The Exhumation of Eclogite-Facies Metamorphic Rocks-a Review of Models Confronted with Examples from the Alps

Abstract

We summarize recently proposed models for the exhumation of (ultra-) high pressure ([U]HP) metamorphic units within collisional orogens. In terms of mechanics, exhumation is either caused by buoyancy or by externally applied stresses. In terms of kinematics, exhumation is either by erosion, extension, or extrusion. The tectonic scenarios that may lead to the exhumation of (U)HP units are: (1) flow within a low-angle or high-angle corner; (2) entrance of the continental margin into the subduction zone; (3) cessation of subduction; (4) slab breakoff; (5) extension in the backarc; and (6) serpentinization of the mantle wedge. The applicability of these models are discussed for some (U)HP terrains in the Alps, in particular the Koralm Complex of the Austroalpine Unit, and the Internal Penninic Nappes of the Eastern, Central, and Western Alps, (in particular, the Eclogite Zone, the Adula Nappe, and the Monte Rosa Nappe). Within the Austroalpine Koralm Complex of the Eastern Alps, the exhumation of HP rocks see...