| 南海海岛海山的重磁响应特征 |
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| 引用本文： | 陈洁,朱本铎,温宁,万荣胜.南海海岛海山的重磁响应特征[J].地球物理学报,2012,55(9):3152-3162. |
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| 作者姓名： | 陈洁 朱本铎 温宁 万荣胜 |
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| 作者单位： | 广州海洋地质调查局, 广州 510760 |
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| 基金项目： | 国家高技术研究发展计划海洋技术领域国家重大项目 |
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| 摘 要： | 南海的海岛、海山等地貌单元的地球物理研究对于南海成因、海岛利用、资源问题和我国海防建设均具有重要意义.过去我国的南海海洋实际测量资料覆盖面小,且多数为测线调查,海底地形测量精度和重磁等测量精度较低,因此,一直无法得到精度较高的研究成果.本文利用半个多世纪我国在南海历年的多波束、重力、磁力等船载海洋实际地球物理调查资料,加上少数卫星、航空测量成果,得到能够覆盖南海全部海域的多波束、重力、磁力实际测量的地球物理基础数据.追溯南海周边的地磁台站与当年调查时间匹配的日变数据,重新校正历年磁力测量成果,并利用"十一五"863国家海洋高科技计划的处理、拼合技术,获得了南海海底地形、重力、磁力三方互为印证的可靠地球物理成果,为海岛海山的地球物理研究奠定基础.研究发现,南海海岛海山按其地球物理性质并结合现有的岩石物性资料,可以分为三大类:1)南海大部分海岛海山为空间重力异常值高、正磁力ΔZ⊥异常值也高的高密度高磁性的双高海山,以基性喷出岩(玄武岩)为主;2)空间重力异常值高、磁力ΔZ⊥异常值低的海山,以花岗岩、变质岩为主;3)空间重力异常值高、部分磁力ΔZ⊥异常值高部分低的海山,可能是花岗岩、变质岩海山的部分区域出现火山喷发形成的. 海山的分布有规律,与南海的成因与南海块体的分异状态有关.
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| 关 键 词： | 南海海底地形 空间重力异常 磁力ΔZ⊥异常值 基性喷出岩海山 花岗岩、变质岩海山 |
| 收稿时间： | 2012-04-06 |
Gravity-magnetic response of the islands and seamounts of South China Sea |
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| CHEN Jie
,
ZHU Ben-Duo
,
WEN Ning
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WAN Rong-Sheng.Gravity-magnetic response of the islands and seamounts of South China Sea[J].Chinese Journal of Geophysics,2012,55(9):3152-3162. |
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| Authors: | CHEN Jie ZHU Ben-Duo WEN Ning WAN Rong-Sheng |
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| Institution: | Guangzhou Marine Geological Survey, Guangzhou 510760, China |
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| Abstract: | The geophysical research of seamounts and islands and other geomorphologic units of South China Sea (SCS) is of particular significance for revealing the geologic history of SCS, utilizing islands properly, solving the problem of resources shortness, constructing coastal defense and so on. But in the past, the number of lines of geophysical survey was not adequate to cover the whole SCS, and quality of these geophysical data was not as high as today because of technological limit. In recent years, new data of multibeam, gravity, magnetic and other marine geophysics with higher quality are surveyed and the lines of geophysical survey are dense around SCS. In this paper, new geophysical data of SCS by ship-survey, satellite-survey and aerial-survey from these years are integrated in order to reveal more reliable geophysical background of SCS. Here, diurnal variation data of onshore geomagnetic stations are used to calibrate the magnetic survey data in SCS. And new processing technology which has been tested in National High Technology Research and Development Program ("863" Program in China) is also adopted during our work. In our study, new result has been obtained for islands and seamounts from their geophysical and lithological data. That is, islands and seamounts can be divided into three kinds according to their different geophysical features and lithological properties: 1) The islands and seamounts which have high value of gravity anomaly, ΔZ⊥ magnetic anomaly, density and magnetism are mainly composed of basic extrusive rocks (mainly basalt); 2) The islands and seamounts which have high value of gravity anomaly and low value of ΔZ⊥ magnetic anomaly are basically composed of granite and metamorphic rocks; 3) The islands and seamounts which have high value of gravity anomaly and fluctuating value of ΔZ⊥ magnetic anomaly which means somewhere has high value but somewhere has low value are composed of granite, metamorphic rocks mixed with volcanic eruption rock. The regular distribution of seamounts in SCS indicates that the formation of SCS is probably related to differentiation of blocks of SCS. This is the first research achievement of the comprehensive research of islands and seamounts in SCS by combining their geophysical data with lithological data. |
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| Keywords: | South China Sea seabed topography gravity anomaly ΔZ⊥ magnetic anomaly basic extrusive rock seamounts granite and metamorphic rock seamounts |
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