矿床（区）尺度岩浆演化过程对斑岩成矿作用的制约: 以玉龙铜矿床为例

The granitic magmatic activity is commonly characterized by multiple stages and similar origin, etc., within almost all of the porphyry copper deposits (districts) worldwide. These different stages of granitic rocks within the porphyry copper deposit (district) are usually similar in mineral components, whole-rock element-isotope chemical compositions, and emplacement ages within the range of error. However, porphyry Cu-mineralization does not occur at all stages of the granitic rocks, but occurs only at one or several stages of the granitic rocks within the porphyry copper deposit (district). Due to limitations from previous research techniques, etc., in most cases, it is difficult to identify the differences of magmatic physical-chemical conditions, etc., between mineralizing and barren stages of granitic rocks, and consequently, it cannot answer the reasons of metallogenic inevitability for specific stages of granitic rocks within the porphyry copper deposit (district), restricting establishment of the metallogenic theory system. In this project, fresh amphibole, biotite, plagioclase, and physical-chemical destruction-resistant accessory minerals, from all the mineralizing and barren (weakly mineralizing) stages of granitic rocks within the giant Yulong porphyry copper deposit (district), will be chosen as the main objects of study; in-situ micro-area element-isotope analysis of these single minerals will be used to systematically examine the detailed change regulations of magmatic physico-chemical condition, etc., key factors that control porphyry Cu-formation, such as oxygen fugacity, water content, water saturation, chlorine content, sulfur content and emplacement depth, etc., between the mineralizing and barren (weakly mineralizing) stages of granitic rocks and as well as within the single stages of granitic rocks, and then a comprehensive assessment on the driving mechanisms of these changes and their roles in controlling porphyry Cu-mineralization will be carried out. We hope that this work will provide a new case study for deeply revealing controls of magma evolution process in ore deposit (district) scale, on the porphyry Cu-mineralization.

全球几乎所有斑岩铜矿床（区）内，花岗质岩浆活动都具有多期次、起源相似等特征，这些不同期次岩石常具有相似的矿物组成、全岩元素-同位素成分和误差范围内相似的年龄，但成矿只集中在其中某个或某几个而不是所有期次。由于受研究手段等方面的限制，以往多数情况下未能识别矿床（区）内成矿与不成矿花岗质岩浆物理化学条件等方面的区别，不能回答具体期次岩石的成矿必然性，制约了成矿理论体系的建立。本研究拟选择玉龙斑岩铜矿床（区）内成矿和不成（贫）矿花岗岩中新鲜的角闪石、黑云母、斜长石和不易受后期改造的副矿物为主要研究对象，采用单矿物微区-原位分析技术，系统研究制约斑岩铜成矿的岩浆物理化学条件（氧逸度、水含量、水饱和情况、氯含量、硫含量、侵位深度等）等关键因素在不同期次及同期花岗岩内的精细变化规律，综合研究这些变化的驱动机制及对成矿的制约作用，为深入揭示矿床（区）尺度内岩浆演化过程对斑岩铜成矿的制约作用提供新的范例。

全球几乎所有斑岩铜矿床（区）内，花岗质岩浆活动都具有多期次、起源相似等特征，这.些不同期次岩石常具有相似的矿物组成、全岩元素-同位素成分和误差范围内相似的年龄，但成矿只集中在其中某个或某几个而不是所有期次。由于受研究手段等方面的限制，以往多数情况下未能识别矿床（区）内成矿与不成矿花岗质岩浆物理化学条件等方面的区别，不能回答具体期次岩石的成矿必然性，制约了成矿理论体系的建立。本研究选择玉龙斑岩铜矿床（区）内成矿和不成（贫）矿花岗岩中新鲜的角闪石、黑云母、斜长石和不易受后期改造的副矿物为主要研究对象，采用单矿物微区-原位分析技术，系统研究制约斑岩铜成矿的岩浆物理化学条件等关键因素在不同期次及同期花岗岩内的精细变化规律，综合研究这些变化的驱动机制及对成矿的制约作用，为深入揭示矿床（区）尺度内岩浆演化过程对斑岩铜成矿的制约作用提供新的范例。研究取得的主要创新性认识包括：⑴ 基性岩浆的补给触发大规模流体出溶是玉龙斑岩矿床矿区尺度内不同阶段岩浆差异性成矿的关键控制因素之一；⑵ 研究还系统揭示三江成矿带新生代斑岩矿床的岩浆起源、成矿斑岩富水-高氧逸度特征及成因机制、成矿带尺度斑岩差异性成矿的原因及机制等一系列重要的科学问题。这些认识对深入认识矿区尺度及成矿带尺度斑岩差异性成矿的机制及找矿勘查具有重要的理论和实际意义。项目执行期间，课题组共发表学术论文11篇（包括SCI论文10篇）、培养研究生4名、2人获得多项重要人才项目的支持等一系列成果。