杭州湾的沉积结构与沉积环境分析

SEDIMENTARY TEXTURES AND ENVIRONMENTS OF THE HANGZHOU BAY

漏斗状的地形、强劲的潮流和长江入海泥沙的输入是制约杭州湾沉积作用的主要因素。根据沉积结构特征可将杭州湾划分为五种不同的沉积环境:东部湾底、西部湾底、庵东浅滩、近岸深槽和水下沙脊。杭州湾内潮流脊发育不好的原因在于没有足够的粗屑物质。

The Hangzhou Bay is a typical macrotidal estuary. Its modern sedimentation is controlled by funnel-shaped topographic configuration, strong tidal currents and silt suspension from the Changjang River estuary. Changes of sedimentary textures are mainly restricted by intensity of the tidal currents. According to the sedimentary textures of bottom sediments and hydrodynamic conditions, the following sub-environments can be identified in the Hangzhou Bay: east part of the bay bottom, west part of the bay bottom, Andong shoal, nearshore deep channel and tidal sand ridges. This paper expounds sedimentary texture characteristics and formation mechanism of the different sub-environments, probes what causes the tidal sand ridges (typical sand bodies in the macrotidal estuary) to poorly develop in the Hangzhou Bay, and also points out that it is difficult to build up sand ridges without sufficient coarsegrained sediments, although tidal current is strong enough.