青藏高原羌塘地体南缘浅成低温热液成矿系统的保存机制及其重要意义——以铁格隆南超大型矿床为例

发布时间：2018-11-16 14:39

【摘要】：由于青藏高原隆升不可避免的强烈剥蚀作用,中生代浅成低温热液矿床的形成、保存和发现就需要多种地质因素的耦合。西藏班公湖—怒江成矿带西段新发现的铁格隆南铜矿是一处隐伏、半隐伏的超大型斑岩-浅成低温热液叠加矿床。系统的地质编录发现,矿床的保存得益于成矿后美日切错组火山岩的覆盖。在矿体和火山岩之间发现了古风化壳,并识别出弱风化残积层、残积古土壤、半风化坡积物三种风化剥蚀界面,说明矿床形成以后经历了一定程度的隆升剥蚀。通过成矿系统的保存程度间接估算,118~111 Ma之间最小剥蚀厚度为600~1 200 m,区间剥蚀速率为0.1~0.2,平均0.15 mm/a。矿床形成时的地表高程可能达到2 000~2 500 m。矿床形成于班公湖—怒江洋盆闭合末期,对其剥蚀作用的研究验证了南羌塘地体在早白垩世晚期经历过一次重要的剥蚀过程,同时指示了早白垩世晚期是青藏高原隆升历史的重要时期。
[Abstract]:Due to the inevitable strong denudation of the uplift of the Qinghai-Xizang Plateau, the formation of Mesozoic epithermal hydrothermal deposits requires the coupling of various geological factors for their preservation and discovery. The newly discovered Tiegelongnan copper deposit in the western section of Bangong Lake-Nujiang metallogenic belt in Tibet is an overlying, semi-concealed super-large porphyry-epithermal superimposed deposit. The systematic geological cataloguing shows that the preservation of the deposit is due to the coverage of the volcanic rocks in the United States and Japan after mineralization. Paleo-weathering crust was found between ore body and volcanic rock, and three weathering denudation interfaces were identified, such as weak weathering residual layer, residual paleosol and semi-weathered slope deposit, indicating that the deposit experienced a certain degree of uplift and denudation after its formation. By indirectly estimating the degree of preservation of the ore-forming system, the minimum denudation thickness is 600 ~ 1 200 m between 118 ~ 111 Ma and the denudation rate is 0.1 ~ 0.2, with an average denudation rate of 0.15 mm/a.. The surface elevation at the time of formation of the deposit may reach 2 000 ~ 2 500 m. The deposit was formed at the end of the closure of Bangong Lake and Nujiang ocean basin. The study of its denudation proved that the South Qiangtang terrane experienced an important denudation process in the late early Cretaceous. It also indicates that the late early Cretaceous is an important period in the uplift history of the Qinghai-Xizang Plateau.
【作者单位】：中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点实验室;成都理工大学;
【基金】：国家自然科学基金项目(编号:41402178) 中国地质科学院基本科研业务费项目(编号:YYWF201608) 国土资源部公益性行业科研专项(编号:201511017) 中国地质调查局二级项目(编号:DD20160026)联合资助~~
【分类号】：P618.41

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