Volume 28, Issue 2 (6-2020)                   www.ijcm.ir 2020, 28(2): 269-284 | Back to browse issues page


XML Persian Abstract Print


Download citation:
BibTeX | RIS | EndNote | Medlars | ProCite | Reference Manager | RefWorks
Send citation to:

Mokhtari N, Ahmadi A, Mirnejad H. Origin and magmatic evolution of the alkaline extrusive rocks of Neogene from Nehbandan-Assagie region, eastern Iran. www.ijcm.ir 2020; 28 (2) :269-284
URL: http://ijcm.ir/article-1-1465-en.html
Abstract:   (1484 Views)
The alkaline extrusive rocks of Neogene from Nehbandan-Assagie region, eastern Iran, include basanite, hawaiite, mugearite and benmoreite. Relatively low Ni and Cr contents and Mg-numbers of basanites are indicative of olivine and clinopyroxene fractionation from their relevant primary magma. Decreasing of CaO, TiO2, FeOt, HREEs and MREEs with increasing SiO2 indicate fractional crystallization of amphibole, clinopyroxene and Fe-Ti oxides. In basanites, hawaiites and mugearites with less than 52 wt.% of SiO2, high Nb/U ratio and lack of Nb and Ta negative anomalies are evidence for the low effect of crustal assimilation, if any, to the chemical composition of these rocks. In more-fractionated rocks, like some mugearites and benmoreites, crustal contamination is inferred from chemical characteristics and existence of quartz xenocrysts. The trace element concentrations and ratios of these rocks are similar to those of alkaline oceanic island basalts (OIB). (Tb/Yb)N more than 1.80 and (Dy/Yb)N more than 1.60 of these rocks are considered here as their generation after partial melting of an asthenospheric mantle in the garnet stability field. In addition, geochemical differences between the basanites and the other rocks are due to formation of their magmas, respectively, after 5-7 percent and 2 percent partial melting of a garnet lherzolite source.
Full-Text [PDF 117 kb]   (472 Downloads)    
Type of Study: Research | Subject: Special

Add your comments about this article : Your username or Email:
CAPTCHA

Rights and permissions
Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

© 2024 CC BY-NC 4.0 | Iranian Journal of Crystallography and Mineralogy

Designed & Developed by : Yektaweb