We report the results of a numerical modelling study based on folds in the western Northern Calcareous Alps (NCA) fold-and-thrust belt. We study boundary conditions of folding based on the mechanical properties of the rocks involved. One key control on the model is stratigraphy that can be simplified to three layers: (1) an incompetent base along the décollement of the thrust sheet, and (2) an up to 3 km thick competent layer, which is overlain by (3) an incompetent top layer. The incompetent base layer needs to be very weak to facilitate folding and is a salt-bearing evaporitic unit. Another key is erosion prior to folding. It needs to remove half of the competent layer to allow the creation of folds with limb lengths comparable to field observations. The results of the numeric model contribute to the understanding of the structural development in the western NCA. Folding within the upper thrust sheet was only possible above a salt-bearing décollement and after a decrease in lithostatic pressure related to Upper Cretaceous and/or Paleogene erosion.

我们报告了基于西部北钙质阿尔卑斯山 (NCA) 褶皱冲断带褶皱的数值模拟研究结果。我们根据所涉及的岩石的力学特性研究折叠的边界条件。该模型的一个关键控制是地层学，它可以简化为三层：(1) 沿推力片脱层的无能基底，以及 (2) 厚达 3 公里的有能力层，由 (3) 覆盖无能的顶层。无能的基层需要非常弱以促进折叠并且是含盐蒸发单元。另一个关键是折叠前的侵蚀。它需要去除一半的主管层，以允许创建具有与现场观察相当的肢体长度的褶皱。数值模型的结果有助于理解NCA西部的结构发展。上冲断层内的褶皱只有在含盐层上方和与上白垩纪和/或古近系侵蚀相关的岩石静压降低之后才有可能发生。