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首页> 外文期刊>Estuarine Coastal and Shelf Science >Dynamic sedimentary environments of an Arctic glacier-fed river estuary (Adventfjorden, Svalbard). I. Flux, deposition, and sediment dynamics
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Dynamic sedimentary environments of an Arctic glacier-fed river estuary (Adventfjorden, Svalbard). I. Flux, deposition, and sediment dynamics

机译：北极冰川河河口的动态沉积环境（Adventfjorden，斯瓦尔巴特群岛）。 I.通量，沉积物和沉积物动力学

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摘要

The spatial patterns of the transport, settling, and deposition of sediments were studied in a small Arctic glacier-fed river estuary (Adventfjorden, west Spitsbergen, Svalbard). Salinity and temperature, suspended solids concentration, and particle fluxes in the water column were measured at seven stations situated on the tidal flat formed at the river mouth, the delta slope, and along the fjord axis down to the fjord mouth. Turbidity currents were measured in situ using a current meter combined with a turbidity meter. The sediments collected with a Niemisto gravity corer were x-rayed and analyzed for granulometric composition. The results of the major sampling campaign undertaken in July 2002 were supplemented with winter hydrological data from January 1996. Since the river is frozen in winter, no fresh water or fluvial sediment supply is observed in the fjord water column. A hypopycnal plume of brackish water (1.5 m thick) extends in summer as far as 0.8 km from the river mouth. The highest concentration (826 mg l~(-1)) and vertical flux (over 1000 g m~(-2) day~(-1)) of suspended solids were noted at the edge of the tidal flat and over the upper slope of the delta. Both concentrations and the solid particle flux decreased as distance from the river mouth increased. Local peaks of turbidity in the intermediate and deep water layers in the central fjord indicated the presence of hyperpycnal plumes. Tidal flat sediments are rhythmically laminated by the tidally controlled resuspension/redeposition cycles and occasionally eroded by catastrophic events such as intense storms or winter ice cover scouring. The steep inclination of the bottom of the slope (15—19°) promotes the gravity-driven processes of sediment transport (debris flows). Frequent resuspension and redeposition events can be traced on x-radiographs and in the granulometric composition of the sediment cores collected on the slope. Turbidity currents are observed throughout the fjord, although their intensity and frequency of occurrence change as distance from the river mouth increases. The near bottom hyperpycnal flows transport the finest sediment over the slope and into the low energy environment of the central basin of Adventfjorden. The current study shows that the patterns of sediment storage and sedimentary dynamics in a glacier-fed river estuary are driven by gravity flows and turbidity currents rather than by the patterns of the vertical sedimentation of suspensions in the water column.
机译：在一个由北极冰川喂养的小河口（Adventfjorden，Spitsbergen西，斯瓦尔巴特群岛）研究了沉积物的运输，沉降和沉积的空间格局。在位于河口，三角洲斜坡和沿峡湾轴线向下至峡湾口形成的潮滩上的七个站点上，测量了水柱中的盐度和温度，悬浮固体浓度以及颗粒通量。使用电流计和浊度计在现场测量浊度电流。用Niemisto重力岩心采集器对沉积物进行X射线分析，并进行粒度分析。 2002年7月进行的主要采样活动的结果补充了1996年1月以来的冬季水文数据。由于河流在冬季结冰，因此在峡湾水柱中未观察到淡水或河流沉积物的供应。咸水的次高羽（1.5 m厚）在夏天延伸至距河口0.8 km。在潮滩的边缘和上坡的上坡，发现悬浮物的最高浓度（826 mg l〜（-1））和垂直通量（超过1000 gm〜（-2）day〜（-1））。三角洲。浓度和固体颗粒通量都随着距河口距离的增加而降低。峡湾中部和深水层的浊度局部峰值表明存在高辉柱状羽流。潮汐平坦的沉积物通过潮汐控制的重悬/再沉积循环有节奏地分层，偶尔会被诸如强风暴或冬季冰盖冲刷之类的灾难性事件侵蚀。斜坡底部的陡峭倾斜（15-19°）促进了重力驱动的泥沙输送（泥石流）过程。频繁的重悬和再沉积事件可以在X射线摄影机上以及在斜坡上收集的沉积物芯的粒度组成中进行追踪。整个峡湾都可以看到浑浊的水流，尽管它们的强度和发生频率会随着距河口距离的增加而变化。近底部的高温流将最细的沉积物通过斜坡输送到Adventfjorden中央盆地的低能环境。目前的研究表明，冰川注入河口的沉积物存储和沉积动力学模式是由重力流和浊流驱动的，而不是由水柱中悬浮物的垂直沉积模式驱动的。

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