Adakitic volcanics of Azerbaijan area (South of Julfa): evidence of magmatism in post-collisional setting

delavari, M; Ghanbari, Samaneh; Dolati, asghar

doi:10.52547/gnf.6.2.295

Volume 6, Issue 2 (Autumn&Winter 2021) KJES 2021, 6(2): 295-320 | Back to browse issues page

‎ 10.52547/gnf.6.2.295

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delavari M, Ghanbari S, Dolati A. Adakitic volcanics of Azerbaijan area (South of Julfa): evidence of magmatism in post-collisional setting. KJES 2021; 6 (2) :295-320
URL: http://gnf.khu.ac.ir/article-1-2776-en.html

Adakitic volcanics of Azerbaijan area (South of Julfa): evidence of magmatism in post-collisional setting

M Delavari ^*

¹, Samaneh Ghanbari

, Asghar Dolati

1- . Faculty of Earth Sciences, Kharazmi University , delavarimza@gmail.com

Abstract: (1377 Views)

Dacitic volcanics are broadly exposed in Azerbaijan area (south of Julfa). They show SiO₂ contents of 66.4 to 69.9 wt.% and calk alkaline nature. The (La/Yb)_Nratio ranging from 19.05 to 40.7 suggests highly fractionated rare earth elements (REE) and relative enrichment of light REE to heavy REE. The normalized multi-element diagrams are characterized by Rb, Ba and K enrichment as well as Nb, Ta and Ti depletion reminiscent of subduction- induced magmatic processes. Based on major element contents such as SiO₂, Al₂O₃, MgO, Na₂O, K₂O, K₂O/Na₂O, Mg# and trace element values of Rb, Sr, Y, Yb, Cr, Ni, La/Yb and Sr/Y, they plot within adakitic fields. Furthermore, geochemical signatures e.g. the value of MgO, Cr, Th/Ce, Rb, Th and K₂O/Na₂O are better consistent with lower crust-derived adakitic melts. It is likely that during post-collisional stage (Neogene), slab break-off and asthenospheric up-welling was accompanied by delamination and thinning of overriding lithosphere. In this period, the mantle, and then after lower crustal mafics (the source of adakitic melt) are partially melted. The adakitic melts are probably more or less assimilated with mantle materials resulted in increasing some compatible element (like Ni) contents. Overall, chemical variation of Neogene magmatism in Azerbaijan area could be explained by the various mantle-crustal melt sources as well as crustal assimilation and fractional crystallization happened in post-collisional setting of Arabia- Eurasia plates.

Keywords: dacite, adakite, post-collision, Azerbaijan, northwestern Iran.

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Type of Study: Case-Study | Subject: Petrology
Received: 2021/02/2 | Accepted: 2021/02/20 | Published: 2021/02/28