High-Pressure Marbles from the Nahavand Area in the Sanandaj-Sirjan Metamorphic Belt, Iran

Marbles containing high-pressure mineral assemblage was found from the sanandaj-sirjan metamorphic belt in the nahavand area in western iran. the high-pressure marbles occur as small bodies or lenses within pelitic schist layers and show compositional banding of carbonate- and silicate- rich bands. textural analysis revealed two metamorphic stages. the early stage is testified by relicts of the minerals such as rounded jadeite-bearing diopside, epidote (clinozoisite), amphibole 1 (pargasite-edenite) and titanite 1. the second stage (main stage) documented to have phlogopite, chlorite, amphibole 2 (tremolite) and titanite 2. p-t-xco2 estimates for the early stage of metamorphism give an average pressure, temperature and xco2 of 13.5 kbar, 670 ?c and 0.35, whereas the second stage has been constrained at p=3.8 kbar, t=500 ?c and xco2=0.45. the high-pressure mineral assemblage documented in the nahavand area, were formed during the subduction stage, while the second metamorphic blastesis were recorded during the exhumation event.