渤海东部潮流地貌及控制因素

发布时间：2018-06-14 21:52

本文选题：渤海东部 + 潮流沉积　；参考：《中国海洋大学》2014年博士论文

【摘要】：渤海东部海底地貌是一个在成因上相互关联的完整潮流地貌体系，地貌类型和分布特征受潮流动力格局的控制。本文根据“中国近海海洋综合调查与评价专项”在渤海区块的表层沉积物、矿物分析资料，利用国家自然科学基金项目“辽东浅滩潮流沙脊演化过程及响应机制”在研究区海域开展的海底地形地貌勘测所获取的沙脊和沟槽海流同步观测、水深地形、表层沉积物及测扫声呐调查资料，研究了沙脊-沟槽-沙席的地貌类型与分布、微地貌特征和不同地貌单元的粒度分布等，采用沙波迁移速率计算和数值模拟等方法探讨了沙波的发育条件等。依据海流平面及垂向观测资料，研究了沙脊-沟槽的海流分布规律，探讨了研究区潮流地貌演化趋势及控制因素，研究结果表明：（1）老铁山水道东侧E-W向长度约49km，西侧NE-SW向长度约43km，中央区深槽长88km，宽度约20km，最大水深86m，表层沉积物主要是粗粒的泥质砂质砾，分选程度极差；辽东浅滩沙脊间距7.0~16.8km，脊槽高差6.8~21.9km，，沉积物以砂为主，分选较好，在沙脊脊部发育大型、中型沙波；沙脊间沟槽沉积物主要为砂质粉砂、粉砂质砂、粉砂等，分选差；渤中浅滩沙席中央区面积约670km2，表层沉积物以泥质砂为主，分选较差。老铁山水道表层沉积物中石榴石、钛铁矿稳定重矿物的含量小于10%，辽东浅滩稳定重矿物含量大于15%；渤中浅滩沙席稳定重矿物含量在10~20%之间。（2）辽东浅滩沙脊区的沙波主要发育在底质平均粒径在1.6~2.9φ、最大底流速52.2~67.0cm/s范围，水深大致在16~26m的沙脊脊部，以不对称沙波为主，缓坡位于西南侧，陡坡位于东北侧，沙波波长在2~23m，波高0.2~1.2m之间，沙波走向基本为WNW-ESE向；沙脊间沟槽底质粒径3.2~5.3φ，最大底流速33.3~35.0cm/s，不发育沙波。根据Shinohara沙波迁移速率计算公式计算的沙波迁移速率在3.26×10-6~2.65×10-4cm/s范围内，最大迁移距离在1.6~7.6cm/d范围内，沙波形态特征和净迁移方向反映出沙脊脊部沉积物净运移方向与潮流主流向大体一致，为NNE向。（3）高、低潮时，沙脊区潮流主流向为NNE-SSW向，流向与沙脊长轴向夹角为9~30°，脊部表层最大流速在103.9~118.8cm/s之间、底层最大流速在52.2~67.0cm/s之间，槽部表层最大流速在108.7~124.3cm/s之间、底层最大流速在33.3~35.0cm/s之间，脊部底流速大于槽部底流速的分界水深约为0.7H层（H为水深值）。沙脊脊部由于流速大，逐渐遭受侵蚀，侵蚀泥沙向NNE净运移；槽部流速小，除大潮期高低潮时外，潮流流速小于沉积物起动流速，因此沙脊间槽部多数时间处于淤积状态，个别时刻略有侵蚀。（4）老铁山水道仍然是沙脊和沙席的主要物源区，在高流速动力条件下，水道海底继续遭受侵蚀，水深会缓慢增加，经老铁山水道向辽东浅滩和渤中浅滩搬运的泥沙趋于减少。辽东浅滩沙脊与沙脊间沟槽潮流流速的差异导致沙脊脊部逐渐侵蚀，槽部趋于淤浅，脊槽高差逐渐减小，脊槽地貌趋于夷平，沙脊沿潮流主流向发生迁移，沙脊-沟槽地貌进入退化阶段。但根据研究区目前的潮流格局、水深地形、沉积物粒度和沙波迁移速率分析，辽东浅滩脊槽地貌格局在百年尺度内仍会保持稳定。
[Abstract]:According to the survey data of surface sediments and minerals in the Bohai Sea area , the authors have studied the geomorphic types and distribution of the sand ridge - channel - sand table , the micro - geomorphic features and the particle size distribution of different geomorphic units .

( 1 ) The east side E - W of Laotieshan waterway is about 49km in length , NE - SW in the west side is about 43km in length , the deep groove of central area is 88km , the width is about 20km , the maximum water depth is 86m , the surface sediments are mainly coarse sand gravel , and the degree of separation is extremely poor ;
The sand ridge spacing of the shallow beach in Liaodong is 7.0 - 16.8km , the height difference of the ridge is 6.8 - 21.9km , the sediments are mainly sand , the separation is better , and large - sized and medium - sized sand waves are developed at the ridge part of the sand ridge ;
The inter - ridge trench sediments are mainly sandy silt , silty sand , silt and the like , with poor sorting ;
The area of the central area of the sand table in Bonzhong shoal is about 670 km2 , and the surface sediments are dominated by muddy sand . The content of the stabilized heavy minerals in the surface sediments of the Laotieshan channel is less than 10 % , and the stable heavy mineral content in the shoal of the Liaodong shoal is more than 15 % ;
The stable heavy mineral content is between 10 and 20 % .

( 2 ) The sand wave in the sand ridge area of the shallow beach in Liaodong area is mainly developed in the range of 1.6 ~ 2.9 蠁 , the maximum bottom flow velocity is 52.2 ~ 67.0 cm / s , the water depth is approximately 16 ~ 26m , the gentle slope is located in the south of the southwest , the steep slope is located in the northeast side , the wave length is between 2 ~ 23m and the wave height is 0.2 ~ 1.2 m , and the wave direction is basically WNW - ESE ;
In the range of 3.26 脳 10 - 6 ~ 2.65 脳 10 - 4 cm / s , the maximum migration distance is within the range of 3.6 脳 10 - 6 ~ 2.65 脳 10 - 4 cm / s . The maximum transfer distance is within the range of 1.6 ~ 7.6 cm / d . The sediment transport direction of sand - wave form is consistent with the trend of the trend of the flow of sediment in the ridge part of the ridge . It is in the direction of the direction of the direction .

( 3 ) When high and low tide , the trend of the tidal current in the sand ridge area is in the direction of NE - SSW , the flow direction and the longitudinal axis of the sand ridge are between 9 and 30 degrees , the maximum flow velocity of the surface layer of the ridge part is between 103.9 and 118.3 cm / s , the maximum flow velocity of the bottom layer is between 53.2 and 67.0 cm / s , and the maximum flow velocity of the bottom layer is between 53.2 and 31.0cm / s , and the maximum flow velocity of the bottom layer is about 0.7H layer ( H is the water depth value ) .
The flow velocity of the trough is small , except for the high tide period . The flow velocity is less than that of sediment start , so most of the time of the trough of the ridge is in the siltation state , and the individual time is slightly eroded .

( 4 ) The Laotieshan water channel is still the main source area of sand ridge and sand table . Under the condition of high flow velocity , the sediment tends to be eroded and the water depth increases slowly .
【学位授予单位】：中国海洋大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P737.2

【参考文献】