土耳其西部斑岩型矿床的深部过程对新特提斯洋俯冲到陆-陆碰撞过程的响应

The formation mechanism of porphyry ore deposits in the deep crust is the essential factors for the porphyry-type mineralization. The current studies of the porphyry ore deposits in the Tethyan domain mainly focus on the features of magmatic source, ore material origin and geodynamic processes in the subduction-related, continental collisional, or intra-continental extensional settings. However, during the successively and dynamically tectonic evolution from oceanic subduction to continent-continent collision, to intra-continental extensional settings, the response in the magmatic control and the evolution of ore-element and volatile contents in the magma related to the geodynamic changes have not yet been well identified and revealed. Therefore, this proposal will focus on the magmatic rocks in the four porphyry-type deposits related to the different tectonic settings from Late Cretaceous to Miocene in the western Turkey. Based on petrology, geochemistry, mineral chemistry and Sr-Nd-Hf-O isotopic features (plagioclase Sr isotope, apatite Sr-Nd-O isotopes and zircon Hf-O isotopes) and melt inclusions studies, the isotopic features of magma sources and volatile-ore-element contents in the causative magma will be obtained. The triggers for the formation of porphyry ore deposits in the deep crust in different tectonic settings will be constrained. Combined with the previous tectonic-magmatic studies (from Mesozoic to Miocene) in the Turkish Tethyan domain, the estimate of crustal thickness during the porphyry ore formation, the crustal-mantle interaction, and the evolution of ore materials in the deep crust will be discussed in the spatial-temporal framework. Finally, we will figure out the connection between the triggers for the formation of Turkish porphyry ore deposits, and the tectonic evolution from the Neo-Tethyan oceanic subduction, the Eurasian-Tauride-Anatolide continental collision and intra-continental extension, and achieve the the scientific aim of the major project.

斑岩型矿床形成的深部过程是矿床学研究的热点。目前对特提斯构造域斑岩矿床的研究集中在单一构造体制下斑岩矿床的岩浆源区性质、成矿物质来源和形成的构造动力学机制等方面，而对俯冲-碰撞-伸展构造体制转变过程中成岩-成矿物质演化规律尚不清楚。本项目拟以土耳其西部4个俯冲、碰撞、伸展环境斑岩矿床中的成矿岩浆岩组合为研究对象，开展岩石学、地球化学、矿物元素-同位素（Sr-Nd-Hf-O）和熔融包裹体成矿元素-挥发分含量等分析工作，厘定成矿岩浆的源区同位素组成和成矿元素-挥发分含量，查明三类构造环境下斑岩矿床形成的深部过程和动力学机制，阐明中特提斯晚白垩世以来三类构造体制转变中斑岩矿床形成时的地壳厚度、壳-幔相互作用方式-程度和成矿物质的演化过程，进而约束新特提斯洋俯冲到欧亚-Tauride-Anatolide板块碰撞过程中深部物质演化规律，实现本重大计划科学目标。

特提斯成矿带斑岩矿床形成的深部过程和稀有金属成矿特征是当今矿床学研究的热点。目前对特提斯构造域斑岩矿床的研究集中在单一构造体制下斑岩矿床的岩浆源区性质、成矿物质来源和形成的构造动力学机制等方面，而对俯冲-碰撞-伸展构造体制转变过程中成岩-成矿物质演化规律尚不清楚。同时，新特提斯单向聚合过程中形成的稀有金属矿床的成矿特征也备受学界关注。研究围绕着“多陆块单向裂解-聚合过程的资源能源响应”这一关键科学问题，利用地质学-地球化学工作系统揭示土耳其西部典型斑岩型铜钼金矿床形成时代及岩浆源区特征，发现成矿岩体普遍发育与成矿岩体同期的基性岩浆注入和岩浆混合作用，为深部岩浆房提供成矿元素，其岩浆源区特征显示碰撞-后碰撞-伸展背景逐渐富集的特征；利用锆石和磷灰石组成约束土耳其西部新生代斑岩成矿岩浆氧逸度-成矿挥发份元素组成演化特征与不同构造背景斑岩矿床形成的深部过程，揭示触发土耳其西部新生代斑岩矿床形成的动力学机制：在新特提斯洋向北单向汇聚的背景下，北部始新世-渐新世斑岩矿床受控于碰撞后俯冲的新特提斯洋Vardar洋后撤-回转-断离过程；南部中新世斑岩矿床的形成则受控于爱琴海板片俯冲控制的地壳伸展-减薄过程。北侧Izmir-Ankara-Erzincan缝合带附近的Tavşanlı与Biga半岛斑岩成矿带始新世-渐新世斑岩型矿床的形成与熔融-同化-储存-均一过程有关，深部地壳热区过程与中新世Afyon-Konya带斑岩型矿床的形成有关；揭示喜马拉雅新发现的超大型琼嘉岗锂矿地质特征、形成时代及其源区特征，表明新特提斯洋单向俯冲-碰撞过程中喜马拉雅锂资源富集发生于新喜马拉雅阶段早期，含锂伟晶岩结晶于高度演化的花岗伟晶岩熔体。本项目取得成果将对理解特提斯成矿带斑岩矿床和稀有金属矿床形成过程及其构造背景，和高喜马拉雅其它地区找寻大型花岗伟晶岩型锂矿提供重要借鉴意义。