| 西沙群岛宣德环礁的精细水下地貌组合特征及其成因机制 |
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| 引用本文： | 何其江,刘刚,王雪木,郑志锋,段轲,韩孝辉,沈爱斯.西沙群岛宣德环礁的精细水下地貌组合特征及其成因机制[J].海洋学报,2021,43(8):81-92. |
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| 作者姓名： | 何其江 刘刚 王雪木 郑志锋 段轲 韩孝辉 沈爱斯 |
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| 作者单位： | 1.海南省海洋地质资源与环境重点实验室，海南 海口 570206 |
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| 基金项目： | 2019年海南省基础与应用基础研究计划（自然科学领域）高层次人才项目（2019RC350）；海南省海洋地质资源与环境重点实验室自主课题（ZZ[2020]2019256-01） |
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| 摘 要： | 海底地形地貌及类型分布特征对指示区域地质构造影响、海平面升降、海洋水动力等有重要意义。本文通过侧扫声呐、单波束测深、表层沉积物取样等方法，分析了西沙群岛宣德环礁精细水下地貌组合特征，并探讨了其成因机制。结果表明:（1）宣德环礁为残缺型环礁类型，中部为潟湖沉积，礁盘之间形成西沙洲口门、“红草门”、环礁西缺口和环礁南缺口等4处水深超过60 m的深水口门，并首次识别了西沙洲口门；（2）宣德环礁水下地貌类型可划分为3级11类地貌类型。研究区的沙波及槽沟等动力地貌单元显示，宣德环礁浅水区海底特征地貌由盛行季风和波浪场所控制，深水口门形成的潮汐通道水体为塑造宣德环礁潟湖区动力地貌的主要因素。研究区东南部向海坡存在6级水下阶地，通过对比南海珊瑚礁阶地特征，宣德环礁向海坡阶地成因很可能是全球海平面变化和地壳沉降的共同作用。
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| 关 键 词： | 侧扫声呐 水下地貌特征 分类体系 宣德环礁 |
| 收稿时间： | 2020-05-16 |
Submarine geomorphologic features and genetic mechanism in the Xuande atoll,Xisha Islands |
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| Institution: | 1.Key Laboratory of Marine Geology Resources and Environment of Hainan Province, Haikou 570206, China2.Marine Geological Survey Institute of Hainan Province, Haikou 570206, China3.HuBei Geological Survey, Wuhan 430034, China |
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| Abstract: | The submarine topographic features and distribution types of the Xuande atoll in the Xisha Islands have important indications for the influence of regional geological structure, sea level rise and fall, and ocean hydrodynamics. In order to study the submarine topography and geomorphology of the Xuande atoll, we detailed survey in the Xuande atoll of the Xisha Islands, including side scan sonar, single-beam sounding, and surface sediment sampling. The results show that: (1) Xuande atoll is a type of incomplete atoll, with lagoon deposits in the middle, and four water channels with a water depth of about 60 m had been divided, namely, the gate of the Xishazhou at the northwest of the atoll, the “Red Grass Gate” of the Nanshazhou-Yongxing, the gap on the west side of the atoll, and the gap on the south side of the atoll; (2) according to the geomorphic features, the underwater geomorphic types of the Xuande atoll are divided into 3 grades and 11 types of grades classification systems. The dynamic geomorphology units such as sand waves and grooves in the study area show that the submarine features in the shallow water area of Xuande atoll are controlled by prevailing monsoons and wave sites. The tidal channel water body formed by the deep water entrance is the main factor shaping the dynamic geomorphology of the Xuande atoll lagoon area. There are six levels of underwater terraces on the seaward slope in the southeastern part of the study area. By comparing the characteristics of the coral reef terraces in the South China Sea, the genesis of the seaward slope terraces on the Xuande atoll is likely to be a combination of global sea level changes and crustal subsidence. |
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