Age, petrologic significance and provenance analysis of the Hamedan low-pressure migmatites; Sanandaj-Sirjan Zone, west Iran

Ali Asghar Sepahi, Seyedeh Razieh Jafari, Yasuhito Osanai, Hossein Shahbazi, Mohssen Moazzen

Research output: Contribution to journalArticle

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Abstract

Meta-pelitic rocks with interlayers of meta-psammites within the inner thermal aureole of the Alvand plutonic complex (Sanandaj-Sirjan Zone (SaSZ), western Iran) underwent partial melting; generating various types of migmatites. The mesosome of the Hamedan migmatites is classified into two groups: (1) cordierite-rich and Al-silicate-poor mesosomes and (2) cordierite-poor, Al-silicate-rich groups. Leucosomes are also variable, ranging from plagioclase-rich to K-feldspar-rich leucosomes. Mineral-chemical studies and thermobarometric estimations indicate temperature and pressure of 640–700°C and 3–5 kbar, respectively, for the formation of mesosomes. U–Pb zircon geochronology on 214 grains from the mesosome of migmatites indicates ages of 160–180 Ma (ca ~170 Ma) for zircon metamorphic rims and variable ages of 190–2590 Ma for the inherited detrital zircon cores. Inherited core ages show various age populations, but age populations at 200–600 Ma are more frequent. The age populations of the detrital zircons clarify that the provenance of the younger zircon grains (200–500 Ma) was more likely the Iranian plate, whereas the older grains (600 Ma to >2.5 Ga) may be sourced from both northern Gondwana (such as Arabian-Nubian Shield) and the neighbouring, old cratons like as Africa. We suggest that magmatic activities, especially mafic plutonism at ~167 Ma, are the main triggers for the heat source of metamorphism, partial melting, and migmatization. In contrast to a presumed idea for a Cretaceous regional metamorphic event in the NW parts of the SaSZ, this study attests that the metamorphism should be older and can be associated with Jurassic magmatic pulses.

Original languageEnglish
Pages (from-to)1446-1461
Number of pages16
JournalInternational Geology Review
Volume61
Issue number12
DOIs
Publication statusPublished - Aug 13 2019

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provenance
low pressure
zircon
leucosome
cordierite
partial melting
metamorphism
silicate
migmatization
aureole
plutonism
heat source
geochronology
Gondwana
analysis
feldspar
craton
shield
plagioclase
Jurassic

All Science Journal Classification (ASJC) codes

  • Geology

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Age, petrologic significance and provenance analysis of the Hamedan low-pressure migmatites; Sanandaj-Sirjan Zone, west Iran. / Sepahi, Ali Asghar; Jafari, Seyedeh Razieh; Osanai, Yasuhito; Shahbazi, Hossein; Moazzen, Mohssen.

In: International Geology Review, Vol. 61, No. 12, 13.08.2019, p. 1446-1461.

Research output: Contribution to journalArticle

Sepahi, Ali Asghar ; Jafari, Seyedeh Razieh ; Osanai, Yasuhito ; Shahbazi, Hossein ; Moazzen, Mohssen. / Age, petrologic significance and provenance analysis of the Hamedan low-pressure migmatites; Sanandaj-Sirjan Zone, west Iran. In: International Geology Review. 2019 ; Vol. 61, No. 12. pp. 1446-1461.
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