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Mirdita Zone ophiolites and associated sediments in Albania reveal Neotethys Ocean origin 总被引：1，自引：1，他引：0
Hans-Jürgen Gawlick Wolfgang Frisch Lirim Hoxha Paulian Dumitrica Leopold Krystyn Richard Lein Sigrid Missoni Felix Schlagintweit 《International Journal of Earth Sciences》2008,97(4):865-881
The Mirdita Ophiolite Zone in Albania is associated with widespread mélanges containing components of up to nappe-size. We
dated matrix and components of the mélange by radiolarians, conodonts, and other taxa. The components consist of radiolarites,
pelagic limestones and shallow-water limestones, all of Triassic age, as well as ophiolites. Triassic radiolarite as a primary
cover of ophiolite material proves Middle Triassic onset of Mirdita ocean-floor formation. The mélange contains a turbiditic
radiolarite-rich matrix (“radiolaritic flysch”), dated as Late Bajocian to Early Oxfordian. It formed as a synorogenic sediment
during west-directed thrusting of ophiolite and sediment-cover nappes representing ocean floor and underplated fragments of
the western continental margin. The tectonic structures formed during these orogenic events (“Younger Kimmeridian or Eohellenic
Orogeny”) are sealed by Late Jurassic platform carbonates. The geological history conforms with that of the Inner Dinarides
and adjoining areas; we therefore correlate the Mirdita-Pindos Ophiolite Zone with the Vardar Zone and explain its present
position by far-distance west-directed thrusting. 相似文献
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A plastic deviatoric model with hardening is developed on the basis of geomechanical tests performed in the saturated case on low permeable porous material such as argillite. This model is a generalized Mohr–Coulomb plastic criterion combined with a Drucker–Prager plastic potential and the hardening parameter is the plastic distortion. Three different hardening functions have been introduced on the basis of triaxial tests: an increase of friction angle, a decrease of cohesion after a threshold and a contractancy to dilatancy transition for volumetric plastic strain. This plastic model has been adapted to the partially saturated case. The effective stress is expressed thanks to the equivalent interstitial pressure π. Numerical results are presented for the excavation and monotonous ventilation of a deep cylindrical cavity. A first plastification due to excavation is followed by a second one due to desaturation. The extent of the non-saturated zone provokes an extent of a plastic zone in the rock mass. Analysis shows that the origin of the plastification can be found in the deviatoric stresses because mean effective stresses are compressive during drying. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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Felix Schlagintweit Hans-Jürgen Gawlick Sigrid Missoni Lirim Hoxha Richard Lein Wolfgang Frisch 《Swiss Journal of Geoscience》2008,101(1):125-138
Several Late Jurassic (Kimmeridgian?-Tithonian) to Early Cretaceous (Late Berriasian-Valanginian) shallow-water carbonate clasts of different facies are contained in mass-flow deposits in a pelagic sequence in the Kurbnesh area of central Albania. These clasts are used to reconstruct shallow-water carbonate platforms, which formed on top of the radiolaritic-ophiolitic wildflysch (ophiolitic mélange) of the Mirdita Zone. Stratigraphic interpretation of the platform carbonates was compiled on basis of calcareous algae, benthic foraminifera, and calpionellids. From biostratigraphic data and microfacies analysis, the Neocomian clasts can be directly correlated with autochthonous platform carbonates of the western part of the Munella carbonate platform, which at least reaches up to the Late Aptian. A Late Jurassic precursor platform (Kurbnesh carbonate platform; nomen novum) was completely eroded until the Valanginian and is only documented by the clasts described here. It was deposited on top of the Mirdita Ophiolite Zone nappe stack, which formed during the Middle to Late Jurassic Kimmeridian orogeny. Thrusting and imbrications as well as the formation of the syntectonic wildflysch (mélange) therefore occurred much earlier than previously assumed. Our results constrain the Kimmeridian orogeny, which was controlled by the closure of the Neotethys Ocean, and show excellent correlation with the Eastalpine-Dinaric- Hellenic orogenic system. 相似文献
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P‐ and S‐wave anisotropy to characterise and quantify damage in media: laboratory experiment using synthetic sample with aligned microcracks 
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下载免费PDF全文 Damage characterisation in solid media is studied in this work through ultrasonic measurements. A synthetic three‐dimensional printed sample including a system of horizontally aligned microcracks is used. In contrast to other manual fabrication methods presented in the literature, the construction process considered here ensures a better control and accuracy of size, shape, and spatial distribution of the microcrack network in the synthetic sample. The acoustic measurements were conducted through a specific device using triple acoustic sensors, which allows capturing at each incident direction three wave modes. The evolution of the ultrasonic velocities with respect to incident angle accounted for the damage‐induced anisotropy. The experimental results are then compared with some well‐known effective media theories in order to discuss their potential use for the following studies. Finally, we highlighted and compared the accuracy of these theories used for inversion procedure to quantify damage in the medium. 相似文献
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The present work aims at introducing an efficient numerical approach based on the immersed interface method to estimate the effective thermal conductivity and permeability of geomaterials as porous media with either perfect or debonded interfaces. The first part deals with the problem of the overall thermal properties of a medium containing perfectly bonded inclusions. The evolution of the homogenized properties with respect to the properties of individual constituents, the volume fraction, the spatial distribution, and the shape of inclusions is highlighted. The second part of the paper is devoted to the case of imperfectly bonded inclusions. An extension of the immersed interface method in this context makes it possible to study other aspects that have an influence on the effective properties such as the interfacial resistance and the size of inclusions. The application of the proposed numerical tool to some porous rocks in partially saturated condition shows good agreement with the available experimental results and demonstrates the performance and the flexibility of the developed procedure.Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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