کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5784060 | 1638630 | 2017 | 70 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Mesozoic-Cenozoic mafic magmatism in Sanandaj-Sirjan Zone, Zagros Orogen (Western Iran): Geochemical and isotopic inferences from Middle Jurassic and Late Eocene gabbros
ترجمه فارسی عنوان
ماگماتیسم مافیایی مزوزوئیک-سنوزوئیک در ناحیه سنندج-سیرجان، زاگرس اوروژن (ایران غربی): نتیجه گیری ژئوشیمیایی و ایزوتوپ از گابروهای ژوراسیک مرکزی و اواخر ائوسن
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کلمات کلیدی
زاگرس اورنگ، نئو تتیس اقیانوس، گابرو، مدل سازی عنصر ردیابی، ترکیب آستنوسفر غنی شده، گوه گوشته
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
چکیده انگلیسی
One of the consequences of Neo-Tethys ocean subduction beneath the Central Iranian Micro-continent (CIMC) is the development of rare gabbroic intrusions in the Malayer-Boroujerd Plutonic Complex (MBPC) located in the Sanandaj-Sirjan Zone (SaSZ) of the Zagros Orogenic belt. The MBPC is a suite of extensive felsic and lesser mafic magmatic products in the northern SaSZ with geochemical signatures of arc-like magmatism during the Middle Jurassic (Ghorveh-Aligudarz arc) and intraplate type in the Late Eocene. Middle Jurassic gabbros (non-cumulate and cumulate) have low-Ti concentrations (< 1 wt.%) and quite uniform isotopic compositions (initial 87Sr/86Sr: 0.7035-0.70593 and εNd(t): â 6.18 to â 0.7), enriched LILE relative to HFSE, variable fractionation between the LREE and HREE ((La/Yb)cn: 2.27-7.45) and both negative to positive Eu anomalies. These distinctive features of arc-type magmatism are consistent with a subduction-modified mantle source for these rocks. Trace element and REE models indicate ~ 15% melting of a metasomatized amphibole-bearing garnet-spinel lherzolite (garnet:spinel ~ 7:3) in the sub-arc mantle wedge. The cumulate gabbros and non-cumulates belong to common liquid line of descent, with complementary trace element patterns. Much of the variation between samples can be modeled by fractional crystallization (FC) of a common parent; only one cumulate gabbro from this suite exhibits isotopic evidence of contamination, probably by Rb-depleted crustal materials. The Late Eocene gabbros have relatively high-Ti (> 1 wt.%) and display isotopically depleted Sr-Nd values (initial 87Sr/86Sr: 0.7044-0.7087, εNd(t): 1.9 -+3.2, barring one crustally-contaminated sample). OIB-like trace element characteristics such as enriched HFSE, and only minor enrichment of LILE and LREE, reflect a within-plate character and asthenospheric source. Trace element modeling indicates small degree melting (fmelting: 0.05) of upper mantle lherzolite (garnet:spinel ~ 3:1) followed by higher degree melting (fmelting: 0.15) at shallower depths (garnet:spinel ~ 4.5:2). The Eocene parental magma underwent FC of olivine and clinopyroxene. We propose that Eocene asthenospheric upwelling was triggered by slab tearing in response to slab-rollback, which is elsewhere reported to have triggered a 'flare-up' of extension-related magmatism across Iran. Three stages of tectono-magmatic evolution in the Ghorveh-Aligudarz arc segment of the N-SaSZ are represented by: 1) arc-like magmatism during active subduction of the Neo-Tethys seaway at Middle Jurassic, 2) magmatic quiescence during an interval of shallow-angle or highly oblique subduction during the Cretaceous-Paleocene, and 3) asthenosphere melting during slab tearing shortly before the onset of the Arabia-Eurasia collision.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Lithos - Volumes 284â285, July 2017, Pages 588-607
Journal: Lithos - Volumes 284â285, July 2017, Pages 588-607
نویسندگان
R. Deevsalar, R. Shinjo, M. Ghaderi, M. Murata, P.W.O. Hoskin, S. Oshiro, K.L. Wang, H.Y. Lee, I. Neill,