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  • 1995-1999  (3)
  • 1900-1904
  • Rodinia  (2)
  • Anterior disk displacement  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    International journal of earth sciences 85 (1996), S. 800-821 
    ISSN: 1437-3262
    Keywords: East Antarctica ; Greenville ; Pan-African ; Rodinia ; Heimefrontfjella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The Heimefrontfjella mountains, Western Dronning Maud Land (East Antarctica), are dominantly composed of Grenville-aged (≈ 1.1 Ga) rocks, which were reworked during the Pan -African orogeny at ≈500 Ma. Three discontinuity-bounded Grenville-aged terranes have been recognized namely (from north to south) the Kottas, Sivorg and Vardeklettane terranes. The terranes contain their own characteristic lithological assemblages, although each is made up of an early supracrustal sequence of metavolcanic and/or metasedimentary gneisses, intruded by various (predominantly granitoid) suites. No older basement upon which the protoliths of these older gneisses were deposited has been recognized. In each terrane the older layered gneisses were intruded by various plutonic suites ranging in age from ≈ 1150 to ≈1000 Ma. The Vardeklettane terrane is characterized by abundant charnockites and two-pyroxene granulite facies parageneses in metabasites, whereas the Sivorg and Kottas terranes were metamorphosed to amphibolite facies grade. P-T estimates show that peak metamorphic conditions changed from ≈600°C at 8 kbar in the south, to ≈700 °C at 4 kbar in the northern Sivorg terrane. Regional greenschist retrogression of high-grade assemblages may be of Pan-African age. The Heimefrontfjella terranes were juxtaposed and pervasively deformed during a complex and protracted period of E-W collision orogenesis in a transpressive regime at ≈ 1.1 Ga. This is manifest as early, gently dipping thrust-related shear fabrics (D1), succeeded by the initiation of an important (D2) steep dextral shear zone (Heimefront shear zone, HSZ), during which the early fabrics and structures were steepened and rotated in an anticlockwise sense. The HSZ is a curvilinear structure which changes from a dextral oblique strike-slip lateral ramp in the north to a steep dip-slip frontal ramp in the south, where it forms the boundary between the Sivorg and Vardeklettane terranes. The Pan-African event is manifested as discrete, low- to medium-temperature ductile to brittle shears (D3) and numerous K/Ar cooling ages.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2102
    Keywords: Schlüsselwörter MRT ; Kiefergelenk ; Diskusverlagerung ; Morphometrie ; Key words MRI ; Temporomandibular joint ; Anterior disk displacement ; Metric analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary In order to evaluate magnetic resonance imaging (MRI) changes in correlation with different degrees of internal derangement of the temporomandibular joint, we evaluated 117 joints of 59 symptomatic patients and 31 volunteers. Data analysis included morphologic and morphometric characteristics. Sixteen joints (19 %) were considered normal, 40 demonstrated anterior displacement with reduction (47 %) and 27 anterior displacement without reduction (32 %). In three of the volunteers anterior displacement with reduction was noted. Advancing anterior position of the disk was associated with reduced ability to open the mouth, progressive deformity and shortening of the disk, thinning of the bilaminar zone, regressive and proliferative bony changes of the condyle, reduced translatory movement of the disk and condyle, thinning of joint space, cranial and dorsal displacement of the condyle and flattening of the slope of the tuberculum. In addition to alterations in condylar and disk morphology, MRI can demonstrate various additional measurable changes that correlate well with the degree of anterior disk displacement.
    Notes: Zusammenfassung Um den Einfluß der Diskusverlagerung im Kiefergelenk auf die Gelenkbinnenstrukturen zu untersuchen, wurden insgesamt 117 Gelenke von 59 symptomatischen Patienten und 31 asymptomatischen Probanden in der MRT untersucht und die Gelenkbinnenstrukturen sowohl morphologisch wie morphometrisch beurteilt. Im Patientengut lag 16mal eine normale Diskusposition (NDP) (19 %), 40mal eine Vorverlagerung mit Reposition (VMR) (47 %) und 27mal eine Vorverlagerung ohne Reposition (VOR) (32 %) vor. Unter den Normalpersonen zeigten 3 eine VMR. Mit zunehmender Diskusvorverlagerung zeigte sich eine kleiner werdende maximale Mundöffnung, ein zunehmend deformierter und verkürzter Diskus, eine Ausdünnung der bilaminären Zone, eine Abnahme des Durchmessers und zunehmende Entrundung des Processus condylaris, eine verminderte translatorische Diskus- und Kondylusbeweglichkeit, eine Verschmälerung der Gelenkspaltweite, eine Verlagerung des Processus condylaris in geschlossener Mundposition nach kranial und dorsal und eine Abflachung des Kondylenbahnwinkels. Neben der Morphologie des Diskus und Kondylus bzw. deren Morphologie lassen sich damit eine ganze Reihe weiterer magnetresonanztomographisch quantifizierbarer Befunde im Rahmen von Verlagerungen des Diskus im Temporomandibulargelenk darstellen.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0016-7835
    Keywords: Key words East Antarctica ; Greenville ; Pan-African ; Rodinia ; Heimefrontfjella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The Heimefrontfjella mountains, Western Dronning Maud Land (East Antarctica), are dominantly composed of Grenville-aged (∼1.1 Ga) rocks, which were reworked during the Pan -African orogeny at ∼500 Ma. Three discontinuity-bounded Grenville-aged terranes have been recognized namely (from north to south) the Kottas, Sivorg and Vardeklettane terranes. The terranes contain their own characteristic lithological assemblages, although each is made up of an early supracrustal sequence of metavolcanic and/or metasedimentary gneisses, intruded by various (predominantly granitoid) suites. No older basement upon which the protoliths of these older gneisses were deposited has been recognized. In each terrane the older layered gneisses were intruded by various plutonic suites ranging in age from ∼1150 to ∼1000 Ma. The Vardeklettane terrane is characterized by abundant charnockites and two-pyroxene granulite facies parageneses in metabasites, whereas the Sivorg and Kottas terranes were metamorphosed to amphibolite facies grade. P–T estimates show that peak metamorphic conditions changed from ∼600  °C at 8 kbar in the south, to ∼700  °C at 4 kbar in the northern Sivorg terrane. Regional greenschist retrogression of high-grade assemblages may be of Pan-African age. The Heimefrontfjella terranes were juxtaposed and pervasively deformed during a complex and protracted period of E–W collision orogenesis in a transpressive regime at ∼1.1 Ga. This is manifest as early, gently dipping thrust-related shear fabrics (D1), succeeded by the initiation of an important (D2) steep dextral shear zone (Heimefront shear zone, HSZ), during which the early fabrics and structures were steepened and rotated in an anticlockwise sense. The HSZ is a curvilinear structure which changes from a dextral oblique strike-slip lateral ramp in the north to a steep dip-slip frontal ramp in the south, where it forms the boundary between the Sivorg and Vardeklettane terranes. The Pan-African event is manifested as discrete, low- to medium-temperature ductile to brittle shears (D3) and numerous K/Ar cooling ages.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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