Geological constraints on the alpine evolution of the Mediterranean Tethys     

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   

Structure and evolution of the passive margin of the eastern tethys     

V. Kazmin  L.-E. Ricou  I.M. Sbortshikov 《Tectonophysics》1986,123(1-4)

An extensive passive margin was formed in the Triassic along the periphery of Arabia, including the Tauric carbonate platform. This event is related to the opening of the Mesozoic Tethys when a number of microcontinents split off from Gondwana. Triassic extension and continental rifting resulted in the formation of a structural pattern which is uniform from the Dinarides to Oman. It includes the following elements:

1. (1) shelf,

2. (2) continental slope,

3. (3) deep basin probably with a floor of attenuated sialic crust,

4. (4) inner carbonate platform. In the Jurassic-Cretaceous stable conditions prevailed, influenced only by eustatic oscillations of the sea level. Turbidites accumulated on the continental rise while cherts and radiolarites were deposited in the deep basins (Hawasina, Pichakun, Antalya, Pindus) below the CCD level. Sedimentation on the shelf was controlled by north-northeast transverse tectonic elements which also continued across the passive margin, dividing it into a number of segments. Collision with an island arc led to obduction of the oceanic crust, deformation of the passive margin and overthrusting of its sedimentary cover onto the Arabian shelf. Obduction and deformation lasted for about 10 m.y. and created a new tectonic pattern with concentric structural zones surrounding the Arabian promontory.

These zones include:

1. (1) the flysch basin—a remnant of the closing Tethys;

2. (2) an uplift—a site of periodical emergence and erosion, corresponding to the frontal part of the ophiolitic nappes;

3. (3) the Border furrow—a depocenter of low-energy calcareous marls,

4. (4) the Arabian shield constantly emerged during the Tertiary. Tectonic deformation of these zones caused by the collision of Arabia with Eurasia began prior to the Early Miocene and it is still going on.

Data on Afghanistan demonstrate that its central part (the Gelmend-Argandab and Kabul blocks) belonged during the Paleozoic and Early Mesozoic to the continental shelf of India.  相似文献   

Continental accretion of the Iran Block to Eurasia as seen from Late Paleozoic to Early Cretaceous subsidence curves     

Abdollah Saidi  Marie-Françoise Brunet  Luc-Emmanuel Ricou 《Geodinamica Acta》2013,26(5):189-208

Abstract

Subsidence analysis is used here to get a better understanding of the Eo-Cimmerian continental accretion to Eurasia of a block (the Iran Block) of Gondwanian origin. The drift of the block from Gondwana to Eurasia is classically considered as a late Triassic event but the lack of unquestionable age evidence leads to investigate the whole Permian to Jurassic history. Indeed, the subsequent Alpine deformation along the proposed suture that should mark the Eo-Cimmerian collision forbids to characterize the collisional event without ambiguity. Moreover, the Iran block is presently represented by different continental slivers that are disconnected from each other, being in places separated by Cretaceous ophiolites, and it makes unclear if one or several blocks should be taken into account. Subsidence analysis is introduced to solve the problem, in the hope that the sedimentary history in any part of the slivers has registered important crustal events such as breakup and collision and that the few well-preserved stratigraphic sections bear the corresponding subsidence signals. Subsidence analysis is thus applied to geologically disconnected objects in a manner that departs from its traditional use in basin analysis. However, as it introduces quantified data on the behaviour of the crust in response to tectonics, it was shown to be an efficient tool in sorting out the major events amongst various local evidences for crustal unstability. Major results are: – dating the breakup as Early Permian and collision as Middle Triassic; – showing that the accretion of the Iran Block to Eurasia was accompanied by a new breakup that formed a passive margin in Nayband to the Southeast, in contrast to the new active margin that was established along the Abadeh, south-western side; – emphasising the tectonic instability that controlled the continental Jurassic deposits upon the new continent before stabilisation was reached during Late Jurassic-Early Cretaceous times.  相似文献