福建近海河口潮流沉積沙體特征
發(fā)布時間：2018-11-23 18:34
【摘要】：福建近海岸線蜿蜒曲折，沿岸發(fā)育眾多河口，海洋環(huán)境受臺灣海峽影響較大。河口是連接陸域和海域水體的媒介，與人類活動息息相關(guān)。福建近海閩江口和九龍江口等河口均屬于中小型強(qiáng)潮河口,河口沙體分布特征和演化趨勢直接影響人類活動和經(jīng)濟(jì)發(fā)展�；谳^新數(shù)據(jù)資料，對河口外沙體的研究有助于加強(qiáng)對我國近海半封閉中小型河口灣海底潮流地貌的認(rèn)識。本文通過多波束調(diào)查采集數(shù)據(jù)和淺剖、沉積物等資料的分析和研究，結(jié)合前人海平面變化的研究資料，對河口外沉積沙體的成因進(jìn)行了探討和論述，初步認(rèn)為其為潮流沙脊。研究結(jié)論如下： （1）在平面分布上，閩江口外潮流沙脊走向近SW-NE向，沙脊局部連片；九龍江口外沙脊走向近ENE-WSW向，沙脊末端有分叉現(xiàn)象。 （2）研究區(qū)沙脊主體生長受現(xiàn)代水動力影響較小，從沙脊相對于現(xiàn)代河口的距離和沉積物粒度特征來看，沙脊主體發(fā)育時的物源并非現(xiàn)代河口沉積物，沙脊表層覆蓋有較薄的現(xiàn)代近海陸架沉積物層,下部地層為保留古河道相沉積的殘留沉積。 （3）通過沙脊間距推算出的古水深與前人研究全新世古海平面位置及當(dāng)時南黃海和東海大量潮流沙脊形成水深是一致的，其中,閩江口外的潮流沙脊主體發(fā)育時期約為11-11.5ka B.P.處于中國近海沙脊演化早期,九龍江口外的潮流沙脊主體發(fā)育時期約為7-8ka B.P.處于演化中期。 （4）研究區(qū)沙脊為古水下三角洲砂質(zhì)淺灘遭受潮流等水動力侵蝕而成，形成的潮流水動力環(huán)境強(qiáng)于現(xiàn)代的淺水陸架平原環(huán)境；在隨后的海平面變化過程中，沙脊上覆水深逐漸大于沙脊發(fā)育的最佳深度，在現(xiàn)代水動力改造作用下，，沙脊頂端圓滑，兩側(cè)坡度較緩，沙脊間溝槽較為平緩，表面發(fā)育沙波，基本處于動力平衡的狀態(tài)。
[Abstract]:Fujian has a winding coastline with many estuaries along the coast, and the marine environment is greatly affected by the Taiwan Strait. Estuaries are the medium that connects land and sea waters and is closely related to human activities. The estuaries such as Minjiang Estuary and Jiulong Estuary in the coastal waters of Fujian Province belong to the middle and small strong tidal estuaries. The distribution characteristics and evolution trend of sediment body in estuaries directly affect human activities and economic development. Based on the new data, the study of the sediment body outside the estuary is helpful to strengthen the understanding of the tidal current landform in the middle and small sized estuarine gulf in the coastal waters of China. Based on the analysis and study of the data collected by multi-beam survey, shallow profile and sediment, combined with the previous research data of sea level change, the origin of sediment body outside the estuary is discussed and discussed, which is considered as tidal current ridge. The results are as follows: (1) in plane distribution, the trend of tidal current sand ridge outside Minjiang Estuary is close to SW-NE direction, and that of sand ridge is locally connected, and the direction of sand ridge outside Jiulong River Estuary is near ENE-WSW direction, with bifurcation at the end of sand ridge. (2) the main body growth of sand ridges in the study area is less affected by modern hydrodynamics. According to the distance between sand ridges and modern estuaries and the grain size characteristics of sediments, the material source of the main body of sand ridges is not modern estuary sediments. The surface layer of sand ridge is covered with a thin layer of modern offshore shelf sediments, and the lower layer is a remnant deposit of paleochannel facies. (3) the paleo-water depth calculated from the distance between sand ridges is consistent with the paleo-sea level position of Holocene and the formation of tidal current ridges in the South Huang Hai and the East China Sea at that time, among which, The main development period of tidal current ridge outside Minjiang Estuary is about 11-11.5ka B.P. The main body of tidal current ridge outside Jiulong River Estuary is about 7-8ka B.P. In the middle of evolution. (4) the sand ridge in the study area is formed by the erosion of sandy shoals in the paleo-underwater deltas by tidal current isohydrodynamic erosion, which is stronger than that of the modern shallow shelf plain environment. During the subsequent sea level change, the water depth on the sand ridge is gradually greater than the optimum depth of the sand ridge development. Under the action of modern hydrodynamic transformation, the top of the sand ridge is smooth, the slope on both sides is relatively slow, the channel between the sand ridges is relatively gentle, and the sand waves are developed on the surface. Basically in a state of dynamic balance.
【學(xué)位授予單位】：國家海洋局第三海洋研究所
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：P736.21
本文編號：2352380
[Abstract]:Fujian has a winding coastline with many estuaries along the coast, and the marine environment is greatly affected by the Taiwan Strait. Estuaries are the medium that connects land and sea waters and is closely related to human activities. The estuaries such as Minjiang Estuary and Jiulong Estuary in the coastal waters of Fujian Province belong to the middle and small strong tidal estuaries. The distribution characteristics and evolution trend of sediment body in estuaries directly affect human activities and economic development. Based on the new data, the study of the sediment body outside the estuary is helpful to strengthen the understanding of the tidal current landform in the middle and small sized estuarine gulf in the coastal waters of China. Based on the analysis and study of the data collected by multi-beam survey, shallow profile and sediment, combined with the previous research data of sea level change, the origin of sediment body outside the estuary is discussed and discussed, which is considered as tidal current ridge. The results are as follows: (1) in plane distribution, the trend of tidal current sand ridge outside Minjiang Estuary is close to SW-NE direction, and that of sand ridge is locally connected, and the direction of sand ridge outside Jiulong River Estuary is near ENE-WSW direction, with bifurcation at the end of sand ridge. (2) the main body growth of sand ridges in the study area is less affected by modern hydrodynamics. According to the distance between sand ridges and modern estuaries and the grain size characteristics of sediments, the material source of the main body of sand ridges is not modern estuary sediments. The surface layer of sand ridge is covered with a thin layer of modern offshore shelf sediments, and the lower layer is a remnant deposit of paleochannel facies. (3) the paleo-water depth calculated from the distance between sand ridges is consistent with the paleo-sea level position of Holocene and the formation of tidal current ridges in the South Huang Hai and the East China Sea at that time, among which, The main development period of tidal current ridge outside Minjiang Estuary is about 11-11.5ka B.P. The main body of tidal current ridge outside Jiulong River Estuary is about 7-8ka B.P. In the middle of evolution. (4) the sand ridge in the study area is formed by the erosion of sandy shoals in the paleo-underwater deltas by tidal current isohydrodynamic erosion, which is stronger than that of the modern shallow shelf plain environment. During the subsequent sea level change, the water depth on the sand ridge is gradually greater than the optimum depth of the sand ridge development. Under the action of modern hydrodynamic transformation, the top of the sand ridge is smooth, the slope on both sides is relatively slow, the channel between the sand ridges is relatively gentle, and the sand waves are developed on the surface. Basically in a state of dynamic balance.
【學(xué)位授予單位】：國家海洋局第三海洋研究所
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：P736.21
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