Koordinatentransformation,Mittelbare Orientierung,Nachbarwinkelstatistik     

Dr. Hans-Rudolf Wenk  Dr. Volkmar Trommsdorff 《Contributions to Mineralogy and Petrology》1965,11(6):559-585

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Sub-solidus Oligocene zircon formation in garnet peridotite during fast decompression and fluid infiltration (Duria, Central Alps)   总被引：1，自引：0，他引：1  

J. Hermann  D. Rubatto  V. Trommsdorff 《Mineralogy and Petrology》2006,88(1-2):181-206

Summary A garnet peridotite lens from Monte Duria (Adula nappe, Central Alps, Northern Italy) contains porphyroblastic garnet and pargasitic amphibole and reached peak metamorphic conditions of ∼830 C, ∼2.8 GPa. A first stage of near isothermal decompression to pressures <2.0 GPa is characterised by domains where fine grained spinel, clinopyroxene, orthopyroxene and amphibole form. The newly formed amphibole contains elevated levels of fluid mobile elements such as Rb, Ba and Pb indicating that recrystallization was assisted by infiltration of a crustal-derived fluid. Further decompression and cooling to ∼720 °C, 0.7–1.0 GPa associated with limited fluid influx is documented by the formation of orthopyroxene-spinel-amphibole symplectites around garnet. Zircon separated from this garnet peridotite exhibits two distinct zones. Domain 1 displays polygonal oscillatory zoning and high trace element contents. It contains clinopyroxene and amphibole inclusions with the same composition as the same minerals formed during the spinel peridotite equilibration, indicating that this domain formed under sub-solidus conditions during decompression and influx of crustal fluids. Domain 2 has no zoning and much lower trace element contents. It replaces domain 1 and is likely related to zircon recrystallization during the formation of the symplectites. SHRIMP dating of the two domains yielded ages of 34.2 ± 0.2 and 32.9 ± 0.3 Ma, respectively, indicating fast exhumation of the peridotite within the spinel stability field. We suggest that the Duria garnet peridotite originates from the mantle wedge above the tertiary subduction of the European continental margin and that it was assembled to the country rock gneisses between 34 and 33 Ma. Third author was Deceased  相似文献   

Construction of a large storage for critical waste     

Volkmar Gossow 《Engineering Geology》1985,21(3-4):349-358

The paper describes the construction of a long-term storage for critical waste. The base impermeability layer consisted of natural clay, whereby an additional 130,000 m³ of clay were placed on the existing 70,000 m² clay stratum. The method of of placement and the permeability coefficients obtained are described.  相似文献   

Halite and sylvite as solid inclusions in high-grade metamorphic rocks     

Volkmar Trommsdorff  George Skippen  Peter Ulmer 《Contributions to Mineralogy and Petrology》1985,89(1):24-29

Solid inclusions of halite and sylvite, formed during regional and contact metamorphism have been identified by microscopy and by electron microprobe analysis in rocks from Campolungo, Switzerland and Cornone di Blumone, Italy. The solid inclusions occur in several of the major minerals crystallized during metamorphism and have been observed as idiomorphic crystals and dendrites. The compositions measured in 100 analyses from Campolungo, Switzerland and 40 analyses from Cornone di Blumone, Italy extend across the two-phase region in the system, KCl-NaCl, indicating that the salt inclusions are high temperature precipitates. In both localities compositionally zoned and unzoned crystals have been found. Measured compositions on the temperature maximum of the two-phase region indicate at least 500° C which can be compared with 500°±20° C determined by Mercolli (1982) and Walther (1983) from the Mg content of calcites from Campolungo. The solid inclusions have been trapped apart from CO₂-rich and saline, H₂O-rich fluid inclusions which have been described by Mercolli (1982) as the earliest preserved fluid inclusions in the rocks. The early precipitation of salt minerals at Campolungo indicates that fluids were saturated with NaCl and KCl at 500° C and pressures of 2,000 bars or higher. Similar relationships exist between solid and fluid inclusions in the rocks of Cornone di Blumone which formed at temperatures as high as 800° C and pressures between 0.5 and 1 kilobar (Ulmer 1983). The entrapment of halite and sylvite as solid inclusions preserves the composition of the minerals which may therefore be useful as geothermometers.  相似文献   

Die fazielle Entwicklung des Alpinen Buntsandsteins (Skyth) im Westabschnitt der Nördlichen Kalkalpen (Tirol/Salzburg, Österreich)     

Volkmar Stingl 《International Journal of Earth Sciences》1987,76(2):647-664

For the first time the origin of the Alpine Buntsandstein (Scythian) in the western part of the Northern Calcarous Alps is outlined by lithofacies types and their relations. The eastern realm of Tyrol seemed to be interesting because of the transition from the terrestric-fluviatile facies of the Alpine Buntsandstein to the marine Werfen beds and the marine influence on the Alpine Buntsandstein. Lithology and sedimentary petrology enable a classification as redcoloured Lower Buntsandstein and white and grey Upper Buntsandstein. Analyses of sedimentary structures, lithofacies types and paleocurrent directions show, that most of the Lower Buntsandstein is composed of sandstones of a braided fluvial system, whose uppermost part ist replaced by sediments of a coastal plain only in the eastern part of Tyrol. Marginal marine influence is testified by sporadic occurrence of gypsum, increased carbonate content, bimodal current directions and trace fossils (Diplocraterion). Fluviatile sedimentation of the Upper Buntsandstein, starting above, is rapidly suppressed by transgression of the »Werfen Sea« from E to W, resulting in the development of estuaries, lastly being replaced by the marine Werfen beds.  相似文献   

Magmatism and metamorphism in the Ladakh Himalayas (the Indus-Tsangpo suture zone)   总被引：1，自引：0，他引：1  

K. Honegger  V. Dietrich  W. Frank  A. Gansser  M. Thöni  V. Trommsdorff 《Earth and Planetary Science Letters》1982,60(2):253-292

Ladakh (India) provides a complete geological section through the northwestern part of the Himalayas from Kashmir to Tibet. Within this section the magmatic, metamorphic and geotectonic evolution of the northern Himalayan orogeny has been studied using petrographic, geochemical and isotope analytical techniques.The beginning of the Himalayan cycle was marked by large basaltic extrusions (Panjal Trap) of Permian to Lower Triassic age at the “northern” margin of the Gondwana continent (Indian Shield). These continental type tholeiitic basalts were followed by a more alkaline volcanism within the Triassic to Jurassic Lamayuru unit of the Gondwana continental margin.Lower Jurassic to Cretaceous oceanic crust and sediments (ophiolitic mélange s.s.) accompany the Triassic to Cretaceous flysch deposits within the Indus-Tsangpo suture zone, the major structural divide between the Indian Shield (High Himalaya) and the Tibetan Platform. So far, no relic of Paleozoic oceanic crust has been found.Subduction of the Tethyan oceanic crust during Upper Jurassic and Cretaceous time produced an island arc represented by tholeiitic and calc-alkaline volcanic rock series (Dras volcanics) and related intrusives accompanied by volcaniclastic flysch deposits towards the Tibetan continental margin.Subsequent to the subduction of oceanic crust, large volumes of calc-alkaline plutons (Trans-Himalayan or Kangdese plutons) intruded the Tibetan continental margin over a distance of 2000 km and partly the Dras island arc in the Ladakh region.The collision of the Indian Shield and Tibetan Platform started during the middle to upper Eocene and caused large-scale, still active intracrustal thrusting as well as the piling up of the Himalayan nappes. The tectonically highest of these nappes is built up of oceanic crust and huge slices of peridotitic oceanic mantle (Spongtang klippe).In the High Himalayas the tectonic activity was accompanied and outlasted by a Barrovian-type metamorphism that affected Triassic sediments of the Kashmir-Nun-Kun synclinorium up to kyanite/staurolite grade and the deeper-seated units up to sillimanite grade. Cooling ages of micas are around 20 m.y. (muscovite) and 13 m.y. (biotite). Towards the Indus-Tsangpo suture zone metamorphism decreases with no obvious discontinuity through greenschist, prehnite-pumpellyite to zeolite grade. Remnants of possibly an Eo-Himalayan blueschist metamorphism have been found within thrust zones accompanying ophiolitic mélange in the suture zone.  相似文献   

Geochemistry of high-grade eclogites and metarodingites from the Central Alps     

Bernard W. Evans  Volkmar Trommsdorff  Gordon G. Goles 《Contributions to Mineralogy and Petrology》1981,76(3):301-311

Analyses for major, minor, and trace element contents of metamorphosed, variably rodingitized mafic rocks demonstrate substantial removal of Na and as much as three-fold gains in Ca as a consequence of rodingitization. Modest declines in Si and Fe can be explained in terms of dilution effects. Losses in K and Ba do not correlate with Ca% and may have been caused by an alteration process not related to the rodingitization. The Ca-metasomatism was not accompanied by a gain in Sr. The relative contents of Ti, Zr, Hf, Y, Co, Sc, and heavy REE show no readily detectable changes, despite the rodingitization (±other alteration) and subsequent metamorphisms, namely, eclogite facies (T800° C, P 20kbar) followed by amphibolite facies, sillimanite zone. Protoliths were tholeiitic basalt or diabase, and gabbro, with trace element contents indicative of a spreading center origin. Trace element and REE patterns indicate low-pressure fractionation of this magma, with plagioclase stable. This petrogenesis is consistent with prior conclusions on the shallow crustal origin of the protolith of the eclogite-metarodingite-garnet lherzolite suite in the Cima Lunga-Adula nappe, Central Alps. Based on their bulk chemical composition, the mafic rocks in this suite could be the equivalent of Mesozoic ophiolitic rocks in the more external parts of the Alps.  相似文献   

Petrogenesis of garnet lherzolite, Cima di Gagnone, Lepontine Alps   总被引：10，自引：0，他引：10  

Bernard W. Evans  Volkmar Trommsdorff 《Earth and Planetary Science Letters》1978,40(3):333-348

Garnet lherzolite at Cima di Gagnone has chemical and mineralogical properties similar to those of other garnet lherzolites in the lower Pennine Adula/Cima Lunga Nappe (Alpe Arami, Monte Duria). The Cima di Gagnone occurrence encloses mafic boudins that belong to an eclogite-metarodingite suite common in the numerous neighboring ultramafic lenses. The ultramafic rocks at Cima di Gagnone, including the garnet lherzolite, are interpreted as tectonic fragments of an originally larger lherzolite body that underwent at least partial serpentinization prior to regional metamorphism. This lherzolite body cycled through at least three metamorphic facies: greenschist or blue-schist (as antigorite serpentinite) → eclogite (as garnet lherzolite), pre-Alpine or early Alpine → amphibolite facies (as chlorite-enstatite-tremolite peridotite), Lepontine metamorphism. Relics of titanoclinohumite in the garnet peridotite, as also recorded by Möckel near Alpe Arami, are consistent with this metamorphic history, since they indicate a possible connection with Pennine antigorite serpentinites, e.g., Liguria, Piedmont, Zermatt-Saas, Malenco, Pustertal, all of which have widespread titanoclinohumite belonging to the antigorite paragenesis. Estimated pressures in excess of 20 kbar and temperatures of 800°±50°C for the garnet lherzolite assemblage are not inconsistent with conditions inferred for Gagnone and Arami eclogites. These conditions could have been reached during deep subduction zone metamorphism. It is shown by calculation that the effects of Fe and Cr on the location of the garnet lherzolite/spinel lherzolite phase boundary largely counter-balance each other.  相似文献   

Sedimentological investigations of metamorphic clastics: the basal clastic rocks of the Brenner Mesozoic (Stubai Alps, Austria/Italy)     

Volkmar Stingl  Peter Krois 《地学学报》1990,2(3):273-281

Sedimentological investigations were carried out in the basal clastic rocks of the Brenner Mesozoic in the Stubai Alps. These are Scythian in age and metamorphosed to a greenschist grade. The increase of temperature and pressure from north to south allows the metamorphic effects on Sedimentological features to be gradually traced into higher grade metamorphic areas. The use of various laboratory methods as well as profiling with lithofacies types shows the limitation of using only single methods in sediments suffering thermal and deformational overprint. Only a combined application of different methods allows the extraction of useful sedimentological information. Based on the results of these investigations, a fan delta to shelf succession is proposed for the basal clastic rocks. Petrographic analyses show the relation of the sediments to an underlying weathering horizon.  相似文献   

Early-Morning Flow Transition in a Valley in Low-Mountain Terrain Under Clear-Sky Conditions     

Björn Brötz  Rafael Eigenmann  Andreas Dörnbrack  Thomas Foken  Volkmar Wirth 《Boundary-Layer Meteorology》2014,152(1):45-63

We investigate the evolution of the early-morning boundary layer in a low-mountain valley in south-western Germany during COPS (convective and orographically induced precipitation study) in summer 2007. The term low-mountain refers to a mountainous region with a relief of gentle slopes and with an absolute altitude that remains under a specified height (usually 1,500 m a.s.l.). A subset of 23 fair weather days from the campaign was selected to study the transition of the boundary-layer flow in the early morning. The typical valley atmosphere in the morning hours was characterized by a stable temperature stratification and a pronounced valley wind system. During the reversal period—called the low wind period—of the valley wind system (duration of 1–2 h), the horizontal flow was very weak and the conditions for free convection were fulfilled close to the ground. Ground-based sodar observations of the vertical wind show enhanced values of upward motion, and the corresponding statistical properties differ from those observed under windless convective conditions over flat terrain. Large-eddy simulations of the boundary-layer transition in the valley were conducted, and statistical properties of the simulated flow agree with the observed quantities. Spatially coherent turbulence structures are present in the temporal as well as in the ensemble mean analysis. Thus, the complex orography induces coherent convective structures at predictable, specific locations during the early-morning low wind situations. These coherent updrafts, found in both the sodar observations and the simulation, lead to a flux counter to the gradient of the stably stratified valley atmosphere and reach up to the heights of the surrounding ridges. Furthermore, the energy balance in the surface layer during the low wind periods is closed. However, it becomes unclosed after the onset of the valley wind. The partition into the sensible and the latent heat fluxes indicates that missing flux components of sensible heat are the main reason for the unclosed energy balance in the considered situations. This result supports previously published investigations on the energy balance closure.  相似文献