Crumpling of the crust above a sinking dense mantle layer, which is underneath central Europe, triggered the formation of the eastern Alps and the Carpathian mountains, and its surroundings were stretched to form the Pannonian Basin.
The Pannonian Basin is a marked topographic low in central Europe, surrounded on all sides by mountain ranges. Basin formation was thought to have been initiated by stretching of one plate as the neighbouring plate progressively sank (subducted) into the mantle. A recent study proposes instead that simultaneous stretching and contraction, triggered by the collapse of previously over-thickened crust, and consequent sinking of the underlying mantle layer can explain the region's unusual topography.
Gregory Houseman and Lykke Gemmer of the University of Leeds, UK, used a numerical model to simulate the deformation of a lithospheric block with an unusually thick crust in one region1. Collapse of the thick part of the crust induces sinking of the underlying dense lithospheric mantle. The crust immediately above is dragged along and buckles up to form a peripheral mountain range. As the warmer and more buoyant mantle comes up, the crust encircled by the mountains is stretched and becomes thinner. In the Pannonian Basin region, the differential stretching of crust and mantle layers is better predicted by these suggested processes than by the subduction explanation.
Deep earthquakes occurring beneath the southeast Carpathian Mountains may delineate the still-sinking lithospheric mantle.
References
Houseman, G. A., & Gemmer, L. Intra-orogenic extension driven by gravitational instability: Carpathian-Pannonian orogeny. Geology 35, 1135–1138 (2007).
Rights and permissions
About this article
Cite this article
Bondre, N. Stretching the crust. Nature Geosci (2007). https://doi.org/10.1038/ngeo.2007.72
Published:
DOI: https://doi.org/10.1038/ngeo.2007.72
