【作者】 张新虎；

【导师】 汤中立；

【作者基本信息】 兰州大学 ， 地质工程， 2007， 博士

【摘要】 甘肃省内具有北山、祁连山和西秦岭三个古生代碰撞型造山带，是中国地质构造最为复杂的地区之一。祁连山是中国最为重要的早古生代与海相火山岩有关的块状硫化物（VHMS）铜多金属矿床成矿带，而其北邻的龙首山则为中国元古宙最主要的岩浆铜镍硫化物（铂族金属）矿床成矿带，西秦岭是中国最主要的蚀变岩型金矿成矿区。甘肃省的古板块构造格局是在古生代生成的。早古生代初期至晚古生代末，甘肃省分属西伯利亚板块、哈萨克斯坦板块、塔里木板块、华北板块、柴达木-祁连板块和扬子板块，其古生代地质历史实际就是板块聚敛的过程。这种聚敛过程不是固定的简单的合，而是在不断运动和运移过程中的消。古秦岭、古祁连、古北山洋壳在寒武纪由于板块运移的挤压而破裂，并相对于刚性块体俯冲，或者沿活动陆缘破裂并产生不同期次的俯沖消减，俯冲线逐渐向大洋及洋盆方向移动，洋面收缩，直至大洋及洋盆消亡；同时在活动大陆边缘形成沉积-火山物质的堆积和加积，每次俯冲运动都会相应地产生一部分新生陆壳（增生地体），使陆块逐渐向外增长，最后导致不同大陆板块的最终碰撞，形成了西秦岭、祁连山、北山古生代碰撞型造山带。因此，甘肃省自新元古代以后的构造发展主要为聚敛过程，并在晚古生代末聚合形成统一大陆。后来的各个地质时期的构造运动仅仅是在原有格局的基础上，加以改造并明显地复杂化。如在中新生代受到印度板块与欧亚块板碰撞作用的波及，产生一系列挤压运动，沿原有的一些断裂构造产生区域性的隆起和沉降，形成了现今复杂的地质景观。论述了甘肃省地球物理场特征和造山带的地壳结构，探讨了地球物理场与成矿的关系。以全省的1：20万水系沉积物测量成果为基础，研究省内39种（SiO₂、Al₂O₃、Fe₂O₃、CaO、MgO、K₂O、Na₂O、P、Ti、Ba、Mn、Cu、Zn、Pb、Sr、Zr、Cr、Ni、La、V、Th、Co、Nb、Y、Ag、Cd、Li、As、Sb、Hg、W、Mo、B、Be、Bi、Sn、F、Au、U）元素（其中前七种为氧化物）在各时代地层中的分布特征。对全省地球化学场进行了归并和划分，共划出地球化学省7个，地球化学域21个，地球化学带14个，讨论了各地球化学带（省、域）的特征及其与已发现矿产的对应关系。提出了全省共划分出5个成矿域（Ⅰ级成矿区带）、8个成矿省（Ⅱ级成矿区带）、12个成矿区带（Ⅲ级成矿区带）、22个成矿亚区带（Ⅳ级成矿区带）的新见解。论证了每个Ⅳ级成矿区带内的地质成矿背景及矿化异常特征，并划分了矿田（Ⅴ级）。同时通过对省内矿床的形成时代、成矿环境、地质成矿作用及矿床“自然组合”的研究认识，基本确定了省内成矿系列序次，重点是对成矿系列类型及成矿系列、成矿亚系列进行了划分和鉴别，提出全省有11个成矿系列类型、39个成矿系列的新认识。对甘肃省内主要的金属矿产金、铜、铅锌、钨矿成矿控制因素从矿质来源、空间定位、成矿元素富集动力等方面进行了研究和总结，提出了主要金属矿产成矿的控制因素及找矿方向和远景区，论证了找矿突破的可能性。更多还原

【Abstract】 Three collision-type orogenic belts （Beishan, Qilian Mountain and West Qinling） in Palaeozoic age are present in Gansu Province, which is thus the most complicated tectonic zone in China. Studies show that Qilian Mountain is the predominant Palaeozoic massive sulfide metallogenic belt of copper polymetallic deposit associated with marine volcanics, whereas Longshoushan in the north Qilian Mountain is believed to be the most significant magmatic copper nickel sulfide （PGE） metallogenic zone. And West Qinlin is suggested to be the key area of altered gold-bearing ore.The palaeo-tectonic pattern in Gansu Province had been formed in Palaozoic. From the Early to Late Paleozoic, Gansu Province once belonged to Siberian plate, Kazakhstan plate, Tarim plate, Northern China plate, Chaidamu-Qilian plate and Yangzi plate, sedately. Actually its Palaozoic history represents the process of plate convergence, which is believed to be a dynamic movement of plate destruction, rather than a simple motion of getting together. In Cambrian, oceanic crust in Paleo-Qinling, Paleo-Qilian and Paleo-Beishan were fractured due to the compression caused by plate movement and then subducted beneath the rigid plate; or fractured along the active continental margins and subducted in different phases. In the later case, the subduction line moved gradually towards the ocean and oceanic basin. Therefore, the ocean shrinked and finally destructed, and sedimentary-volcanic accumulations and accretions were consequently formed in active continental margins. Each subduction could result in the formation of small piece of continental crust, leading to continental plates expanding and colliding to others eventually, and thus the development of Beishan, Qilian Mountain and West Qinling collision-type orogenic belts in Palaeozoic age. In conclusion, Gansu Province was largely in the process of plate convergence after Proterozoic Era into a mono-plate in the Late Palaeozoic. Tectonic activities in later phases had not changed, but altered the primary pattern into more complicated stages. For example, Gansu plot was compressed by the collision between Hindu and Eurasia plate in Middle Cenozoic, and regional uplifting and subsidence occurred along the original fractures, which contributed to the complex of the present geologic pattern.This project aims to analyze the natures of geophysical field and crustal structure of the orogenic belts in Gansu Province, and then interpret the links between geophysical field and metallization. Based on the investigated results of hydrographic deposits（scale:1:200000）, we analyzed the distributions of 39 elements （SiO₂. Al₂O₃, Fe₂O₃, CaO, MgO, K₂O, Na₂O, P, Ti, Ba, Mn, Cu, Zn, Pb, Sr, Zr, Cr, Ni, La, V, Th, Co, Nb, Y, Ag, Cd, Li, As, Sb, Hg, W, Mo, B, Be, Bi, Sn, F, Au and U, the first 7 elements were measured as oxides） in strata of different ages. Thus, we divided the geochemical field of Gansu Province into 7 geochemical provinces, 21 geochemical regions and 14 geochemical zones; Then we also discussed their characteristics and the relations with the already found ore deposits.We also proposed an original idea that Gansu Province can be divided into 5 metallogenic regions （type I）, 8 metallogenic provinces （type II）, 12 metallogenic belts （type III） and 22 sub-belts of metallizaion （type IV）. We investigated the metallogenic background and the anomalies of each sub-belt （type IV） and further partitioned metallogenic fields （type V）. According to the study of the mineralogenetic epoch, environments, geological metallogenesis and naturally grouping of ore deposits, the minerogenic series, types and sub-series in Gansu Province have been generally determined. We finally drew the conclusion that Gansu Province has 11 types of metallogenic series and 39 metallogenetic series.In addition, we also focused on the the main metallic ores, such as gold, copper, lead, zinc and tungsten ore deposits, in the aspect of the sources, the spatial distribution and enrichment of main metallic ores, suggested the possible controlling factors on metallic ore deposits, provide evidence in exploring prospects.更多还原