The gabbro (shoshonitic)-monzonite-granodiorite association of Khankandi pluton, Alborz Mountains, NW Iran

被引:82
作者
Aghazadeh, Mehraj [2 ]
Castro, Antonio [1 ]
Omran, Nematallah Rashidnejad [2 ]
Emami, Mohamad Hashem [2 ]
Moinvaziri, Hossien [2 ]
Badrzadeh, Zahra [2 ]
机构
[1] Univ Huelva, Dept Geol, Huelva 21071, Spain
[2] Univ Tarbiat Modares, Dept Geol, Tehran, Iran
关键词
Shoshonite; Gabbro; Monzonite; Alborz Mountains; Iran; Subduction; Mantle wedge; LIQUID IMMISCIBILITY; ALKALINE MAGMATISM; LESSER CAUCASUS; TRACE-ELEMENTS; IBERIAN MASSIF; OROGENIC BELT; K-AR; SR; ND; GENESIS;
D O I
10.1016/j.jseaes.2010.01.002
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
The Khankandi pluton forms part of a group of gabbro-granodiorite intrusions in the Alborz Mountains of NW Iran. A petrographical and geochemical study of this plutonic association reveals the existence of several magmatic cycles with different origins and slight differences in age. The oldest cycle (Cl) is represented by granodiorites. A second cycle (C2) is formed by a gabbro-monzonite association, with a clear shoshonitic affinity, that dominates most of the intrusive volume. Gabbros and monzonites form a co-magmatic association. Zircons from the monzonites were analyzed by LA-ICP-MS for U-Pb dating. An average age of 28.9 Ma, ranging from 23.7 to 33.6 Ma was obtained. Gabbros, monzonites and granodiorites share a nearly common isotopic ratio for Sr and Nd. Both initial Sr and Nd ratios are clustered within a narrow range from 0.7045 to 0.7047 for the Sr-87/Sr-86 ratio and epsilon(Nd) from 1.46 to 1.89. Comparison with experimental studies, together with mantle-like isotopic ratios and comparisons of REE patterns, points to an origin by variable melting rates from a common metasomatised mantle source for gabbros and monzonites. Melting of a subducted m lange is suggested for the granodiorite magmas predating the gabbro-monzonite intrusion. The two sources, a metasomatised mantle and ascending silicic plumes, are direct consequence of subduction. (C) 2010 Elsevier Ltd. All rights reserved.
引用
收藏
页码:199 / 219
页数:21
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