| 中条山铜矿峪变质火山岩的时代、构造背景及对成矿的制约 |
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| 引用本文：杨崇辉,杜利林,任留东,宋会侠,耿元生,王彦斌,路增龙,王昊,李有核.2015.中条山铜矿峪变质火山岩的时代、构造背景及对成矿的制约[J].地球学报,36(5):613-633. |
| DOI：10.3975/cagsb.2015.05.10 |
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| 基金项目:中国地质调查局地质调查项目(编号: 12120114021501; 1212010811033);科技部基础性工作专项(编号: 2015FY310100);国家自然科学基金(编号: 41172171; 41203025);全国地层委员会项目(编号: 1212011120142) |
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| 中文摘要:中条山绛县群变质火山岩是铜矿峪铜矿的赋矿岩石, 其形成的年龄期次还没有很好的限定, 构造背景还存在很大的争议。本文确定了变质石英斑岩的形成年龄为(2179±7) Ma, 变质酸性火山岩的形成年龄为(2142±11) Ma, 建议重新划分铜矿峪变质火山岩的层序, 自下而上分别为变质石英斑岩(骆驼峰组)、变质基性火山岩(西井沟组)和变质酸性火山岩(竖井沟组)。其中铜矿峪铜矿主要赋存于骆驼峰组变质石英斑岩中。变质石英斑岩具有后碰撞花岗岩的特征, 形成于由挤压向伸展转变的环境, 其εNd(t)值为–2.21 ~ –2.15, 两阶段Nd模式年龄TDM2为2.75~2.79 Ga。变质酸性火山岩具有A2型花岗岩的特征, 其εNd(t)值为–1.59~ –0.94, 两阶段Nd模式年龄TDM2为2.63~2.69 Ga, 与变质石英斑岩一样都是由老地壳再造而来。变质基性火山岩富集LREE、LIL及HFS等元素, 具有Nb、Ta的负异常, 无明显的Ti负异常, 部分样品具有Zr、Hf的正异常, 具有受陆壳混染的大陆玄武岩特征, 形成于伸展的构造背景。推测中条山—吕梁山在古元古代可能为华北克拉通古陆块的边缘, 具有从造山到造山后伸展的复杂演化过程。铜矿峪斑岩型铜矿形成于陆块边缘由挤压转变到伸展的构造背景。 |
| 中文关键词:中条山 铜矿峪 绛县群 古元古代 构造背景 |
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| The Age and Tectonic Setting of Metavolcanic Rocks in the Tongkuangyu Deposit, Zhongtiao Mountain, and Their Constraints on Copper Mineralization |
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| Abstract:The formation time and tectonic setting of metavolcanic rocks of the Jiangxian Group in the Tongkuangyu copper ore district of the Zhongtiao Mountain remain controversial. SHRIMP zircon U-Pb dating reveals that the formation ages of the metamorphic quartz porphyry and metamorphic acidic volcanic rocks are (2179±7) Ma and (2142±11) Ma, respectively. The authors redivided the sequence of the metavolcanic rocks of the Jiangxian Group, in ascending order, into metamorphic quartz porphyrys (the Luotuofeng Formation), metamorphic mafic volcanics (the Xijinggou Formation) and metamorphic acidic volcanic rocks (the Shujinggou Formation). With post-collision granite features, the metamorphic quartz porphyry was formed in a tectonic setting from compression to extension between 2.18 Ga and 2.14 Ga. Nd isotopic analyses show that εNd(t) values of the metamorphic quartz porphyry range from –2.21 to –2.15, and the corresponding two stage model ages TDM2 are mainly between 2.75 Ga and 2.79 Ga. The metamorphic acidic volcanic rocks are of A2 type granite features, with εNd(t) values being –1.59 ~ –0.94, and two stage model ages being mainly between 2.63 Ga and 2.69 Ga. It is inferred that their magmatic origin was related to partial melting of older continental crust. The metamorphic mafic volcanic rocks are enriched in LREE, LIL and HFS elements, with Nb, Ta negative anomalies but no significant negative Ti anomalies. Some samples show Zr, Hf positive anomalies. These features are consistent with geochemical features of continental basalt, with assimilation of crust materials to various degrees in an extension tectonic setting. Zhongtiao–Lüliang Mountains might be located on the margin of the North China ancient continental block and underwent complicated geological evolution from orogeny to post-orogenic extension in the Paleoproterozoic period. The Tongkuangyu porphyry copper deposit was formed on the margin of the land mass in the conversional stage from compression to extension. |
| keywords:Zhongtiao Mountain Tongkuangyu Jiangxian Group Paleoproterozoic tectonic setting |
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