新老岛弧斑岩铜(金)矿中间岩浆房过程对比研究：以菲律宾 Black Mountain和我国多宝山为例

Island arc-related porphyry Cu (Au) deposits serve as important sources of Cu and Au to the world. Yet the magma chamber formation processes for these deposits are still unclear, which significantly restricts our understanding on the early magmatic processes. Philippine Black Mountain and Chinese Duobaoshan are typical Pliocene and Early Paleozoic island arc-related porphyry Cu deposits, respectively. They are ideal cases for investigating the key scientific question of ‘deep magma chamber formation processes of present and ancient island arc-related porphyry Cu deposits’. Therefore, in this proposal, we are going to focus on the above deposits. Based on systematic geological mapping including igneous rocks crosscutting relationship and emplacement features, we will conduct detailed microstructure observations on various magmatic minerals from different types of igneous rocks. Then, we will analyze in situ major, trace elements on these minerals, and also plagioclase and clinopyroxene Sr isotope via EPMA, LA-(MC)-ICPMS and (Nano)-SIMS. Combining with whole-rock geochemistry, we will discuss the systematic mineral crystallization environment and formation processes, which will provide us insights on the comparison of magma chamber formation processes for present and ancient porphyry Cu deposits, with implications on mineralization and mineral deposit scale. Finaly we will build a model of magma chamber formation processes. This study would lead to a better understanding on magma chamber formation processes for island arc-related porphyry Cu deposits, and shed new lights on petrogenesis of igneous rocks, the source of ore-related materials, and especially on how the magma chamber contributes to the mineralization processes.

岛弧斑岩铜(金)矿床是全球铜、金的重要来源，然而目前对其中间岩浆房过程尚不清晰，严重阻碍了对早期岩浆过程的深入理解。菲律宾Black Mountain和我国多宝山分别代表典型现今和早古生代岛弧斑岩矿床，是研究“新老岛弧背景斑岩铜(金)矿中间岩浆房过程”这一关键科学问题的理想场所。本申请拟以二者为研究对象，基于详实的岩浆岩侵位序列和产出规模，对各岩相岩浆矿物进行精细显微结构观察，利用电子探针、激光剥蚀(多接收)等离子体质谱和(纳米)离子探针对其开展原位微区主-微量元素、斜长石和单斜辉石Sr同位素等研究，并辅以全岩地球化学结果，探讨岩浆矿物的结晶环境和形成过程，揭示新老岛弧斑岩铜矿中间岩浆房过程的异同，以及对成矿作用和矿床规模的控制因素，建立岛弧斑岩铜矿中间岩浆房模型。以上研究将有助于进一步理解岛弧斑岩铜矿中间岩浆房过程，并为岩石成因、成矿物质来源和岩浆房如何控制斑岩铜矿成矿作用提供科学依据。

斑岩铜矿床是全球铜的重要来源，主流观点认为成矿物质主要来自深部岩浆房，然而目前对深部岩浆房形成过程认识严重不足，制约了对斑岩铜矿早期岩浆过程的深入理解。菲律宾黑山和我国多宝山分别代表典型现今和早古生代俯冲斑岩矿床，是研究“俯冲斑岩铜矿深部岩浆过程”的理想对象。为此，我们对菲律宾黑山和我国多宝山斑岩铜矿各岩相及岩浆矿物进行精细显微研究，通过矿物原位微区结构-主微量元素-Sr-Nd-Hf-O同位素结果，并辅以全岩地球化学结果，探讨岩浆矿物的结晶环境、形成过程及岩石成因。对菲律宾黑山的研究揭示出现今岛弧背景斑岩铜矿深部存在大规模富铜镁铁质岩浆注入，注入同时带来了大规模物质铜，且深部岩浆房具有多级产出的特点，证实富含成矿物质的成矿流体主要来自深部岩浆房，伴随着流体的演化发生矿质卸载形成矿床。对黑龙江多宝山矿床各期岩浆岩的研究，揭示出多宝山斑岩铜矿床可能是多期岩浆-构造-成矿作用的结果，对应于古亚洲洋和蒙古-鄂霍茨克洋构造体制复合造山作用。据此综合建立了岛弧斑岩铜矿深部岩浆房模型，并为岩石成因、成矿物质来源和岩浆房如何控制斑岩铜矿成矿作用提供科学依据。.同时，我们对新疆包古图铜矿、白山斑岩钼矿、以及拉萨地块弧岩浆开展了深入岩石学和矿物学研究，结果显示：1）包古图成矿岩体存在镁铁质和长英质岩浆混合，岩石具有相对低的氧逸度特征；2）磷灰石Sr同位素可受到中低温热液流体的改造，为利用磷灰石Sr同位素示踪热液流体来源奠定了理论基础；3）随着俯冲作用的进行，弧岩浆氧逸度逐渐升高；4）具有高氧逸度、埃达克质特征的成熟弧岩浆具有较大的斑岩铜矿成矿潜力。.相关研究成果为利用矿物学示踪岩浆-流体精细过程提供了范例和理论基础，同时为找矿勘查提供了新的思路。本项目共发表国际SCI论文11篇，分别为EG（3篇）、JGR、JP、AM、MD、OGR、Lithos（2篇）、Gondwana Research等期刊文章。