Late Cenozoic tectonic evolution of the western Eger Rift

波希米亚西北部的Eger裂谷和Cheb盆地与地震群、大量CO2释气和第四纪幔源火山作用有关。一阶构造关系表明，切布盆地的主断裂——北北西向的Marianske Lazne断裂（MLF）与埃格尔裂谷呈直角相交，并以正常运动感为主与之相抵消。这些关系表明，在裂谷历史的后期（大约上新世早期），MLF上的活动加剧，反映了控制应力场的根本变化。我们建议限制两个盆地的构造演化，特别是在晚新生代的Krusne Hory （Erzgebirge）和Marianske Lazne边界断裂。这将通过从地层资料中模拟盆地的沉降来完成。低t热年代学，特别是磷灰石（AHe）上的(U-Th)/He，将限制裂谷肩隆升、掘出和断层偏移。沉降和挖掘数据必须与Eger裂谷- cheb盆地连接处的三维可恢复结构模型相匹配，从而限制大断裂的深层结构。基于高分辨率数字高程模型（dem）的构造地貌分析，并辅以地面真相和断层滑动分析，将用于探测较小规模的分布式断层。这些数据以及我们在捷克合作项目中从分布地震活动中得到的数据将与结构模型在不同运动方向下预测的应变模式进行比较。MLF的这种运动学变化将通过详细的地貌学和古地震学调查来破译，这也是捷克项目的一部分。这两个项目的结果将结合在中新世到近代演化的详细构造模型中。这个模型也将有助于理解流体上升和地震群的现今定位。

The Eger Rift and Cheb basin in northwestern Bohemia are associated with earthquake swarms, voluminous CO2 outgassing and Quaternary mantle-derived volcanism. First-order structural relationships indicate that the NNW-striking Marianske Lazne Fault (MLF), the master fault of the Cheb basin, has cross-cut the Eger rift at right angles and offset it with dominantly normal sense of motion. These relationships suggest that activity on the MLF was accentuated late in the history of the rift - around early Pliocene time -, reflecting a fundamental change of the governing stress field. We propose to constrain the tectonic evolution of the two basins, and in particular of the Krusne Hory (Erzgebirge) and Marianske Lazne bounding faults over Late Cenozoic time. This will be done by modelling the subsidence of the basins from stratigraphic data. Rift shoulder uplift, exhumation and fault offsets will be constrained by low-T thermochronology, especially (U-Th)/He on apatite (AHe). Subsidence and exhumation data must be matched by a 3D, restorable structural model of the Eger Rift-Cheb basin junction, thus constraining the deep architecture of the large faults. Tectonic geomorphologic analysis based on high-resolution digital elevation models (DEMs) and complemented by ground truthing and fault-slip analysis will be used to detect smaller-scale, distributed faulting. These data as well as those derived from distributed seismicity in our Czech companion project are to be compared to strain patterns predicted by the structure model under varying movement directions. Such kinematic variations for the MLF will be deciphered by detailed geomorphological and paleoseismological investigations that are also part of the Czech project. The results of both projects will be combined in a detailed tectonic model of the evolution in Miocene through Recent time. This model will also help to understand the present-day localisation of fluid ascent and earthquake swarms.