The Northern Carpathians plate tectonic evolutionary stages and origin of olistoliths and olistostromes

The olistostromes formed in Northern Carpathians during the different stages of the development of flysch basins, from rift trough post-rift, orogenic to postorogenic stage. They are known from the Cretaceous, Paleocene, Eocene, Oligocene and Early Miocene flysch deposits of main tectonic units. Those units are the Skole, Subsilesian, Silesian, Dukla and Magura nappes as well as the Pieniny Klippen Belt suture zone. The oldest olistoliths in the Northern Carpathians represent the Late Jurassic-Early Cretaceous rifting and post-rifting stage of the Northern Carpathians and origin of the proto-Silesian basin. They are known from the Upper Jurassic as well as Upper Jurassic-Lower Cretaceous formations. In the southern part of the Polish Northern Carpathians as well as in the adjacent part of Slovakia, the olistoliths are known in the Cretaceous- Paleocene flysch deposits of the Pieniny Klippen Belt Zlatne Unit and in Magura Nappe marking the second stage of the plate tectonic evolution - an early stage of the development of the accretionary prism. The most spectacular olistostromes have been found in the vicinity of Haligovce village in the Pieniny Klippen Belt and in Jaworki village in the border zone between the Magura Nappe and the Pieniny Klippen Belt. Olistoliths that originated during the second stage of the plate tectonic evolution occur also in the northern part of the Polish Carpathians, in the various Upper Cretaceous-Early Miocene flysch deposits within the Magura, Fore-Magura, Dukla, Silesian and Subsilesian nappes. The Fore-Magura and Silesian ridges were destroyed totally and are only interpreted from olistoliths and exotic pebbles in the Outer Carpathian flysch. Their destruction is related to the advance of the accretionary prism. This prism has obliquely overridden the ridges leading to the origin of the Menilite-Krosno basin.

In the final, postcollisional stage of the Northern Carpathian plate tectonic development, some olistoliths were deposited within the late Early Miocene molasse. These are known mainly from the subsurface sequences reached by numerous bore-holes in the western part of the Polish Carpathians as well as from outcrops in Poland and the Czech Republic.

The largest olistoliths (kilometers in size bodies of shallow-water rocks of Late Jurassic-Early Cretaceous age) are known from the Moravia region. The largest olistoliths in Poland were found in the vicinity of Andrychów and are known as Andrychów Klippen. The olistostromes bear witness to the processes of the destruction of the Northern Carpathian ridges. The ridge basement rocks, their Mesozoic platform cover, Paleogene deposits of the slope as well as older Cretaceous flysch deposits partly folded and thrust within the prism slid northward toward the basin, forming the olistostromes.     

Tectonics of the western part of the Polish Outer Carpathians

The western part of the Polish Outer Carpathians is built up from the thrust, imbricated Upper Jurassic-Neogene flysch deposits. The following Outer Carpathian nappes have been distinguished: Magura Nappe, Fore-Magura group of nappes, Silesian, Subsilesian and Skole nappes. Interpretation of seismic and magnetotelluric survey from the region South of Wadowice, allows observation of relationship between basement and flysch nappes in the Outer Carpathians. It also allows identification of dislocation cutting both flysch nappes and their basement. All the Outer Carpathian nappes are thrust over the southern part of the North European Platform. The platform basement is composed of older Precambrian metamorphic rocks belonging to the Bruno-Vistulicum terrane. Sedimentary cover consists of Paleozoic, Mesozoic and Neogene sequences. The characteristic features of this boundary are horsts and troughs of general direction NW-SE, turning W-E. Faults cutting only the consolidated basement and the Paleozoic cover were formed during the Hercynian Orogeny in the Carboniferous and the Early Permian. Most of the older normal faults were covered by allochtonous flysch nappes forming thus the blind faults. During the last stage of the geodynamic development the Carpathians thrust sheets moved towards their present position. Displacement of the Carpathians northwards is related to development of dextral strike-slip faults of N—S direction. The orientation of this strike-slip fault zones zone more or less coincides with the surface position of the major faults perpendicular to the strike of the Outer Carpathian thrustsheets. The huge fault cuts formations from the Paleozoic basement through the flysch allochton between the boreholes in Sucha Beskidzka area. The displacement of nappes of the Carpathian overthrust and diapiric extrusion of plastic formations of the lower flysch units occurred along this fault.     

Age of Detrital Zircons from Sandstones of the Mesozoic Flysch Formation in the South Anyui Suture Zone (Western Chukotka)

The South Anyui fold zone (western Chukotka) is considered a suture zone related to closure of the South Anyui oceanic basin and collision of Eurasia with the Chukotka–Arctic Alaska microcontinent in the Early Cretaceous. The existence of a compensatory sedimentation basin (foredeep) during folding in the terminal Jurassic–initial Cretaceous remains debatable. This work presents first data on age estimates of detrital zircons from Upper Mesozoic terrigenous sequences of the South Anyui suture zone obtained by the fission-track method. The distal flysch of presumably Late Jurassic age and the proximal flysch of probably Late Triassic age were sampled in the Uyamkanda River basin. The fission-track dating showed that sandstones from the flysch sections contain detrital zircons of two different-age populations. Young zircon populations from sandstones of distal turbidites in the upper course of the Uyamkanda River (two samples) are 149 ± 10.2 and 155.4 ± 9.0 Ma old (Late Jurassic), whereas those from coarse-grained proximal turbidites sampled in the lower course of the Uyamkanda River (one sample) is 131.1 ± 7.5 Ma old (Early Cretaceous). The data obtained indicate that the Late Mesozoic folding in the South Anyui suture zone was accompanied by the formation of a marginal sedimentary basin. Sediments accumulated in this basin compose tectonic nappes that constitute a fold–thrust structure with the northern vergence.     

Multi-stage thrusting at the "Penninic Front" in the Western Alps between Mont Blanc and Pelvoux massifs

The different segments of the tectonic boundary between external (European) and internal (Penninic) units in the Western Alps, the so-called Penninic Front (PF), formed at different times and according to different kinematic scenarios. During a first episode (Eocene), the PF corresponds to a transpressive suture zone between Penninic and European units. North- to NNW-trending stretching lineations, found along internal nappe contacts within the Penninic units, are related to this episode. This subduction zone was sealed by the Priabonian flysch of the Aiguilles d'Arves, a detrital trench formation that formed during the final stages of subduction. During a second episode, starting in mid-Oligocene times, the PF, imaged along the ECORS-CROP profile, acted as a WNW-directed thrust. This thrust, the Roselend Thrust (RT), only partially coincides with the PF. South of Moûtiers, the RT propagates into the Dauphinois units, carrying the former Eocene PF (including the Priabonian flysch) passively in its hangingwall. South of the Pelvoux massif the RT finds its continuation along the "Briançonnais Front", an out-of-sequence thrust behind the Embrunais-Ubaye nappes. On a larger scale, our findings indicate oblique (sinistral) collision within the future Western Alps during the Eocene, followed by westward indentation of the Adriatic block.     

Late Cretaceous-Eocene marginal seas in the Black Sea-Caspian region: Paleotectonic reconstructions

A series of seven reconstructions is presented to illustrate the evolution of marginal seas in the Black Sea-South Caspian segment of the margin of the Tethys Ocean from the Late Jurassic to the middle Eocene. After Middle Jurassic inversion and until the Aptian Age, no marginal (backarc) basins were formed in the region, while the Pontides-Rhodope margin developed in the passive regime. The retained relict of the Late Triassic-Early Jurassic backarc basin includes the southeastern part of the Greater Caucasus, the northern part of the South Caspian Basin, and the shallow-water Kopetdagh Basin. The basins of the southern slope of the Greater Caucasus, Balkans (Nish-Trojan Trough), and Dobrogea developed as flexural foredeeps in front of the Middle Jurassic fold systems. The next, Aptian-Turonian epoch of opening of marginal seas was related to the origination of subduction zones at the Pontides-Rhodope margin and to the incipient consumption of the Vardar Basin lithosphere with formation of the West Black Sea Basin and its western continuation in the Bulgarian Srednogorie. The backarc rifting in the Greater Caucasus resulted in transformation of the foredeep into the backarc basin. Two basins approximately 2000 km in total extent were separated by the bridge formed by the Shatsky and Andrusov rises. The last, late Paleocene-middle Eocene epoch of the formation of backarc basins was associated with the newly formed subduction zone south of the Menderes-Taurus Terrane that collided with the active margin in the early Paleocene. The Greater Caucasus Basin widened and deepened, while to its south the East Black Sea Basin, the grabens in the Kura Depression, and the Talysh Basin, all being separated by a chain of uplifts, opened. The Paleogene South Caspian Basin opened in the course of the southward motion of the Alborz volcanic arc at the late stage of closure of the Iranian inner seas.     

Oligocene uplift of the Western Greater Caucasus: an effect of initial Arabia–Eurasia collision

The Greater Caucasus is Europe's largest mountain belt. Significant uncertainties remain over the evolution of the range, largely due to a lack of primary field data. This work demonstrates that depositional systems within the Oligocene–Early Miocene Maykop Series on either side of the Western Greater Caucasus (WGC) display a similar provenance and divergent palaeocurrents away from the range, constraining a minimum age for the subaerial uplift of the range as early Early Oligocene. An Eocene–Oligocene hiatus, basal Oligocene olistostromes and a marked increase in nannofossil reworking also point to initial deformation in the earliest Oligocene. The initial uplift of the WGC occurred during the final assembly of the Tethysides to its south. Uplift commenced after the Late Eocene final suturing of northern Neotethys and during the initial collision of Arabia with the southern accreted margin of Eurasia. This suggests that compressional deformation was rapidly transferred across the collision zone from the indenting Arabian plate to its northern margin.     

Manifestations of miocene acid intrusive magmatism on the southern slope of the Greater Caucasus: First evidence from isotope geochronology

New isotope-geochronological data (K-Ar, Rb-Sr) provide tight geochronological constraints on the history of Late Cenozoic magmatism on the southern slope of the Greater Caucasus. Several previously unknown, rhyodacite intrusive bodies with an emplacement age of 6.9 ± 0.3 Ma (Late Miocene) are reported from the Kakheti-Lechkhumi regional fault zone in the Kvemo Svaneti-Racha area. Therefore, a pulse of acid intrusive magmatism took place in a period previously considered amagmatic in the Greater Caucasus. The petrological, geochemical, and isotopic data suggest that these rhyodacites are produced by crystallization differentiation of mantle-derived magmas, which are similar in composition to Miocene mafic lavas that erupted a few hundred thousand years later in the adjacent Central Georgian neovolcanic area. The presented results allow the conclusion that the volcanic activity within the Central Georgian neovolcanic area occurred at 7.2–6.0 Ma in two discrete pulses: (1) the emplacement of acid intrusions and (2) the eruption of trachybasaltic lavas. The emplacement of rhyodacite intrusions in the Kvemo Svaneti-Racha area marked the first pulse of young magmatism on the southern slope of the Main Caucasus range and simultaneously represented the second magmatic pulse (after granitoid magmatism of the Caucasian Mineral Waters region) within the entire Greater Caucasus.     

Accretionary history of the Rhenodanubian flysch zone in the Eastern Alps – evidence from apatite fission-track geochronology

The thermotectonic evolution of the East Alpine Rhenodanubian flysch zone (RDFZ) and the collisional history along the orogenic front is reconstructed using apatite fission-track (FT) thermochronology. The apatite FT data provides evidence for a burial depth of at least 6 km for the samples, which were totally reset. Burial was not deeper than 11 km, since the zircon fission-track system was not reset. The RDFZ represents an accretionary wedge with a complex burial and cooling history due to successive and differential accretion and exhumation. The sedimentary sequences were deposited along a convergent margin, where accretion started before Maastrichtian and lasted until Miocene. Accretion propagated from a central area (Salzburg-Ybbsitz) both to the west and to the east. In the west, accretion lasted from Middle Eocene to Early Oligocene, reflecting underplating of the RDFZ by the European continental margin sediments. In the east, where three nappes (Greifenstein, Kahlenberg and Laab nappes) can be distinguished, the exhumation started between Late Oligocene and Early Miocene. The Kahlenberg and Laab nappes show total resetting of the apatite FT ages, while in the Greifenstein nappe there is only partial resetting. According to a new paleogeographic reconstruction, the Kahlenberg and Laab nappes were placed on top of the Greifenstein nappe by an out-of-sequence thrust.     

Structures and tectonic evolution of the external zone of Alpine Corsica

This paper presents a structural analysis of the external zone of Alpine Corsica, including the autochthonous domain and overlying external nappes (Santa Lucia and Balagne nappes). Two stages of nappe emplacement are identified occurring prior to and after the deposition of the Eocene sediments which were laid down upon first generation thrust contacts but are imbricated with their composite (continental and ophiolitic) basement by second generation thrusts. Five generations of structures with regional extent have been distinguished. However, the first generation has not been recognized within the visible part of the autochthon domain.Eoalpine first generation structures, restricted to allochthonous units, and Late Eocene to Early Oligocene second generation structures were nearly contemporaneous with the two stages of thrusting. The precise significance of E-W third generation structures is poorly understood. Broadly N-S fourth generation structures resulted from Oligocene compressive tectonics (folding and local backthrusting). Finally, fifth generation structures were generated during a Miocene extensional stage.These results are partly consistent with structural features previously reported in the southern and the northern outcrops of the Schistes lustrés, i.e. the main part of the allochthonous domain. A summary of a regional tectonic evolution is thus proposed for Alpine Corsica from Eoalpine obduction to Miocene extension.     

The Upper Paleozoic preflysch and overthrusting in the Türkstan-Alay ranges,southern Fergana

The Upper Paleozoic preflysch sedimentary rocks in the Türkstan-Alay ranges are combined in a common section with limestone of autochthon and synsedimentation carbonate nappes, thus forming the upper-most layers of the stratigraphic section of the latter. By their lithology, relatively small thickness, facies variability, and position at the boundary between carbonate and flysch-olistostrome sequences (in the autochthon), these rocks correspond to a certain extent to preflysch of the Urals and the Mediterranean Alpine Belt. This association of clayey, carbonate, and terrigenous rocks is strictly constrained in stratigraphy (the upper portion of the lower Moscovian substage and the lower portion of the upper Moscovian substage) and localization (the southern slopes of carbonate platforms). The formation of this rock association immediately predated the Late Paleozoic overthrusting and deposition of terrigenous flysch. In paleotectonic terms, preflysch is an indicator of the initial stage of tectonic and magmatic activation that led to the replacement of carbonate sedimentation with deposition of terrigenous and clayey sediments, coeval volcanism, and stratiform ore formation. The following sequence of events has been outlined in the Early and Middle Carboniferous: (1) thrusting of volcanic-sedimentary rocks filling troughs over the northern margins of carbonate platforms, (2) lateritic weathering and deposition of marine bauxite in the Bashkirian and early Moscovian, (3) repeated overthrusting and deposition of preflysch on southern slopes of platforms, (4) invasion of the frontal flysch trough from the south, (5) scouring of preflysch and the underlying limestone, and (6) formation of flysch-olistostrome sequences and tectonic and gravity nappes in the late Moscovian time. This interpretation takes into account the southward vergence of thrust sheets and nappes, the structure and localization of allochthonous fragments of marginal zones of carbonate platforms, and the pre-Bashkirian thrusting of volcanic and sedimentary rocks over the condensed pelagic deposits of the Shalan Group. It is suggested that bauxite and preflysch materials had the same source and were deposited in the Middle Carboniferous on the offshore carbonate shoals.     

Cretaceous flysch and pelagic sequences of the Eastern Alps: correlations, heavy minerals, and palaeogeographic implications

Flysch and pelagic sedimentation of the Penninic and Austroalpine tectonic units of the Eastern Alps are results of the closure of the Tethyan-Vardar and the Ligurian-Piemontais Oceans as well as of the progressive deformation of the Austroalpine continental margin. The Austroalpine sequences are characterized by Lower Cretaceous pelagic limestones or minor carbonate flysch and various siliciclastic mid- and Upper Cretaceous flysch formations. Chrome spinel is the most characteristic heavy mineral delivered by the southern Vardar suture, the northern obduction belt at the South Penninic-Austroalpine margin and its continuation into the Klippen belt sensu lato of the Carpathians. The South Penninic sequences, e.g. the Arosa zone, the Ybbsitz Klippen zone and some flysch nappes also contain chrome spinel, whereas the sediments of the North Penninic Rhenodanubian flysch zone are characterized by stable minerals and garnet.     

Tectonics of the Lepontine Alps: ductile thrusting and folding in the deepest tectonic levels of the Central Alps

The Lepontine dome represents a unique region in the arc of the Central and Western Alps, where complex fold structures of upper amphibolite facies grade of the deepest stage of the orogenic belt are exposed in a tectonic half-window. The NW-verging Mont Blanc, Aar und Gotthard basement folds and the Lower Penninic gneiss nappes of the Central Alps were formed by ductile detachment of the upper European crust during its Late Eocene–Early Oligocene SE-directed underthrust below the upper Penninic and Austroalpine thrusts and the Adriatic plate. Four underthrust zones are distinguished in the NW-verging stack of Alpine fold nappes and thrusts: the Canavese, Piemont, Valais and Adula zones. Up to three schistosities S1–S3, folds F1–F3 and a stretching lineation XI with top-to-NW shear indicators were developed in the F1–F3 fold nappes. Spectacular F4 transverse folds, the SW-verging Verzasca, Maggia, Ziccher, Alpe Bosa and Wandfluhhorn anticlines and synclines overprint the Alpine nappe stack. Their formation under amphibolite facies grade was related to late ductile folding of the southern nappe roots during dextral displacement of the Adriatic indenter. The transverse folding F4 was followed since 30 Ma by the pull-apart exhumation and erosion of the Lepontine dome. This occurred coevally with the formation of the dextral ductile Simplon shear zone, the S-verging backfolding F5 and the formation of the southern steep belt. Exhumation continued after 18 Ma with movement on the brittle Rhone-Simplon detachment, accompanied by the N-, NW- and W-directed Helvetic and Dauphiné thrusts. The dextral shear is dated by the 29–25 Ma crustal-derived aplite and pegmatite intrusions in the southern steep belt. The cooling by uplift and erosion of the Tertiary migmatites of the Bellinzona region occurred between 22 and 18 Ma followed by the exhumation of the Toce dome on the brittle Rhone–Simplon fault since 18 Ma.     

The Gramscatho Basin, south Cornwall, UK: Devonian active margin successions

Deep marine deposits of the Gramscatho Basin of south Cornwall reflect two tectonic regimes; Early to Middle Devonian rifting of continental lithosphere with formation of oceanic lithosphere to the south, and Middle Devonian to earliest Carboniferous convergence along its southern margin. Sediments on thinned continental crust to the north and oceanic lithosphere to the south were juxtaposed in the Late Devonian when nappes of deep water flysch and olistostrome were thrust up on to the northern continental margin of the basin. Basin closure was accommodated by forward propagating thrust nappes, accompanied by penecontemporaneous sedimentation. The stratigraphical sequences of major nappes illustrate the progradation of flysch with climactic sedimentation of olistostrome in late Mid- to Late Devonian times. The Lizard Complex, including the Lizard ophiolite, within that nappe stack, constitutes part of one of the GCR sites which are largely in the allochthonous rocks. Many of those sites feature the olistostrome, Roseland Breccia Formation, with its great variety of sedimentary, igneous and metamorphic clasts (up to 1.5 km), and the association of ocean floor basalt and penecontemporaneous acidic volcanics indicative of the coming together of oceanic and continental plates. A site at the top of the parautochthonous continental margin succession displays the erosion products of the youngest nappe as it emerged and advanced across the sediment surface, marking closure of the oceanised Gramscatho Basin and continental collision.     

秦岭三叠系分带及印支期发展史

秦岭及共邻区的三叠系自北而南可分为四带.北秦岭三叠系具有富含植物化石的陆相上三叠统,其下的优地槽型细碧角斑岩系时代未定.中秦岭下三叠统为复理石夹多层砾状灰岩,后者系斜坡沉积,物源可能来自北方,安尼期为复理石.南秦岭北带在二叠纪晚期已裂陷接受复理石及以砾状灰岩为代表的斜坡沉积.早三叠世至安尼期为深水相黑色板岩、薄层灰岩、复理石并夹火山岩.南秦岭南带及巴顿喀喇从早三叠世至安尼期为扬子地台的一部分,岩相及化百群与之一致,具有发育良好的安尼期陆棚边缘生物滩.从拉丁期开始裂陷．出现鱼鳞蛤页岩、砾状灰岩及巨厚复理石,后者延续至晚三叠世,有放射虫为证.整个中,南秦岭呈现一个由二叠纪晚期开始,延续于印支期的裂陷槽发育史.它的北部—中秦岭和南秦岭北带于二叠纪末及三叠纪初先后裂陷,并于拉丁期褶皱回返.它的南部—南秦岭南带及巴颜喀喇于拉丁期裂陷,并于三叠纪末回返.这个裂陷槽是否构成印支期秦岭的主体,抑或它仅是“北秦岭小洋盆”在扬子大陆边缘的弧后扩张盆地,取决于北秦岭是否存在早、中三叠世优地槽沉积.后者尚未证实.     

THE CENTRAL PAMIR—AN ALPINE COLLISION ZONE

THE CENTRAL PAMIR—AN ALPINE COLLISION ZONE     

Contrasting metamorphic evolution of metasedimentary rocks from the Çine and Selimiye nappes in the Anatolide belt, western Turkey

Abstract P–T conditions, mineral isograds, the relation of the latter to foliation planes and kinematic indicators are used to elucidate the tectonic nature and evolution of a shear zone in an orogen exhumed from mid‐crustal depths in western Turkey. Furthermore, we discuss whether simple monometamorphic fabrics of rock units from different nappes result from one single orogeny or are related to different orogenies. Metasedimentary rocks from the Çine and Selimiye nappes at the southern rim of the Anatolide belt of western Turkey record different metamorphic evolutions. The Eocene Selimiye shear zone separates both nappes. Metasedimentary rocks from the Çine nappe underneath the Selimiye shear zone record maximum P–T conditions of about 7 kbar and >550 °C. Metasedimentary rocks from the overlying Selimiye nappe have maximum P–T conditions of 4 kbar and c. 525 °C near the base of the nappe. Kinematic indicators in both nappes are related to movement on the Selimiye shear zone and consistently show a top‐S shear sense. Metamorphic grade in the Selimiye nappe decreases structurally upwards as indicated by mineral isograds defining the garnet‐chlorite zone at the base, the chloritoid‐biotite zone and the biotite‐chlorite zone at the top of the nappe. The mineral isograds in the Selimiye nappe run parallel to the regional S_R foliation, parallel the Selimiye shear zone and indicate that the Selimiye shear zone formed during this prograde greenschist to lower amphibolite facies metamorphic event but remained active after the peak of metamorphism. ⁴⁰Ar/³⁹Ar mica ages and the tectonometamorphic relationship with the Eocene Cyclades–Menderes thrust, which occurs above the Selimiye nappe in the study area, suggests an Eocene age of metamorphism in the Selimiye nappe. Metasedimentary rocks of the Çine nappe 20–30 km north of the Selimiye shear zone record maximum P–T conditions of 8–11 kbar and 600–650 °C. An age of about 550 Ma is indicated for amphibolite facies metamorphism and associated top‐N shear in the orthogneiss of the Çine nappe. Our study shows that simple monophase tectonometamorphic fabrics do not always indicate a simple orogenic development of a nappe stack. Preservation in some areas and complete overprinting of those fabrics in other areas apparently occur very heterogeneously.     

Late Cretaceous ophiolite obduction and Paleocene India-Asia collision in the westernmost Himalaya

Abstract

Collision of the Kohistan island arc with Asia at ~100 Ma resulted in N-S compression within the Neo-Tethys at a spreading center north of the Indo-Pakistani craton. Subsequent India-Asia convergence converted the Neo-Tethyan spreading center into a short-lived subduction zone. The hanging wall of the subduction zone became the Waziristan, Khost and Jalalabad igneous complexes. During the Santonian- Campanian (late Cretaceous), thrusting of the NW IndoPakistani craton beneath Albian oceanic crust and a Cenomanian volcano-sedimentary complex, generated an ophiolite-radiolarite belt. Ophiolite obduction resulted in tectonic loading and flexural subsidence of the NW Indian margin and sub-CCD deposition of shelf-derived olistostromes and turbidites in the foredeep. Campanian-Maastriehtian calci- clastic and siliciclastic sediment gravity flows derived from both margins filled the foredeep as a huge allochthon of Triassic-Jurassic rise and slope strata was thrust ahead of the ophiolites onto the Indo-Pakistani craton. Shallow to intermediate marine strata covered the foredeep during the late Maastrichtian. As ophiolite obduction neared completion during the Maastrichtian, the majority of India-Asia convergence was accommodated along the southern margin of Asia. During the Paleocene, India was thrust beneath a second allochthon that included open marine middle Maastrichtian colored mélange which represents the Asian Makran-Indus-Tsangpo accretionary prism. Latérites that formed on the eroded ophiolites and structurally higher colored mélange during the Paleocene wei’e unconformably overlapped by upper Paleocene and Middle Eocene shallow marine limestone and shale that delineate distinct episodes of Paleocene collisional and Early Eocene post-collisional deformation.     

点苍山新生代推覆构造的确立及其地质意义

点苍山地处三江构造带东缘，其东侧扬子陆块上的古生代地层，越过洱海断裂推覆到苍山西坡的中、新生代地之上：下泥盆统青山组推覆至下白垩统景星组之上；上二叠叠统乌龙坝组及红岩子组推覆在始新统宝相寺组之上。三江构造带中的上三维统歪古村组及三合洞组推覆在上侏罗统坝注路组之上。推覆时期为始新世－上新世，推覆构造机制是陆内汇聚挤压所至。     

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.