Tidal deposition systems of China's continental shelf, with special reference to the eastern Bohai Sea
Tidal deposition systems of China's continental shelf, with special reference to the eastern Bohai Sea
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DOI：
10.1016/s0025-3227(97)00116-3
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发表时间：
1998-03
期刊：
影响因子：
2.9
通讯作者：
Liu Zhenxia;Xia Dong-xing;S. Berné;Wang Kui-yang;T. Marsset;Tang Yuxiang;J. Bourillet
中科院分区：
文献类型：
--
作者：
Liu Zhenxia;Xia Dong-xing;S. Berné;Wang Kui-yang;T. Marsset;Tang Yuxiang;J. Bourillet
中国大陆架经历了一次大规模的海侵。潮流已成为主要的活动力，并对陆架的沉积和地貌产生了深远的影响。中国大陆架有五大现代潮沉积体系：(1)黄海东部、(2)渤海东部、(3)长江口外；(4)台湾以西；(5)琼州海峡。当潮流速度大于150cm /s时，侵蚀占主导地位，往复流形成深冲刷沟。当潮流速度为50 ~ 150 cm/s时，以沉积为主，潮流形成潮滩（即潮沙脊和潮沙片），其边缘在M2潮分量的绝对椭圆度值0.4附近。当M2绝对值小于0.4时，往复流足以形成潮沙脊。当绝对值大于0.4时，旋流增大，形成潮沙片。潮汐沉积物质主要来自晚更新世沉积物的潮汐侵蚀和局部再沉积，以及邻近的海底。渤海东部的潮汐沉积体系就是一个典型的例子。它由老铁山海峡冲刷沟、辽东浅滩沙脊和渤中浅滩沙洲组成。老铁山海峡的最大潮流速度可达250 cm/s，是侵蚀较强的通道。辽东浅滩最大潮流速度为64 ~ 115 cm/s， M2潮汐分量的绝对椭圆度值小于0.4。渤中浅滩最大潮汐速度为58 ~ 79 cm/s， M2潮汐分量的绝对椭圆度值在0.4以上。在该地区进行的详细的小尺度地貌调查表明，沙脊和沙洲目前仍处于潮流作用下。根据潮流、河床和沉积物厚度的解释，推断研究区泥沙输运的大致方向为NNW，由老铁山海峡至辽东和渤中浅滩。详细调查区内的小尺度地层显示了局部净沙由南向北输运。
The continental shelf of China has undergone a large-scale marine transgression. Tidal currents have become the main active agent and have had a profound influence on the deposition and geomorphology of the shelf. The continental shelf of China has five modern tidal deposition systems: (1) the eastern part of the Yellow Sea, (2) the eastern part of the Bohai Sea, (3) off the mouth of Yangtze River; (4) to the west of Taiwan, and (5) the Strait of Qiongzhou. When the tidal current speed is above 150 cm/s, erosion dominates and reciprocating currents form deep scour furrows. When the tidal current speed is 50 to 150 cm/s, deposition is dominant, and tidal currents form tidal shoals (i.e., tidal sand ridges and tidal sand sheets) whose margins are near an absolute ellipticity value for the M2 tidal component of 0.4. When the absolute M2 value is less than 0.4, a reciprocating current is strong enough to form tidal sand ridges. When the absolute value is above 0.4, a rotating current increases so as to form a tidal sand sheet. Tidal deposition material came mainly from tidal erosion and locally redeposition of Late Pleistocene sediments, and from the neighbouring sea bottom. The tidal deposition system in the eastern Bohai Sea is a typical example. It consists of the Laotieshan Channel scour furrow, the Liaodong Shoal sand ridges and the Bozhong Shoal sand sheet. The maximum tidal current speed in the Laotieshan Channel where strong erosion occurs, is up to 250 cm/s. In the Liaodong Shoal, the maximum tidal current speed is 64–115 cm/s and the absolute ellipticity value of the M2 tidal component is less than 0.4. In the Bozhong Shoal, the maximum tidal speed is 58–79 cm/s and the absolute ellipticity value of the M2 tidal component is above 0.4. The small-scale bedforms surveyed in detail in the area show that the sand ridges and sand sheet are still under the action of tidal current processes at the present time. Based on the interpretation of tidal currents, bedforms and sediment thickness, it is inferred that the general direction of sediment transport within the study area is NNW from the Laotieshan Channel to the Liaodong and Bozhong Shoals. The small-scale bedforms in the detailed survey area indicate a local net sediment transport from south to north.