Vein-controlled boudin segment separation (Spitz-Marble, Austria)
- Author(s)
- Fiona Gašparac, Bernhard Grasemann, Marcin Dąbrowski
- Abstract
Boudinage, a common feature in extended competent layers, is primarily controlled by the mechanical contrast between the layer and its surrounding host rock. Recent numerical modelling has demonstrated that the aperture of veins precipitated between the inter-boudin surfaces of adjacent segments influences both the evolving boudin geometry and the degree of segment separation. This study examines natural aplite boudins from an abandoned quarry near Spitz an der Donau (Bohemian Massif, Austria) to quantify their segment aspect ratios ( A ) and the normalized initial gap widths ( B ) of quartz veins separating the segments. The objective is to assess the influence of parameters A and B on boudin shape and segment separation, and to provide natural examples that complement previous numerical investigations. Consistent with model predictions, no statistically significant correlation was found between aspect ratio A and boudin shape. In contrast, the calculated B -values qualitatively show a strong influence on both boudin geometry and segment separation, supporting numerical results that suggest larger B -values promote more efficient separation. Additionally, small B -values favour the development of a central convex bulge on the otherwise concave inter-boudin surface, a feature documented here for the first time in natural examples. However, the findings indicate that using boudins as strain gauges to estimate background extension is challenging and yields only minimum strain values. The observed variability in initial inter-boudin gap widths within a single dyke, along with evidence of internal foliation predating segment separation, suggests that both the standard and strain reversal methods may substantially underestimate extensional strain.
- Organisation(s)
- StudiesServiceCenter Earth Sciences, Geography and Astronomy, Department of Geology
- External organisation(s)
- Polish Geological Institute (PGI)
- Journal
- Journal of Structural Geology
- Volume
- 209
- ISSN
- 0191-8141
- DOI
- https://doi.org/10.1016/j.jsg.2026.105718
- Publication date
- 08-2026
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 105124 Tectonics
- Keywords
- ASJC Scopus subject areas
- Geology
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/8950e52b-b791-421f-bd3a-a9caca9331de