褚岛连岛沙坝的形成与演变

THE FORMATION AND EVOLUTION OF THE CHUDAO ISLAND TOMBOLO

本文运用沉积动力学的理论和方法,对褚岛连岛沙坝的形成与演变进行了动力机制方面的探讨。

The Chudao Island tombolo, some 3. 6 km in length, located in the northeast of the Nigjin Peninsula, was formed by the alongshore currents entraining abundant clastic sediments from the south to the north.In this region,the large areas of exposed rocks ,the long-time tectonic uplift,the active hydraulic characters and the shielding of the Chudao Island provided the geological foundation and the hydraulic conditions necessary for the formation of the Chudao Island tombolo, which are reflected by the sedimentary characters, such as the components of the sediments, the beach stratifications of the tombolo, the variation of the heavy minerals percentage, and so on. According to these sedimentary characters, the processes of the formation and evolution of the Chudao Island tombolo can be revealed, and its trend of development can also be predicted.An along-shore sand-transport played the most important role in the process of formation of the Chudao Island tombolo. As a result, the heavy minerals concentratead at the end of the tombolo bounding the Nigjin Peninsula . After the tombolo has completely developed, the sediments will be mainly across-shore transported, and the heavy minerals enrichment will occur in the backshore or the landward parts of the forshore on the tombolo beach in accordance with the process of selective entrainment and selective transport during the erosion stages. For the time being , the development of the tombolo is between the intermidiate period of the two states mentioned above. The coast in the studied area will reach a relative moving equilibrium.