Dating and source determination of volcanic rocks from Khunik area (South of Birjand, South Khorasan) using Rb-Sr and Sm-Nd isotopes
The Khunik area is located in the south of Birjand, Khorasan province, in the eastern margin of Lut block. Tertiary volcanic rocks have andesite to trachy-andesite composition. Dating analyzing by Rb-Sr method on plagioclase and hornblende as well as whole-rock isochron method was performed on pyrox...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | fas |
| Published: |
University of Isfahan
2016-12-01
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| Series: | پترولوژی |
| Subjects: | |
| Online Access: | http://ijp.ui.ac.ir/article_21241_ad988595166024a6c2d9b2a53d092cb3.pdf |
| Summary: | The Khunik area is located in the south of Birjand, Khorasan province, in the eastern margin of Lut block. Tertiary volcanic rocks have andesite to trachy-andesite composition. Dating analyzing by Rb-Sr method on plagioclase and hornblende as well as whole-rock isochron method was performed on pyroxene-hornblende andesite rock unit. On this basis the emplacement age is Upper Paleocene (58±11 Ma). These rocks have initial 87Sr/86Sr and εNd 0.7046-0.7049 and 2.16-3.12, respectively. According to isotopic data, volcanic rocks originated from depleted mantle and have the least crust contamination while it was fractionated. Geochemically, Khunik volcanic rocks have features typical of calk-alkaline to shoshonite and are metaluminous. Enrichment in LILEs and typical negative anomalies of Nb and Ti are evidences that the volcanic rocks formed in a subduction zone and active continental margin. Modeling suggests that these rocks were derived dominantly from 1–5% partial melting of a mainly spinel garnet lherzolite mantle source that is metasomatized by slab-derived fluid. |
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| ISSN: | 2228-5210 2322-2182 |