Petrology and mineral chemistry in the Calc-silicates of the Deh-salm metamorphic complex, East of Lut block: evidence of progressive metamorphism to the granulite facies

The Deh-Salm Metamorphic Complex (DMC) is composed of metapelite, metabasite, metaperidotite, and calc-silicate rocks and is one of the few outcrops of the Lut block’s basement which emerged near to the Sistan suture zone. In the eastern part of the Deh-Salm metamorphic complex, the calc-silicate and marble appeared in the form of elongated tectonic lenses that have been metamorphosed in similar temperature and pressure conditions of the confined rocks. Evidences from mineralogical and petrographic studies indicate the existence of different mineral assemblages in the calc-silicates but with similar metamorphism conditions. Scapolite + alkali feldspar + plagioclase + sphene, scapolite + pyroxene, garnet + amphibole + epidote and garnet + pyroxene + Wollastonite are most important paragenesis recognized. The results provided by this study, based on the EPMA method, classify the scapolite into the calcic group that can be called mizzonite (Me% 70 – 80), alkali feldspar with a composition close to orthoclase, and plagioclase as an andesine composition. Garnet in the studied rocks are rich grassular end-member. Pyroxene of the calc-silicate rocks are the clinopyroxene with the diopside composition. Based on the metamorphic paragenesis, geochemical analyses, and comparsion of the metamorphic grade between the calc-silicate and the adjacent metabasites, a progressive metamorphism up to the upper amphibolite-granulite facies from the west to the east of the complex has taken place. It may be considered that the Late Jurassic regional metamorphism event was synchronous with the Shah Kuh granitization at the eastern margin of the Lut Block due to the subduction of the Neotethys ocean.