THE PERMIAN VOLCANICS OF CENTRAL ALBORZ: IMPLICATIONS FOR PASSIVE CONTINENTAL MARGIN ALONG THE SOUTHERN BORDER OF PALEOTETHYS

Authors

  • Morteza Delavari Faculty of Earth Sciences, Kharazmi University, Tehran, Iran.
  • Asghar Dolati Faculty of Earth Sciences, Kharazmi University, Tehran, Iran.
  • Ali Mohammadi Department of Earth Sciences, ETH Zurich, Switzerland
  • Farzaneh Rostami Faculty of Earth Sciences, Kharazmi University, Tehran, Iran.

DOI:

https://doi.org/10.4454/ofioliti.v41i2.460

Keywords:

Alkaline basalt, intra-plate volcanism, Permian, Central Alborz

Abstract

The Permian volcanics of Central Alborz (PVCA) crop out between the Ruteh and Nesen Formations in the Baladeh-Siahbisheh area. The volcanics are predominantly basaltic and plagioclase-phyric. Ferromagnesian minerals such as clinopyroxene and olivine are not modally abundant and sometimes are totally altered. Chemical composition of clinopyroxene is characterized by high TiO2 contents (4.9-7.2 wt.%). Based on whole rock geochemistry, the samples display sodic alkaline nature (Na2O = 3.7 to 7.8 wt.%). Chondrite-normalized rare earth element (REE) patterns are extremely LREE-enriched with (La/Yb)N of 8.3-20.5. Both normalized REE and multi-element diagrams represent ocean island basalt (OIB) characteristics. Modeling based on trace element values, and the content of some major elements reveal low partial melting degree (< 10%) of a deep garnet-bearing mantle source. As the samples geochemically show an intra-plate tectonomagmatic setting without subduction zone signatures, during the Permian (and earlier times), the Alborz area was possibly a passive continental margin along the southern border of Paleotethys. As a result, the Alborz Permian magmatism could have  been reasonably induced by an extensional tectonic regime along the northward-moving Cimmerian terranes during the early stages of Neotethys development.

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Published

2016-12-22

How to Cite

Delavari, M., Dolati, A., Mohammadi, A., & Rostami, F. (2016). THE PERMIAN VOLCANICS OF CENTRAL ALBORZ: IMPLICATIONS FOR PASSIVE CONTINENTAL MARGIN ALONG THE SOUTHERN BORDER OF PALEOTETHYS. Ofioliti, 41(2), 59-74. https://doi.org/10.4454/ofioliti.v41i2.460

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