Window (geology)

As a window or tectonic window, an exposed by erosion or horizontal crustal movements ( open-minded ) part of the subsurface tectonic ceiling is called in the geology. They often occur in those fold mountains like the Alps, whose structure is ( tectonics ) strongly influenced by thrust faults.

Geological construction

Such windows appear as holes or gaps revealed in a spacious thrust sheet, with the underlying underground - mostly elderly - rocks on the false ceiling emerge. This one originally higher -lying part of the earth's crust is visible amidst originally deeper rocks and formations.

The rocks in the window are therefore tectonically deeper ( tectonically Lying ) as their confining units and are completely out of tectonically higher-lying rocks ( tectonic hanging wall ) surrounded. They thus allow through a window insight into the geological subsurface. Most of the older rocks are pushed over younger, only in special geological situations, this is reversed.

From a half-window is when this digestion of the substrate is not surrounded on all sides by the rocks of the ceiling.

The counterpart to the geological window is the Tectonic cliff. The distance between a cliff and a window specifies the minimum thrust length.

Examples from the Eastern Alps

In mountains - especially young fold mountains - you can find many windows in valleys or in the core of anticlines ( calipers ).

The two largest window in the Eastern Alps are the Lower Engadine Window (Eastern ) and the Tauern Window (Salzburg / Carinthia ). Smaller windows are in the West, among others Vättner the window and the Gargellenfenster, in the east window and the Semmering to the Hungarian border the Rechnitz window.

Gases and mineral sources

In the window, a geologically significant erosion gap in the otherwise impermeable gneiss and granite layer, gases can permeate from inside the earth through cracks and soft shale upward, mix with the groundwater, thus forming mineral springs. Examples are the 25 mineral springs in radius along the Engadine Scuol (fault ) line of the Lower Engadine window or mineral source of Bad Ragaz when Vättner window.