Resuspension and advection processes affecting suspended particulate matter concentrations in the central English Channel

Suspended particulate matter (SPM) measurements obtained along a cross-section in the central English Channel (Wight-Cotentin transect) indicate that the area may be differentiated into: (1) an English coastal zone, associated with the highest concentrations; (2) a French coastal zone, with intermediate concentrations; and (3) the offshore waters of the Channel, characterised by a very low suspended-sediment load. The SPM particle-size distribution was modal close to the English coast (main mode 10-12 mu m); the remainder of the area was characterised by flat SPM distributions. Examination of the diatom communities in the SPM suggest:; that material resuspended in the intertidal zone and the estuarine environments was advected towards the offshore waters of the English Channel. Considerable variations in SPM concentrations occurred during a tidal cycle: maximum concentrations were sometimes up to 3 times higher than the minimum concentrations, Empirical orthogonal function (EOF) analysis of the SPM concentration time series indicates that, although the bottom waters were more turbid than the surficial waters, this was not likely to be the result of in situ sediment resuspension. Instead, the observed variations appear to be controlled mainly by advective mechanisms. The limited resuspension was probably caused by: (1) the limited availability of fine-grained material within the bottom sediments, and (2) 'bed-armouring' processes which protect the finer-grained fractions of the seabed material from erosion and entrainment within the overlying flow during the less energetic stages of the tide.

渤海海底埋藏黄土及沿海出露黄土的成因

本文分析了我国内陆黄土以及东部沿渤海黄土的分布特点，重新分析了渤海自西向东大量地质钻孔以及大量海底的浅地层剖面记录，第一次发现并确定了全新世海相层下面的埋藏黄土的存在。将第二海相地层之上的埋藏黄土与沿岸的出露的马兰期黄土上部进行对比，研究表明，渤海海底埋藏黄土与沿岸出露黄土具有时代一致，同一类型，同一成因的特点。提出了沿渤海马兰期黄土的近源沉积及分布关系，建立了沿渤海黄土成因的扇型分布模式。