摘要
长江中下游是中国东部一个重要的与中生代岩浆作用有关的Cu-Au-Mo-Fe矿成矿带。近期勘查工作在庐枞矿集区东顾山地区深部首次发现了与隐伏花岗岩密切相关的钨钼多金属矿化。岩石学和岩石地球化学研究结果表明,隐伏花岗岩具有高硅富碱高钾、贫铁贫镁及铝弱饱和的特征,属于高钾钙碱性系列岩石;具有富集Rb、Th、U等强不相容元素和轻稀土元素,亏损Nb、P、Ti、Y等高场强元素,低ε_(Nd)(t)(-18.2^-17.1)和相对高的((^(87)Sr/^(86)Sr)_i)(0.70596~0.70631)的特征,推测其岩浆来源于扬子下地壳的部分熔融,岩浆在就位之前经历了一定程度的分异结晶作用。利用LA-ICP MS锆石U-Pb定年获得96.7±1.3Ma的锆石年龄,表明其属于晚白垩世早期岩浆活动的产物。结合区域成岩成矿时空格架,认为东顾山地区隐伏花岗岩及与之有关的钨钼多金属矿化可能代表了长江中下游成矿带的新一期成岩成矿事件。
The Middle and Lower Reaches of Yangtze River Metallogenic Belt is an important Cu-Au-Mo-Fe metallogenic belt in eastern China, most deposits in the belt are associated with Mesozoic magmatism. A new type of tungsten-molybdenum polymetallic deposit which is discovered in the Donggushan district, north of Luzong orefield, and it has a close relationship with the concealed granites. The petrological and geochemical studies indicated that the granitic rocks contained relatively high SiO2, Na2O and K2O, low FeO and MgO, and are nearly saturated in Al2O3, suggesting that they are high-K calc-alkaline series rocks. These granites are also characterized by enrichment of highly incompatible elements such as Rb, Th and U as well as LREE, depletion of high field strong elements such as Nb, P, Ti and Y, as well as low εNd（t） （-18.2～-17.1） and relatively high （87Sr/86Sr）i （0.70596～0.70631）. It can be concluded that their parental magmas have been derived from partial melting of Yangtze lower crust. And the magmas had been undergone fractional crystallization before their emplacements. Zircon U-Pb LA-ICP-MS dating of the granites have yielded age of 96.7±1.3Ma, indicating that the granitic intrusive rocks formed at earlier stage of Late Cretaceous. Compared with the previous geochronology data, a new diagenesis-mineralization event in the Middle and Lower Reaches of Yangtze River Metallogenic Belt was identified by the concealed granitic magmatism and tungsten-molybdenum polymetallic mineralization.
作者
张赞赞
吴明安
杜建国
张舒
张千明
陆三明
ZHANG ZanZan;WU MingAn;DU JianGuo;ZHANG Shu;ZHANG QianMing;LU SanMing(Geological Survey of Anhui Province, Hefei 230001, China;Bureau of Geology and Mineral Exploration of Anhui Province, Hefei 230001, China;No. 327 Team of Bureau of Geology and Mineral Exploration of Anhui Province, Hefei 230011, China;Public Geological Survey Management Center of Anhui Province, Hefei 230001, China)
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2018年第1期217-240,共24页
Acta Petrologica Sinica
基金
本文受中国地质调查局地质调查工作项目(1212011120862、12120114038001)资助.
关键词
花岗岩
锆石U-PB定年
岩石地球化学
长江中下游成矿带
安徽东顾山地区
Granite
Zircon U-Pb dating
Petrogeochemistry
Middle and Lower Reaches of Yangtze River Metallogenic Belt
Donggushan district, Anhui
