| 胶东地区晚中生代伸展构造与金成矿:短周期密集台阵背景噪声成像的启示 |
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| 引用本文： | 俞贵平,徐涛,刘俊彤,艾印双.胶东地区晚中生代伸展构造与金成矿:短周期密集台阵背景噪声成像的启示[J].地球物理学报,2020,63(5):1878-1893. |
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| 作者姓名： | 俞贵平 徐涛 刘俊彤 艾印双 |
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| 作者单位： | 1. 中国科学院地质与地球物理研究所, 岩石圈演化国家重点实验室, 北京 100029;2. 中国科学院地质与地球物理研究所, 中国科学院地球与行星物理重点实验室, 北京 100029;3. 中国科学院大学, 北京 100049;4. 中国科学院青藏高原地球科学卓越创新中心, 北京 100101 |
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| 基金项目： | 国家重点研发计划项目（2016YFC0600101）和国家自然科学基金（41522401，41474068）联合资助. |
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| 摘 要： | 晚中生代以来,华北克拉通东部经历了以岩石圈减薄作用为主要特征的大规模岩石圈破坏.在此背景下,位于华北克拉通东部的胶东地区形成了大规模的伸展构造、广泛发育的花岗岩类侵入体和巨量的金矿化.为揭示胶东地区控矿构造在上地壳层次的发育特征及其与金成矿之间的联系,本文基于跨胶东半岛的NWW-SEE向短周期密集地震台阵剖面,开展了背景噪声成像研究,获得了胶东地区8km以浅的上地壳S波速度结构,其主要特征为:(1)胶东地区沉积层较薄,基底平均深度为1～2km左右;(2)垂向速度梯度显示胶西北基底/浅层高速间断面错断特征显著,与主要拆离断层对应关系良好,且相对速度扰动显示沿主要拆离断层发育SE倾向的条带状低速异常;(3)牟乳成矿带下方S波速度具有横向分块特征,与五莲—烟台等控矿断裂的陡倾特征吻合,且东部苏鲁造山带上地壳平均速度较胶西北地区明显偏高.综合本文成像结果及已有地质、地球物理资料,我们认为胶西北成矿带的控矿构造深部以大规模拆离断层为主要特征,而东部牟乳成矿带则以高角度的脆性(走滑)断裂为主,故控矿断裂构造的差异可能是胶东成矿区域性差异的主要控制因素.
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| 关 键 词： | 胶东地区 金成矿作用 伸展构造 短周期密集地震台阵 背景噪声成像 |
| 收稿时间： | 2019-12-16 |
Late Mesozoic extensional structures and gold mineralization in Jiaodong Peninsula,eastern North China Craton: an inspiration from ambient noise tomography on data from a dense seismic array |
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| YU GuiPing,XU Tao,LIU JunTong,AI YinShuang.Late Mesozoic extensional structures and gold mineralization in Jiaodong Peninsula,eastern North China Craton: an inspiration from ambient noise tomography on data from a dense seismic array[J].Chinese Journal of Geophysics,2020,63(5):1878-1893. |
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| Authors: | YU GuiPing XU Tao LIU JunTong AI YinShuang |
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| Affiliation: | 1. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;2. Key Laboratory of Earth and Planetary Physics, Chinese Academy of Sciences, Beijing 100029, China;3. University of Chinese Academy of Science, Beijing 100049, China;4. CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China |
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| Abstract: | Research suggests that since the late Mesozoic, the eastern North China Craton has experienced large-scale lithospheric destruction characterized by lithospheric thinning. Under this context, large-scale extensional structures, widespread granitoid intrusions and massive gold deposits have been formed in Jiaodong Peninsula in the eastern North China Craton. In order to reveal the characteristics of ore-controlling structures in upper crust and their genetic linkage with gold mineralization, we probe the fine S-wave velocity structure of the shallow crust above 8km by using ambient noise tomography from a NWW-SEE trending linear short-period dense seismic array across Jiaodong Peninsula. Results show that (1) the sedimentary layer in Jiaodong Peninsula is generally thin, with an average basement depth about 1~2 km. (2) The vertical velocity gradient image shows that the dislocation of basement/shallow high-velocity discontinuity in northwest Jiaodong is significant, corresponding well to the main detachment faults, and the relative velocity disturbance image exhibits several banding low-velocity anomalies with SE tendency along the main detachment faults. (3) The S-wave velocity under the Muru metallogenic belt has a block feature in horizontal direction, which is consistent with the steeply dipping feature of ore-controlling faults such as the Wulian-Yantai fault zone, and the average velocity of upper crust in the Sulu orogenic belt is significantly higher than that in northwest Jiaodong. Based on the imaging results of this paper and other geological and geophysical data available, we suggest that northwest Jiaodong is mainly controlled by large-scale detachment faults represented by the Zhaoping fault, while the Muru metallogenic belt in the east is mainly controlled by steep brittle (strike-slip) faults with a relatively low degree of extension. And the differences of ore-controlling structures may be the main reason for regional differences of gold mineralization in Jiaodong Peninsula. |
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| Keywords: | Jiaodong Peninsula Gold mineralization Extensional structure Short-period dense seismic array Ambient noise tomography |
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