伊朗扎格罗斯造山带构造演化与成矿

扎格罗斯造山带是特提斯构造域的重要组成,其内赋存有世界级规模的金属矿产资源。本文综述了扎格罗斯造山带构造格架、物质组成、矿床分布及特征,讨论了该区构造演化与成矿。扎格罗斯造山带由南至北由扎格罗斯褶皱冲断带(ZFTB)、萨南达杰-锡尔詹岩浆变质带(SSZ)、乌尔米耶-达克塔尔火山岩浆带(UDMA)和伊朗中部地块四个构造单元组成。新元古代—早寒武世时,萨南达杰-锡尔詹带和伊朗中部地块位于冈瓦纳大陆北缘,受始特提斯洋盆俯冲影响,边缘发育大陆岩浆弧。晚石炭世—二叠纪萨南达杰-锡尔詹带和伊朗中部地块与冈瓦纳大陆裂解,新特提斯洋盆形成。三叠纪伊朗中部地块与北侧的欧亚大陆汇聚,古特提斯洋盆闭合。侏罗纪—白垩纪新特提斯洋盆向北侧的萨南达杰-锡尔詹带俯冲,形成弧岩浆岩及弧后盆地,其中弧前蛇绿岩中发育铬铁矿床,弧后盆地双峰式火山岩中产有块状硫化物矿床,碳酸盐岩内发育梅迪阿巴德密西西比河谷型超大型铅锌矿床。白垩纪末—新生代初洋壳向萨南达杰-锡尔詹带仰冲,含铬铁矿的蛇绿岩就位。始新世末—渐新世新特提斯洋闭合,南侧的阿拉伯板块与北侧的萨南达杰-锡尔詹带和中伊朗地块所在的欧亚大陆碰撞,在阿拉伯板块前缘形成扎格罗斯褶皱冲断带,在欧亚大陆南缘形成乌尔米耶-达克塔尔火山岩浆带。伴随碰撞,在萨南达杰-锡尔詹带的碳酸盐岩中形成类密西西比河谷型铅锌矿床,中中新世以来扎格罗斯地区进入后碰撞阶段,在乌尔米耶-达克塔尔带内发育了包括萨尔切实梅和松贡超大型矿床在内的众多斑岩型铜矿床。

Tectonic Evolution and Metallogeny of Zagros, Iran

Located in the southwest of Iran, the Zagros orogen is an important segment of the Tethyan domain. Meanwhile, it contains numerous large or giant ore deposits, such as Mehdi Abad, Sar Cheshmeh, and Sungun. The tectono-magmatic and metallogenic evolution of the Zagros orogen is reviewed. Four major tectonic units have been recognized, they are the Zagros fold-and-thrust belt (ZFTB), the Sanandaj Sirjan zone (SSZ), the Urumieh Dokhtar magmatic assemblage (UDMA), and the central Iran block (CI). The main significant metallogenic belts in the Zagros include the Zagros podiform chromite, the Arasbaran Kerman porphyry Cu Mo Au, and the Takab-Yazd Pb Zn deposits. Among them, the Takab-Yazd belt is composed of two types of deposits, e.g., MVT-like deposits and volcanogenic massive sulfide (VMS) deposits. The Zagros is created by collision between the Arabian and Eurasian continents, but the tectonic and metallogenic evolution is complex. During Neoproterozoic to early Cambrian, the area resembled a modern continental arc environment as recorded by numerous granitiods in the SSZ and CI. These blocks separated from Gondwana during late Carboniferous to Permian, and accreted to the Eurasian continent in the Triassic times. The Neo-Tethyan oceanic slab subducted beneath the SSZ during Jurassic and Cretaceous, left back arc basin in the north of the SSZ where volcanogenic massive sulphide deposits and Mehdi Abad Pb Zn deposit formed. Mafic to ultramafic complex hosting Cr mineralizations formed in the south of the SSZ. These podiform chromites were emplaced 40 Ma later during obdution of the oceanic crust. At the end of Eocene to Oligocene, collision between the Arabian and Eurasian continents happened, which made the northern margin of the Arabian plate had been deformed (ZFTB), and abundant magmatic activity occurred bewteen the SSZ and CI (UDMA). Some adakitic granite hosting Cu mineralizations intruded during the early Miocene. The collision also led to Pb-Zn mineralizations in the SSZ. The Zagros orogen has been in post-collisional stage since middle Miocene.