Geochemistry and Isotope Geology of Adakitic Domes from Chakane Area in South of Quchan (Northeast of Iran)
The Chekneh subvolcanic domes with dacite and trachydacite compositions from the Miocene is located 110 km NE of Sabzevar, and are parts of the North Sabzevar-South Ghochan magmatic belt. The dome rocks have porphyry, sieve, trachytic and glomeroporphyritic textures, consisting of plagioclase and a...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | fas |
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University of Isfahan
2019-02-01
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| Series: | پترولوژی |
| Subjects: | |
| Online Access: | http://ijp.ui.ac.ir/article_22973_5dd3b00123fb55d561f685e79c38d5c7.pdf |
| Summary: | The Chekneh subvolcanic domes with dacite and trachydacite compositions from the Miocene is located 110 km NE of Sabzevar, and are parts of the North Sabzevar-South Ghochan magmatic belt. The dome rocks have porphyry, sieve, trachytic and glomeroporphyritic textures, consisting of plagioclase and amphibole. Primitive mantle normalized spider diagram and chondrite-normalized REE patterns of the study domes suggest that they are enriched in LREE and LILE and are depleted in HREE and HFSE. They are calc-alkaline with significant negative HFSE (e.g., P, Nb and Ti) anomalies and (La/Yb)N>12 which are characteristics of magmas formed in active continental margin. Based on SiO<sub>2</sub>, high Sr/Y, low K<sub>2</sub>O/Na<sub>2</sub>O and low Y, Yb, Cr and Mg<sup>#</sup> contents, the study rocks are similar to high-silica adakites (HSA). Thus, it seems that the parent magma of the study domes was originated from amphibole eclogite or garnet amphibolite rocks of metamorphosed Neotethys oceanic lithosphere during its subduction beneath the southern part of eastern Alborz in the Miocene. The initial <sup>87</sup>Sr/<sup>86</sup>Sr (0.7039-0.7043) and ɛNd<sub>10Ma</sub> (2.9-4.98) of the Chekaneh domes is similar to MORB composition, which are coincided with those adakites originated from the partial melting of the Cenozoic oceanic lithosphere. |
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| ISSN: | 2228-5210 2322-2182 |