Abstract

Lake Seliger has been always classified as a former glacial water body, a remnant of a vast proglacial lake, which has existed since the disappearance of the last glacial Ice Sheet in the territory 18–19 thousand years ago. The study was focused on areas of southern pools of the lake looking like underflooded meandering river channels. Bottom sediments were drilled in three such areas and ground penetrating radar profiling was carried out on two areas. Lake silt, several meters thick, was found to overlay coarse sand, which is most likely of riverine origin. A feature in favor of this is a characteristic asymmetrical bed profile in the supposed parts of ancient river bends and the time of transition from active flow to the regime of stagnant water body since 14.5 thousand years ago: in that time, glacier edge already lied far from here, and glacial melt water did not penetrate into this area. The inundation of segments of river valleys and their transformation into lake pools was provoked by damming of the Selizharovka River, which originally flowed out from Lake Seliger near Ostashkov Town. About 14.5 thousand years ago, the rapidly growing delta of the Krapivenka River, a left tributary of the Selizharovka, started growing rapidly, damming the latter river. In the period of 2 thousand years, the damming effect extended over the entire 15-km segment of the valley and reached the source of the river in Lake Seliger. In the Holocene, the level rise continued, though at a lesser rate. The total rise of lake level was 7–8 m, which caused flooding of the lower reaches of the valleys of rivers emptying into the lake and transformed them into estuaries. It is shown that glacioisostatic deformations of the Earth crust could not reverse the flow from Seliger into the Baltic Basin. After the disappearance of the most recent glacier, Lake Seliger and its tributaries have always belonged to the Volga Basin; this is to be taken into account in the reconstruction of the Volga runoff and the water balance of the receiving water body (the Caspian Sea).

中文翻译：

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塞利格湖的河流过去

摘要

塞利格湖一直被归类为前冰川水体，是一个巨大的前冰湖的残余，自 18-19 千年前该领土上最后一个冰川冰盖消失以来一直存在。该研究的重点是看起来像淹没的蜿蜒河道的南部水池区域。在三个这样的区域钻探底部沉积物，并在两个区域进行了探地雷达剖面分析。发现几米厚的湖淤泥覆盖在粗沙上，这很可能来自河流。有利于这一点的一个特征是在假定的古河道弯道部分具有​​特征性的不对称河床剖面，以及自 14500 年前以来从活跃流向停滞水体状态过渡的时间：在那个时候，冰川边缘已经很远从这里，并且冰川融水没有渗透到这个区域。最初从奥斯塔什科夫镇附近的塞利格湖流出的塞利扎罗夫卡河（Selizharovka River）的筑坝引发了河谷段的淹没及其转变为湖池。大约 14500 年前，快速增长的克拉皮文卡河三角洲（Selizharovka 的左支流）开始快速增长，并堵塞了后一条河流。在 2000 年的时间里，堤坝效应延伸到整个 15 公里的山谷段，并到达塞利格湖的河流源头。在全新世，水平继续上升，但速度较慢。湖面总水位上升 7～8 m，造成下游河流入湖泛滥，河口变河口。结果表明，地壳的冰川等静压变形不能逆转从塞利格流入波罗的海盆地的流动。在最近的冰川消失后，塞利格湖及其支流一直属于伏尔加盆地；在重建伏尔加河径流和接收水体（里海）的水平衡时要考虑到这一点。