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涌潮是地表过程非常特殊的地质营力,是一种周期性发生的、破坏力极强的高能事件且塑造了典型的沉积地貌特征.涌潮及随后的急流为一高流态(Fr>1.0)的强紊流(Re>104),流速可达每秒数米,非常类似于浊流,却明显有别于常规的潮流.钱塘江涌潮是世界上最强的漩滚涌潮,2010年5月在涌潮最强的河段北岸开展了水文观测,采取边滩沉积物短柱样进行沉积特征研究.结果表明,仅占潮周期约1/10时长的涌潮及紧随其后的急流和流速骤降的涨潮流共同控制了涌潮河段沉积物再悬浮、搬运与沉积作用.在强烈紊流与快速沉积共同作用下,涌潮沉积物一般分选较差,发育块状层理、递变层理,常见底冲刷构造,层内发育包卷层理与泄水构造等,C-M图上缺失牵引流沉积组分等.这些也是浊流沉积常见的特征,但涌潮是以浅水环境强烈变形的潮波为动力机制,在其快速回复到常规潮汐作用之后,可在中高潮滩形成和保存具典型潮汐层理的沉积层.除了差别迥异的沉积构造特征外,涌潮沉积(tidal bore deposit,TBD)与潮成砂、泥质沉积(tidal sandy or muddy deposit,TSD或TMD)的粒度特征也差异显著,可用粒度参数散点图加以区分,其中平均粒径:TBD>TSD>TMD,分选系数:TMD>TBD>TSD(值大分选差),偏态与峰度值均为TSD>TBD>TMD.上述认识对于深入研究涌潮沉积学、古代涌潮沉积相与环境及油气勘探均有重要意义.
Tidal tide is a very special geological tectonic force with a superficial process and is a periodically occurring and highly destructive high-energy event that creates a typical sedimentary topography. The tidal and subsequent rapids are characterized by a high fluidity (Fr> 1.0), with a turbulent flow (Re> 104) of up to several meters per second, which is very similar to the turbidity current but distinctly different from the conventional tidal current. The Qiantang River tidal current is the strongest swirling tide in the world. Hydrological observations were carried out on the north bank of the strongest tidal reach in May and the sedimentary characteristics of the short beach samples of the beach were studied.The results show that the tidal current is only about 1/10 of the tidal cycle and the Rapids and the tidal current with sudden drop of flow control the resuspension, sedimentation and transport of sediments in the tidal reach. Under the joint action of intensive turbulence and rapid sedimentation, the tidal sediments are generally poorly sorted, with the development of massive layers Rough stratification, common under-flushing structures, stratification and drainage structures in the layers, missing sediment components on CM maps, etc. These are also common features of turbidity-current sedimentation, but tidal currents are based on The strong deformation of the shallow water environment tidal wave as a dynamic mechanism, in its rapid response to conventional tidal effects After tidal flat sediments are formed and preserved in the middle and high tidal flats, except tidal bore deposit (TBD) and tidal sandy or muddy deposit, TSD or TMD) were also significantly different, which can be distinguished by the scattergram of particle size parameters, where the average particle size is: TBD> TSD> TMD, the sorting coefficient is TMD> TBD> TSD, The skewness and kurtosis are both TSD> TBD> TMD. The above understanding is of great significance for the further study of gully sedimentology, ancient tidal sedimentary facies and environment, and oil and gas exploration.