Nappejes

Nappejes is a term that refers to a geological structure formed by the overthrusting of large masses of rock over underlying rock. These structures are typically found in compressional tectonic regimes, such as those associated with continental collision or the formation of mountain ranges. The overthrusting can occur along a low-angle fault plane, known as a thrust fault, causing the upper block (the nappe) to slide significant distances over the lower block.

Nappes can be composed of sedimentary, metamorphic, or igneous rocks and can vary greatly in size, from a few kilometers to hundreds of kilometers in extent. The formation of nappes often involves complex folding and deformation of the rock layers within the nappe. Erosion can subsequently expose the underlying rocks, revealing the distinct geological units that have been juxtaposed by the thrusting event.

The study of nappes is crucial for understanding the tectonic history and evolution of mountain belts. Evidence for nappes includes the repetition of rock strata, the presence of fault zones with characteristic deformation features, and the displacement of rock units that were originally deposited in different environments. Prominent examples of regions with extensive nappe structures include the Alps, the Himalayas, and the Appalachians. The recognition and interpretation of nappes have significantly advanced the field of structural geology.