胶州湾口潮流沙脊特征

THE CHARACTERISTICS OF TIDAL SAND RIDGES IN THE MOUTH OF JIAOZHOU BAY,SHANDONG,CHINA

胶州湾内外的涨、落潮三角洲上发育有一定规模的潮流沙脊体系,通过多波束调查采集数据和浅剖、沉积物资料的分析,对沙脊特征进行了研究。湾内涨潮三角洲上分别分布有冒岛沙脊、中央沙脊和岛耳河沙脊;湾外落潮三角洲上分别发育了潮流沙脊大竹、南沙、北沙和位于主潮流通道末端的弧状沙脊。潮流沙脊体系的演变具有较为明显的继承性。沙脊以海侵时期发育的沙体为内核,沉积物组成以粒度较粗的砂质沉积物为主,物源基础为低海平面时期胶州湾盆地内堆积的河流三角洲相沉积物。据分析,沙脊现代物源较为匮乏,整体目前处于冲刷不淤的状态。在现代潮流水动力条件下,研究区潮流沙脊处于活动状态。

Submarine tidal ridges on certain scale occur on both the flood and ebb tidal deltas inside and outside the Jiaozhou Bay mouth. Multi-beam acoustic sounding, sub-bottom profiling and sediment analysis are conducted for study of the characteristics of the tidal sand ridges. The Maodao sand ridge, Zhongyang sand ridge and Daoer River sand ridge occur on the flood tidal delta inside the Jiaozhou Bay mouth, whereas the Dazhu sand ridge, Nansha sand ridge, Beisha sand ridge and the arc-shaped sand ridges occur on the ebb tidal delta outside the Jiaozhou Bay mouth. The sand ridges are developed as the continuation of the sand cores which were formed in the Holocene transgression. The sand ridges are mainly composed of coarse sands. Our data suggests that the sands of tidal sand ridges are primarily from estuarine sandy shoals during the period of low sea-level. They are still active now according to the study of the recent marine hydrodynamics. They are growing slowly due to the deficiency of sediment input and strong erosion.