Geomorphology and sedimentology of features formed at the outlet during the final drainage of the Baltic Ice Lake
Geomorphology and sedimentology of features formed at the outlet during the final drainage of the Baltic Ice Lake
复制标题
波罗的海冰湖最终排水过程中出口处形成的地貌和沉积学特征
作者：
Mark D. Johnson;C. Öhrling;Adrian Bergström;Oskar Dreyer Isaksson;Emma Pizarro Rajala
我们提出了一个概念模型的性质的11.6卡尔。ka BP排水的波罗的海冰湖在出口地区的基础上，一个新的地貌图以及新的沉积信息。我们结合联合收割机这一新的信息与审查以前的工作在这一充分研究的领域。该模型包括了先前工作者提出的在Lången山谷残留冰的前提，并表明排水开始于冰下。以前被解释为海滩沉积物的东北比林根卵石沉积物被解释为冰下滞留存款。蒂默斯达拉的山脊由排水初期的排水沉积物组成，沉积在一个冰下隧道中，该隧道通向克利夫塔蒙中部。持续的排水使隧道因摩擦融化而变宽，最终使冰上升并破裂。在排水事件期间，Klyftamon中部和南部形成了悬垂杆、膨胀杆和巨石片。砂坝中的卵石和巨砾排水沉积物，质量大且分选差，是从含泥沙的水中沉积的推移质。叠瓦作用、砂坝方向、粒度变化和寒武纪碎屑含量表明流向西北偏西。沙洲中的大部分沉积物来自于克里夫塔蒙的侵蚀，但存在来自比林根的寒武纪岩石，直接由洪水沃茨和/或来自破碎的残余冰的富含碎片的冰山。该洪水事件与其他第四纪特大洪水的区别在于沉积物供应有限，并且具有短的陆上洪水通道（20 km）。
We present a conceptual model for the character of the 11.6 cal. ka BP drainage of the Baltic Ice Lake in the outlet area based on a new geomorphological map as well as new sedimentological information. We combine this new information with a review of the previous work on this well‐studied area. The model includes the premise of remnant ice in the Lången valley as suggested by previous workers and indicates the drainage began subglacially. Cobbly sediment on northeast Billingen formerly interpreted as beach sediment is interpreted to be a subglacial lag deposit. The ridge at Timmersdala is composed of drainage sediment from the initial phases of the drainage, deposited in a subglacial tunnel that emptied out on to central Klyftamon. Continued drainage widened the tunnel by frictional melting, eventually lifting and fracturing the ice. Pendant bars, expansion bars and boulder sheets on central and southern Klyftamon formed during the drainage event. Cobbly and bouldery drainage sediment in the bars, which is massive and poorly sorted, was deposited as bedload from sediment‐charged water. Imbrication, bar orientation, and changes in grain size and Cambrian‐clast content indicate flow to the west–northwest. Most sediment in the bars was derived from erosion on Klyftamon, but Cambrian rock from Billingen is present, delivered directly by the flood waters and/or from debris‐rich icebergs from the broken‐up remnant ice. This flood event is distinguished from other Quaternary megafloods by being sediment‐supply limited and having a short, subaerial floodway (20 km).