| 洛南-卢氏地区与铁铜多金属矿床有关的中酸性侵入岩锆石U-Pb定年及其地质意义 |
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| 引用本文：胡浩,李建威,邓晓东.2011.LA-ICP-MS zircon U-Pb dating of granitoid intrusions related to iron-copper polymetallic deposits in Luonan-Lushi area of southern North China Craton and its geological implications[J].Mineral Deposits,30(6):979~1001 |
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| 基金项目:本文得到国家自然科学基金重大研究计划重点项目(No.90814004)、中央高校基本科研业务费专项资金（CUG090102）、地质过程与矿产资源国家重点实验室科技部专项经费（MSFGPMR201005）的联合资助 |
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| 中文摘要:位于华北克拉通南缘的洛南-卢氏地区出露大量与成矿密切相关的中酸性小侵入体，主要岩性包括石英闪长岩和钾长花岗斑岩，其中大部分是该区矽卡岩型和斑岩型铁-铜-钼-铅锌多金属矿床的成矿母岩，但迄今为止对这些岩体的侵位时代及岩浆活动构造背景的研究还很薄弱。文章利用激光剥蚀电感耦合等离子体质谱法对该区典型侵入岩（夜长坪、柳关、后瑶峪、圪老湾、蒲阵沟、黑山及杨沟岩体）进行了详细的锆石U-Pb定年。结果表明这些岩体的侵位时代介于158～131 Ma之间，是华北克拉通南缘晚侏罗世—早白垩世期间大规模岩浆活动的产物。定年结果还表明，闪长岩类岩石的侵位时间很短，主要集中在晚侏罗世末期〔（150±1）～（149±1） Ma〕，而花岗斑岩侵位则断续持续了近30 Ma〔（158±2）～（131±1） Ma〕。锆石U-Pb定年还首次为洛南_卢氏地区矽卡岩型和斑岩型铁铜钼多金属矿床的成矿时代提供了准确限定，表明这些矿床形成于晚侏罗世—早白垩世。综合前人资料，认为华北克拉通南缘燕山期岩浆活动始于晚侏罗世初，在早白垩世早期达到顶峰，并于早白垩世末期结束。华北克拉通南缘洛南-卢氏地区晚侏罗世—早白垩世中酸性侵入岩形成于强烈的伸展构造背景，是华北克拉通破坏的浅部地质响应，其空间分布和侵位时代为了解华北克拉通南缘岩石圈减薄的时空分布特征提供了重要依据。 |
| 中文关键词:地质学 锆石U-Pb定年 LA-ICP-MS 洛南-卢氏 华北南缘 克拉通破坏 |
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| LA-ICP-MS zircon U-Pb dating of granitoid intrusions related to iron-copper polymetallic deposits in Luonan-Lushi area of southern North China Craton and its geological implications |
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| Abstract:Granitoid intrusions, which are widely distributed in Luonan-Lushi area on the southern margin of the North China Craton, consist mostly of K-feldspar granite porphyry and quartz diorite and are closely related to lots of porphyry and skarn Fe-Cu-Mo-Pb-Zn polymetallic deposits in this area. Nevertheless, precise numerical constraints on the emplacement ages of these intrusions, which are of importance in the understanding of the tectonic setting of regional magmatism, are very insufficient. In this paper, the authors present high-precision zircon U-Pb ages of seven representative granitoid intrusions by using laser ablation inductively coupled plasma mass spectrometry. The results indicate that these intrusions were emplaced in the time interval from (158±2) Ma to (131±1) Ma (2σ)，suggesting that they are products of Late Jurassic to Early Cretaceous magmatism. The age data also show that the quartz diorites were emplaced in a short-lived magmatic pulse at the end of late Jurassic 〔(150±1) Ma～（149±1） Ma〕, whereas the K-feldspar granite porphyries were emplaced in a prolonged period between (158±2) Ma and (131±1) Ma. Zircon U-Pb ages of the granitoid intrusions also pose important constraints, for the first time, on the timing of related porphyry and skarn polymetallic deposits in Luonan-Lushi area. These results, in combination with data available, document an extensive magmatic event at the southern edge of the North China Craton that commenced in the late Jurassic, climaxed in the Early Cretaceous and continued until the end of Late Cretaceous. This magmatic event occurred in an extensional environment related to the lithospheric thinning of North China Craton. Age and distribution of the late Mesozoic intrusions in southern North China Craton have shed light on the timing and extent of the Mesozoic decratonization of North China Craton. |
| keywords:geology, zircon U-Pb dating, LA-ICP-MS, Luonan-Lushi area, North China Craton, decratonization |
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