胶东中生代动力学演化及主要金属矿床成矿系列

胶东处于古特提斯和太平洋两大成矿域的结合部位,经历了强烈的中生代构造岩浆活动和重要金属矿床成矿作用。本文通过对中生代各期岩浆活动背景、典型矿床成因类型的分析判别,结合区域地质构造特征,总结提出胶东中生代成岩成矿动力学演化主要受扬子板块、华北板块碰撞造山作用和古太平洋板块俯冲作用影响,并可划分为晚三叠世陆陆碰撞造山期,中侏罗世被动陆缘向活动陆缘转换、地壳增生期,早白垩世早期地壳增生向垮塌转换期,早白垩世中期岩石圈大规模拆沉、壳幔强烈作用期,早白垩世晚期陆缘弧俯冲作用期,和晚白垩世早期弧后岩石圈强烈伸展期六个演化阶段,分别对应着区域~205Ma、160~155Ma、135~125Ma、125~115Ma、115~100Ma、100~90Ma等六期主要金及多金属成矿作用;形成的贵金属及有色金属矿床具有较为明显的时空分布规律,大致包括6个矿床成矿系列,分为9个亚系列和16个矿床式。自西向东,可划分出莱州西部、招远-平度、栖霞-蓬莱-福山、胶莱盆地东北缘、牟平-乳山、文登-威海、荣成等7个贵金属、有色金属成矿区(带)。区内造山型金矿仍是找矿的重点,斑岩型有色金属矿床可望取得突破,中低温热液脉型多金属矿床应受到充分重视。

Mesozoic geodynamic evolution and metallogenic series of major metal deposits in Jiaodong Peninsula, China

The Jiaodong area is located in the conjunctional site of the Paleotethys and the Pacific metallogenic domains, and experienced strong Mesozoic tectonic-magmatic activities and metallogenisis of major metal deposits. In this paper, based on a comprehensive analyses and identification on tectonic setting of major Mesozoic magmatisms and metallogenic type of typical deposits, combined with the geological and structural features in the Jiaodong area, we conclude that the geodynamic evolution of the metallogenisis is manly controlled by the collisional orogeny of the Yangtze and the North China plates as well as subduction of the Paleopacific plate, and further divide it into six periods of continental collisional orogen in Late Triassic, transformation from passive to active continental margin and crustal accretion in Middle Jurassic, transformation from crust accretion to collapse in Early Cretaceous, large-scale delamination of lithosphere and intense crust-mantle interaction in Early Cretaceous, subduction of the continental margin arc, and intense extension of post-arc lithosphere in Late Cretaceous, corresponding to six phases of gold and polymetallic metallogenisis: ~205Ma, 160~155Ma, 135~125Ma, 125~115Ma, 115~100Ma and 100~90Ma, respectively. The precious and nonferrous deposits which formed in the six periods of metallogenisis show regular spatial and temporal distribution, and roughly include six metallogenic series, nine sub-series and sixteen deposit types, which can be subdivided into seven precious and nonferrous metallogenic zones (belts) from west to east: the western Laizhou, Zhaoyuan-Pingdu, Qixia-Penglai-Fushan, the northeastern margin of the Jiaolai Basin, Muping-Rushan, Wendeng-Weihai, and Rongcheng. In general, in the Jiaodong area, orogenic gold deposits are still prospecting focal targets, and the exploration of the porphyry-type nonferrous deposits are potential to make breakthroughs. Meanwhile, we should also pay enough attention into the meso-epithermal multiple-metal deposits.