| 南海西北部沉积盆地晚新生代沉降、沉积特征:对深部异常过程的响应 |
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| 引用本文： | 陈梅,施小斌,任自强,徐子英,刘凯,刘航.南海西北部沉积盆地晚新生代沉降、沉积特征:对深部异常过程的响应[J].地球物理学报,2019,62(2):587-603. |
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| 作者姓名： | 陈梅 施小斌 任自强 徐子英 刘凯 刘航 |
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| 作者单位： | 1.中国科学院边缘海与大洋地质重点实验室(南海海洋研究所), 广州 510301;2.中国科学院大学, 北京 100049;3.国土资源部海底矿产资源重点实验室, 广州海洋地质调查局, 广州 510075;4.中海石油(中国)有限公司湛江分公司, 广东湛江 524057 |
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| 基金项目： | 国家自然科学基金项目（41576036，41776078）和中国地质调查局项目（GZH201400202）资助. |
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| 摘 要： | 南海西北部雷琼区域出露大量晚新生代碱性玄武岩,且地震层析成像结果显示其地幔存在类似地幔热柱特征的低速异常体.为了揭示该异常体的活动信息及其对表层地质过程的影响,本文选择位于雷琼区域的北部湾盆地和珠三坳陷为研究对象,系统分析了它们早中新世以来的构造沉降、与基底隆升有关的剥蚀面和岩浆活动特征.结果显示,研究区晚中新世构造沉降速率表现为低速异常;晚中新世以来,研究区发育了2个因基底隆升形成的局部剥蚀面,剥蚀范围大致以雷琼火山区为中心呈环状分布,中心区域剥蚀量较大,累积厚度100～200m;中中新世后研究区部分区域因岩浆活动导致上覆地层隆起和沉积环境变化.分析表明雷琼地区深部低速异常体对表层升降影响有限,推测该深部异常体规模较小,可能是深部更大规模异常体的一个分支.
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| 关 键 词： | 雷琼低速异常体 构造沉降 剥蚀面特征 北部湾盆地 珠三坳陷 |
| 收稿时间： | 2018-04-25 |
Late Cenozoic subsidence and sedimentary features of the basins in the northwestern South China Sea: implications for the development of the deep anomalous progress |
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| CHEN Mei,SHI XiaoBin,REN ZiQiang,XU ZiYing,LIU Kai,LIU Hang.Late Cenozoic subsidence and sedimentary features of the basins in the northwestern South China Sea: implications for the development of the deep anomalous progress[J].Chinese Journal of Geophysics,2019,62(2):587-603. |
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| Authors: | CHEN Mei SHI XiaoBin REN ZiQiang XU ZiYing LIU Kai LIU Hang |
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| Institution: | 1.CAS Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Guangzhou 510301, China;2.University of Chinese Academy of Sciences, Beijing 100049, China;3.Guangzhou Marine Geological Survey, MLR Key Laboratory of Marine Mineral Resources, Guangzhou 510075, China;4.Zhanjiang Branch of CNOOC Ltd., Zhanjiang Guangdong 524057, China |
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| Abstract: | A large amount of alkaline basalts developed in the Leiqiong area, northwestern South China Sea during the Late Cenozoic. Seismic tomography shows that just below the Leiqiong region, there is a mantle plume-like low-velocity thermal anomalous structure (LVA). In order to reveal the LVA's activity and effect on surface processes, we have systematically analyzed the Late Cenozoic subsidence history, erosion surfaces and magma activity of the Zhu Ⅲ depression and the Beibuwan Basin. The results show that tectonic subsidence in these basins slow down abnormally in the Late Miocene. Furthermore, since the Late Miocene two erosion surfaces (T1 and T0) have been developed due to local basement uplift events. The T1 and T0 erosion surfaces distributed annularly around the Leiqiong volcanic region, and the accumulated erosion thickness in interior is larger, ranging from 100 to 200 m. In addition, since the end of Middle Miocene, local magmatism leaded to arching of overlying strata and sedimentary environment changing. Our analysis show that the observed LVA has limited effect on superficial vertical motion. We speculate that the LVA is small in scale, and might be just a branch of deep much larger low-velocity abnormal structure. |
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| Keywords: | Leiqiong low-velocity anomalous structure Tectonic subsidence Erosion surface feature Beibuwan Basin Zhu Ⅲ Depression |
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