High temperature - low pressure metamorphism during subduction of Neo-Tethys beneath the Iranian plate
- Subduction of Neo-Tethys oceanic lithosphere beneath the Iranian plate during the Mesozoic formed several igneous bodies of ultramafic to intermediate and felsic composition. Intrusion of these magmas into a regional metamorphic sequence (the Sanandaj-Sirjan Zone) caused partial melting and formation of migmatites with meta-pelitic protoliths. The Alvand complex (west Iran) is a unique area comprising migmatites of both mafic and pelitic protoliths. In this area, the gabbroic rocks contain veins of leucosome at their contact with pyroxenite and olivine gabbro. These leucosomes are geochemically and mineralogically different from leucosomes of the meta-pelitic migmatites and clearly show properties of I-type granites. Microscopic observations and whole rock compositions of the mafic migmatite leucosomes show that migmatization occurred through partial melting of biotite, hornblende and plagioclase. Thermobarometric calculations indicate 800 degrees C and 3.7 kbar for partial melting, although phase diagram modeling demonstrates thatSubduction of Neo-Tethys oceanic lithosphere beneath the Iranian plate during the Mesozoic formed several igneous bodies of ultramafic to intermediate and felsic composition. Intrusion of these magmas into a regional metamorphic sequence (the Sanandaj-Sirjan Zone) caused partial melting and formation of migmatites with meta-pelitic protoliths. The Alvand complex (west Iran) is a unique area comprising migmatites of both mafic and pelitic protoliths. In this area, the gabbroic rocks contain veins of leucosome at their contact with pyroxenite and olivine gabbro. These leucosomes are geochemically and mineralogically different from leucosomes of the meta-pelitic migmatites and clearly show properties of I-type granites. Microscopic observations and whole rock compositions of the mafic migmatite leucosomes show that migmatization occurred through partial melting of biotite, hornblende and plagioclase. Thermobarometric calculations indicate 800 degrees C and 3.7 kbar for partial melting, although phase diagram modeling demonstrates that the presence of water could decrease the solidus temperature by about 40 degrees C. Our results suggest an asthenospheric magma upwelling as the source of heat for partial melting of the gabbroic rock during subduction of Neo-Tethys oceanic crust under the western edge of the Iranian plate. The present study also reveals relationships between migmatization and formation of S- and I -type granites in the area.…
Author details: | Adel SakiORCiD, Mirmohammad MiriORCiD, Roland OberhänsliGND |
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DOI: | https://doi.org/10.1007/s00710-020-00721-z |
ISSN: | 0930-0708 |
ISSN: | 1438-1168 |
Title of parent work (English): | Mineralogy and petrology |
Subtitle (English): | evidence for mafic migmatite formation in the Alvand complex (western Iran) |
Publisher: | Springer |
Place of publishing: | Wien [u.a.] |
Publication type: | Article |
Language: | English |
Date of first publication: | 2020/09/05 |
Publication year: | 2020 |
Release date: | 2023/04/17 |
Tag: | Gabbroic rocks; Neo-Tethys; mafic migmatite; partial melting; pelitic migmatite; subduction |
Volume: | 114 |
Issue: | 6 |
Number of pages: | 19 |
First page: | 539 |
Last Page: | 557 |
Funding institution: | Shahid Chamran University of Ahvaz [SCU.EG98.44295] |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Geowissenschaften |
DDC classification: | 5 Naturwissenschaften und Mathematik / 55 Geowissenschaften, Geologie / 550 Geowissenschaften |
Peer review: | Referiert |