A description of the tides and effect of Qeshm canal on that in the Persian Gulf using two-dimensional numerical model

The main semidiurnal (M2 and S2) and diurnal (K1 and O1) tidal constituents are simulated in the Persian Gulf (PG). The topography is discretized on a spherical grid with a resolution of 30 s in both latitude and longitude. It includes coastal areas prone to flooding. The model permits flooding of drying banks up to 5 m above mean sea level. At the open boundary, it is forced by 13 harmonic constituents extracted from a global tidal model. The model results are in good agreement with tide gauge observations. Co-tidal charts and flow extremes are presented for each tidal constituent. The co-tidal charts show two amphidromic points for semidiurnal and one for diurnal tidal constituents. Maximum amplitudes of sea level are obtained for the north-western part of the PG, where coastal flooding prevails in wide areas. Strong tidal currents occur in different parts of the PG for different types of constituents. Maximum velocities are found in shallow regions. Particularly, high amplitudes of elevations and high speed currents are founded in the canal between Qeshm Island and the mainland. Rectification of tides around Qeshm Island affects the propagation of tides in the PG as far as the coast of Saudi Arabia and the northern part of the PG.     

East Avalonia,the third partner in the Caledonian collisions: evidence from deep seismic reflection data

Further evidence for the existence of the terrane East Avalonia (Cadomia) in north-west Europe, its boundaries and its role in the Caledonian collisional processes comes from studies of deep seismic reflection data at sea and on land. Various sutures are found in the north-east and the north-west, and a generally poor reflectivity dominates in the major part. Further details of reflectivity patterns support the idea that a huge terrane which split from the northern rim of Gondwana moved northward and collided with the merging plates Laurentia-Baltica. Its docking features are analysed.     

Atacamite formation by deep saline waters in copper deposits from the Atacama Desert,Chile: evidence from fluid inclusions,groundwater geochemistry,TEM, and <Superscript>36</Superscript>Cl data

The presence of large amounts of atacamite in oxide zones from ore deposits in the Atacama Desert of northern Chile requires saline solutions for its formation and hyperarid climate conditions for its preservation. We investigated the nature and origin of atacamite-forming solutions by means of coupling groundwater geochemical analyses with fluid inclusion data, high-resolution mineralogical observations, and chlorine-36 (³⁶Cl) data in atacamite from the Mantos Blancos and Spence Cu deposits. In both deposits, the salinities of fluid inclusions in atacamite are comparable to those measured in saline groundwaters sampled from drill holes. The average salinity of fluid inclusions in atacamite for the Mantos Blancos and Spence deposits (~7–9 and 2–3 wt.% NaCl_eq, respectively) are strongly correlated to the salinities at which gypsum supersaturates from groundwaters in both deposits (total dissolved solids ~5–9 and 1–3 wt.% NaCl_eq, respectively). This correlation is confirmed by transmission electron microscopy observations of atacamite-bearing samples, revealing an intimate association between atacamite and gypsum that can be traced down to the nanometer scale. ³⁶Cl data in atacamite provide new lines of evidence concerning the origin and age of the saline waters that formed atacamite in various stratabound and porphyry Cu deposits from the Atacama Desert. All atacamite samples show very low ³⁶Cl-to-Cl ratios (11 × 10⁻¹⁵ to 28 × 10⁻¹⁵ at at⁻¹), comparable to previously reported ³⁶Cl-to-Cl ratios of deep formation waters and old groundwaters. In addition, ³⁶Cl-to-Cl ratios in atacamite correlate with U and Th concentration in the host rocks but are independent from distance to the ocean. This trend supports an interpretation of the low ³⁶Cl-to-Cl ratios in atacamite as representing subsurface production of fissiogenic ³⁶Cl in secular equilibrium with the solutions involved in atacamite formation. Therefore, ³⁶Cl in atacamite strongly suggest that the chlorine in saline waters related to atacamite formation is old (>1.5 Ma) but that atacamite formation occurred more recently (<1.5 Ma) than suggested in previous interpretations. Our data provide new constraints on the origin of atacamite in Cu deposits from the Atacama Desert and support the recent notion that the formation of atacamite in hyperarid climates such as the Atacama Desert is an ongoing process that has occurred intermittently since the onset of hyperaridity.     

An asymptotic solution of hydrodynamic equations at the mid-plane of a plume in the Earth's mantle

From the partial differential equations of hydrodynamics governing the movements in the Earth's mantle of a Newtonian fluid with a pressure- and temperature-dependent viscosity, considering the bilateral symmetry of velocity and temperature distributions at the mid-plane of the plume, an analytical solution of the governing equations near the mid-plane of the plume was found by the method of asymptotic analysis. The vertical distribution of the upward velocity, viscosity and temperature at the mid-plane, and the temperature excess at the centre of the plume above the ambient mantle temperature were then calculated for two sets of Newtonian rheological parameters. The results obtained show that the temperature at the mid-plane and the temperature excess are nearly independent of the rheological parameters. The upward velocity at the mid-plane, however, is strongly dependent on the rheological parameters.     

Mapping of desert locust habitats in Africa using Landsat Thematic Mapper data

The results of the research at the Sudan Red Sea coast, which is part of the GTZ project Integrated Biological Control of Grasshoppers and Locusts will be presented. For detecting desert locust biotopes multitemporal Landsat Thematic Mapper data and ground truth information are analyzed. The Normalized Difference Vegetation Index (NDVI) shows the areas covered with vegetation. These areas are masked and then classified with the maximum likelihood classifier. Rectification and ground truthing are carried out by means of a GPS (Global Positioning System). The results of the multitemporal classification are merged with an enhanced satellite scene. The final map shows the potential desert locust biotopes. The current desert locust breeding area can be demarcated by combining the classification results with up-to-date data from monitoring satellites, such as Meteosat and NOAA. Further research is carried out in Mali and Mauritania.     

Structure and evolution of the terrestrial planets

Geo-scientific planetary research of the last 25 years has revealed the global structure and evolution of the terrestrial planets Moon, Mercury, Venus and Mars. The evolution of the terrestrial bodies involves a differentiation into heavy metallic cores, Fe-and Mg-rich silicate mantles and light Ca, Al-rich silicate crusts early in the history of the solar system. Magnetic measurements yield a weak dipole field for Mercury, a very weak field (and local anomalies) for the Moon and no measurable field for Venus and mars. Seismic studies of the Moon show a crust-mantle boundary at an average depth of 60 km for the front side, P- and S-wave velocities around 8 respectively 4.5 km s^–1 in the mantle and a considerable S-wave attenuation below a depth of 1000 km. Satellite gravity permits the study of lateral density variations in the lithosphere. Additional contributions come from photogeology, orbital particle, x-and -ray measurements, radar and petrology.The cratered surfaces of the smaller bodies Moon and Mercury have been mainly shaped by meteorite impacts followed by a period of volcanic flows into the impact basins until about 3×10⁹ yr before present. Mars in addition shows a more developed surface. Its northern half is dominated by subsidence and younger volcanic flows. It even shows a graben system (rift) in the equatorial region. Large channels and relics of permafrost attest the role of water for the erosional history. Venus, the most developed body except Earth, shows many indications of volcanism, grabens (rifts) and at least at northern latitudes collisional belts, i.e. mountain ranges, suggesting a limited plate tectonic process with a possible shallow subduction.List of Symbols and Abbreviations a=R _e mean equatorial radius (km) - A(r, t) heat production by radioactive elements (W m^–3) - A, B equatorial moments of inertia - b polar radius (km) - complex amplitude of bathymetry in the wave number (K) domain (m) - C polar moment of inertia - C _Fe moment of inertia of metallic core - C _Si moment of inertia of silicate mantle - C _p heat capacity at constant pressure (JK^–1 mole^–) - C _nm,J _nm,S _nm harmonic coefficients of degreen and orderm - C/(MR _e ² ) factor of moment of inertia - d distance (km) - d nondimensional radius of disc load of elastic bending model - D diameter of crater (km) - D flexural rigidity (dyn cm) - E Young modulus (dyn cm^–2) - E maximum strain energy - E energy loss during time interval t - f frequency (Hz) - f flattening - F magnetic field strength (Oe) (1 Oe=79.58A m^–1) - g acceleration or gravity (cms^–2) or (mGal) (1mGal=10^–3cms^–2) - mean acceleration - g _e equatorial surface gravity - complex amplitude of gravity anomaly in the wave number (K) domain - g free air gravity anomaly (FAA) - g Bouguer gravity anomaly - g _t gravity attraction of the topography - G gravitational constant,G=6.67×10^–11 m³kg^–1s^–2 - GM planetocentric gravitational constant - h relation of centrifugal acceleration (² R _e ) to surface acceleration (g _e ) at the equator - J magnetic flux density (magnetic field) (T) (1T=10⁹ nT=10⁹ =10⁴G (Gauss)) - J ₂ oblateness - J _nm seeC _nm - k ₍₀₎ (zero) pressure bulk modulus (Pa) (Pascal, 1 Pa=1 Nm^–2) - K wave number (km^–1) - K ^* thermal conductivity (Jm^–1s^–1K^–1) - L thickness of elastic lithosphere (km) - M mas of planet (kg) - M _Fe mass of metallic core - M _Si mass of silicate mantle - M(r) fractional mass of planet with fractional radiusr - m magnetic dipole moment (Am²) (1Am²=10³Gcm³) - m _b body wave magnitude - N crater frequency (km^–2) - N(D) cumulative number of cumulative frequency of craters with diameters D - P pressure (Pa) (1Pa=1Nm^–2=10^–5 bar) - P _z vertical (lithostatic) stress, see also _z (Pa) - P _n ^m (cos) Legendre polynomial - q surface load (dyn cm^–2) - Q seismic quality factor, 2E/E - Q _s ,Q _p seismic quality factor derived from seismic S-and P-waves - R=R ₀ mean radius of the planet (km) (2a+b)/3 - R _e =a mean equatorial radius of the planet - r distance from the center of the planet (fractional radius) - r _Fe radius of metallic core - S _nm seeC _nm - t time and age in a (years), d (days), h (hours), min (minutes), s (seconds) - T mean crustal thickness from Airy isostatic gravity models (km) - T temperature (°C or K) (0°C=273.15K) - T _m solidus temperature - T sideral period of rotation in d (days), h (hours), min (minutes), s (seconds), =2/T - U external potential field of gravity of a planet - V volume of planet - V _p ,V _s compressional (P), shear (S) wave velocity, respectively (kms^–1) - w deflection of lithosphere from elastic bending models (km) - z, Z depth (km) - z (K) admittance function (mGal m^–1) - thermal expansion (°C^–1) - viscosity (poise) (1 poise=1gcm^–1s^–1) - co-latitude (90°-) - longitude - Poisson ratio - density (g cm^–3) - mean density - ₀ zero pressure density - _m , _Si average density of silicate mantle (fluid interior) - average density of metallic core - _t , _top density of the topography - density difference between crustal and mantle material - electrical conductivity (^–1 m^–1) - _r , radial and azimuthal surface stress of axisymmetric load (Pa) - _z vertical (lithostatic) stress (seeP _z ) - _II second invariant of stress deviation tensor - latitude - angular velocity of a planet (=2/T) - ages in years (a), generally 0 years is present - B.P. before present - FAA Free Air Gravity Anomaly (see g - HFT High Frequency Teleseismic event - LTP Lunar Transient Phenomenon - LOS Line-Of-Sight - NRM Natural Remanent Magnetization Contribution No. 309, Institut für Geophysik der Universität, Kiel, F.R.G.     

Rheologic properties of the lithosphere and applications to passive continental margins

Thermal and petrologic models of the crust and upper mantle are used for calculating effective viscosities on the basis of constant creep rates. Viscosity—depth models together with pressure—depth models are calculated for continental and oceanic blocks facing each other at continental margins. It is found from these “static models” that the overburden pressure in the lower crust and uppermost mantle causes a stress which is directed from the ocean to the continent. The generally low viscosity of 10²⁰–10²³ poise in this region should permit a creep process which could finally lead to a “silent” subduction. In the upper crust static stresses act in the opposite direction, i.e. from the continent to the ocean, favouring tension which could produce normal faulting in the continent. Differences between observations and the results obtained from the static models are attributed to dynamical forces.     

Einjährige Feldstärkemessungen im UKW-Rundfunkband in Kolberg bei Berlin

Zusammenfassung Es wird über einjährige UKW-Ausbreitungsmessungen auf festen Meßstrecken im UKW-Rundfunkband berichtet. Im jährlichen Verlauf der Empfangsfeldstärken konnten im Mittel in den Monaten Juni und Dezember die niedrigsten Feldstärken festgestellt werden. Es zeigte sich ein Zusammenhang zwischen den Temperatursprüngen an Inversionen und den Feldstärken sowohl bei den Monatsmitteln als auch bei den Einzelwerten. Bei der Untersuchung des Korrelationskoeffizienten zwischen den Temperatursprüngen an Inversionen und den Feldstärken ließ sich eine Entfernungsabhängigkeit nachweisen. Auch die Amplitude des Tagesganges und die Schwankungen der Tagesmittelwerte zeigen eine eindeutige Entfernungsabhängigkeit mit Höchstwerten in 200 bis 300 km Entfernung. Mit einem Korrelationskoeffizienten von 0.49 wurde ein guter Zusammenhang zwischen den Feldstärken und dem Bodenluftdruck ermittelt. Da sich außerdem eine Abhängigkeit der Feldstärken von den Temperaturschwankungen der unteren Troposphärenschichten gezeigt hatte, wurde unter Heranziehung des Luftdruckverlaufes und der Temperaturänderungen der 700 mb-Fläche eine Erhöhung des Korrelationskoeffizienten bei Verwendung von Tageswerten auf 0.58 festgestellt. Neben der Abhängigkeit der Feldstärken von der jeweils herrschenden Luftmasse, von der Höhe der 700 mb-Fläche u.a. wurden die Feldstärkeerhöhungen bei Vergrößerung des vertikalen Temperatursprunges an Inversionen untersucht und in Diagrammen mitgeteilt. Die Feldstärkeabhängigkeit mit der Entfernung ergab eine Kurve, die für Entfernungen über 300 km etwas unterhalb der vom Meteorologischen Observatorium Kühlungsborn mitgeteilten Kurve lag und außerdem etwas höhere Werte zeigt als die auf der CCIR-Konferenz in Warschau 1956 neuen mitgeteilten amerikanischen Feldstärkekurven.

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Summary The results of field-strength-measurements over some propagation paths in the frequency range from 88–100 Mc are presented. On the average the lowest field-strength could be observed in June and December. There was found a correlation between the temperature gradient at inversions and the field-strength when using the average values of field-strenght and the single values. The correlation coefficient between the field-strength and the temperature gradient at the inversions is a function of the length of the propagation path. In the same way the amplitude of the daily variation of field-strength depends on the length of the propagation path; the values being a maximum at a distance of 200 to 300 km. With a coefficient of 0.49 there was found a good correlation between the field-strength and the air pressure variation at ground level. As there also exists a correlation between the field-strength and the temperature variations in the lower part of the troposphere a better correlation coefficient of 0.58 was found when comparing the field-strength with the air pressure variation and the variation of the temperature at the 700 mb-level.There are given some diagrams of the field-strengt dependent upon the available air mass, the height of the 700 mb-level a.o. Some diagrams present the field-strength variation with varying temperature gradient on inversions.As to the field-strength variation with distance there was found a curve which for more than 300 Km is somewhat below this curve that was measured by the Meteorological Observatory Kühlungsborn. The curve showed somewhat higher values compared with one curve which wac published in a document of the USA presented at the CCIR Assembly in Warsaw in 1956.