| 长江中下游铜陵矿集区深部地壳结构——来自宽频地震P波接收函数成像的证据 |
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| 引用本文：赵荣涛,刘沙沙,杨艳,黄什,郑凯,史大年.2024.长江中下游铜陵矿集区深部地壳结构——来自宽频地震P波接收函数成像的证据[J].地球学报,45(6):965-976. |
| DOI：10.3975/cagsb.2023.121202 |
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| 基金项目:中国地质调查局地质调查项目“地质调查科技创新发展与新技术推广研究”(编号: DD20221829)；“羌塘盆地油气资源调查评价与战略选区”(编号: DD20233002)；“全国油气重点调查区战略性矿产调查评价”(编号: DD20233001) |
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| 中文摘要:铜陵矿集区位于长江中下游成矿带中部, 自中生代以来经历了大规模构造变形和岩浆活动。矿集区地壳结构对于认识华南—华北板块的碰撞过程, 以及长江中下游成矿带乃至整个华南中生代成矿的动力学过程都具有重要意义。本文利用26个宽频地震台站记录的49个远震事件, 通过P波接收函数成像方法获取了长江中下游成矿带铜陵矿集区的地壳结构。结果显示, 地壳浅部存在一个深度2~3 km的速度不连续界面, 可能是浅部盖层与基底之间的分界面。在铜陵南部的蛤蟆岭地区, 该界面向永村桥背斜两翼有加深趋势。铜陵地区Moho面深度约为29~32 km, 横向略有变化, 且有一定厚度, 表明Moho面可能是速度逐渐增加的“过渡带”。地壳平均纵横波速比约为1.79, 相对较高, 说明该地区地壳基性成分较高。该区较薄的地壳厚度和较高的波速比, 表明铜陵地区经历过地壳减薄和底侵过程。我们认为长江中下游中生代大规模岩浆作用可能与上地幔物质上涌并底侵到下地壳的过程有关。 |
| 中文关键词:铜陵矿集区 地壳结构 P波接收函数 波速比 底侵作用 |
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| Deep Crustal Structure of the Tongling Ore Concentration Area in the Middle-lower Reaches of the Yangtze River: Evidence from Teleseismic P-wave Receiver Functions |
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| Abstract:The Tongling Ore Concentration Area, located in the central part of the mineralization belt in the middle and lower reaches of the Yangtze River, has experienced large-scale tectonic deformation and magmatic activity since the Mesozoic. Its crustal structure is of great significance in understanding the collision process of the South-North China blocks as well as the dynamics of Mesozoic mineralization in the middle and lower reaches of the Yangtze River and throughout South China. In this study, the crustal structure of the Tongling Ore Concentration Area in the middle and lower reaches of the Yangtze River was investigated using P-wave receiver function imaging of 49 teleseismic events recorded at 26 broadband seismic stations. The results showed that a velocity discontinuity with a depth of approximately 2–3 km exists in the shallow part of the crust, which may be the interface between the basement and overlying strata. In the Hamaling area of southern Tongling, it deepens towards the two flanks of the Yongcunqiao Anticline. The Moho depths in Tongling and its surrounding areas are about 29–32 km with weak lateral variation and certain thickness, which indicates that the Moho beneath Tongling is probably a “transition zone” but not a “sharp interface.” The average Vp/Vs ratio was approximately 1.79, which is higher than normal and suggests a more mafic crust in the region. The lower crustal thickness and higher wave velocity ratio in this region suggest that the Tongling Area may have experienced crustal thinning and basaltic underplating. Our results suggest that large-scale magmatism in the middle-lower reaches of the Yangtze River during the Mesozoic was likely associated with magmatic emplacement at the base of the crust in Tongling. |
| keywords:Tongling ore concentration area crustal structure P-wave receiver function velocity ratio underplating |
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