Late Cretaceous exhumation history of an extensional extruding wedge (Graz Paleozoic Nappe Complex, Austria)

Late Cretaceous structures within the eastern Graz Paleozoic Nappe Complex define an extruding wedge with north-eastward directed thrusting in eastern portions and strike-slip shear along the margins. Stacking structures are overprinted by south-westward directed extension with low-grade metamorphic rocks in the hangingwall and high-grade basement rocks in the footwall. Pressure–temperature and structural data are obtained from successively opening quartz veins that record various stages of progressive deformation and metamorphism. Fluid inclusion data and related structures show that during extension isothermal decompression from ca. 550°C and 8 kbar down to ca. 450°C and 2 kbar was related to exhumation of rocks from deep crustal levels. The data point to a high geothermal gradient and explain condensed paleo-isotherms due to ductile normal faulting in the eastern areas of the Graz Paleozoic Nappe Complex. The investigated Late Cretaceous structural elements suggest that the Graz Paleozoic Nappe Complex decoupled from the surrounding basement units and operated as a large-scale extension–extrusion corridor that evolved prior to Miocene extrusion tectonics in the Eastern Alps.     

Das Altpaläozoikum und Unterkarbon des Gurktaler Deckensystems (Ostalpen) und ihre paläogeographischen Beziehungen

The Paleozoic sequences of the Gurktal nappe (Eastern Alps) can be divided into two tectonic units by means their facies development: (1) The lower Murau nappe is characterized by low grade metamorphic black schists, calcareous phyllites of predominantly Silurian age (?) and some hundred meters of carbonates of predominantly Lower Devonian age. (2) The higher Stolzalpe nappe, metamorphosed very low to low grade, contains Ordovician to Lower Silurian volcanic formations. There can be recognized three facies during Upper Silurian to Lower Devonian times. The higher Devonian to Lower Carboniferous is dominated by more or less pelagic carbonates. After the facies distribution of Paleozoic rocks other parts of southern Austroalpine show a similar tectonic feature. The Stolzalpe nappe is related to the upper nappes of Austroalpine (i. e. Noric nappe system, northern parts of Paleozoic of Graz) and also western Carnics. The clastic and carbonate complexes of Murau nappe, Schöckel nappe s. 1. (Paleozoic of Graz) and Murides crystalline (middle Austroalpine) are developed very similar. Some features of Paleozoic fades distribution show a NE to SW trend crossing the alpidic structure. Because of conglomerates with crystalline components near the base is postulated a preUpper Ordovician basement complex for this realm.     

Internal structural geometry of the Paleozoic of Graz

The Paleozoic of Graz is an isolated nappe complex of about 1,500 km² size and belongs to the Austroalpine units of the eastern European Alps. Despite more than 500 publications on stratigraphy, paleontology and local structure, many aspects of the internal geometry of this complex as a whole remained unclear. In this contribution, we present integrated geological profiles through the entire nappe complex. Based on these profiles, we present (1) a simplified lithological subdivision into 13 rock associations, (2) a modified tectonostratigraphy where we consider only two major tectonic units: an upper and a lower nappe system and in which we abandon the traditionally used facies nappe concept, and (3) a modified paleogeography for the whole complex. Finally, we discuss whether the internal deformation of the Paleozoic of Graz is of Variscan or Eo-Alpine age and which of the published models best explain the tectonic evolution of the Paleozoic of Graz.     

Re-imbrication of the Hawasina allochthons in the Sufrat ad Dawh range,Oman Mountains

The Hawasina complex consists of deformed slope to basinal sedimentary rocks of Mesozoic age, emplaced on the Arabian continental margin in the Late Cretaceous as a series of nappes. This complex is well exposed in the Sufrat ad Dawh range where it is represented by the Hamrat Duru Group and the Wahrah Formation. Two generations of imbricate faults are recognized in this area. The first is the imbrication of the Hamrat Duru and the Wahrah units into two separate nappes. These nappes were then folded and cross-cut by a second set of imbricate faults, resulting in the systematic tectonic repetition of the Wahrah-Hamrat Duru Nappe stratigraphy. The late-stage faulting event correlates with the origin of re-imbrication structures documented from other parts of the Oman orogen, interpreted to be of a post-emplacement, Early Tertiary age. This implies that Tertiary deformation of the Oman allochthons was expressed at least in part as a continuation of nappe development, initiated during the Late Cretaceous orogeny.     

Thermal evolution of an extensional detachment as constrained by organic metamorphic data and thermal modeling: Graz Paleozoic Nappe Complex (Eastern Alps)

Following Early Cretaceous nappe stacking, the Eastern Alps were affected by late-orogenic extension during the Late Cretaceous. In the eastern segment of this range, a Late Cretaceous detachment separates a very low- to low-grade metamorphic cover (Graz Paleozoic Nappe Complex, GPNC) above a low- to high-grade metamorphic basement. Synchronously, the Kainach Gosau Basin (KGB) collapsed and subsided on top of the section.Metamorphism of organic material within this section has been investigated using vitrinite reflectance data and Raman spectra of extracted carbonaceous material. In the southern part of the GPNC, vitrinite reflectance indicates a decrease in organic maturity towards the stratigraphic youngest unit. The remaining part of the GPNC is characterized by an aureole of elevated vitrinite reflectance values and Raman R2 ratios that parallels the margins of the GPNC. Vitrinite reflectance in the KGB shows a steep coalification gradient and increases significantly towards the western basin margin. The observed stratigraphic trend in the southern GPNC is a result of deep Paleozoic to Early Cretaceous burial. This maturity pattern was overprinted along the margins by advective heat and convective fluids during Late Cretaceous to Paleogene exhumation of basement rocks.During shearing, the fault zone was heated up to ca. 500 °C. This overprint is explained by a two-dimensional thermal model with a ramp-flat fault geometry and a slip rate of 1 to 1.5 cm/year during 5 Ma fault movement. The collapse basin above the detachment subsided in a thermal regime which was characterized by relaxing isotherms.     

Structural evolution of a nappe complex,southern Vanoise massif,French Penninic Alps

The Arpont-Parrachée region in the southern Vanoise massif comprises a stack of minor fold- and thrust-nappes that were emplaced during subduction and closure of the Piémont ocean basin in Late Cretaceous to Eocene time. The stack includes the Arpont nappe, composed mainly of pre-Permian schist metamorphosed to blueschist facies early in the Alpine history, and several sheets of Permian to Eocene metasedimentary rocks. Nappe formation, recumbent folding, and associated ductile deformation postdated the high-pressure metamorphic peak, and probably involved translation to the northwest. The rocks were then refolded by large- and small-scale folds trending roughly E-W. These deformational events were accompanied by a decrease in metamorphic pressure, indicating uplift. They were followed by regional greenschist-facies metamorphism, which caused breakdown of high-pressure parageneses, annealing of microstructures, and widespread growth of albite porphyroblasts. The entire nappe pile was then refolded by large- and small-scale folds overturned towards the southeast. Reorientation of small-scale structures with increasing strain by this event indicates a large component of ESE-directed shear, which culminated in the formation of anastomosing ductile shear-zones.     

Position of the Blyb Complex in the pre-Mesozoic crustal structure of the Front Range Zone in the Northern Caucasus

A number of Variscan nappe complexes were recognized in the Late Mesozoic structure of the Front Range Zone of the Greater Caucasus in the 1970s. They consist predominantly of greenstone units and override one another in a consecutive order. The only exception is the upper, Atsgara Nappe, which is composed of crystalline schists, amphibolites, and microgneisses. Crystalline schists, gneisses, amphibolites, and other rocks of the so-called Blyb Complex occur at the base of the nappe packet. The affinity of crystalline rocks of the Blyb Complex to one of the upper Variscan nappes is substantiated in this paper. The Middle Paleozoic rocks, which originally were located below the Blyb Complex in the Front Range structure, overrode its rocks along the surface of the Blyb Thrust Fault in the Early Triassic. Since that time, the crystalline rocks of the Blyb Complex have occupied the lowermost position in the structure of the Front Range. The absence of Upper Paleozoic rocks in the footwall of the thrust fault is due to the fact that, in the Late Paleozoic, the area underlain by the Blyb Complex was an inlier and a source of clastic material. The hanging wall of the Blyb Thrust Fault may be traced farther southward into the Main Range Zone, where it most likely consists of the Laba Group and other rocks. As has been established previously, the lower portion of the Laba Group consists of analogues of the Middle Paleozoic successions of the Front Range Zone, while its upper portion consists of crystalline schists of the Lashtrak Nappe, which occupy a position similar to that of the Atsgara Nappe metamorphic rocks. These relationships suggest that the rock complexes of the Front Range Zone could have undergone repeated displacements due to post-Variscan (Indosinian) tectonic events and overrode crystalline rocks in the Main Range Zone and more easterly areas. Owing to the uplift of the Central Caucasus, they are now eroding. The difference in the metamorphic grade of the Blyb Complex and the rocks of the Atsgara and Marukha nappes is due to the fact the Blyb Complex lies close to the root zones of nappes or belongs to different nappe sheets. The Blyb Thrust Fault pertains to the Indosinian faults that played the main role in the formation of the Front Range structure.     

Deformation history of the ophiolite sequence from the Balagne Nappe,northern Corsica: insights in the tectonic evolution of Alpine Corsica

In Alpine Corsica, the Jurassic ophiolites represent remnants of oceanic lithosphere belonging to the Ligure‐Piemontese Basin located between the Europe/Corsica and Adria continental margins. In the Balagne area, a Jurassic ophiolitic sequence topped by a Late Jurassic–Late Cretaceous sedimentary cover crops out at the top of the nappe pile. The whole ophiolitic succession is affected by polyphase deformation developed under very low‐grade orogenic metamorphic conditions. The original palaeogeographic location and the emplacement mechanisms for the Balagne ophiolites are still a matter of debate and different interpretations for its history have been proposed. The deformation features of the Balagne ophiolites are outlined in order to provide constraints on their history in the framework of the geodynamic evolution of Alpine Corsica. The deformation history reconstructed for the Balagne Nappe includes five different deformation phases, from D1 to D5. The D1 phase was connected with the latest Cretaceous/Palaeocene accretion into the accretionary wedge related to an east‐dipping subduction zone followed by a Late Eocene D2 phase related to emplacement onto the Europe/Corsica continental margin. The subsequent D3 phase was characterized by sinistral strike‐slip faults and related deformations of Late Eocene–Early Oligocene age. The D4 and D5 phases were developed during the Early Oligocene–Late Miocene extensional processes connected with the collapse of the Alpine belt. Copyright © 2003 John Wiley & Sons, Ltd.     

Polyphase late Palaeozoic deformation in the southeastern foreland and northwestern Piedmont of the Alabama Appalachians

Late Palaeozoic deformation in the southern Appalachians is believed to be related to the collisional events that formed Pangaea. The Appalachian foreland fold and thrust belt in Alabama is a region of thin-skinned deformed Palaeozoic sedimentary rocks ranging in age from Early Cambrian to Late Carboniferous, bounded to the northwest by relatively undeformed rocks of the Appalachian Plateau and to the southeast by crystalline thrust sheets containing metasedimentary and metaigneous rocks ranging in age from late Precambrian to Early Devonian. A late Palaeozoic kinematic sequence derived for a part of this region indicates complex spatial and temporal relationships between folding, thrusting, and tectonic level of décollement. Earliest recognized (Carboniferous(?) or younger) compressional deformation in the foreland, observable within the southernmost thrust sheets in the foreland, is a set of large-scale, tight to isoclinal upright folds which preceded thrafing, and may represent the initial wave of compression in the foreland. Stage 2 involved emplacement of low-angle far-traveled thrust sheets which cut Lower Carboniferous rocks and cut progressively to lower tectonic levels to the southwest, terminating with arrival onto the foreland rocks of a low-grade crystalline nappe. Stage 3 involved redeformation of the stage 2 nappe pile by large-scale upright folds oriented approximately parallel to the former thrusts and believed to be related to ramping or imbrication from a deeper décollement in the foreland rocks below. Stage 4 involved renewed low-angle thrusting within the Piedmont rocks, emplacement of a high-grade metamorphic thrust sheet, and decapitation of stage 3 folds. Stage 5 is represented by large-scale cross-folding at a high angle to previous thrust boundaries and fold phases, and may be related to ramping or imbrication on deep décollements within the now mostly buried Ouachita orogen thrust belt to the southwest. Superposed upon these folds are stage 6 high-angle thrust faults with Appalachian trends representing the youngest (Late Carboniferous or younger, structures in the kinematic sequence.     

The Ust-Belaya ophiolite terrane,West Koryak Orogen: Isotopic dating and paleotectonic interpretation

The Ust-Belaya ophiolite terrane in the West Koryak Orogen, which is the largest in northeastern Asia, consists of three nappe complexes. The upper Ust-Belaya Nappe is composed of a thick (>5 km) sheet of fertile peridotites and mafic rocks (remnants of the proto-Pacific lithosphere); its upper age boundary is marked by Late Neoproterozoic plagiogranites. In the middle Tolovka-Otrozhny Nappe, the Late Precambrian lherzolite-type ophiolites are supplemented by fragments of tectonically delaminated harzburgite-type ophiolites, which make up the Tolovka rock association. The isotopic age of metadacite (K-Ar method, whole-rock sample) and zircons from plagiogranite porphyry (U-Pb method, SHRIMP) determines the upper chronological limit of the Tolovka ophiolites as 262–265 Ma ago. It is suggested that igneous rocks of these ophiolites were generated in a backarc basin during the Early Carboniferous and then incorporated into the fold-nappe structure in the Mid-Permian. This was the future basement of the Koni-Taigonos arc, where the Early Carboniferous ophiolites together with Late Neoproterozoic precursors were subject to low-temperature metamorphism and intruded by plagiogranite porphyry dikes in Permian-Triassic. The polymicte serpentinite mélange, which was formed in the accretionary complex of the Koni-Taigonos arc comprises rock blocks of the upper units of Late Precambrian ophiolites (in particular, plagiogranite), the overlying Middle to Upper Devonian and Early Carboniferous deposits, as well as Early Carboniferous (?) Tolovka ophiolites and meta-ophiolites. Mélange of this type with inclusions of Late Precambrian “oceanic” granitoids also developed in the lower Utyosiki Nappe composed of Middle Jurassic-Lower Cretaceous sedimentary and volcanic sequences, the formation of which was related to the next Uda-Murgal island-arc systems.     

Initial tectonothermal evolution within the Scandinavian Caledonide Accretionary Prism: constraints from 40Ar/39Ar mineral ages within the Seve Nappe Complex, Sarek Mountains, Sweden

In the Caledonide orogen of northern Sweden, the Seve Nappe Complex is dominated by rift facies sedimentary and mafic rocks derived from the Late Proterozoic Baltoscandian miogeocline and offshore-continent–Iapetus transition. Metamorphic breaks and structural inversions characterize the nappe complex. Within the Sarek Mountains, the Sarektjåkkå Nappe is composed of c. 600-Ma-old dolerites with subordinate screens of sedimentary rocks. These lithological elements preserve parageneses which record contact metamorphism at shallow crustal levels. The Sarektjåkkå Nappe is situated between eclogite-bearing nappes (Mikka and Tsäkkok nappes) which underwent high-P metamorphism at c. 500 Ma during westward subduction of the Baltoscandian margin. ⁴⁰Ar/³⁹Ar mineral ages of c. 520–500 Ma are recorded by hornblende within variably foliated amphibolite derived from mafic dyke protoliths within the Sarektjåkkå Nappe. Plateau ages of 500 Ma are displayed by muscovite within the basal thrust of the nappe and are consistent with metamorphic evidence which indicates that the nappe escaped crustal depression as a result of detachment at an early stage of subduction. Cooling ages recorded by hornblende from variably retrogressed eclogites in the entire region are in the range of c. 510–490 Ma and suggest that imbrication of the subducting miogeocline was followed by differential exhumation of the various imbricate sheets. Hornblende cooling ages of 470–460 Ma are recorded from massive dyke protoliths within the Sarektjåkkå Nappe. These are similar to ages reported from the Seve Nappe Complex in the central Scandinavian Caledonides. Probably these date imbrication and uplift related to Early Ordovician arrival of outboard terranes (e.g. island-arc sequences represented by structurally lower horizons of the Köli Nappes). Metamorphic contrasts and the distinct grouping of mineral cooling ages suggest that the various Seve structural units are themselves internally imbricated, and were individually tectonically uplifted through argon closure temperatures during assembly of the Seve Nappe Complex. The cooling ages of 520–500 Ma recorded within Seve terranes and along terrane boundaries of the Sarek Mountains provide evidence of significant accretionary activity in the northern Scandinavian Caledonides in the Late Cambrian–Early Ordovician.     

Eoalpine tectonics of the Eastern Alps: implications from the evolution of monometamorphic Austroalpine units (Schneeberg and Radenthein Complex)

Monometamorphic metasediments of Paleozoic or Mesozoic age constituting Schneeberg and Radenthein Complex experienced coherent deformation and metamorphism during Late Cretaceous times. Both complexes are part of the Eoalpine high-pressure wedge that formed an intracontinental suture and occur between the polymetamorphosed Ötztal–Bundschuh nappe system on top and the Texel–Millstatt Complex below. During Eoalpine orogeny Schneeberg and Radenthein Complexes were south-dipping and they experienced a common tectonometamorphic history from ca. 115 Ma onwards until unroofing of the Tauern Window in Miocene times. This evolution is subdivided into four distinct tectonometamorphic phases. Deformation stage D1 is characterized by WNW-directed shearing at high temperature conditions (550–600°C) and related to the initial exhumation of the high-pressure wedge. D2 and D3 are largely coaxial and evolved during high- to medium-temperature conditions (ca. 450 to ≥550°C). These stages are related to advanced exhumation and associated with large-scale folding of the high-pressure wedge including the Ötztal-Bundschuh nappe system above and the Texel–Millstatt Complex below. For the area west of the Tauern Window, F2/F3 fold interference results in the formation of large-scale sheath-folds in the frontal part of the nappe stack (formerly called “Schlingentektonik” by previous authors). Earlier thrusts were reactivated during Late Cretaceous normal faulting at the base of the Ötztal–Bundschuh nappe system and its cover. Deformation stage D4 is of Oligo-Miocene age and accounted for tilting of individual basement blocks along large-scale strike-slip shear zones. This tilting phase resulted from indentation of the Southern Alps accompanied by the formation of the Tauern Window.     

Alpine geodynamic evolution of passive and active continental margin sequences in the Tauern Window (eastern Alps, Austria, Italy): a review

The Penninic oceanic sequence of the Glockner nappe and the foot-wall Penninic continental margin sequences exposed within the Tauern Window (eastern Alps) have been investigated in detail. Field data as well as structural and petrological data have been combined with data from the literature in order to constrain the geodynamic evolution of these units. Volcanic and sedimentary sequences document the evolution from a stable continent that was formed subsequent to the Variscan orogeny, to its disintegration associated with subsidence and rifting in the Triassic and Jurassic, the formation of the Glockner oceanic basin and its consumption during the Upper Cretaceous and the Paleogene. These units are incorporated into a nappe stack that was formed during the collision between a Penninic Zentralgneis block in the north and a southern Austroalpine block. The Venediger nappe and the Storz nappe are characterized by metamorphic Jurassic shelf deposits (Hochstegen group) and Cretaceous flysch sediments (Kaserer and Murtörl groups), the Eclogite Zone and the Rote Wand–Modereck nappe comprise Permian to Triassic clastic sequences (Wustkogel quartzite) and remnants of platform carbonates (Seidlwinkl group) as well as Jurassic volcanoclastic material and rift sediments (Brennkogel facies), covered by Cretaceous flyschoid sequences. Nappe stacking was contemporaneous to and postdated subduction-related (high-pressure) eclogite and blueschist facies metamorphism. Emplacement of the eclogite-bearing units of the Eclogite zone and the Glockner nappe onto Penninic continental units (Zentralgneis block) occurred subsequent to eclogite facies metamorphism. The Eclogite zone, a former extended continental margin, was subsequently overridden by a pile of basement-cover nappes (Rote Wand–Modereck nappe) along a ductile out-of-sequence thrust. Low-angle normal faults that have developed during the Jurassic extensional phase might have been inverted during nappe emplacement.     

Stratigraphy and Mesozoic–Cenozoic tectonic history of northern Sierra Los Ajos and adjacent areas,Sonora, Mexico

Geologic mapping in the northern Sierra Los Ajos reveals new stratigraphic and structural data relevant to deciphering the Mesozoic–Cenozoic tectonic evolution of the range. The northern Sierra Los Ajos is cored by Proterozoic, Cambrian, Devonian, Mississippian, and Pennsylvanian strata, equivalent respectively to the Pinal Schist, Bolsa Quartzite and Abrigo Limestone, Martin Formation, Escabrosa Limestone, and Horquilla Limestone. The Proterozoic–Paleozoic sequence is mantled by Upper Cretaceous rocks partly equivalent to the Fort Crittenden and Salero Formations in Arizona, and the Cabullona Group in Sonora, Mexico.Absence of the Upper Jurassic–Lower Cretaceous Bisbee Group below the Upper Cretaceous rocks and above the Proterozoic–Paleozoic rocks indicates that the Sierra Los Ajos was part of the Cananea high, a topographic highland during the Late Jurassic and Early Cretaceous. Deposition of Upper Cretaceous rocks directly on Paleozoic and Proterozoic rocks indicates that the Sierra Los Ajos area had subsided as part of the Laramide Cabullona basin during Late Cretaceous time. Basal beds of the Upper Cretaceous sequence are clast-supported conglomerate composed locally of basement (Paleozoic) clasts. The conglomerate represents erosion of Paleozoic basement in the Sierra Los Ajos area coincident with development of the Cabullona basin.The present-day Sierra Los Ajos reaches elevations of greater than 2600 m, and was uplifted during Tertiary basin-and-range extension. Upper Cretaceous rocks are exposed at higher elevations in the northern Sierra Los Ajos and represent an uplifted part of the inverted Cabullona basin. Tertiary uplift of the Sierra Los Ajos was largely accommodated by vertical movement along the north-to-northwest-striking Sierra Los Ajos fault zone flanking the west side of the range. This fault zone structurally controls the configuration of the headwaters of the San Pedro River basin, an important bi-national water resource in the US-Mexico border region.     

大别山商城石门冲一带中生代逆冲推覆构造

笔者运用1∶5万双柳树幅、白雀园幅区域地质调查成果,阐述商城石门冲一带发育的逆冲推覆构造。大别山商城石门冲一带中生代逆冲推覆作用,使本区发育的中—新元古界龟山岩组、下古生界石门冲岩组、上古生界石炭系及中生界朱集组等,不同程度卷入NE向逆冲推覆系统中,形成一系列构造窗、飞来峰和叠瓦状逆冲断层带。逆冲推覆距离最小约为6 km,形成时代约为中侏罗世—晚侏罗世之间,最晚不超过早白垩世。     

The curved translation path of the Parpaillon Nappe (French Alps)

The Parpaillon Nappe is one of the two Helminthoid Flysch nappes emplaced on the external Dauphinois zone of the Western Alps. A structural analysis of the nappe is presented. Two superposed deformations D1 and D2 are described, that are mainly characterized by large-scale recumbent folds whose axes are quasi-orthogonal: NE-SW for D1 and NW-SE for D2. Their vergence is northwestward for D1 and southwestward for D2. During the D2 deformation, the nappe was separated into two units, one of these being thrusted over the other. An analysis of incremental strain using quartz and calcite fibre growth indicates that D2 follows D1 without discontinuity. Therefore the superposition of D1 and D2 structures is interpreted as a progressive deformation instead of two distinct phases of deformation. The emplacement of the nappe is discussed under two aspects, the relations between displacement and strain and the role of gravity. It is concluded that the translation has been twofold, first towards the NW and then towards the SW, and that the displacement result essentially from gravity forces. Kinematic implications for the Alpine collision are suggested.     

Absolute age determinations of crystalline rocks of Manali-Jaspa region,Northwestern Himalaya

Comparison of “argon” absolute age determinations of crystalline rocks of the “Crystalline Nappe” (Kumar, 1971, unpublished Ph. D. thesis) and of the “root-zone” (Jaspa granite) has led to an important conclusion concerning the interpretation of the development of the “crystalline nappe” and its rejuvenation.     

Terrane character of the north-east margin of the Moldanubian Zone: the Kutná Hora Crystalline Complex,Bohemian Massif

Three major allochthonous units have been distinguished on the north-eastern border of the Moldanubian Zone, which differ each from other in lithology and structural and metamorphic evolution. Their present day position displays significant metamorphic and structural inversion resulting from progressive nappe stacking during the Variscan orogeny. The uppermost-Gföhl Unit consists of anatectic rocks containing high temperature/high pressure relics, i.e. granulites, eclogites and garnet peridotites. The rocks of the Gföhl Unit were strongly mylonized during uplift and later also extensively migmatized in the kyanite stability field. The Kouiim Nappe is built up by a sequence of fine-grained leucocratic migmatites with preserved relics of a pre-Variscan deformation event. This event was terminated by the intrusion of coarse-grained porphyritic granites, converted into augen orthogneisses by the Variscan orogeny. The lowermost Micaschist Zone was formed from a sequence of metapelites intercalated with diopsidic amphibolites.During uplift from deep crustal zones the Gföhl Unit cut off a thick slice of the basement crustal material represented by the Kourim Nappe. The quartzo-feldspathic material of the Kourim Nappe acted as a major shear interface because of its extreme ductility under the conditions found in the middle crust. This process occurred under amphibolite facies metamorphism. The continuous uplift of the nappe pile induced another crustal segment in the nappe stack, represented by the Micaschist Zone. The whole nappe sequence was then thrust over the Moldanubian Zone. A westward sense of shear is suggested for the whole uplift history. The kinematic pattern was complicated by later strike-slip ductile faults which finished the recent geological configuration.Correspondence to: J. Synek