全新世以来珠江三角洲海鸥沙形成过程的地貌动力学分析

海鸥沙是珠江三角洲一个极富特色的沉积砂体。本文基于钻孔资料并结合长周期“动力-沉积-形态”模型, 从沉积学和地貌动力学角度对全新世以来海鸥沙的形成演变过程进行了探讨。海欧沙在全新世的沉积层序自下而上分别为河流相、河口湾浅海相和三角洲相。全新世海侵盛期以来, 虎门涨潮射流和东北—西南向涨落潮流是影响海鸥沙形成演变的主要动力。6000—2500a BP, 受东北—西南向涨落潮流的影响, 海鸥沙中北部地区一直处于冲刷无沉积状态, 由虎门涨潮射流带来的泥沙主要在海鸥沙南部沉积, 沉积速率约为0.67mm·a ^-1; 2500—1700a BP, 随着番禺平原的发育, 东北—西南向涨落潮流逐渐消弱, 海鸥沙进入一个快速沉积期, 平均沉积速率约为15mm·a ^-1, 沉积由两端向中间发展; 1700—600a BP, 随着沙湾水道的形成, 海鸥沙中部迅速发展, 至600a BP左右, 海鸥沙基本形成并出露水面。

Morphodynamic analysis of Haiou sandbody evolution in Pearl River delta since Holocene

Haiou Sandbody (HS) is a characteristic deposition body in the Pearl River delta. Based on the borehole data and the long-term morphodynamic model, the formation and evolution of the HS were studied. The bottom-up sedimentary sequence of the HI during Holocene is river facies, estuary shallow sea facies and delta facies. Since the maximum of the Holocene transgression, Humen tidal current and northeast-southwest tidal current have been the main forces influencing the formation and evolution of HS. From 6000 to 2500 a BP, due to the influence of the northeast to southwest fluctuating tide, the middle and northern parts of HS have been in a scour and non-sedimentary state. From 2500 to 1700 a BP, with the development of Panyu Plain, the northeast-southwest fluctuating trend gradually weakened, and the HS entered a rapid sedimentary period, with the mean deposition rate of about 15 mm·a ^-1. Between 1700 and 600 a BP, with the formation of the Shawan channel, the middle part of HS developed rapidly. To about 600 a BP, HS basically formed a dew surface.