新疆东准噶尔卡拉麦里构造带多期变形和金叠加成矿

Multi-stage Tectonic Deformation and Superimposed Gold Mineralization in the Karamaili Structural Belt of Eastern Junggar,Xinjiang

卡拉麦里韧-脆性剪切构造带形成于华力西中晚期,分属碰撞造山挤压和伸展造山走滑-伸展2个构造变形期,历经逆冲推覆、左行走滑、右行走滑和伸展4个主要演化阶段,金成矿空间上分布于碰撞期逆冲推覆型韧性剪切带中,成矿发生在转换造山及伸展造山时期,属C2-P(290～260Ma)走滑伸展阶段成矿事件。构造变形对金成矿的控制作用在空间上表现为深部构造层次韧性变形与其之上的中浅构造层次的韧脆性和脆性变形存在地质间断,金成矿与韧脆性、脆性变形同步且与韧性变形呈明显叠加复合关系,赋矿韧脆性和脆性构造统一于右行走滑剪切-伸展成矿体系中,具有不同的构造变形层次、变形特征和矿化特征。构造与金成矿空间叠加关系,有相应的两期成矿年龄响应和多阶段、多物质复合成矿的记录,代表一种时间有早晚、空间有重叠、物质来源多成因的叠加复合成矿关系。构造带韧-脆性变形转换与金成矿活动是区域构造背景发生明显转换过程中的多期变形和叠加成矿的形成机制,(成矿)动力学背景分别代表了碰撞造山期的逆冲推覆韧性变形、碰撞造山-伸展造山转变期的右行走滑韧脆性变形和金初始成矿、伸展造山期的脆性变形和金主成矿活动。与周围地质体的时间、物质关系探讨表明,金成矿受火山质围岩矿源层、构造生成演化及华力西晚期碱性花岗质岩浆侵位活动三大因素控制。

The Karamaili ductile-brittle shear structural beh was formed in the middle-late Variscan time, which can be divided into two different tec- tonic deformation periods the collision extrusion period and post-collision strike-slip extension period, corresponding to four major evolutionary stages of thrust nappe, left-lateral strike-slip, right-lateral strike-slip and extension. Gold mineralization occurred in thrust nappe type ductile shear zone of the col- lision period, and metallogenesis occurred in the late post-collision period, C2-P（290 ~ 260Ma） , belonging to right-lateral strike-slip and extensional de- formation stage. The tectonic deformation control on gold mineralization in space is expressed by geological discontinuity between the ductile-brittle and brittle deformation in the shallow subsurface and ductile deformation at depth. The gold mineralization kept up with the ductile-brittle and brittle deforma- tion and had a significant superposition relationship with the ductile deformation. Ductile-brittle and brittle structure controlled ore body unified in the right-lateral strike-slip shear and extensional system, with different deformation levels, deformation characteristics and mineralization characteristics. Su- perposition relationships between tectonic deformation and gold mineralization in space have two mineralization time response and multi-stage metallogenic records, which showed superimposed and complex mineralization in time successively, spatial superposition and material various sources. The compres- sion-extension conversion process of regional tectonic background was the formation mechanism of ductile-brittle deformation conversion and gold minerali- zation. Geodynamic background of mineralization contains thrust-nappe type ductile deformation in the collision orogenic stage, right-lateral strike-slip type ductile-brittle deformation and gold initial mineralization in collision orogenic compression-extension conversion s^age, brittle deformation and main gold mineralization in extension orogenic stage. The study on the relationship between gold mineralization, time, and material around geological bodies indi- cates that the gold mineralization was jointly controlled by source beds of volcanic host rocks, tectonic deformation evolution and alkaline granitic intrusion activities in the late Variscan time.