The Central Alborz Permian basaltic magmatism: an evidence of southern passive continental margin of Paleo- Tethys
The study area is located in the Central Alborz (northeast of Baladeh). The Permianmagmatism in this area occurs as a basaltic unit between Ruteh-Nessen Formation.Petrographically, the rocks are plagioclase phyric and geochemically, display alkalinesodic nature. Chondrite- normalized rare earth elem...
| Main Authors: | , , |
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| Format: | Article |
| Language: | fas |
| Published: |
University of Isfahan
2017-03-01
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| Series: | پترولوژی |
| Subjects: | |
| Online Access: | http://ijp.ui.ac.ir/article_21500_3516d6dfa7c49ed900e88baced9515dd.pdf |
| Summary: | The study area is located in the Central Alborz (northeast of Baladeh). The Permianmagmatism in this area occurs as a basaltic unit between Ruteh-Nessen Formation.Petrographically, the rocks are plagioclase phyric and geochemically, display alkalinesodic nature. Chondrite- normalized rare earth element (REE) patterns are extremely LREE- enriched similar to those of oceanic island basalts (OIB) with (La/Sm)N,(Sm/Yb)N and (La/Yb)N in the ranges of 1.95- 4.62, 4.23- 5.45 and 8.30- 20.52,respectively. Furthermore, primitive mantle normalized multi element diagramsrepresent OIB characteristics. Modeling based on trace element values and the contentof some major elements reveal low degree partial melting (< 10%) of a deep (~110 km)garnet-bearing mantle source. In addition, variation of some trace element ratios such asNb/Rb, K/La, La/Nb, Ba/Nb, Th/Nb and K/Nb suggests a HIMU mantle origin. As thesamples geochemically show intra-plate tectonomagmatic setting without subductionzone signatures. Thus, during the Permian (and earlier times), Alborz has been as apassive continental margin in the southern border of Paleo-Tethys and its magmatism was more probably affected by extensional tectonism or mantle plume activity related toearlier stages of Neo-Tethys ocean development. |
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| ISSN: | 2228-5210 2322-2182 |