Investigations on temperature and pressure of formation of schists and gneisses of the Allahyarlu complex, NW Iran

Salimi, Zohreh; Moazzen, Mohsen; Hajialioghli, Robab

doi:10.22071/gsj.2019.183520.1645

Document Type : Original Research Paper

Authors

¹ Ph.D. Student, Department of Earth Sciences, Faculty of Natural Science, University of Tabriz, Tabriz, Iran

² Professor, Department of Earth Sciences, Faculty of Natural Science, University of Tabriz, Tabriz, Iran

³ Associate Professor, Department of Earth Sciences, Faculty of Natural Science, University of Tabriz, Tabriz, Iran

https://doi.org/10.22071/gsj.2019.183520.1645

Abstract

The ophiolitic-metamorphic complex of Allahyarlu, attributed to pre-Cretaceous, is exposed at the core of Allahyarlu anticline in NW Iran and NE of Meshginshahr. The metamorphic rocks are important constituents of this complex. These rocks include garnet schist, garnet gneiss, amphibolite, marble, associated with blocks of serpentinite and tectonic slices of gabbro, dunite and diabase. Quartz, garnet, biotite, muscovite and chlorite are the primary minerals in the garnet schists, while zircon, secondary chlorite, opaque minerals and plagioclase make the minor phases. The main minerals in the garnet gneiss samples are K-feldspar, quartz, plagioclase, muscovite, biotite and garnet and tourmaline, zircon and secondary chlorite are the minor phases. Garnet in garnet schists and garnet gneisses is almandine-rich and white mica is muscovite –rich. According to microprobe analyses, brunvigite is the main constituent in chlorite solid-solution. Te average temperature estimated for metamorphism of garnet schists and garnet gneisses, using different methods is 530 to 570 C. Using apetrogenetic grid indicates pressure of ca. 4.5 kbar for the paek of metamorphism. The estimated pressure and temperature are in accordance of Barrovian metamorphic gradient for these rocks, which occurs in crustal thickenning zones such as island arcs, volcanic arcs and collision zones.

Keywords

20.1001.1.10237429.1399.29.116.4.7

Main Subjects

Petrology

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Scientific Quarterly Journal of Geosciences

Investigations on temperature and pressure of formation of schists and gneisses of the Allahyarlu complex, NW Iran

References

References

Volume 29, Issue 116 - Serial Number 116
Volume 29, Serial Number 116, Summer 2020
August 2020
Pages 35-48

Investigations on temperature and pressure of formation of schists and gneisses of the Allahyarlu complex, NW Iran

References

References

Volume 29, Issue 116 - Serial Number 116Volume 29, Serial Number 116, Summer 2020August 2020Pages 35-48

Volume 29, Issue 116 - Serial Number 116
Volume 29, Serial Number 116, Summer 2020
August 2020
Pages 35-48