Buried Quaternary valleys in the south-western Baltic Sea (BurVal-Baltic)

本项目旨在了解构造对隐谷演化的控制作用。隐谷（冰下河道）是指冰川地形在前第四纪沉积记录中切割出的深沟槽状特征。这些切割和填充结构在最近的研究中一直是激烈争论的问题，因为它们拥有大量的地下水供应，它们含有用于建筑的骨料，并且通常具有最完整的冰川地质过程和古气候条件的沉积记录。它们的形成一般归因于冰川覆盖时期冰下融水输送切割下伏地层。几位作者注意到隐伏山谷与下方构造断层之间的空间相关性；然而，一个主要的因果关系从未建立。对于建议的研究，我们拥有一个密集的剖面网格，包括来自波罗的海西南部约20,000公里的多通道和约6,000公里的参数沉积物回声测深数据。这些数据首次允许在盆地范围内研究隐伏谷的演化，通过数据解决了详细的山谷和山谷填充几何形状，以及断层和褶皱在后二叠纪演替下。根据对一些剖面的初步解释，我们提出了以下工作假设：1)后二叠纪演替被丰富的近垂直断层所分割。(2)第四纪近垂直断裂中最大、最密集的是宽几公里、高10米左右的背斜。3)在某些情况下，观察到的断层-背斜组合与垂直流体运移有关。(4)断裂-背斜演化促进了隐谷的切割，从而在空间上控制了隐谷的切割。(5)近垂直断裂及其伴生背斜主要是冰荷构造作用的结果。我们将通过地震解释来接近这些假设。假设1-4将通过对埋藏谷、垂直断层和背斜附近以及流体地震指标的系统测绘和量化来检验。冰荷载诱发构造的概念是基于以前发表的，而不是局部的研究。关于这一概念，这里提出的项目是量化（冰荷载引起的）近代构造及其在盆地范围内第四纪地质意义的第一步和关键一步。如果这些假设成立，所得到的模式有可能影响所有暂时被冰覆盖的高纬度地区的第四纪研究。横切二叠纪后地层的近垂直断层的预期丰度代表了可能的流体运移路径，这将成为包括地下水循环模型在内的所有应用的重要限制。

This project strives for understanding the tectonic control on Buried Valley evolution. Buried Valleys (subglacial channels) are defined as deep channel-form features incised into the pre-Quaternary sedimentary record from glaciated terrains. These cut and fill structures have been a matter of intense debate in recent studies as they hold significant supplies of groundwater, they contain aggregate for construction and typically have a most complete sedimentary record of glacial geological processes and paleo-climate conditions. Their formation is generally attributed to subglacial melt-water transport incising the underlying strata during periods of glacial coverage. Several authors noticed a spatial correlation between Buried Valleys and tectonic faults beneath; however, a principle causative correlation was never established. For the suggested study we hold a dense profile grid comprising ca. 20.000 km of multi-channel and ca. 6.000 km of parametric sediment echosounder data from the south-western Baltic. These data allow for the first time a study of Buried Valley evolution on a basin wide scale by means of data that resolve both the detailed valley and valley fill geometry as well as faults and folds within the Post-Permian succession beneath. According to a preliminary interpretation of some profiles we elaborated the following working hypotheses to be tested: 1) The Post-Permian succession has been dissected by abundant near vertical faults. 2) The largest and most densely spaced Quaternary near vertical faults are associated with few kilometers wide and some 10 m high anticlines. 3) In some instances the observed fault-anticline assemblages are associated with vertical fluid migration. 4) The fault-anticline evolution facilitated and thus spatially controlled the incision of Buried Valleys. 5) The near vertical faults and associated anticlines result mainly from ice-load induced tectonics. We will approach these hypotheses by seismic interpretation. Hypotheses 1-4 will be tested by systematic mapping and quantification of Buried Valleys, near vertical faults and anticlines as well as seismic indicators for fluids. The ice-load induced tectonic concept is based on previously published, but rather local studies. Regarding this concept the here proposed project is a first and crucial step to quantify (ice-load induced) recent tectonics and its meaning for Quaternary geology on a basin wide scale. If the hypotheses hold, the resulting models bear the potential to influence Quaternary research in all regions of high latitudes which were temporally ice-covered. The expected abundance of near vertical faults which cross-cut the post-Permian strata represent possible fluid migration paths, which would represent important constrains for all applications which include models about ground water circulation.