中国东部燕山期俯冲走滑体制及其对成矿定位的控制

Yenshanian subduction and strike-sliping regime of East China,and its control of ore localization

通过中国东部 180～ 90Ma前地质构造演化与北美西部 15 5～ 0Ma间地质构造演化的对比 ,说明中国东部燕山期由活动大陆边缘向陆内过渡的构造属性 ,进一步阐明中国东部燕山期金属成矿大爆发的地球动力背景—伊泽奈歧海洋板块对欧亚大陆的低角度斜向俯冲和NNE向左行平移剪切运动。活动大陆边缘地壳缩短增厚和伸展减薄两个阶段产出有不同的岩石组合和金属成矿组合。NNE向平移剪切带切割先成断裂体系形成控矿断裂网络分级控制金属聚集的定位 :超级控矿断裂网络控制金属矿集区和大型矿床定位 ,区域一级控矿断裂网络控制大、中型及部分小型矿床定位 ,区域二级控矿断裂网络控制部分小型矿床和矿化点定位 。

Based on the geological comparison of Mesozoic continent margin (180～90Ma) of East China with Meso-Cenozoic continent margin(155～0Ma) of the western North America,the transition nature from active continental margin to continent interior of East China was identified and the combined geodynamic setting for the Yenshanian metallogeny “flare-up”of East China was discussed:low angle diagonal B-type subduction of the Izanagi plate under the Eurasia plate and NNE trending left lateral strike-slip shearing.Further the Yenshanian tectonic evolution was divided into two periods:1.crust shortening and thickening ,2.crust streatching and thinning.Generally, the crust extension favours diversified ore-forming processes, and deep-generated ore affiliated magma suites and ore deposits tend to be emplaced along the deep-seated NW trending tectonic discontinuities. In the combined geodynamic background, were formed ore controlling fault networks of four grades,which control the localization of different scale metallic accummulation.The superior ore controlling fault network controls localization of ore concentration districts and large scale ore deposits;the first grade regional ore controlling fault network controls localization of medium to large scale ore deposits and a part of small scale ore deposits;the second grade regional ore controlling fault network controls the localization of small scale ore deposits and mineralization occurrences of non-economic importance;while the local ore controlling fault network controls the localization of ore deposits within an ore concentration district or an ore field.