Modelled palaeo-temperature on Vøring, offshore mid-Norway — The effect of the Lower Crustal Body     

W. Fjeldskaar  I. Grunnaleite  J. Zweigel  R. Mjelde  J.I. Faleide  J. Wilson   《Tectonophysics》2009,474(3-4):544-558

The Vøring area, offshore mid-Norway has a complex geological history, has experienced several extensional phases and was significantly influenced by the break-up of the North Atlantic. We have modelled a cross-section over the Vøring Basin aiming to 1) reconstruct the basin evolution in a realistic way, and 2) to investigate the heat flow and temperature history in the basin.For the modelling we used the following tectonic events: the opening of the basin during the Permo-Triassic, an event during the Middle to Late Cretaceous and an event in the Late Cretaceous/Paleocene. The theoretical effects of the lithospheric stretching are depending on the palaeo-water depths of the area. We present a prediction of the palaeo-water depth, and a sensitivity analysis of the influence of the palaeo-water depth on the estimated beta-factors in the area.A lower crustal high-velocity body found in the area is often interpreted as magmatic underplating related to the break-up of the Norwegian Sea. We show the temperature history calculated by models that were run with and without assumption of underplating by a magmatic body emplaced during the Early Tertiary. The observed vitrinite reflectance in the Vøring area is best explained by numerical calculations of the vitrinite reflectance without a magmatic underplating. Our conclusion is that the Lower Crustal Body is not related to magmatic underplating or to significant sill intrusions. The body may consist of older mafic rocks, or a mixture of old continental crust and mafic intrusions.  相似文献   

Middle Pleistocene (Saalian) lake outburst floods in the Münsterland Embayment (NW Germany): impacts and magnitudes     

Janine Meinsen  Jutta Winsemann  Axel Weitkamp  Nils Landmeyer  Andreas Lenz  Manfred Dölling 《Quaternary Science Reviews》2011,30(19-20):2597-2625

During the late Saalian Drenthe glaciation ice-damming of the Upper Weser Valley led to the formation of glacial Lake Weser. The lake drained catastrophically into the Münsterland Embayment as the western ice dam failed, releasing up to 110 km³ of water with a calculated peak discharge of 2.5 × 10⁵ m³/s to 1.3 × 10⁶ m³/s. Geographic information systems (GIS) and high-resolution digital elevation models (DEM) were used to map streamlined landforms and channel systems in front of lake overspills. Geological maps, 2450 boreholes and the DEM were integrated into the 3D modeling program GOCAD to reconstruct the distribution of flood-related deposits, palaeotopographic surfaces and the internal facies architecture of streamlined hills. The drainage pathways are characterized by the occurrence of deep plunge pools, channels, streamlined hills and 4 km long and 12 m deep V-shaped megaflutes. Plunge pools are deeply incised into Mesozoic basement rocks and occur in front of three major overspill channels. The plunge pools are up to 780 m long, 400 m wide and 35 m deep. Approximately 1–10.5 km downslope of the overspill channels fan shaped arrays of streamlined hills are developed, each covering an area of 60–130 km², indicating rapid flow expansion. The hills commonly have quadrilateral to elongated shapes and formed under submerged to partly submerged flow conditions, when the outburst flood entered a shallow lake in the Münsterland Embayment. Hills are up to 4300 m long, 1200 m wide, 11 m high and have characteristic average aspect ratios of 1:3.3. They are separated by shallow, anabranching channels in the outer zones and up to 30 m deep channels in the central zones. Hills partly display V-shaped chevron-like bedforms that have apices facing upslope, are 1.6–2.5 km long, 3–10 m high, 0.8–1.2 m from limb to limb, with limb separation angels of 20–35°. These bedforms are interpreted as mixed erosional depositional features. It is hypothesized that the post-Saalian landscape evolution of the Münsterland Embayment has considerably been influenced by catastrophic floods of glacial Lake Weser, creating large and deep valleys, which subsequently became the new site of river systems. The outburst floods probably followed the east-west-trending Saalian Rhine-Meuse river system eventually flowing into the North Sea, the Strait of Dover and the Bay of Biscay. It is speculated that the Hondsrug ice stream may have been enhanced or even triggered by the formation and outburst of glacial lakes in the study area.  相似文献   

Conceptual understanding of climate change with a globally resolved energy balance model     

Dietmar Dommenget  Janine Fl?ter 《Climate Dynamics》2011,37(11-12):2143-2165

The future climate change projections are essentially based on coupled general circulation model (CGCM) simulations, which give a distinct global warming pattern with arctic winter amplification, an equilibrium land-sea warming contrast and an inter-hemispheric warming gradient. While these simulations are the most important tool of the Intergovernmental Panel on Climate Change (IPCC) predictions, the conceptual understanding of these predicted structures of climate change and the causes of their uncertainties is very difficult to reach if only based on these highly complex CGCM simulations. In the study presented here we will introduce a very simple, globally resolved energy balance (GREB) model, which is capable of simulating the main characteristics of global warming. The model shall give a bridge between the strongly simplified energy balance models and the fully coupled 4-dimensional complex CGCMs. It provides a fast tool for the conceptual understanding and development of hypotheses for climate change studies, which shall build a basis or starting point for more detailed studies of observations and CGCM simulations. It is based on the surface energy balance by very simple representations of solar and thermal radiation, the atmospheric hydrological cycle, sensible turbulent heat flux, transport by the mean atmospheric circulation and heat exchange with the deeper ocean. Despite some limitations in the representations of the basic processes, the models climate sensitivity and the spatial structure of the warming pattern are within the uncertainties of the IPCC models simulations. It is capable of simulating aspects of the arctic winter amplification, the equilibrium land-sea warming contrast and the inter-hemispheric warming gradient with good agreement to the IPCC models in amplitude and structure. The results give some insight into the understanding of the land-sea contrast and the polar amplification. The GREB model suggests that the regional inhomogeneous distribution of atmospheric water vapor and the non-linear sensitivity of the downward thermal radiation to changes in the atmospheric water vapor concentration partly cause the land-sea contrast and may also contribute to the polar amplification. The combination of these characteristics causes, in general, dry and cold regions to warm more than other regions.  相似文献   

3s²3p–3s3p² transitions in S iv     

Alan Hibbert  Tomas Brage  Janine Fleming 《Monthly notices of the Royal Astronomical Society》2002,333(4):885-893

We use both the civ3 and mchf codes to calculate oscillator strengths of allowed and intercombination lines in the  3s²3p–3s3p²  multiplets. Valence, core–valence and some core–core correlation effects are included. The two approaches give results in excellent agreement. Core effects are particularly important for the intercombination lines, though relatively minor for allowed transitions.
We obtain a branching ratio of 1.42 with an estimated accuracy of 0.02 for the     transitions, compared with an experimental value of  1.12±0.1  . The A -values of the     intercombination lines are substantially different from those of previous calculations.  相似文献   

Atlantic and Mediterranean synoptic drivers of central Spanish juniper growth     

Jan Esper  Janine Großjean  Jesús Julio Camarero  Ana I. García-Cervigón  José M. Olano  J. Fidel González-Rouco  Fernando Domínguez-Castro  Ulf Büntgen 《Theoretical and Applied Climatology》2015,121(3-4):571-579

  相似文献   

Response of a bounded atmosphere to a non-resonant excitation     

Janine Provost 《Solar physics》1975,40(2):257-273

The response of a bounded atmosphere to a non-resonant excitation applied at its basis is studied. It is shown that the essential feature related to this kind of excitation is that the distribution of the energy of the velocity field relatively to the frequency and horizontal wavelength is a function of height and merely depends on the structure of the atmosphere above the level at which it is considered. The preliminary results concerning an isothermal atmosphere are presented and their relevance to the solar case is discussed.  相似文献   

Wave reflections in the solar atmosphere     

Janine Provost  Nicole Mein 《Solar physics》1979,64(1):43-56

The small phase-lag between velocities observed at different chromospheric levels is interpreted as being due to acoustic waves reflected by the very hot atmospheric layers of the chromosphere-corona transition zone. We consider first an isothermal slab, then a realistic solar atmospheric model and calculate weighting functions for velocities in Ca ii lines. It is shown that taking into account these functions and integrating over horizontal wave numbers leads to a good agreement with previous observations (Mein, 1977) in the case of 8498 and 8542 Ca ii lines. For the K line, the less good agreement shows that magnetoacoustic waves become important in the upper chromospheric layers.  相似文献   

Narrative analysis as a strategy for understanding interview talk in geographic research   总被引：1，自引：0，他引：1  

Janine L Wiles  Mark W Rosenberg  Robin A Kearns 《Area》2005,37(1):89-99

Narrative analysis produces strategies to inform the conduct, interpretation and presentation of interview talk, and encourages and enables researchers to take account of research participants' own evaluations. We suggest this to be a useful method for geographers because it focuses on how people talk about and evaluate places, experiences and situations, as well as what they say. With an example from health geography, we show how it allows for interactive texts, thus providing a tool for geographers doing qualitative research to connect intimate details of experience to broader social and spatial relations.  相似文献   

⁴⁰Ar/³⁹Ar ages for the alkaline volcanism and the basement of Gorringe Bank,North Atlantic ocean     

Gilbert Féraud  Janine Gastaud  Jean-Marie Auzende  Jean-Louis Olivet  Guy Cornen 《Earth and Planetary Science Letters》1982,57(1):211-226

Gorringe Bank is situated on the Europe-Africa plate boundary at the eastern end of the Azores-Gibraltar fracture zone. It has two summits, Gettysburg Bank to the Southwest and Ormonde Bank to the northeast.We applied the⁴⁰Ar/³⁹Ar stepwise heating method to date six samples of the alkaline volcanic rocks, two gabbros from the Ormonde Bank and a dolerite from the Gettysburg Bank. The results that the alkaline volcanism lasted probably for less than 6 Ma(66-60 Ma).Although the nature of this volcanism precludes any subduction feature during its setting, the alkaline volcanism of Ormonde is probably linked to Upper Cretaceous/Eocene compressive tectonic events.The basement rocks of Gorringe Bank reveal distrubed⁴⁰Ar/³⁹Ar age spectra. One plagioclase and one biotite from a gabbro give evidence for a thermic event whose age is tentatively estimated at about 75 Ma, and related to a variation in the direction of the relative movement between Europe and Africa. The more probable age given by a plagioclase of another gabbro and by a dolerite (110 Ma) corresponds to tilting northeastward of the Gorringe massif.  相似文献   

VIRGO: Experiment for helioseismology and solar irradiance monitoring   总被引：1，自引：0，他引：1  

Claus Fröhlich  José Romero  Hansjörg Roth  Christoph Wehrli  Bo N. Andersen  Thierry Appourchaux  Vicente Domingo  Udo Telljohann  Gabrielle Berthomieu  Philippe Delache  Janine Provost  Thierry Toutain  Dominique A. Crommelynck  André Chevalier  Alain Fichot  Werner Däppen  Douglas Gough  Todd Hoeksema  Antonio Jiménez  Maria F. Gómez  José M. Herreros  Teodoro Roca Cortés  Andrew R. Jones  Judit M. Pap  Richard C. Willson 《Solar physics》1995,162(1-2):101-128

The scientific objective of the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) is to determine the characteristics of pressure and internal gravity oscillations by observing irradiance and radiance variations, to measure the solar total and spectral irradiance and to quantify their variability over periods of days to the duration of the mission. With these data helioseismological methods can be used to probe the solar interior. Certain characteristics of convection and its interaction with magnetic fields, related to, for example, activity, will be studied from the results of the irradiance monitoring and from the comparison of amplitudes and phases of the oscillations as manifest in brightness from VIRGO, in velocity from GOLF, and in both velocity and continuum intensity from SOI/MDI. The VIRGO experiment contains two different active-cavity radiometers for monitoring the solar constant, two three-channel sunphotometers (SPM) for the measurement of the spectral irradiance at 402, 500 and 862 nm, and a low-resolution imager (LOI) with 12 pixels, for the measurement of the radiance distribution over the solar disk at 500 um. In this paper the scientific objectives of VIRGO are presented, the instruments and the data acquisition and control system are described in detail, and their measured performance is given.died 13 October 1994  相似文献