نقش گارنت در تفسیر سنگ‌زایی همبافت گرانیتوئیدی بروجرد و هاله‌ی دگرگونی آن

Pyralespite garnet group (Almandine group) is common minerals in the metamorphic and igneous complex of Boroujerd area. Moreover, Almandin (Fe enriched garnet) is the most common mineral but the content of Spessartin (Mn enriched garnet) is high in this area. The changes of mineral composition in different grains show that these minerals are zoning chemical and core to rim composition is varied. The garnet composition in core to rim respectively in granodiorite changes to Alm0.65, Prp0.05, Sps0.264, Grs0.193 in core to Alm0.76, Prp0.05, Sps0.14, Grs0.04 in rim, in pegmatite, Alm0.71, Prp0.02, Sps0.26, Grs0 in core to Alm0.76, Prp0.03, Sps0.2, Grs0.007 in rim of pegmatite, and in hornfels, Alm 0.81, Prp0.07, Sps 0.09, Grs0.03 in core to Alm 0.63, Prp0.06, Sps 0.3, Grs0.002 in rim. Petrography (for exampl, crystallization of tourmaline to garnet pegmatites and Andalusite to granodiorites) and mineral chemistry (oscillatory zoning Al in pegmatite garnet, Mg decrease and Mn increase in granodiorites garnet and liner trend Al in garnet hornfelse) show that metamorphic source for garnet in granodiorite and hornfels and magmatic source for pegmatites.