New evidence for Jurassic continental rifting in the northern Sanandaj Sirjan Zone, western Iran: the Ghalaylan seamount, southwest Ghorveh

被引:42
作者
Azizi, Hossein [1 ]
Nouri, Fatemeh [1 ]
Stern, Robert J. [2 ]
Azizi, Marie [3 ]
Lucci, Federico [4 ]
Asahara, Yoshihiro [5 ]
Zarinkoub, Mohammad Hossein [6 ]
Chung, Sun Lin [7 ,8 ]
机构
[1] Univ Kurdistan, Fac Engn, Min Dept, Sanandaj, Iran
[2] Univ Texas Dallas, Geosci Dept, Richardson, TX 75083 USA
[3] Univ Kurdistan, Fac Basic Sci, Earth Sci Dept, Sanandaj, Iran
[4] Univ Roma Tre, Dipartimento Sci, Rome, Italy
[5] Nagoya Univ, Grad Sch Environm Studies, Dept Earth & Environm Sci, Nagoya, Aichi, Japan
[6] Birjand Univ, Fac Sci, Dept Geol, Birjand, Iran
[7] Acad Sinica, Inst Earth Sci, Taipei 11529, Taiwan
[8] Natl Taiwan Univ, Dept Geosci, POB 13-318, Taipei 10617, Taiwan
基金
日本学术振兴会;
关键词
ZIRCON U-PB; SHAHREKORD METAMORPHIC COMPLEX; MAFIC-ULTRAMAFIC INTRUSIONS; BOROUJERD PLUTONIC COMPLEX; EMEISHAN FLOOD BASALTS; SOUTHERN RED-SEA; VOLCANIC-ROCKS; MANTLE SOURCES; ZAGROS OROGEN; TARIM BASIN;
D O I
10.1080/00206814.2018.1535913
中图分类号
P5 [地质学];
学科分类号
0709 ; 081803 ;
摘要
We address the growing controversy about the tectonic setting in which Jurassic magmatism of Iran occurred: arc or continental rift. In the Ghorveh area of the northern Sanandaj Sirjan zone (SaSZ), the Ghalayan metabasites are interlayered with marble and schist and locally cut by acidic dikes. Zircon U-Pb dating of the metabasitic rocks shows that these crystallized at ca. 145-144 Ma ago in the Late Jurassic (Tithonian). This complex was metamorphosed in the lower greenschist facies, however, some protolithic structures such as pillow lava and primary minerals are preserved. The metabasites are tholeiites with low SiO2(45.6-50.5 wt.%), moderate Al2O3(11.3-17.0 wt.%), and high TiO2(0.7-2.9 wt.%) and Fe2O3(9.4-14.1 wt.%). The Ghalayan metabasites are enriched in Light rare earth elements (LREEs) without significant Nb, Ta, Pb, Sr and Ba anomalies, similar to modern continental intra-plate tholeiitic basalts such as Afar and East African rifts. The Ghalaylan metabasites show wide ranges for(87)Sr/Sr-86((i))(0.7039-0.7077) and positive epsilon(Nd)(t) values (+0.1 to +4.6). These isotopic compositions are similar to those expected for slightly depleted subcontinental lithospheric mantle sources. Independently built discrimination diagrams indicate an intra-continental rifting regime for the source of Jurassic metabasites in the northern SaSZ. Geochemical and tectonic evidence suggests that rifting or a mantle plume was responsible for volcanic activity in the Upper Jurassic SaSZ. Considering the variation of ages of basaltic volcanism along the SaSZ, we suggest that Ghalayan basaltic magmatism reflected a submarine volcano that formed as part of the late stage continental rift, similar to Afar in the East African Rift system. Our results indicate that an extensional tectonic regime dominated SaSZ tectonics in the Middle to Late Jurassic.
引用
收藏
页码:1635 / 1657
页数:23
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