ژيوترموبارومتري سنگهاي رخساره الكوژيت در مجموعه افيوليتي منطقه سولابست در جنوب شرق بيرجند

Geothermobarometry of Eclogite Facies Rocks in Ophiolitic Complex of Sulabest in SE of Birjand

In the eastern part of an ophiolitic complex in Sulabest area (in south east of Birjand) has exposed a metamorphic series including eclogite, blue schist, garnet bearing blue schist, amphibolite, epidote amphibolite, greenschist and mica schist. In addition to basaltic pillow lavas and cherts which have changed to eclogite and blueschist, were also metamorphosed most of gabbroic cumulate series to overlaying sheeted dibasic dykes. This metamorphism is within the limit of prehnite-actinolite(sub green schist) to greenschist facieses. Presence of orbitoides microfossil within micritic limestones in ophiolitic complex, indicates Maastrichtian age of emplacement for ophiolitic complex. Thermobarometry results of eclogites showing that peak temperature of eclogites from Sulabest varies from 496 to 592 ^C and their peak pressures ranging from 22.0 to 26.4 Kbars. Epidote amphibolite retrograde metamorphism of these eclogites has been done in a temperature of 549 to 592 °C and a pressure of 6.7 to 7.4 Kbars. Textural evidences and analyses results showing that, the second stage of metmorphism were taken place during ascending root of these rocks on to the surface. Coexisting of eclogites in studied area with blueschists, amphibolites and garnet amphibolites in the eastern part of an ophiolitic complex and combination of field observations and laboratory works, indicates that a subduction activity with a late Cretaceous age were responsible for the studied area and consequently for east of Iran, which were followed by an thrusting process during colliding ofAfghan(Helmand) and Lut-Block plates.