Document Type : Original Research Paper


1 Ph.D. , Department of Geology, Faculty of Science, Payame Noor University (PNU), Tehran,Iran.

2 Ph.D.,Associate Professor, Department of Geology, Faculty of Science, Tarbiat Modares University, Tehran, Iran

3 Ph.D., Associate Professor , Geological Survey of Iran (GSI), Tehran, Iran

4 Ph.D., Professor, Department of Geology, Faculty of Earth Science, California University, Santabarbara, USA



In this article, metabasic and gneissic rocks of Gelmandeh and Zamanabad mountain (Boneh-Shurow complex, Saghand region ) have been used for U-Pb dating. Analyses of zircon crystals yielded concordant U–Pb ages with weighted mean 206Pb/238U ages of 545.4 ±3.6 Ma (MSDW=1.7) for garnet amphibolite, 541.2 ± 4.4 Ma (MSDW=1.8) for metagabbro, 541.3 ±3.5 Ma (MSDW=0.26) for quartz-feldspatic gneiss and 549.2 ± 2.6 Ma (MSDW=0.28) for amphibole- biotite gneiss. The studied zircon crystals has continental, crustal nature and show a strong affinity to magmatic zircons in Chondrite-normalized patterns.

The ages that approximately ranges between 541-549 Ma are interpreted as the Crystalline age of the garnet amphibolite and gneissic parental magma. These ages previously assumed as the timing of peak-metamorphism of the Boneh-Shurow garnet-amphibolite and emplacement ages for the granitic precursor of gneissic rocks.


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