胶东区域断裂蚀变岩带构造-流体成矿特征  

A study of distribution and change of regional tectonic-fluid in goldfields of Jiaodong Peninsula

作　　者：吕承训 吴淦国[2] Norbert H.MAERZ Kenneth J.BOYKO 

机构地区：[1]Missouri University of Science and Technology, MO 65401, USA [2]中国地质大学(北京),北京100083

出　　处：《地学前缘》2015年第4期113-121,共9页Earth Science Frontiers

基　　金：国家自然科学基金项目(40972061)

摘　　要：胶东是目前中国最大的金矿集中区,矿床位于花岗岩与老地层之间的区域剪切断裂带,围岩是在花岗岩区段的断裂破碎蚀变岩带,成矿作用与岩浆期后热液交代直接相关。区域构造流体研究的一个难题是:如何选择既能保证流体包裹体分析质量,又可以观测交代蚀变阶段构造应力应变的岩石样品。文中选择断裂蚀变带中钾长石化和绢英岩化两个蚀变岩带采集样品,试图解决区域流体研究中的问题。研究发现,胶东区域断裂蚀变岩带构造与热液的物理化学条件变化具有规律性:在钾长石化蚀变阶段,西部构造强度更强,而在绢英岩化蚀变阶段,东部构造应变值相对更大;钾长石化阶段的流体温度西部低东部高,绢英岩化阶段西部高东部低,显示了热力来源东部更强。胶东区域主要断裂蚀变岩带的构造附加静水压力从西到东逐渐降低,表明区域成矿热液的流动方向为自西向东。绢英岩化蚀变岩流体成分的区域变化显示:Na+/K+变化预示,胶东西部K+富集,有利于金的富集成矿,而胶东东部Na+富集,利于成矿流体的迁移;CH4和CO2等流体成分的含量自西向东逐渐降低,与金元素富集正相关。胶东区域断裂蚀变岩带的构造流体特征揭示了成矿热液在胶东地区自西向东运移的趋势。这种趋势影响了这一地区金矿床的规模、矿床类型和分布规律。Jiaodong is the biggest gold mineralization concentration area in China. The mineralization has direct relationship with Mesozoic granite. Most of deposits exist in regional shear zone where has the broken altered rock zone, which is the result of magmatic hydrothermal metasomatism. The main research problem of structure-fluid is how to guarantee the chosen rock sample can be used to do chemical fluid composition analysis and also used to observe tectonic deformatioil. We suggested that the potash feldspathized altered rock and the quartz-sericitized altered rock can be chosen as the research samples to solve this problem. This research method overcame the research difficulty in the regional structure-fluid area. The research result showed that the strain value decreases in potash feldspathized altered rock zone but increases in quartz-sericitized altered rock zone from west to east in the Jiaodong areal that the fluid homogenization temperatures increase in potash feldspathized altered rock zone but decrease in quartz-sericitized altered rock zone from west to east in the Jiaodong area. The chemical fluid composition has an obvious variation tendency. The Na^＋/K^＋ variation tendency in quartz-sericitized altered rock zone shows that the west of Jiaodong has more K^＋ than east and K^＋ is beneficial for mineralizatiom that the east of Jiaodong has more Na^＋ than west and Na^＋ is beneficial for fluid migration. The contents of CH4 and CO2 decrease from west to east, which is positively correlated with the enrichment of Au element. The characteristics of structure-fluid in fractured altered rock zone revealed the trend that the metallogenic hydrothermal fluid migrated from west to east in the Jiaodong region. This trend had its impact on the gold deposit scale, type and distribution.

关 键 词：胶东金矿 断裂蚀变岩分带 构造物理化学条件 流体地球化学成分 

分 类 号：P613[天文地球—矿床学] P623.3[天文地球—地质学]