Die geoelektrische Überprüfung von Zementinjektionen zur Verfestigung des Baugrundes

Zusammenfassung Um den Kluftraum im Baugrunde von Staumauern zu schliessen, presst man in diesen Zementmilch. Es wird nun ein geoelektrisches Verfahren beschrieben, mit dem folgende Angaben bestimmt werden können: Das offene Kluftvolumen vor der Injektion; das durch die Injektion gefüllte Kluftvolumen; die Menge von Injektionsmilch, die aus dem für die Injektion bestimmten Raume nach entfernten Räumen ausfloss. Das Verfahren wurde in Oesterreich an mehreren hundert Einzelinjektionen erprobt.

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Summary In order to close the clefts in subsoil of dams, cement is pressed into them. A geoelectrical method of measuring is now described, with which the following data may be determined: the open volume of the clefts before injection of cement, the volume that has been filled with cement during injection and the still open volume after injection. Further we can state, whether cement has flows to distant spaces. The method was esamined by some hundred injections in Austria.

     

Lo smorzamento delle onde hertziane attraverso i conduttori geologici

Riassunto L'A. dimostra ed illustra le seguenti deduzioni: 1) La propagazione delle onde hertziane attraverso formazioni geologiche è dipendente dall'estinzione che provocano le stesse formazioni e dalla frequenza delle onde emesse. 2) L'effetto determinato dalla frequenza viene illustrata dalla cosìdetta curva radiogeologica, la quale manifesta una forma complessa per onde inferiori ai 100 m. 3) I campi elettromagnetici penetranti nel suolo risultano fortemente smorzati per effetto degli strati vegetali (humus) superficiali; con notevoli ricoprimenti di tal tipo la ricezione in profondità non è in generale possibile; il limite per il quale ciò si verifica si ha all'incirca per uno spessore di 2 metri dello strato vegetale. 4) Allorquando la stazione transmittente e quella ricevente sono ambedue sotterranee la portata di ricezione può raggiungere i 500 m. con possibilità di riuscire notevolmente più grande nelle formazioni aride e compatte. Infine, la propagazione delle onde hertziane in profondità è particolarmente dipendente dalle condizioni tettoniche, oltre da altri fattori.

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Zusammenfassung 1) Die Reichweite der Hertzschen Wellen im Gebirge ist von der Extinktion des Gebirges und der Betriebsfrequenz abhängig. 2) Der Einfluss der Frequenz wird durch die sogenannte funkgeologische Kurve dargestellt; diese zeigt im Bereich der Wellen unter 100 m einen ziemlich komplizierten Verlauf. 3) Von aussen her eindringende Felder werden durch die oberste Humusschichte stark gedämpft. Bei starker Ueberdeckung ist im allgemeinen Empfang unter Tage nicht möglich. Die Grenze liegt bei ungefähr 2 m Mächtigkeit der Deckschichte. 4) Stehen Sender und Empfänger unter Tags, so sind auch grössere Reichweiten möglich. Bisher wurden solche bis zu ungefähr 500 m erzielt. Im Die Ausbreitung unter Tags wird insbesondere durch die Tektonik und durch andere trockenen, festen Gebirge sind indessen weit grössere Reichweiten noch durchaus möglich. Faktoren stark beeinflusst.

     

Fluid inclusions in granulite-facies metapelites of the Hercynian ancient lower crust of the Serre,Calabria, Southern Italy

Investigations of fluid inclusions in granulitefacies metapelites of southern Calabria enable characterization of the fluid composition of these lower crustal rocks, and constrain the petrologically deduced retrograde P-T path characterized by isothermal uplift prior to isobaric cooling in middle crustal levels. Fluid inclusions in cordierite, garnet and sillimanite have a CO₂-rich composition. Inclusions in cordierite rarely contain minor amounts of N₂ and H₂O, and in garnets some CO₂–CH₄–N₂ inclusions have been analyzed by Raman microprobe. Quartz reveals the most complex fluid melusion compositions (1) CO₂-rich, (2) CO₂–CH₄–N₂, (3) CH₄–N₂, (4) H₂O–MgCl₂–CaCl₂–NaCl, (5) H₂O–NaCl and (6) H₂O–CO₂. The earliest fluid inclusions after peak metamorphism are rich in CO₂ with minor amounts of N₂ and H₂O. An early CO₂–(H₂O–N₂) fluid composition has been confirmed by detection of CO₂, H₂O and N₂ in the channels of the cordierite structure. Most of the early CO₂-rich fluid inclusions were modified during the uplift from the lower to the middle crustal level, resulting in a density decrease with CO₂ still dominant. The subsequent isobaric cooling led to further modifications of the fluid inclusions. High-density inclusions around implosion textures or scattered amongst lower-density ones must have formed during this cooling episode. Aqueous inclusions in quartz are mostly formed late and are consistent with trapping during retrograde rehydration.This project has been supported by the DFG as contribution to the special program Continental Lower Crust     

Spatio‐temporal variability of zooplankton biomass and environmental control in the Northern Benguela Upwelling System: field investigations and model simulation

Spatial and temporal distribution patterns of zooplankton are highly variable in the Northern Benguela Upwelling System. We studied the distribution of zooplankton (size class ≥ 0.33 mm) and used field data from four cruises that took place between March 2008 and February 2011, as well as simulation results of a regional ecosystem model. Remotely sensed sea surface temperatures (SST) and surface chlorophyll concentrations were analysed to investigate environmental influences on zooplankton biomass. The Intense Benguela Upwelling Index showed a distinct seasonal signal throughout the years and the highest upwelling peaks in August/September. Even though surface chlorophyll concentrations were very variable throughout the year, the highest concentrations were always detected in September, following the upwelling of nutrient‐rich water. In field catches, zooplankton biomass concentration in the upper 200 m was highest above the outer shelf and shelf‐break in December 2010 and February 2011, i.e. 6 months after the upwelling peaks. In contrast, zooplankton biomass simulated by the model in the surface water was highest in September. In March/April, biomass maxima were typically measured in the field at intermediate water depths, but the vertical distribution was also affected by extensive oxygen minimum zones. The ecosystem model reproduced this vertical pattern. Although general trends were similar, simulation data of zooplankton standing stocks overestimated the field data by a factor of 3. In upwelling systems, food webs are generally considered to be short and dominated by large cells. However, our field data indicate more small‐sized zooplankton organisms above the shelf than offshore.     

Characterizing hydraulic conductivity with the direct-push permeameter

The direct-push permeameter (DPP) is a promising approach for obtaining high-resolution information about vertical variations in hydraulic conductivity (K) in shallow unconsolidated settings. This small-diameter tool, which consists of a short screened section with a pair of transducers inset in the tool near the screen, is pushed into the subsurface to a depth at which a K estimate is desired. A short hydraulic test is then performed by injecting water through the screen at a constant rate (less than 4 L/min) while pressure changes are monitored at the transducer locations. Hydraulic conductivity is calculated using the injection rate and the pressure changes in simple expressions based on Darcy's Law. In units of moderate or higher hydraulic conductivity (more than 1 m/d), testing at a single level can be completed within 10 to 15 min. Two major advantages of the method are its speed and the insensitivity of the K estimates to the zone of compaction created by tool advancement. The potential of the approach has been assessed at two extensively studied sites in the United States and Germany over a K range commonly faced in practical field investigations (0.02 to 500 m/d). The results of this assessment demonstrate that the DPP can provide high-resolution K estimates that are in good agreement with estimates obtained through other means.     

Submillimeter Wave Astronomy Satellite observations of Comet 9P/Tempel 1 and Deep Impact

On 4 July 2005 at 5:52 UT the Deep Impact mission successfully completed its goal to hit the nucleus of 9P/Tempel 1 with an impactor, forming a crater on the nucleus and ejecting material into the coma of the comet. NASA's Submillimeter Wave Astronomy Satellite (SWAS) observed the ₁₁₀-₁₀₁ ortho-water ground-state rotational transition in Comet 9P/Tempel 1 before, during, and after the impact. No excess emission from the impact was detected by SWAS and we derive an upper limit of 1.8×¹⁰⁷ kg on the water ice evaporated by the impact. However, the water production rate of the comet showed large natural variations of more than a factor of three during the weeks before and after the impact. Episodes of increased activity with alternated with periods with low outgassing (). We estimate that 9P/Tempel 1 vaporized a total of N∼4.5×¹⁰³⁴ water molecules (∼1.3×¹⁰⁹ kg) during June-September 2005. Our observations indicate that only a small fraction of the nucleus of Tempel 1 appears to be covered with active areas. Water vapor is expected to emanate predominantly from topographic features periodically facing the Sun as the comet rotates. We calculate that appreciable asymmetries of these features could lead to a spin-down or spin-up of the nucleus at observable rates.     

Resolving cosmic structure formation with the Millennium-II Simulation

We present the Millennium-II Simulation (MS-II), a very large N -body simulation of dark matter evolution in the concordance Λ cold dark matter (ΛCDM) cosmology. The MS-II assumes the same cosmological parameters and uses the same particle number and output data structure as the original Millennium Simulation (MS), but was carried out in a periodic cube one-fifth the size  (100  h ⁻¹ Mpc)  with five times better spatial resolution (a Plummer equivalent softening of  1.0  h ⁻¹ kpc  ) and with 125 times better mass resolution (a particle mass of  6.9 × 10⁶  h ⁻¹ M_⊙  ). By comparing results at MS and MS-II resolution, we demonstrate excellent convergence in dark matter statistics such as the halo mass function, the subhalo abundance distribution, the mass dependence of halo formation times, the linear and non-linear autocorrelations and power spectra, and halo assembly bias. Together, the two simulations provide precise results for such statistics over an unprecedented range of scales, from haloes similar to those hosting Local Group dwarf spheroidal galaxies to haloes corresponding to the richest galaxy clusters. The 'Milky Way' haloes of the Aquarius Project were selected from a lower resolution version of the MS-II and were then resimulated at much higher resolution. As a result, they are present in the MS-II along with thousands of other similar mass haloes. A comparison of their assembly histories in the MS-II and in resimulations of 1000 times better resolution shows detailed agreement over a factor of 100 in mass growth. We publicly release halo catalogues and assembly trees for the MS-II in the same format within the same archive as those already released for the MS.     

Nitrogen recycling in subducted oceanic lithosphere: The record in high- and ultrahigh-pressure metabasaltic rocks

This paper provides the first measurements of the nitrogen (N) concentrations and isotopic compositions of high- and ultrahigh-pressure mafic eclogites, aimed at characterizing the subduction input flux of N in deeply subducting altered oceanic crust (AOC). The samples that were studied are from the Raspas Complex (Ecuador), Lago di Cignana (Italy), the Zambezi Belt (Zambia) and Cabo Ortegal (Spain), together representing subduction to 50-90 km depths. The eclogites contain 2-20 ppm N with δ¹⁵N_air values ranging from −1 to +8‰. These values overlap those of altered oceanic crust, but are distinct from values for fresh MORB (for the latter, ∼1.1 ppm N and δ¹⁵N_air ∼ −4‰). Based on N data in combination with other trace element data, the eclogite suites can be subdivided into those that are indistinguishable from their likely protolith, AOC, with or without superimposed effects of devolatilization (Lago di Cignana, Cabo Ortegal), and those that have experienced metasomatic additions during subduction-zone metamorphism (Zambezi Belt, Raspas). For the former group, the lack of a detectable loss of N in the eclogites, compared to various altered MORB compositions, suggests the retention of N in deeply subducted oceanic crust. The metasomatic effects affecting the latter group can be best explained by mixing with a (meta)sedimentary component, resulting in correlated enrichments of N and other trace elements (in particular, Ba and Pb) thought to be mobilized during HP/UHP metamorphism. Serpentinized and high-pressure metamorphosed peridotites, associated with the eclogites at Raspas and Cabo Ortegal, contain 3-15 ppm N with δ¹⁵N_air values ranging from +3 to +6‰, significantly higher than the generally accepted values for the MORB mantle (δ¹⁵N_air ∼ −5‰). Based on their relatively high N contents and their homogeneous and positive δ¹⁵N values, admixing of sedimentary N is also indicated for the serpentinized peridotites.One possible pathway for the addition of sediment-derived N into eclogites and peridotites involves mixing with fluids along the slab-mantle wedge interface. Alternatively, sedimentary N could be incorporated into peridotites during serpentinization at bending-related faults at the outer rise and, during later deserpentinization, released into fluids that then infiltrate overlying rocks. Deep retention of N in subducting oceanic crust should be considered in any attempt to balance subduction inputs with outputs in the form of arc volcanic gases. If materials such as these eclogites and serpentinized peridotites are eventually subducted to beyond sub-arc depths into the deeper mantle, containing some fraction of their forearc-subarc N inventory (documented here), they could deliver isotopically heavy N into the mantle to potentially be sampled by plume-related magmas.     

Eckfeld Maar: Window into an Eocene Terrestrial Habitat in Central Europe

<正>To mark the occasion of the 175th anniversary of the Rheinische Naturforschende Gesellschaft in 2009 and of the centennial of the Mainz Natural History Museum in 2010,we present a short account of our present knowledge of the Eckfeld Maar after 20 years of continuous research.This paper does not attempt to include all of the detailed results on the geology of the Eckfeld site or its biota.To date,nearly 250 papers and books have been published since the start of our project.An up-to-date list of these publications can be found at www.eckfeldermaar. de.