Phanerozoic mafic magmatism in the southern Siberian craton: geodynamic implications     

D.P. Gladkochub  T.V. Donskaya  A.V. Ivanov  R. Ernst  A.M. Mazukabzov  S.A. Pisarevsky  N.A. Ukhova 《Russian Geology and Geophysics》2010,51(9):952-964

The Phanerozoic history of mafic magmatism in the southern Siberian craton included three major events. The earliest event (～500 Ma) recorded in dolerite dikes occurred during accretion and collision at the early stage of the Central Asian orogen. Injection of mafic melts into the upper crust was possible in zones of diffuse extension within the southern Siberian craton which acted as an indenter. The Late Paleozoic event (～275 Ma) produced dikes that intruded in a setting of subduction-related extension at the back of the active continental margin of Siberia during closure of the Mongolia–Okhotsk ocean, as well as slightly older volcanics (290 Ma) in the Transbaikalian segment of the Central Asian orogen. Early Mesozoic magmatism in the southern Siberian craton resulted in numerous 240–250 Ma mafic intrusions in the Angara–Taseeva basin. The intrusions (Siberian traps) appeared as the subducting slab of the Mongolia–Okhotsk ocean interacted with a lower mantle plume. The post-Late Paleozoic ages of flood basalts (290–275 Ma) correspond to progressive northwestward (in present coordinates) motion of the slab beneath the southern craton margin which likely ceased after the slab had reached the zone of the Siberian superplume. Since its consolidation after the Early Mesozoic activity, the crust in the area has no longer experienced extension favorable for intrusion of basaltic magma.  相似文献   

Raman microspectrometry of fluid inclusions   总被引：45，自引：0，他引：45  

Ernst A. J. Burke 《Lithos》2001,55(1-4):139-158

For many kinds of fluid inclusions, the coupling of microthermometry and Raman microspectrometry is still the only viable option to obtain compositions of single fluid inclusions. A review is given on the basis of 16 years of experience and helped with about 120 references of the instrumentation, analytical conditions and methodology of the application of Raman microspectrometry to gaseous, aqueous and hydrocarbon inclusions, and their daughter minerals.  相似文献   

Geological setting and SHRIMP U–Pb geochronological evidence for ca. 2680–2660 Ma lode-gold mineralization at Jundee–Nimary in the Yilgarn Craton, Western Australia     

Christopher J. Yeats  Ernst A. Kohler  Neal J. McNaughton  Luke J. Tkatchyk 《Mineralium Deposita》2001,36(2):125-136

The 7 million oz. Jundee–Nimary lode-gold deposit occurs in the northern portion of the Yandal greenstone belt in the northeastern part of the Archean Yilgarn Craton of Western Australia. Gold mineralization at Jundee–Nimary is similar in structural style, mineralogy, geochemistry and relative timing with respect to deformation and metamorphism, to other Western Australian Archean greenstone-hosted gold deposits, but is unusual in the fact that mineralized structures are crosscut by structurally late intermediate to felsic dykes. Within the Deakin South open cut, gold mineralization is hosted in brittle–ductile shear zones primarily developed within the dacitic Mitchell Porphyry. The Moore Porphyry, a broad dyke of porphyritic granodiorite, intrudes the Mitchell Porphyry, crosscutting and post-dating gold mineralization. Analytically indistinguishable SHRIMP U–Pb zircon ages of 2678 ± 5 Ma for the Mitchell Porphyry and 2669 ± 7 Ma for the Moore Porphyry require that gold mineralization at Jundee–Nimary occurred at ca. 2680–2660 Ma, approximately 40 million years earlier than the majority of published robust ages for gold mineralization in the Yilgarn Craton, which mostly overlap at ca. 2640–2630 Ma. The close spatial and temporal relationship between gold mineralization and felsic to intermediate magmatism at Jundee–Nimary also raises the possibility of a genetic link between hydrothermal and igneous activity. However, additional work is required to establish a firm connection. Current research on lode-gold mineralization in Archean, Paleozoic and Phanerozoic terranes suggests a model which postulates that these deposits formed during transpressional to compressional deformation in accretionary and collisional orogens and that their formation is intimately related to orogenic processes. Consequently, mineralization and regional metamorphism are expected to be diachronous, as terranes are accreted and the front of orogenesis migrates. Consideration of the new data presented in this paper in conjunction with previously published dates supports the hypothesis that gold mineralization, along with regional metamorphism, was generally diachronous from northeast to southwest across the Yilgarn Craton, over a period of approximately 40 million years from ca. 2680–2660 Ma to ca. 2640–2630 Ma. This is directly analogous to the accepted model for the timing of orogenic lode-gold mineralization in other provinces and therefore provides further support for a unified model for this style of deposit through geological time. Received: 17 March 2000 / Accepted: 8 September 2000  相似文献   

Crustal structure of the central Sunda margin at the onset of oblique subduction   总被引：1，自引：0，他引：1  

Heidrun Kopp  Ernst R. Flueh  Dirk Klaeschen  Jörg Bialas  Christian Reichert 《Geophysical Journal International》2001,147(2):449-474

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Occurrences of hydrous and carbonate phases in ultrahigh-pressure rocks from east-central China: Implications for the role of volatiles deep in cold subduction zones   总被引：3，自引：0，他引：3  

J. G. Liou    R. Y. Zhang  W. G. Ernst 《Island Arc》1995,4(4):362-375

Abstract Minor epidote-zoisite, phengite, glaucophane, nyböite, talc, magnesite, and dolomite occur as matrix phases or as mineral inclusions in some ultrahigh-pressure (UHP) rocks from the Dabie-Sulu terrane. Some of these phases contain inclusions of coesite or coesite pseudomorphs and appear to have been in equilibrium with coesite at the time of formation. Their occurrences in the UHP rocks together with experimentally determined and calculated phase relations indicate that they are stable at mantle depths in relatively low-temperature environments. Because of the apparently dry nature of subducted continental protoliths of the Yangtze craton, small amounts of volatile components at depths exceeding 50 km along a cold subduction zone may have been stored mainly by these hydrous and carbonate phases. These minerals, in addition to some dense hydrous magnesian silicates, act as important carriers for H₂O and CO₂ recycled at mantle depths. Available petrological and geochemical data support limited or no fluid flow in this region. At very high pressures and low temperatures, the subducted sialic crust evidently served as a desiccating agent. Partial melting of the subducting slab, therefore, may not have occurred, and near absence of volatile expulsion from the subducting slab to the overlying mantle wedge + continental crust may have inhibited large-scale partial melting, accounting for the lack of a typical contemporaneous calc-alkaline magmatic arc.  相似文献   

Vergleichende Betrachtungen zur Talausbildung Schwedischer und hessischer Flüsse     

Dr. Ernst Sobotha 《International Journal of Earth Sciences》1962,51(2):681-683

Ohne ZusammenfassungTitularbeitrag.  相似文献   

Turbulence in a Katabatic Flow     

Ernst Van Der Avoird  Peter G. Duynkerke 《Boundary-Layer Meteorology》1999,92(1):37-63

Turbulence measurements performed in a stable boundary layer over the sloping ice surface of the Vatnajökull in Iceland are described. The boundary layer, in which katabatic forces are stronger than the large-scale forces, has a structure that closely resembles that of a stable boundary layer overlying a flat land surface, although there are some important differences. In order to compare the two situations the set-up of the instruments on an ice cap in Iceland was reproduced on a flat grass surface at Cabauw, the Netherlands. Wind speed and temperature gradients were calculated and combined with flux measurements made with a sonic anemometer in order to obtain the local stability functions _m and _h as a function of the local stability parameter z/L. Unlike the situation at Cabauw, where _m was linear as a function of z/L, in the katabatically forced boundary layer, the dependence of _m on stability was found to be non-linear and related to the height of the wind maximum. Thermal stratification and the depth of the stable boundary layer however seem to be rather similar under these two different forcing conditions.Furthermore, measurements on the ice were used to construct the energy balance. These showed good agreement between observed melt and components contributing to the energy balance: net radiation (supplying 55% of the energy), sensible heat flux (30%) and latent heat flux (15%).Local sources and sinks in the turbulent kinetic energy budget are summed and indicate a reasonable balance in near-neutral conditions but not in more stable situations. The standard deviation of the velocity fluctuations _u, _v, and _w, can be scaled satisfactorily with the local friction velocity u_* and the standard deviation of the temperature fluctuation with the local temperature scale _*.  相似文献   

Über die Ursache von Rissen in der Eiskappe des nördlichen Polarmeeres     

Prof. Dr.-Ing. Ernst Schmidt 《Meteorology and Atmospheric Physics》1969,18(3-4):391-394

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Beziehungen zwischen Planktonentwicklung und Bakterien im Vierwaldstättersee und Rotsee     

Ernst Schegg dipl. sc. nat. ETH 《Aquatic Sciences - Research Across Boundaries》1968,30(2):289-296

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NIZUSE: a deep seismic reflection line in north-eastern Germany     

Wolfgang Horst  Michael Börngen  Ernst R. flueh 《International Journal of Earth Sciences》1994,83(1):161-169

Out of a dense network of seismic reflection lines for hydrocarbon exploration in the North-east German Basin, several lines were recorded to 12 s TWT to obtain information about the structure of the crust and the crust-mantle transition. One of these profiles is presented here. This stretches for 110 km in a NNE direction between Neustrelitz and the island of Usedom. It reaches from the External Variscides in the south across the North German Massif into the Rügen-Pomorze Terrane in the Baltic Sea. Below Cenozoic-Mesozoic-Paleozoic cover with clear reflections down to base Zechstein, the reflectivity varies considerably with depth and also laterally. The Paleozoic and Precambrian sediments and basement are generally void of reflections, but the lower crust and the Moho show strong reflections. To the north the reflectivity decreases, and the Moho depth increases to beyond the bottom of the record section at 12 s. There are no direct indications for deep-reaching faults such as the Trans-European Fault in the north. The North German Massif acted as a ramp towards the Variscan Orogeny, similar to the London-Brabant Massif further west.  相似文献