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陈衍景,翟明国,蒋少涌. 2009. 华北大陆边缘造山过程与成矿研究的重要进展和问题. 岩石学报, 25(11): 2695-2726
华北大陆边缘造山过程与成矿研究的重要进展和问题
作者单位
陈衍景 中国科学院广州地球化学研究所 成矿动力学重点实验室 
翟明国 中国科学院地质与地球物理研究所 
蒋少涌 南京大学地球科学系 内生金属矿床成矿机制研究国家重点实验室 
基金项目:国家973计划项目“华北大陆边缘造山过程与成矿”(2006CB403500)和国家自然科学基金项目(40730421,40425006)的资助
摘要:
      本文简要总结了国家973计划项目“华北大陆边缘造山过程与成矿”前4年取得的重要进展,包括提出了镁铁质岩石容矿的热液铜镍-贵金属矿床、浅成作用的概念,将热液成矿系统分为岩浆热液、变质热液和浅成热液三大系列; 基于一批造山型银、铅锌、铜、钼等矿床的发现或识别,将造山金矿的概念和成矿分带模式拓展为造山型矿床; 确定华北克拉通南缘和北缘均发生了印支期成矿事件,尤其是浆控高温热液型钼矿床; 发现大陆内部浆控高温热液成矿系统以富CO2、富钾、富氟为特征,不同于岛弧区同类矿床; 挤压造山带的卡林型-类卡林型金矿成矿系统也以含CO2-H2O包裹体而区别于弧后盆岭省的同类成矿系统; 发现中央造山带和中亚造山带在成矿类型、优势矿种等方面差异显著,缘于它们分别经历了弱增生-强碰撞和强增生-弱碰撞的造山作用; 确定华北陆块及其陆缘造山带东部在燕山期大规模成矿,自西向东成矿年龄梯级变新,优势成矿类型和矿种不同,缘于太平洋板块作用叠合于造山带自身的演化; 发现碰撞前的热液成矿系统均或多或少地遭受改造,甚至活化、再就位成另类矿床; 在秦岭造山带新发现了1.9Ga和1.75Ga浆控热液钼矿床以及430Ma的造山型银金钼矿床,在兴蒙造山带新发现了泥盆纪造山型铜金矿床,据此预测了前中生代矿床的找矿潜力; 提出矿床是地球动力学研究的探针,厘定秦岭-大别-苏鲁造山带在120Ma之后的隆升剥蚀幅度总体小于10km,平均每年0.04mm,快速隆升剥蚀只能发生在130Ma之前; 初步厘定古亚洲洋沿索伦-延吉缝合带自西向东闭合于260~250Ma,古特提斯洋北支最终闭合于220Ma; 揭示华北克拉通对于Kenor、Columbia、Rodinia、Gondwana和Pangea超大陆事件均有响应,发现了拉马甘迪(Lomagundi)事件的碳同位素正向漂移现象,确定孔兹岩系主要形成于2.3Ga以后。提出急需加强研究的重要科学问题是大陆碰撞造山事件的起止时限和标志,前中生代成矿系统的识别和预测,燕山期大规模成矿的区域规律性和差异性,构造域叠合-转化过程的细节和机理。
英文摘要:
      The significant achievements in past four-year study of Orogenesis and Metallogenesis Surronding the North China Continent, which is a huge project granted by the National 973-Program, are briefly summarized in this paper. The concepts of ultramafic-mafic rock-hosted hydrothermal Cu-Ni-precious metals deposit and epizonogenism are defined; and consequently, the hydrothermal ore-systems can be classified into three series, i.e. magmatic, metamorphic and epizonogenic. On the basis of discovery and identification of numerous orogenic-type Ag, Pb-Zn, Cu and Mo deposits in the interest area, a new term of orogenic-type deposits and a new element zoning model for orogenic-type ore-system have been introduced to renew the concept of orogenic-type gold and its crustal continuum model, respectively. Indosinian mineralizations, especially intrusion-related hypothermal Mo mineralization, were determined to have occurred in both southern and northern margins of the North China continent. Intra-continental intrusion-related hypothermal ore-systems are rich in CO2, K and F, which differ from those developed in island arcs. The Carlin-type and Carlin-like gold deposits in compressive orogenic areas usually contain CO2-H2O fluid inclusions which cannot be observed the same kind ore-systems developed in back-arc Basin-and-Range provinces. The Central Asian and Central China orogenic belts have been from strongly continental accretion and weakly continental collision and weakly continental accretion and strongly continental collision, respectively, which leads them to have quite different type ore-systems and metallic commodities. The eastern portions of the North China continent and its adjacent orogenic belts accommodate large-scale Yanshanian mineralization gradiently younging eastward, with differing genetic types and metal inventories, which possibly resulted from their tectonic evolution combined with interaction with Pacific plate. Pre-collision hydrothermal ore-systems were reworked more or less, of which some re-mobilized and re-emplaced as other genetic types of ore deposits. Intrusion-related hypothermal Mo mineralizations of ca 1.9 Ga and 1.75 Ga and orogenic type Ag-Au-Mo mineralization of ca 430 Ma were recently discovered in Qinling Mountains, whilst the Mongolia-Hinggan Mountains were reported to have Devonian orogenic Cu-Au lodes, indicating the exploration potential for pre-Mesozoic ore deposits. Ore-system is evidenced to be an ideal probe to geodynamics, and by this way the post-120Ma erosion total of Qinling-Dabie-SuLu orogen is estimated less than 10 km with an average rate of 0.04 mm per year, suggesting that the rapid uplift must occur before 130 Ma if there is. It is constrained that the Paleo-Asian Ocean closed from west to east along the Solonker-Yanji geosuture during the period of from 260 to 250 Ma; while the northern branch of the Paleo-Tethys Ocean was finally closed at ca 220 Ma. The North China craton is revealed to have been involved in supercontinent cycles including Kenor, Columbia, Rodinia, Gondwana and Pangea, as well as the Lomagundi Event which is characterized by positive δ13Ccarb excursion; and deposition of the khondalite series in North China craton was dated to be <2.3 Ga. Suggested key open issues include: duration and geologic marker of onset and end of continental collision orogenesis; identification and targeting of pre-Mesozoic ore-systems; regional regularities and differences of Yanshanian large-scale mineralizations; and detailed process and mechanism of transition and/or combination of tectonic domains or regimes.
关键词:华北克拉通  中亚造山带  中央造山带  成矿作用  造山作用
投稿时间:2009-10-10  修订日期:2009-11-12
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