长江中下游金牛盆地花岗斑岩和流纹斑岩的锆石U-Pb年龄、Hf同位素组成及其地质意义  

Zircon U-Pb dating and Hf isotopic compositions of granite porphyry and rhyolite porphyry from Jingniu basin in the Middle-Lower Yangtze River Belt and its geological significance

作　　者：李瑞玲[1] 朱乔乔[2] 侯可军[2,3] 谢桂青[2,3] 

机构地区：[1]中国地质调查局发展研究中心,北京100037 [2]中国地质科学院矿产资源研究所,北京100037 [3]国土资源部成矿作用与资源评价重点实验室,北京100037

出　　处：《岩石学报》2012年第10期3347-3360,共14页Acta Petrologica Sinica

基　　金：国家自然科学面上基金(40972054);中央级公益性科研院所基本科研业务费专项资金(K1203)联合资助

摘　　要：金牛盆地位于鄂东南矿集区,是长江中下游成矿带重要的火山岩盆地之一。相对宁芜和庐枞盆地,金牛盆地找矿一直没有取得重大突破,对其中次火山岩的年代学、成因和成矿属性的研究也很少。本次选择盆地中心吴佰浩地区深部钻孔中的花岗斑岩和流纹斑岩,开展锆石U-Pb年龄和Hf同位素的研究工作,获得了流纹斑岩锆石206Pb/238U的加权平均年龄为128±1Ma(n=14,MSWD=2.5),锆石Hf同位素(176Hf/177Hf)i和εHf(t)分别为0.28247～0.28262和-2.5～-7.7;花岗斑岩锆石206Pb/238U的加权平均年龄为129±1Ma(n=12,MSWD=1.3),锆石Hf同位素(176Hf/177Hf)i和εHf(t)分别为0.28239～0.28259和-3.6～-10.7。本文确定金牛盆地中流纹斑岩和花岗斑岩的形成时代为129～128Ma,与金牛盆地火山岩的形成时代(130～125Ma)相当,暗示金牛盆地火山岩和次火山岩均形成于早白垩世,流纹斑岩和花岗斑岩是壳幔混合的产物。金牛盆地火山岩的形成时代与宁芜、、庐枞盆地相当,次火山岩的形成时代也与宁芜、庐枞盆地玢岩铁矿的成矿岩体相当。提出金牛盆地除应关注玢岩铁矿外,更应该关注与次火山岩有关的热液金矿。The Jinniu basin located in Southeast Hubei ore cluster, is one of volcanic basins of the Middle-Lower Yangtze Reaches metallogenic belt. Compared with Nanjing-Wuhu basin and Lujing-Zongyang basin, new mineral deposits have not been discovered in the Jinniu basin in recent years. To date, no geochronological or geochemical studies have been undertaken to sub-volcanic rocks in the Jinniu basin. The zircon U-Pb dating of rhyolite porphyry yielded an age of 128 ± 1Ma in central of the Wubaihao area from Jinniu basin, its（ 176Hf/177 Hf） i and εHf（t） values are ranging from 0. 28247 to 0. 28262 and -2. 5 to -7.7, respectively. The zircon U-Pb dating of granite porphyry yielded an age of 129 ± 1Ma, its （376Hf/177Hf）i and εHf（t） values are ranging from O. 28239 to 0. 28259 and - 3.6 to - 10. 7. The ages of granite porphyry and rhyolite porphyry are 129 ～ 128Ma, suggesting that they were developed during Early Cretaceous. The granite porphyry and rhyolite porphyry from Jingniu basin are derived from mixture enriched mantle and crustal. Both volcanic rocks and sub-volcanic rocks in the Jinniu basin were coeval with those in the Luzong, and Ningwu basins in the Middle-Lower Yangtze River Belt. The hydrothermal gold deposits and porphyry iron deposits have been played attention in the Jinniu Basin in the future.

关 键 词：次火山岩 成岩时代 找矿方向 金牛盆地 长江中下游 

分 类 号：P588.13[天文地球—岩石学] P597.3[天文地球—地质学]