胶东金矿集中区构造体系多层次控矿规律研究

STUDY ON THE MULTI-LEVEL CONTROLLING RULE FOR TECTONIC SYSTEM IN JIAODONG GOLD-CENTRALIZED AREA

提出中新生代东亚大陆与西太平洋带活动带相互关联的构造剪切带即是NNE向新华夏系巨型构造带。胶东金矿集中区产生于洋-陆过渡关联的该NNE向构造剪切带。对胶东构造体系进行了进一步研究,指出胶东中生代主要发育新华夏体系和华夏式构造系,而纬向构造体系,即EW向构造不发育。在此基础上,对胶东金矿集中区构造控制矿带、矿床、矿脉、地球化学分布和物理化学条件等不同层次特征加以分析,提出了胶东金矿成矿期构造具有多层次控矿特点,新华夏系NEE向泰山式构造控制胶东区域金矿带的展布;新华夏系NNE向区域剪切带控制金矿田产生部位;构造带断裂性质控制金矿矿床类别;构造断裂带的产状控制矿床矿体的倾伏侧伏规律;剪切构造两盘的运移特点和断裂组合形式控制矿脉的分布规律;构造变形岩相带控制构造地球化学特征;构造控制水岩系统成矿物理化学条件等认识。成矿构造研究、测量和资料分析证实,成矿阶段构造应力场最大主应力和最小主应力轴面是近于水平的,而中间主应力接近于垂直;区域成矿期应力场呈水平反钟向扭动剪切状,具有新华夏系应力场特征。从中生代应力场分析发现,除了区域反钟向挤压剪切构造特征外,主要成矿阶段构造环境还表现出应力松弛和拉张的特点,有普遍的断裂上盘下滑的构造成矿的特征。

In this paper it is proposed that the tectono-shear belt located between the East Asia continent and the West Pacific Ocean activity belt in mid-Cenozoic is a Neocathaysian NNE-oriented large-scale tectonic belt. The Jiaodong gold-centralized area is along this NNE-oriented tectono-shear belt of oceanic-continental transition region. Based on further study on the tectonic system of Jiaodong area, the authors point out that the area is dominated by the Neocathaysian system and Cathaysian tectonic system during the Mesozoic as well as the latitudinal direction tectonic system, which is the EW-oriented tectonic belt that has never before been discovered. On the basis of these data, the authors analyze in detail the characteristics of the ore belts, deposits, ore veins, geochemical distribution and physical-chemical features controlled by the tectonics, and bring forward the conclusion that the tectonics in the metallogenic epoch for Jiaodong gold deposits obviously shows multi-level ore-controlling features. This is to say, the Neocathaysian NNE-oriented ＂Taishan＂ pattern tectonics that controls the gold ore belt＇s extension in Jiaodong area, and the second level regional shear belt in the Neocathaysian NNE-trending system controls the occurrence of the gold ore field, the features of the faults in the tectonic belt control the type of the gold deposit, the attitudes of the faults control the pitches and rakes of the ore bodies in the deposits, the characteristics of the movement of the component blocks of the faults and forms of combination of the faults control the distribution mode of the ore veins, the tectono-deformed lithofacies controls the tectono-geochemical characteristics, and the tectonics controls the metallogenic and physical-chemical conditions of the liquid-rock system, and so on. By tectonic analysis and measurement, the authors draw the conclusion that that the axes for the maximum main stress and the minimum main stress are nearly horizontal, and the intermediate main stress is nearly upright. Meanwhile, the regional stress field at the metallogenic stage appears to be counterclockwise twisting plus shearing at the horizontal level and shows the characteristics of the Neocathaysian stress field. Based on analysis of the stress field in Mesozoic, the authors observe that the tectonic environment for the major metallogenic episode shows features of stress relaxation and extension and that the fault＇s upper block moves upward in addition to counterclockwise twisting.