Garmichay metapelites, NW Iran: whole rock chemistry, mineral chemistry, provenance and metamorphic conditions
Amir Mahamed
1
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)
Mohsen Moayyed
2
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)
Monir Modjarrad
3
(
)
Keywords: Garmichaygeochemistrymetapelitespetrofabricsprovenance,
Abstract :
In order to study the provenance and metamorphic conditions of the Garmichay metapelites located in Northern Miyaneh, NW Iran the whole rock chemistry of this assemblage is investigated. Petrofabric scrutinizes have revealed the syn-tectonic nature of cordierite porphyroblasts (regional metamorphism) in the metapelites. Besides, C' shear band structures are observed. Two regional metamorphic (RMP1, RMP2), one contact metamorphic (CMP) and two deformation (D1, D2) phases are identified. The major oxide geochemistry implies two sedimentary progenitors: shale and greywacke. Based on major, rare earth and trace elements (Ti, Ni, TiO2, Zr and K2O) the igneous source rock has had andesite to dacite/rhyodacite nature. The chemical index of alteration and weathering indexes (CIA, CIW) imply a medium degree of alteration in the igneous progenitor. The Garmichay metapelites, in comparison with the PAAS and UCC, are enriched in Cs, La and Ce and depleted in Sr, Nb and Ta. The representative samples in the compatibility diagrams lie inside the paragenetic triangles that imply their stable conditions. Finally, based on the standard pseudosections the temperature and pressure range of the highest degree paragenesis has been 535-635 °C and 1-3 kb, respectively.