【作者】 郭少丰；

【导师】 汤中立； 罗照华；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2010， 博士

【摘要】 冀东地区位于河北省东北部,燕山山脉东段,是我国重要金矿富集区之一。在燕山地区,都山岩体周边分布着大量的金矿床(点),其形成时代既不同于都山岩体,也不同于其他类型的岩株和矿床,暗示金的成矿作用有其特殊性。都山岩体是一个岩基,岩基形成过程中伴随着地壳的隆升和镁铁质下地壳的产生,后者在造山带冷却以后有利于岩石圈拆沉作用,拆沉作用为后续的大规模成矿事件提供了极为有利条件。本文在前人工作的基础上,通过扎实的野外调研、先进的测试分析及大量的综合研究,取得以下主要认识和进展:(1)首次采用SHRIMP锆石U-Pb法测得唐杖子金矿的花岗斑岩株形成年龄为173±2Ma,笔者认为这也是隐爆角砾岩形成的时间及唐杖子金矿的形成时间下限。该年龄与峪耳崖岩体(174±3 Ma)、牛心山岩体(173±2Ma)在误差范围内,表明这些致矿岩体形成于中生代燕山早中期,可认为是同一岩浆活动的产物。结合前人测试结果,推断冀东地区金矿存在一个主成矿期,燕山早中期为主成矿期时间下限;(2)提出冀东地区金矿形成于一个主成矿期、一次主成矿事件、围绕一个成矿中心的观点,援引“小岩体成大矿”学说和透岩浆流体成矿体系的基本概念,将区内不同金矿类型归属为不同的金矿成矿体系(包括正岩浆成矿体系、接触带成矿体系和远程热液成矿体系),认为它们是性质类似的成矿流体在不同的地质条件下的产物;(3)首次提出了岩基“被盖效应”的概念,认为完整性好的厚板状花岗质岩基有利于屏蔽从小岩浆体逸出的含矿流体。结合对岩基形成过程中区域岩石圈结构的改变及其对后续地质过程的可能影响,提出了一个以都山岩体为代表的“岩基后成矿”模式,较为合理地解释了冀东地区金矿围绕都山岩体集中分布的原因,并可能具有普遍意义;(4)通过对峪耳崖金矿及都山岩体的讨论,本文认为峪耳崖小岩体之所以能成大矿,很可能与都山岩体这个大岩基有着成因上的联系;(5)通过对冀东地区金矿成因的探讨,本文认为冀东地区下一步找矿应以都山岩体为中心,加强都山岩体深部及各金矿之间深部联系通道的研究,争取冀东地区找矿早日取得更大突破。更多还原

【Abstract】 Located in northeast Hebei Province, and east sector of Yanshan mountain ridge, Jidong area is one of the most important gold deposits zones in China. In Yanshan terrain, a great number of gold deposits (or occurrences) have been found around Dushan complex.The metallogenic epoch of these gold deposits is different from not only that of the Dushan complex, but also other intrusions and deposits, suggesting their ore-forming particularity. As a batholith, Dushan complex occurred with the uplift of the crust and the forming of the lower mafic crust which is favorable for the delamination of the lithosphere. The detachment provided advantageous conditions for the large scale ore-forming event. Based on the previous work, field investigation, modern testing methods and a great deal of synthesized studies, new ideas and achievement were acquired as followed:1. SHRIMP U-Pb dating showed that the age of the granitic porphyry in Tangzhangzi gold ore district was 173±2Ma. This result also can be regarded as the lower age limit of cryptoexplosion breccia and the gold ore deposit. Both Yuerya (174±3 Ma) and Niuxinshan complex (173±2Ma) have the similar age, showing they were the outcome the magmatic activities in the early-middle Yanshania period in Cenozoic. A main metallogenic epoch can be inferred in Jidong area, the lower limit of which being the early-middle Yanshania period.2. The idea that gold deposits occurred in one main metallogenic epoch, one main metallogenic event, encircled in one ore-forming center, was put forward. Based on the theory of good mineralization occurred in small intrusions, different ore-forming systems, including orthomagmatic metallogenic system, contact belt system and long-distance hydrothermal system, have been identified. They were regarded as the outcome of similar ore-forming fluid in different geological conditions.3. The“laccolith effect”of batholith was brought forward firstly. The thick plank-like batholith with good integrality is helpful to shied the ore-bearing fluid bleeding from small intrusions. Combined with the alteration of the lithosphere structure during the batholith emplacement and the later geological process, the“post-batholith metallogenic model”have been put forward to make clear the distribution of the gold deposits around Dushan complex reasonably. it may have universal implication.4 The small Yueryan intrusion, which can bring on big type gold deposit, may implicate its close origin relation with Dushan complex.5. The next step ore prospecting should be focused on Dushan complex, and the study on the deep channel between the complex and gold deposits should be strengthened, so that a great breakthrough for ore exploration can be achieved in Jidong area.更多还原