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| 安徽滁县琅琊山一带燕山期岩浆岩成因及区域找矿方向 | |
| 引用本文： | 段留安,杨晓勇,孙卫东,孙健,洪长春,胡俊杰.安徽滁县琅琊山一带燕山期岩浆岩成因及区域找矿方向[J].大地构造与成矿学,2012,36(2):259-273. |
| 作者姓名： | 段留安 杨晓勇 孙卫东 孙健 洪长春 胡俊杰 |
| 作者单位： | 1. 中国科学技术大学地球和空间科学学院,安徽合肥230026;武警黄金第七支队,山东烟台264004 2. 中国科学技术大学地球和空间科学学院,安徽合肥,230026 3. 中国科学院广州地球化学研究所矿物学与成矿学重点实验室;同位素地球化学国家重点实验室,广东广州510640 4. 安徽省地质勘查局332地质队,安徽黄山,245000 |
| 基金项目： | 中国科学院知识创新工程，国家自然科学基金重点项目，安徽省公益性地质科研项目 |
| 摘 要： | 滁县琅琊山铜矿床是长江中下游成矿带北东段滁县-庐江铜金成矿带的一部分,为安徽东部目前发现规模最大的铜及伴生金矿床。与成矿关系密切的滁县岩体,长期以来前人鲜有系统的地球化学研究,本文在野外地质调查的基础上,系统采集了一套滁县岩体样品,发现其地球化学特征与典型的埃达克岩基本一致:具有SiO2>56%,Al2O3≥15%,富Sr、Ba和Cr、Ni,具有高的Sr/Y和(La/Yb)N值,但Y和Yb含量低,无明显Eu异常,另外岩石具有较高的MgO、Mg#及Sr/La值,显示海水蚀变MORB相似的地球化学特征。分析认为,该区燕山期岩浆岩为洋壳俯冲产物,属比较典型的和成矿有关的埃达克岩,伴随着该期侵入岩的上侵,富含Cu、Au的成矿物质随着温度、压力或者氧逸度的降低,在合适的部位富集成矿。对比分析了上腰铺岩体的地球化学特征,认为它和滁县岩体特征基本一致,应该有着相似的成岩成矿背景。同时在滁县岩体西南段发现一条含微细粒黄铁矿碎裂状白云岩质硅化带,在上腰铺岩体周边发现一条多金属矿化硅质脉,并对琅琊山含铜矿化矽卡岩及上述白云岩质硅化带和多金属矿化硅质脉进行了地质分析和痕量元素测试,认为它们与燕山期侵入岩有着密切的关系,上腰铺岩体周边可以作为下步铜及伴生金矿床勘查的新的远景地区,同时指出该区找矿不能只盯着矽卡岩型铜金矿而忽视多金属矿化硅质脉新类型矿的寻找。 |
| 关 键 词： | 滁县琅琊山 燕山期岩浆岩 岩石化学特征 岩石成因 找矿方向 |
Study on the Yanshanian Intrusions in Langyashan Area of Chuxian County: Petrogenesis and Regional Ore Prospection |
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| DUAN Liuan , YANG Xiaoyong , SUN Weidong , SUN Jiang , HONG Changchun , HU Junjie.Study on the Yanshanian Intrusions in Langyashan Area of Chuxian County: Petrogenesis and Regional Ore Prospection[J].Geotectonica et Metallogenia,2012,36(2):259-273. | |
| Authors: | DUAN Liuan YANG Xiaoyong SUN Weidong SUN Jiang HONG Changchun HU Junjie |
| Institution: | 1.School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, Anhui, China; 2.The 7th Detachment of Armed Police for Gold Exploration, Yantai 264004, Shandong, China; 3.CAS Key Laboratory of Mineralogy and Metallogeny; State Key Laboratory of Geochemistry; Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, Guangdong, China; 4.No.332 Geological Team, Bureau of Geology and Mineral Exploration of Anhui Province, Huangshan 245000, Anhui, China) |
| Abstract: | The Langyashan copper deposit in Chuxian, Anhui province, is part of the Lower Reaches of the Yangtze River metallogenic belt, where the largest copper deposit associated with gold was found so far in east Anhui. There are few case studies on geochemical features of the Chuxian magmatic intrusion that closely related to the mineralization. Base on field geological survey, a suit of samples from the Chuxian magmatic intrusion and Shangyapu magmatic intrusion was analyzed. The results show that these Yanshanian intrusive rocks have geochemical characteristics similar to those of adakite, with features of SiO2>56%, high Al content (Al2O3≥15%), rich in Sr, Ba and Cr, Ni, high in Sr/Y(145~181) and (La/Yb)N≥21 ratios; with low Y(7.5~9.1 μg/g) and Yb (0.68~0.71 μg/g) contents, and no significant Eu anomalies (δEu=0.96~1.04). The high MgO contents (3.15%~3.36%), Mg#(56~66) and Sr/La(56~67), display characteristics of seawater alteration of MORB. The Yanshanian magmatic rocks in this region are the typical adakites which were derived from subducted oceanic crust, During the emplacement of the rocks, the ore-forming materials were enriched and mineralized in the suitable position. The Shangyaopu magmatic intrusion nearby has similar geochemical features, and thus, should have similar genetic and mineralization background like that of the Chuxian intrusion. Moreover, we found a pulse of silicified shattered dolomite belt with micron pyrite on the north-west side of the Chouxian magmatic body occurring as siliceous vein and polymetallic mineralization around the Shangyaopu magmatic body. Comparing the silicified belt and siliceous vein to the Langyashan copper mineralization skarn, we deduced that they are closely related to the Yanshanian intrusive rocks, the Shangyaopu magmatic body and surrounding areas can be prospective area for copper associated with gold deposit. In conclusion, the authors propose that regional ore exploration should not be limited to the present skarn-type copper-gold deposit while the new type of siliceous veins with polymetallic mineralization be ignored. |
| Keywords: | Langyashan in Chuxian Yanshannian intrusions petrochemical features petrogenesis ore prospection |
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