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   

From source terrains of the Eastern Alps to the Molasse Basin: Detrital record of non-steady-state exhumation   总被引：2，自引：1，他引：2  

J. Kuhlemann  I. Dunkl  A. Brügel  C. Spiegel  W. Frisch 《Tectonophysics》2006,413(3-4):301-316

Fission-track cooling ages of detrital apatite (AFT) in the East Alpine Molasse Basin display age groups corresponding to geodynamic events in the orogen since Jurassic times. These age groups are typical of certain thermotectonic units, which formed a patchwork in the Swiss and Eastern Alps. By a combination of petrographic and thermochronologic data, progressive erosion of source terrains is monitored in different catchments since the Oligocene. The AFT cooling ages show a decrease in lag time until when rapidly cooled debris derived from tectonically exhumed core complexes became exposed. After termination of tectonic exhumation, lag times of debris derived from the core complexes increased. Neither on the scale of the entire Eastern Alps, or on the scale of individual catchments, steady-state exhumation is observed, due to the highly dynamic changes of exhumation rates since Late Eocene collision.  相似文献   

Exhumed fault-bounded Alpine blocks along the Periadriatic lineament: the Eder unit (Carnic Alps, Austria)     

A. L. Läufer  W. Frisch  G. Steinitz  J. Loeschke 《International Journal of Earth Sciences》1997,86(3):612-626

The Eder unit in the Carnic Alps, which is situated immediately south of the Periadriatic lineament (PL), represents a fault-bounded block consisting of a low-grade (up to 400?°C, indicated by epizonal illite “crystallinity” values, recrystallized quartz, and non-recrystallized white mica) metamorphic Paleozoic metasedimentary sequence. Until now, it has been assumed to represent a separate Variscan nappe. The rocks of the Eder unit show a strong E- to W-oriented stretching lineation on steep foliation planes (D₁) subparallel to the PL. D₁ structures originated near the temperature peak of metamorphism, and shear sense indicators show dextral ductile shear parallel to the PL. Tight mesoscale D₂ folds formed on the cooling path. K–Ar and Ar–Ar ages from newly formed white mica cluster around 32–28 and 18–13 Ma and suggest a two-stage Tertiary history of the Eder unit. We interpret the Eder unit as a fault-bounded block formed during Oligocene large-scale dextral shearing along the PL (near T_max) and exhumed in mid-Miocene times during another phase of activity along the PL. Its nature as a separate Variscan nappe is questioned.  相似文献   

雅鲁藏布中新生代深水沉积盆地形成和演化(Ⅰ)——喜马拉雅造山带沉积特征及演化          下载免费PDF全文

刘宝珺  余光明  徐强  G. Einsele  W. Frisch  刘光华  J. Wendt  A. Wetzel  L. Ratschbacher  H. P. Luterbacher 《沉积与特提斯地质》1993,(1):32-49

通过对喜马拉雅三叠纪到第三纪区域沉积特征分析,阐明了雅鲁藏布喜马拉雅特提斯造山带从裂谷—被动大陆边缘—前陆盆地的沉积盆地演化史。随着以雅鲁藏布带为代表的喜马拉雅特提斯打开,三叠纪到早侏罗世为特提斯早期裂开的大陆边缘裂谷盆地。早期裂谷中心部位不是现在大陆缝合线的雅鲁藏布一带,而在低分水岭带。晚侏罗世到早白垩世,雅鲁藏布江南测为典型被动大陆边缘,其沉积盆地沉降、海平面变化与沉积作用相吻合。晚白垩世到第三纪为前陆盆地演化阶段,从沉积作用可以识别出晚白垩世晚期为造山第一暮,第三纪初为第二幕。  相似文献   

Eucolite from oldoinyo Lengai,Tanzania     

J.B. Dawson  T. Frisch 《Lithos》1971,4(3):297-303

Eucolite occurs in ejected blocks of agpaitic wollastonite-bearing nepheline syenite in the pyroclastics of the active carbonatite volcano Oldoinyo Lengai, northern Tanzania. An analysis of the syenite is given, and chemical, optical and X-ray data for the eucolite are presented. The agpaitic paragenesis at Oldoinyo Lengais is one of the few recorded instances of agpaitic rocks in carbonatite environment.  相似文献   

Petrology of clinopyroxene-amphibole inclusions from the roque nublo volcanics,gran canaria,canary islands     

T. Frisch  H. U. Schmincke 《Bulletin of Volcanology》1969,33(4):1073-1088

Inclusions consisting of clinopyroxene, amphibole, Fe-Ti oxides and apatitc are abundant in the Roque Nublo volcanics, a unit of Late Tertiary age that is widespread on Gran Canaria Island. The unit includes alkalic basalts and breccias. Mafic minerals in several inclusions and in one basalt host have been analysed with the electron microprobe. Although the inclusions vary in size, texture and mineralogy, they show certain common teatures. The pyroxenes analyzed are all salites-augites and their position in the Ca-Fe Mg quadrilateral suggests that they are early formed representatives of the pyroxene crystallization trend characteristic of alkaliolivine basalt. The amphibole is invariably kaersutite. A common variety of inclusion is composed largely of kaersutite and titaniferous clinopyroxene. The kaersutite (TiO₂ 5.27%, K₂O 1.58%) is homogeneous, except for slight iron enrichment in the margins of crystals. The clinopyroxene is an hourglass-zoned, brownish titansalite, Ca 50 Mg 35 Fe 15, TiO₂ 3.08%, with a green core of Ca 49 Mg 38 Fe 13, TiO₂ 2.15%. Compositions of coexisting titanilerous magnetite and ilmenite, Usp 44 Mt 56 and Ilm 85 Hem 15, respectively, indicate they formed at approximately 975°C and pO, 10^?10.5 atm. In another type of inclusion and its host basalt, pyroxene relations are more complex. Inclusion pyroxene is markedly but diffusely zoned. Predominant is a green salite, Ca 47 Mg 38 Fe 15, TiO₂ 1.11%, which has small, patchy core zones of brownish. Ti-rich salite. Ca 48 Mg 35 Fe 17, TiO₂ 1.94%. Cores of crystals in the host basalt are Ca 47 Mg 41 Fe 12, TiO₂ 2.23%; rims are pale green, Cr-rich diopsidic augite, Ca 44 Mg 45 Fe 11, TiO₂ 1.32%, Cr₂O₃ 0.48%. This «reverse» Fe-Mg zoning is attributed to increasing partial pressure of oxygen as crystallization proceeded. Kaersutite similar to that mentioned above occurs in both the inclusion and its host, in which it is highly resorbed. The available field and analytical evidence strongly suggests that the inclusions and the associated basalts are genetically related. Resorption of the kaersutite at depth may have given rise to the alkalic basalts of the Roque Nublo series.  相似文献   

Wavelet analysis of the standard map: Structure and scaling     

A. D. Gilbert  C. Froeschlé  U. Frisch 《Celestial Mechanics and Dynamical Astronomy》1993,56(1-2):263-272

Wavelet analysis is applied to distributions of points generated by iterating the standard map. The initial condition is chosen so that the points fill the largest chaotic region. When the standard map parameterk=1.3, the distribution of points contains many voids corresponding to islands in the chaotic region. The wavelet transform is dominated by contributions from these islands. Fork=10 the chaos fills phase space and no structure is apparent; the wavelet transform reveals statistical fluctuations in the distribution of points.  相似文献   

Observations of boundary-layer convection cells measured by dual-Doppler radar and echosonde,and by microbarograph array     

A. S. Frisch  R. B. Chadwick  W. R. Moninger  J. M. Young 《Boundary-Layer Meteorology》1976,10(1):55-68

Three-dimensional air motion, observed with radar in a convective planetary boundary layer under light wind conditions, is organized in cellular structures scaled from 2 to 5 km; simultaneous acoustic echosonde measurements indicate that near the ground there are smaller cells than those observable by the radar. At heights of 400 m, cell scales become as large as those observable by the radar. Pressure fluctuations at the ground measured with spatial pressure transducers, at the same time as the radar and echosonde observations, traveled at the same speed and direction as the radar volume-averaged wind. The length scale determined at the ground with pressure fluctuation data was between 1.2 and 2.4 km, smaller than the largest radar-measured motion scales.  相似文献   

Kinematic models of a dry convective boundary layer compared with dual-Doppler radar observations of wind fields     

Gossard  Earl E.  Frisch  A. S. 《Boundary-Layer Meteorology》1976,10(3):311-330

The kinematic structure of the convective boundary layer, observed by a dual-Doppler radar system, is compared with the structure predicted by simple shear models. We first consider the models to be inviscid, then add viscous effects. Model 1 assumes a linear ambient wind profile from the surface through the boundary layer, and a constant wind above. The shear layer is assumed to be statically neutral, but static stability is permitted in the region above the shear. Model 2 has a hyperbolic tangent ambient wind profile.After considering the inviscid models, some of the effects of viscosity are incorporated into the models in a crude way, and the results are compared.We conclude that although the presence of shear is important, the kinematic structure is relatively independent of the details of the wind and temperature profiles. Viscosity has important effects, especially near the critical level where the disturbance velocity is equal to the wind speed. The patterns predicted by both models agree very well with the dual-Doppler radar observations when viscosity is included.  相似文献   

Clinopyroxenes as geobarometric indicators in mafic and ultramafic rocks from Canary Islands     

Thomas Frisch 《Contributions to Mineralogy and Petrology》1974,48(4):315-316

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