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Ιδρυματικό Αποθετήριο [SANDBOX]
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| URI | http://purl.tuc.gr/dl/dias/505213E1-879D-45CB-9E8C-CC86F75EC2E2 | - |
| Αναγνωριστικό | https://doi.org/10.1180/clm.2020.21 | - |
| Αναγνωριστικό | https://pubs.geoscienceworld.org/claymin/article-abstract/55/2/150/591962/Rare-earth-element-geochemistry-of-altered | - |
| Γλώσσα | en | - |
| Μέγεθος | 16 pages | en |
| Τίτλος | Rare earth element geochemistry of altered pyroclastic rocks in the Hashtjin area of north-west Iran | en |
| Δημιουργός | Nouri Tohid | en |
| Δημιουργός | Tehrani Parvin Najafzadeh | en |
| Δημιουργός | Masoumi Rahim | en |
| Δημιουργός | Christidis Georgios | en |
| Δημιουργός | Χρηστιδης Γεωργιος | el |
| Εκδότης | Cambridge University Press | en |
| Περίληψη | This study evaluates the rare earth element (REE) geochemistry in altered trachyandesitic ignimbrites, tuff and lava flows in the Hashtjin area by assessing chondrite-normalized REE patterns and Y/Ho geochemical ratios. Modifications in the REE patterns took place along altered fault zones that were affected by hypogene and supergene alterations. The precursor volcanic and pyroclastic rocks contain phenocrysts of plagioclase accompanied by augite, zircon, apatite and pyrite. Based on X-ray diffraction analysis, the main mineral assemblages of the altered units consist of kaolinite as the main clay mineral, SiO2 polymorphs (quartz and cristobalite) and anatase as a minor constituent. The chondrite-normalized REE patterns of argillic samples reveal fractionation of light REEs (LREEs) compared to heavy REEs (HREEs), together with a marked Eu anomaly and a weak W-type tetrad effect related to the weak non-charge radius control (CHARAC) behaviour of REEs and slightly higher Y/Ho and Zr/Hf ratios. The relationship between the Y/Ho and Zr/Hf ratios and recognizable T3 and T4 effects (tetrad effect) suggests that an increasing degree of water–rock interaction occurred during hypogene alteration processes by acidic hydrothermal fluids that were overprinted by supergene alteration. Water–rock interaction and adsorption by Mn-oxides and clay minerals are considered to have played important roles in determining the close to non-CHARAC behaviour of REEs during the argillic alteration of the pyroclastic rocks in the Hashtjin area. | en |
| Τύπος | Peer-Reviewed Journal Publication | en |
| Τύπος | Δημοσίευση σε Περιοδικό με Κριτές | el |
| Άδεια Χρήσης | http://creativecommons.org/licenses/by/4.0/ | en |
| Ημερομηνία | 2021-07-21 | - |
| Ημερομηνία Δημοσίευσης | 2020 | - |
| Θεματική Κατηγορία | Argillic alteration | en |
| Θεματική Κατηγορία | Hashtjin | en |
| Θεματική Κατηγορία | Ignimbrite | en |
| Θεματική Κατηγορία | Kaolinization | en |
| Θεματική Κατηγορία | Lanthanide tetrad effect | en |
| Θεματική Κατηγορία | Pyroclastic rocks | en |
| Θεματική Κατηγορία | Rare earth elements (REEs) | en |
| Βιβλιογραφική Αναφορά | T. Nouri, P. N. Tehrani, R. Masoumi, and G. E. Christidis, “Rare earth element geochemistry of altered pyroclastic rocks in the Hashtjin area of north-west Iran,” Clay Min., vol. 55, no. 2, pp. 150–165, Jun. 2020. doi: 10.1180/clm.2020.21 | en |
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