- Lepontin dome
The Lepontine dome or Lepontin dome is a region of
tectonic uplift in the Swiss part of theAlps . It is located in theLepontine Alps andGlarus Alps .The Alps north of the
Periadriatic Seam are usually divided into three largenappe complexes. From bottom to top these are the Helvetic, Penninic andAustroalpine nappes . East of the dome all three are found on top of each other. The same counts for the region west of the dome, if theSesia unit is seen as part of the Austroalpine nappes. The dome itself however only shows Penninic and Helvetic (the boundary between the two is still disputed) rocks. Apparently the uplift of the dome caused the upper Austroalpine material to be totally eroded away.The creation of the dome was caused by a phase of east-west directed extension in the
Miocene that occurred throughout the Eastern and Central Alps. This extensional phase was probably a result ofslab detachment in the upper mantle. Similar large extensional structures appear in more places in the Alps, examples are theHohe Tauern window and the smaller Engadin andRechnitz window s.
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