Reconstruction of a Pleistocene meandering river in East Hungary by VHR seismic images, and its climatic implications
Reconstruction of a Pleistocene meandering river in East Hungary by VHR seismic images, and its climatic implications
复制标题
利用 VHR 地震图像重建匈牙利东部更新世曲流河及其气候影响
DOI：
10.1016/j.geomorph.2012.02.025
复制
发表时间：
2012
期刊：
影响因子：
3.9
通讯作者：
O. Sztanó
中科院分区：
文献类型：
--
作者：
Ágnes Cserkész‐Nagy;E. Thamó;T. Tóth;O. Sztanó
利用200 km长的VHR单道地震剖面对匈牙利蒂萨河上更新统冲积层系上部20- 30 m进行了研究。频繁的内部配置，如（1）倾斜反射束，（2）槽形会聚，（3）水平，平行反射解释，分别为点坝，废弃的河道充填和河漫滩沉积的侧向加积。根据光释光资料，在整个地区同一深度出现的一系列5- 8 m厚的倾斜地层组合表明，在晚更新世存在一条曲流河，时间约为43- 47 ka。新记录的准三维地震剖面表明，每一个1- 3 km长的倾斜岩系都对应着一个沿同一方向连续迁移的点沙坝。迁移方向的小偏差是由曲流弯曲的自然漂移引起的。利用点沙形态参数计算古河道参数（宽200- 500 m，深5- 8 m）。数值表明成槽流量为Q=400- 900 m3/s。这些结果意味着更大量的径流和供应在流域MIS 3相比，现在的一天。长期的曲流表明，当地因素的作用和不同的河流环境相比，通常在欧洲西北部的河流系统。我们的数据支持三轴流域系统的论文。提供了新的证据，除了多瑙河和蒂萨河的祖先，一个时间上活跃的第三干河的前身存在，今天的两轴排水模式相反。
The upper 20–30m of the Pleistocene alluvial sequence on the Tisza River, Hungary is investigated by 200km of VHR single-channel seismic sections. Frequent internal configurations, such as (1) bundles of inclined reflections, (2) trough-shaped converging, and (3) horizontal, parallel reflections are interpreted, respectively, as lateral accretion of point bars, abandoned channel fills and floodplain deposits. The series of 5–8m-thick inclined strata sets occurring at the same depth throughout the area suggest the presence of a meandering river dated to about 43–47ka in the Late Pleistocene according to OSL data. Newly recorded quasi-3D seismic profiles reveal that each 1–3km-long inclined series correlates with an individual point bar continuously migrating in the same direction. Small deviations in the direction of migration are caused by natural wandering of the meander bend. Morphometric parameters of point bars are used to calculate ancient channel parameters (width and depth of 200–500m and 5–8m, respectively). Values imply a channel-forming discharge of Q=400–900m3/s. These results imply a greater amount of runoff and supply in the basin during MIS3 compared to the present day. Long-lasting meandering indicates the role of local factors and a different fluvial environment compared to the commonly anastomosing systems in NW Europe. Our data support the thesis of the three-axis drainage system for the basin. New evidence is provided for the antecedent existence of a temporally active third trunk river in addition to the ancestors of Danube and Tisza Rivers, contrary to the present-day two-axis drainage pattern.