir Khajeh garnetschists classifies their protholites as shale and sandstone that geodynamicaly formed in a continental island arc setting.