| 南海西南次海盆基底形态特征及控制因素 |
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| 引用本文： | 丁航航,丁巍伟,方银霞.南海西南次海盆基底形态特征及控制因素[J].地学前缘,2019,26(2):222-232. |
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| 作者姓名： | 丁航航 丁巍伟 方银霞 |
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| 作者单位： | 自然资源部第二海洋研究所,浙江 杭州,310012;自然资源部海底科学重点实验室,浙江 杭州,310012 |
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| 基金项目： | 国家重点研发计划项目(2016YFC0600402)；国家海洋局“全球变化与海气相互作用”专项(GASI-GEOGE)；国家自然科学基金项目(41676027，41376066) |
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| 摘 要： | 本文解释了横穿南海西南次海盆的两条多道地震测线，对南海西南次海盆的基底形态特征进行了描述和分类，并讨论了基底形态与扩张速率之间的对应关系。研究结果表明，西南次海盆基底可以分为两种类型：类型1为岩浆作用主导的平坦基底，局部有岩浆侵入；类型2为构造作用主导的掀斜断块。扩张速率的计算表明：N3测线所代表的西南次海盆北东段的半扩张速率在13~36 mm/a之间周期性变化，而在NH973-1所代表的中段半扩张速率基本稳定在19 mm/a左右，未有明显变化。海盆基底的类型变化与扩张速率的对应关系明显，在扩张速率较快的区域以类型1为主，而在扩张速率慢的区域以类型2为主。西南次海盆北东段扩张速率呈现周期性变化，相应海盆基底也表现为相间排列；而西南次海盆中段的基底比较单一，以类型2为主。南海西南次海盆北东段扩张时间更久，并可能存在周期性活动的岩浆房；而海盆中段海底扩张发生较晚，岩浆作用较弱，从而造成西南次海盆从北东到南西不同的基底形态特征。
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| 关 键 词： | 西南次海盆 基底类型 扩张速率 岩浆-非岩浆过程 南海 |
| 收稿时间： | 2018-05-14 |
Morphological characteristics and control factors of oceanic basement in the Southwest Sub-Basin,South China Sea |
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| DING Hanghang,DING Weiwei,FANG Yinxia.Morphological characteristics and control factors of oceanic basement in the Southwest Sub-Basin,South China Sea[J].Earth Science Frontiers,2019,26(2):222-232. |
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| Authors: | DING Hanghang DING Weiwei FANG Yinxia |
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| Abstract: | We interpreted two multi-channel seismic profiles across the Southwest Sub-Basin (SWSB) of the South China Sea to clarify the oceanic basement types based on the regional morphological and structural features. We calculated half-spreading rates in different areas and analyzed their relationship with the basement types. Our geological interpretations recognized two typical types of the oceanic basement: type Ⅰ represents flat basement influenced by localized volcanic eruptions; and type Ⅱ features rotated blocks controlled by normal faulting. The calculated spreading rates showed that the half-spreading rate in the northeastern SWSB, represented by seismic profile N3, was between 13 and 36 mm/a; whereas in the middle SWSB, represented by the seismic profile NH973-1, the rate was largely stable at about 19 mm/a. The correlation between basement type and half-spreading rate is clear: typeⅠbasement corresponds to higher spreading rate and type II to lower spreading rate. The spreading rate in the northeastern SWSB varies periodically, following the inter-phase distribution pattern of the two basement types. The middle SWSB is dominated by type Ⅱ basement with a stable spreading rate. We suggest that the longer spreading history and higher magma budget in the northeastern SWSB may be the controlling factors for the complex basement morphology in this area. |
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| Keywords: | Southwest Sub-Basin oceanic basement type spreading rate magmatic-amagmatic process South China Sea |
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