| 刘晓瑜,冯秀丽,陈义兰,唐秋华,刘乐军,路波,焦鹏飞.北黄海海底麻坑群形态的定量研究及控制因素[J].海洋学报,2018,40(3):36-49 |
| 北黄海海底麻坑群形态的定量研究及控制因素 |
| Quantitative study of morphological features and control factors of seabed pockmarks in the North Yellow Sea |
| 投稿时间：2017-05-05 |
| DOI：10.3969/j.issn.0253-4193.2018.03.004 |
| 中文关键词: 海底麻坑 地形地貌 形态学 北黄海 多波束 |
| 英文关键词:pockmark landform morphology the North Yellow Sea multibeam |
| 基金项目:中央级公益性科研院所基本科研业务费专项资金（2015G15）；国家自然科学基金资助项目（41506069，40706038）。 |
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| 中文摘要: |
| 本文基于高分辨率多波束水深数据和反向散射强度数据，对北黄海海底麻坑群的形态参数进行定量研究，结合水深、地形坡度和后向散射强度的变化准确界定了麻坑的轮廓，识别出圆形、椭圆形、拉长型麻坑共282个，并在ArcGIS软件中对其形态参数进行了分析计算，麻坑的平均长轴1.36 km，短轴0.78 km，直径0.94 km，面积0.88 km2，平均周长3.82 km，长宽比1.83，深度0.3~2.5 m，平均面积密集度13%，麻坑的剖面形态有麻坑边缘凹陷、中部有明显凸起（W1型），麻坑边缘凹陷、中部略凸起（W2型），麻坑中部单纯凹陷（V型），分别集中分布在麻坑群的北部、南部、西部。麻坑的平面规模大、深度小的原因与地层中形成麻坑的游离气体浓度较小有关，也可能受到了地震、海啸等外力的诱发。麻坑的长轴优势走向为ENE-WSW、NNE-SSW，底流对其形状的塑造起了较大作用，部分麻坑成串排列，形成串珠状的麻坑链，其排列方式受到海底古河道、古潟湖等沉积地层结构的控制。海底麻坑群发育区反向散射强度为-60~-71 dB，麻坑内部较麻坑外部平均高5 dB，可能为麻坑内部气体泄漏引起海底沉积物被剥蚀后残留下的粗颗粒物质或海底生物活动留下的遗迹导致的。 |
| 英文摘要: |
| Based on the high-resolution multi-beam bathymetry and backscatter intensity data, this study calculated the morphological parameters of the seabed pockmarks in the North Yellow Sea and carried out quantitative analysis. Combined with the water depth, terrain slope and the back-scattering intensity data, the outline of the seabed pockmarks were accurately defined, and 282 pockmarks were identified which have circle, elliptic, or elongated shape in the plan view. By using ArcGIS software, the morphological parameters of the pockmarks were calculated and analyzed, the average long axis and short axis were 1.36 km and 0.78 km respectively, the average diameter were 0.94 km, average area and the average circumference were 0.88 km2 and 3.82 km, the pockmarks also have a aspect ratio of 1.83, average relief of 0.3 m to 2.5 m, and the average area concentration 13%, profile shapes of the pockmarks have W1, W2 and V type three categories, distributed in the north, south, and west of the pockmark group respectively. The large plane size but small vertical scale may be associated with the low concentration of the fluid, the external forces such as earthquake, tsunami or storm may also induced the formation as a trigger. The orientation of the major axis of the pockmarks aligned around ENE-WSW, NNE-SSW direction, consistent with the main direction of the bottom current in the study area. Some pockmarks string arranged along the same direction as the long axis, which shows that the development of the pockmarks may be controlled by the sedimentary strata as ancient river, or ancient lagoon etc. Acoustic backscatter strength of the area ranges from -60 dB to -71 dB, the data inside the pockmarks significantly higher than that of the outside, the average difference up to 5 dB, the high backscatter strength may attribute to the coarse sediments that left inside the pockmark due to winnowing of fine-grained sediments, or result of the precipitation of diagenitic or authigenic minerals associated with fluid venting. |
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