1. klippe 2. nappe 3. window
gray = allochthon (thrusted), brown = autochthon (in situ)
A thrust fault is a special case of low dip-angle fault that formed during regional compressional deformation. The folds associated with nappes are sheared to such an extent that they fold back over on themselves and break apart, producing large-scale recumbent folds of the hanging wall block.
The underlying autochthonous (original, in-place) rocks are visible in tectonic windows beneath nappes when erosion removes the allochthonous rocks of the nappe. An isolated island of allochthonous nappe rock surrounded by autochthonous rock is termed a klippe.
Nappes or nappe belts arose during the complex tectonic history of the European Alps. The Austroalpine nappes of the eastern Alps comprise three thrust faulted nappe stacks that lie atop three older Penninic nappes [Subalpine nappes].
◙ subduction zone magmas ◙
[links: images: formations: nappe: folds in the Musconetcong Nappe within the Reading Prong nappe megasystem in Lehigh County; unconformity between coarse basal breccia-conglomerate and the underlying Quarff Nappe metasediments; Morcles nappe; overturned folds in the Liassic limestone and marls of the Helvetic Doldenhorn Nappe, Ferdenrothorn, 3180 m (Loetschental Mountains between the Bernese Oberland and Valais); Flysch turbidite of the Ligurian nappe (constructed of "olistrostromes", undersea landslides), and another overturned turbidite of the Ligurian nappe, siliclastic in the lower (younger) layer, carbonate in the upper (older) layer; the upper part of the Matterhorn is a fragment of Africa, and the lower part is the Jurassic Tethys oceanic crust (Zermatt-Saas ophiolite (lower photo) including pillow lavas and serpentinite bodies (foreground knob on left); klippe: Chief Mountain klippe; Cam Loch klippe; klippe, Salto de gitano; klippe; Carrancas Klippe, Andrelândia Sequence, Minas Gerais; limestone klippe, near Nowy Targ, erosional remnant of a thrust sheet that rests on younger flysch deposits; petrology: eclogites (resulting from prograde metamorphic history of garnet growth during subduction of the oceanic crust) are common in both the Zermatt-Saas complex and older units such as the Sesia nappe (SE) and reflects sections of African continental margin, and HP granitic rocks, including jadeite- and phengite-bearing granites (and relict biotite) in the Sesia nappe; closure of the Donara nappe at the metamorphic core of the Himalaya and Karakoram; Viyazón-Reigada Syncline, Somiedo nappe; maps: 3D topographic/bathymetric render looking down on the Alps from the NW into the Mediterranean Sea and northern Africa (upper). Prior to opening of the Mediterranean, the Apulian plate ("Africa") was thrust onto Europe in the late Mesozoic to early Cenozoic, forming the HP-UHP terranes of the Alps, as well as Greece (upper left) - geological map; geologic map of the Gades Cove geologic window, created as the Great Smoky Thrust Fault was eroded; Map of Cam Loch klippe]