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1.
Jean-Pierre Burg Luc-Emmanuel Ricou Zivko Ivano Ivan Godfriaux Dimo Dimov Laslo Klain 《地学学报》1996,8(1):6-15
Mylonitic gneisses of the Bulgarian and Greek Rhodope were deformed under medium pressure-type metamorphism. The kinematic information contained in these gneisses shows that shear-deformation occurred during development of a nappe complex. Lithologies and metamorphic histories allow a lower (footwall) and an upper (hanging wall) terrane to be distinguished that define a crustal-scale duplex. As oceanic crust is involved, collision between two continental units with subsequent crustal thickening is inferred. The blocks would be Moesia to the north, and the Lower-Rhodope promontory to the south, which collided in the Mesozoic to early Cenozoic. The nappe complex is characterized by south to southwestward (foreland directed) piling-up and is associated with both coeval and subsequent extension. The late extension is associated with the establishment of a high temperature-low pressure metamorphic gradient and plutonism that predates, but makes a transition to, the lithospheric extension of the Aegean Arc. 相似文献
2.
Luc-Emmanuel Ricou 《Geodinamica Acta》2013,26(4-5):225-232
Abstract— Accepting that the opening or closure of seaways has consequences on the oceanic circulation which in turn influences sedimentation, major changes in Tethyan geometry are checked against major changes in sedimentation. Time relationships can be demonstrated between the two group of phenomena and causal links are discussed. As the causes for major sedimentary changes are numerous and their respective roles controversial, it is speculated if the observed change in geometry could have had a positive effect on the associated change in sediments.Ever since the birth of the Mesozoic Tethys which formed from the break-up of Pangea till its death through multiple collisions, this ocean played a major role in the world ocean circulation, being the sub-equatorial seaway which permitted a circumterrestrial circulation at low latitudes. Five successive steps, separated by four major changes, are recognized : i) during the Trias and the Jurassic, the young Tethys was a triangular cul-de-sac expanding westward through distensive tectonics and subsidence, and influenced along its southern margin by a westward current and associated upwelling; radiolarites take a growing part in its sedimentation; ii) during the Tithonian, radiolarites were abruptly replaced by pelagic limestones (Majolica) in many places and the corresponding CCD drop is tentatively correlated with the full opening of the Tethyan seaway which reached the Pacific Ocean through the Caribbean and with the corresponding reorganization of currents; iii) during the Early Cretaceous, Apulia began its collision with the precursor elements of the European margin, thus hindering deep water exchange; this pre collision favoured the mid Cretaceous anoxia with affected sedimentation in numerous basins; iv) during the Late Cretaceous, repeated distension and subsidence (since the Aptian) between Apulia and Africa gave a growing importance to the south Apulian seaway; this new opportunity of water exchange favoured the end of anoxia and the deposition of new pelagic limestones (scaglia); as a matter of fact, the location of the Late Cretaceous to Early Eocene phosphorites testify to a well-established westward current along this south-Apulian seaway; v) the late Eocene to Oligocene general collision was responsable for the death of this current and the corresponding breakdown of the Tethyan seaway into independent groups of basins. 相似文献
3.
J. Besse F. Torcq Y. Gallet L. E. Ricou L. Krystyn & A. Saidi 《Geophysical Journal International》1998,135(1):77-92
A palaeomagnetic study of Late Permian to early Jurassic rocks from the Alborz and Sanandaj–Sirjan zones in Iran and a compilation of selected palaeopoles from the Carboniferous to the present provide an updated history of the motion of the Iranian block within the Tethys Ocean. The Iran assemblage, part of Gondwana during the Palaeozoic, rifted away by the end of the Permian. We ascertain the southern-hemisphere palaeoposition of Iran at that time using magnetostratigraphy and show that it was situated close to Arabia, near to its relative position today. A northward transit of this block during the Triassic is shown, with an estimated expansion rate of the Neotethyan ridge of 100–140 km Myr−1 . The northward convergence with respect to Eurasia ended during the Ladinian (Middle Triassic), and is marked by a collision in the northern hemisphere with the Turan platform, which was the southern margin of the Eurasian continent at that time. No north–south component of shortening is evidenced north of Iran afterwards. An analysis of the declinations from the Late Permian to the present shows different, large rotations, emphasizing the important tectonic phases suffered since the Triassic. Finally, we propose palaeomagnetic reconstructions of the Tethys area during the Late Permian and the Late Triassic, showing that the Palaeotethys Ocean was narrower than previously thought, and did not widen its gate to the Panthalassa before the Triassic period. 相似文献
4.
RésuménLa zone métamorphique qui jalonne la faille nord-pyrénéenne est caractérisée à la fois par son étroitesse et par les hautes températures atteintes à faible profondeur.Les données géologiques sont assez nombreuses et précises, tant sur la zone métamorphique elle-même que sur le contexte régional pour contraindre une modélisation du transfert thermique dans le cadre de l’amincissement crustal, très important au Crétacé Moyen. On s’aperçoit alors que les modèles de transfert par conduction, appliqués à un amincissement homogène et hétérogène, ne peuvent pas rendre compte d’une anomalie aussi chaude et étroite.On conclut au rôle essentiel joué par le transfert par circulation de fluides chauds, en s’appuyant sur les données de terrain. On discute les paramètres significatifs du problème et l’on est amené à proposer un fonctionnement thermique discontinu le long du couloir de faille qui reste pendant plus de 15 Ma une zone d’instabilité mécanique majeure à l’échelle de la zone frontière Ibérie/Europe. 相似文献
5.
AbstractThe Rhodope massif of Bulgaria and Greece is a complex of Mesozoic synmetamorphic nappes stacked in an Alpine active margin environment. A new analysis of the Triassic to Eocene history of the Vardar suture zone m Greece discloses its Cretaceous setting as a subduction trench. We present a geological traverse that takes into account these new observatons and runs from the Hellenides to the Balkans, i.e. from he African to the Eurasian sides of the Tethys ocean, respectively. The present review first defines the revisited limits of the Rhodope metamorphic complex. In particular, the lower part of the Serbo- Macedonian massif is an extension of the Rhodope units west of the Struma river. Its upper part is separated as the Frolosh greenschist unit, which underlies tectonic slivers of Carpathc-Balkanic type. Several greenschist units which locally yield Mesozoic fossils, follow the outer limits of the Rhodope. Their former attribution to a stratigraphic cover of the Rhodope has been proven false. They are divided into roof greenschists, which partly represent an extension of the Strandza Jurassic black shales basin, and western greenschists, which mostly derive from the Vardar Cretaceous olistostromic assemblage. The Rhodope complex of synmetamorphic nappes includes Continental Units and Mixed Units. The Continental Units comprise quartzo-feld-spathic gneisses in addition to thick marble layers. The Mixed Units comprise meta-ophiolites as large bodies or small knockers. They are imbricated, forming an open dome whose lower, Continental Unit constitutes the Drama window. The uppermost Mixed Unit is overlain by remnants of the European plate. The present-day structure results from combined large-scale thrust and exhumation tectonics. Regional inversions of synmetamorphic sense-of-shear indicate that intermediate parts of the wedge moved upward and forward with respect to both the lower and upper plates. A kinematic model is based on buoyancy-driven decoupling at depth between subducted continental crust and the subducting lithosphere. Continuing convergence allows coeval underthrusting of continental crust at the footwall, decoupling at depth, and upward-forward expulsion of a low-density metamorphic wedge above. The continental crust input and its upward return may have lasted for at least the whole of the Early Cretaceous, as indicated by isotopic ages and the deformation history of the upper plate. A Late Eocene marine transgression divides the ensuing structural and thermal evolution into a follow-up uplift stage and a renewed uplift stage. Revision of the limits of the Vardar belt in Greece first resulted in separating the Paikon mountain as a tectonic window below the Vardar nappes. It belongs to the western, Hellenic foreland into which a system of thrust developed downward between 60 and 40 Ma. The eastern limit is a dextral strike-slip fault zone that developed greenschist facies foliations locally dated at 50–40 Ma. Revision of the lithological components discloses the preponderance of Cretaceous volcano-detritic and olistostromic sequences that include metamorphite blocks of Rhodope origin. Rock units that belong to the Vardar proper (ophiolites, Triassic and Jurassic radiolarites, remnants of an eastern Triassic passive margin) attest for a purely oceanic basin. The Guevgueli arc documents the Jurassic change of the eastern Triassic passive margin into an active one. This arc magmatic activity ended in the Late Jurassic and plate convergence was transferred farther northeast to the subduction boundary along which the Rhodope metamorphic complex formed. We interpret the Rhodope and the Vardar as paired elements of a Cretaceous accretionary wedge. They document the tectonic process that exhumed metamorphic material from under the upper plate, and the tectonic-sedimentary process that fed the trench on the lower plate. The history of the Rhodope-Vardar pair is placed in the light of the history of the Tethys ocean between Africa and Europe. The Cretaceous subduction then appears as the forerunner of the present Hellenic subduction, accounting for several shifts at the expense of the lower plate. The Late Eocene shift, at the closure of the Pindos basin, is coeval with the initiation of new uplift and magmatism in the Rhodope, which probably document the final release of the low-density, continental root of the Rhodope from subduction drag. 相似文献
6.
7.
Reviewing the ophiolites of the Alpine chain from the Western Mediterranean to the Indian Ocean, we subdivide them into ten groups of outcrops. The geological environment through time, the internal composition and history are given for each. Emphasis is put on the variegated and successive geodynamic processes which can be reconstructed for the different ophiolitic belts since their birth as an ocean-like crust to their incorporation through accretion to a continent.One can distinguish: low versus high tholeiitic partial melting; fairly or poorly established ridges; simple ridge-type crust versus complex ridge + ensimatic arc (and even more complex) type; long-lived versus short-lived oceanic crust stages; abrupt, large-scale, pure obduction versus progressive collision-related obduction or simple progressive juxtaposition to continent.The major events through time in the Tethyan ophiolitic belts can be listed as follows: spreading ridge activity during the Jurassic (Liguria, Dinaro-Hellenides, Lesser Caucasus) and the Cretaceous (Peri-Arabic, Nain Sabzewar) with a jump of ridge in between; repeated change from ridge to ensimatic arc (Dinaro-Hellenic, Lesser Caucasus, Peri-Arabic, ? West Indian) during the latest Jurassic and Cretaceous; Upper Cretaceous (+Tertiary) collision-related obductions (Pontic-Lesser Caucasus, Liguria) squeezing out the elevated portions of these basins; lack of oceanic magmatism during the Cenozoic but progressive accretion along accretionary wedges of the elevated portions of the remaining Mesozoic crust (Van, Naïn, Sabzewar, Zahedan, MeKran). 相似文献
8.
Geological evolution of the tethys belt from the atlantic to the pamirs since the LIAS 总被引：3，自引：0，他引：3
J. Dercourt L.P. Zonenshain L.-E. Ricou V.G. Kazmin X. Le Pichon A.L. Knipper C. Grandjacquet I.M. Sbortshikov J. Geyssant C. Lepvrier D.H. Pechersky J. Boulin J.-C. Sibuet L.A. Savostin O. Sorokhtin M. Westphal M.L. Bazhenov J.P. Lauer B. Biju-Duval 《Tectonophysics》1986,123(1-4)
We discuss nine palinspastic geological maps (Plates 1–9), at
scale, which depict the evolution of the Tethys belt from the Pliensbachian (190 Ma) to the Tortonian (10 Ma). A Present structural map (Plate 10) is shown for comparison at the same scale with the same conventions. Our reconstructions are based on a kinematic synthesis (Savostin et al., 1986), a paleomagnetic synthesis (Westphal et al., 1986) and geological compilations and analyses concerning in particular the western domain (Ricou et al., 1986), the eastern passive margins (Kazmin et al., 1986a), the eastern active margins (Kazmin et al., 1986b), the Black Sea-Caspian Sea basins (Zonenshain and Le Pichon, 1986) and the ophiolites (Knipper et al., 1986). 相似文献
9.
Habibollah Ghasemi Thierry Juteau Hervé Bellon Mossaieb Sabzehei Hubert Whitechurch Luc-Emmanuel Ricou 《Comptes Rendus Geoscience》2002,334(6):431-438
The mafic–ultramafic complex of Sikhoran presents a long geological history, marked out by various magmatic, metamorphic and tectonic events. This history is much more complex than a simple ophiolite obduction over a continental margin. As early as the Upper Permian, following a mantle uprise in a Tethysian supra-subduction zone, the opening of a (back-arc?) basin in extensional/transtensional conditions provoked the intrusion of multiple gabbroic dykes, veins and plutons charged with fluids, through a mafic/ultramafic complex and its metamorphic cover. Several basins, characterised by abundant submarine basaltic volcanism developed during Jurassic, whose feeding dykes may be represented by the diabase dyke swarms intruding the whole Sikhoran complex and its metamorphic cover. To cite this article: H. Ghasemi et al., C. R. Geoscience 334 (2002) 431–438. 相似文献
10.
L.E. Ricou J. Dercourt J. Geyssant C. Grandjacquet C. Lepvrier B. Biju-Duval 《Tectonophysics》1986,123(1-4)
The geological data on the Mediterranean chains and basins are used to point out the constraints that they put on the location through time of oceanic versus continental lithosphere and on the successive relations between them. Emphasis is put on the rules and conventions which enable us to interpret the geological data in terms of plate tectonics and on the major disputed points for which a solution must be chosen.In the first part, the location of oceanic versus continental lithosphere is dealt with, using the data on the present-day basins, the ophiolites and the subduction processes. A Neogene age is retained for the Western Mediterranean and the surrounding continental blocks are considered to have been previously a part of Iberia. A Cretaceous age is retained for the Eastern Mediterranean; Apulia is considered as a part of the African plate except for this period. The Black Sea is considered as a back-arc basin formed mostly during the Upper Cretaceous. The ophiolites are used to locate the Mesozoic oceans; for the double ophiolitic belts of the Dinaro-Hellenides and the Taurides, the tectonic interpretations which minimise the number of oceanic basins have been retained. For the Kirsehir block of Turkey, the chosen solution locates a Jurassic ocean to the north and makes it disappear when a Cretaceous ocean opens to the south. Data on the subduction processes added to the information on these basins and led us to consider as oceanic the unknown basements of the Carpathian flysch and the Maghrebian flysch basins.The second part deals with the organisation of basins and platforms, emphasising the chronology of their formation and subsequent crushing. It furnished step by step constraints on the tectonic history of the system which is related to plate displacement.The general pattern derived from these data shows a wedge-shaped Tethyan ocean which disappeared mostly through repeated subduction below the eastern part of its northern margin. The Jurassic stage shows westward extension of the ocean between the Eurasian and African plates and ends with the Dinaro-Hellenic obduction; the Cretaceous stage shows a complete reorganisation including individual displacement of the Iberian, Apulian and Kirsehir sub-plates; the Tertiary stage shows the general collision between the renewed Eurasian and African plates and Neogene subduction of the basins which avoided collision. 相似文献