山东省蓬莱—栖霞金成矿带地壳结构对金成矿的约束

Constraint of Crustal Structures on Gold Mineralization in Penglai-Qixia Gold Metallogenic Belt

摘要:

岩浆活动和构造活动是胶东地区金成矿的主要成矿要素，建立岩浆活动和构造活动间的成因联系是成矿机理研究的重要内容。本次贯穿笏山金矿和蓬莱栖霞断裂带的高精度反射地震剖面测量显示，控矿的陡崖台前断裂为地壳浅层的铲式断裂，其深部与垂向的蓬莱栖霞断裂带的主干断裂栖霞杨础断裂相交。栖霞杨础断裂切穿地壳，表现出走滑断裂特征，沿断裂存在岩浆活动行迹。蓬莱栖霞金矿带为以解宋营紫现头断裂、栖霞杨础断裂为主干,发育的右旋走滑断裂构造系统。岩浆活动和成矿作用分布于构造系统的局部张性域内。研究表明：胶东地区存在以剪切走滑为主控的构造活动和沿垂直地壳的剪切带与之耦合的岩浆活动。在此基础上，提出了以岩石剪切破裂模式为基础的，右旋走滑断裂控制的岩浆活动和成矿作用相耦合的基于岩石圈剪切破裂的成矿系统模型。

Abstract:

Magmatic activity and tectonic activity are key metallogenic factors of gold mineralization in Jiaodong area. It is important to establish genetic relationship between magmatic activity and tectonic activity in the study of metallogenic mechanism. The previous crustal structure exploration in the northwest Jiaodong area shows that there is a vertical fault system in the crust accompanied by magmatic activity, which indicates the coupling of magmatic activity and tectonic activity. The high-resolution reflection seismic section survey crossing the Hushan Gold Deposit and Penglai-Qixia fault zone shows that the Taiqian-Douya fault controlling the ore deposit is a shovel type fault on the surface of crust, and it intersects with Qixia-Yangchu fault in deep-the main branch fault of Penglai-Qixia strick-slip fault zone. Qixia-yangchu fault cuts through the crust, showing the characteristics of strike-slip fault, and there are magmatic activity traces along the fault. The Penglai-Qixia gold deposit belt is a dextral strike-slip fault structural system with Jiesongying-Zixiantou fault and Qixia-Yangchu fault as the main trunk. Magmatic activity and mineralization are distributed in the local tensional domain of the tectonic system. This study reconfirms the previous knowledge that there are tectonic activities dominated by shearing movement, and magmatic activities coupled with the shear zones cutting through crust in Jiaodong area. On this basis, a new metallogenic system model based on rock shear fracture model is proposed, which is coupled with magmatic activity and mineralization controlled by right-lateral strike-slip fault.