Abstract The late Neoproterozoic (Ediacaran) igneous and metamorphic complex that constitutes the main part of the Precambrian basement in Iran is exposed in southwestern Saqqez in the northern Sanandaj-Sirjan zone (SaSZ), which is called the Ediacaran complex in this study. New zircon U–Pb dating from five samples shows that the crystallization of the main granitic bodies happened 559 to 547 Ma in the late Neoproterozoic (Ediacaran). The Ediacaran complex in southwest Saqqez includes: (a) metarhyolite-sedimentary sequences; (b) metagranite; and (c) metadiorite-monzonitic bodies with some late stage dikes. Whole-rock compositions of the granites show high contents of SiO2 (62.9–80.5 wt.%), K2O (0.1–4.0 wt.%), and Al2O3 (9.7–19.1 wt.%) with low contents of MgO (0.2–2.4 wt.%), Fe2O3 (0.7–6.9 wt.%), and TiO2 (0.1–1.0 wt.%). Negative eNd(t) (−5.2 to −3.0) and high initial ratios of 87Sr/86Sr (0.7101 to 0.7328) indicate the main role of crustal components in the sources of the granitic bodies. The metadiorite-monzonitic rocks have high contents of Fe2O3 (6.4–10.7 wt.%), MgO (6.6–8.1 wt.%), CaO (5.7–9.7 wt.%), and TiO2 (0.4–1.2 wt.%) with positive eNd(t) (+2.9 to +4.4) values. Whole rocks compositions and 87Sr/86Sr–143Nd/144Nd isotope ratios show different sources for the metagranite and metadiorite-monzonite groups, which are consistent with continental crust and subcontinental lithospheric mantle released melts, respectively. The high contents of Th with low contents of the transitional elements such as Nb-Ta with calc-alkaline affinity of the both intermediate and acidic rocks infer the relation of these rocks to an active continental margin over the subduction zone in the late Neoproterozoic which is associated with Proto-Tethys subduction beneath northern Gondwana in that time.

中文翻译：

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伊朗西北部 Saqqez 西南部埃迪卡拉纪 (550 Ma) 花岗岩复合体（变花岗岩）的岩石成因和地球动力学意义

摘要 构成伊朗前寒武纪基底主要部分的晚新元古代（Ediacaran）火成变质杂岩出露在北部Sanandaj-Sirjan带（SaSZ）的Saqqez西南部，在本研究中称为埃迪卡拉纪杂岩。5个样品的新锆石U-Pb定年表明，主要花岗岩体的结晶发生在新元古代晚期（埃迪卡拉纪）559～547 Ma。Saqqez 西南部的 Ediacaran 杂岩体包括： (a) 变晶石-沉积层序；(b) 变花岗岩；(c) 带有一些晚期岩脉的变闪长岩-二长岩体。花岗岩的全岩成分显示出高含量的 SiO2 (62.9-80.5 wt.%)、K2O (0.1-4.0 wt.%) 和 Al2O3 (9.7-19.1 wt.%) 和低含量的 MgO (0.2-2.4 wt.%) wt.%)、Fe2O3 (0.7–6.9 wt.%) 和 TiO2 (0.1–1.0 wt.%)。负 eNd(t) (-5. 2 至 -3.0) 和 87Sr/86Sr 的高初始比值 (0.7101 至 0.7328) 表明地壳成分在花岗岩体的来源中起主要作用。变闪长岩-二长岩的 Fe2O3 (6.4–10.7 wt.%)、MgO (6.6–8.1 wt.%)、CaO (5.7–9.7 wt.%) 和 TiO2 (0.4–1.2 wt.%) 含量较高，正 eNd(t)（+2.9 至 +4.4）值。全岩成分和 87Sr/86Sr-143Nd/144Nd 同位素比值显示了变花岗岩和变闪长岩-二长岩群的不同来源，分别与大陆地壳和次大陆岩石圈地幔释放的熔体一致。