Die Laufzeitfunktion und ihre Interpretation in der Refraktionsseismik des einachsig inhomogenen Körpers

Zusammenfassung Es wird das Interpretationsproblem der Refraktionsseismik in einem einachsig inhomogenen Körper allgemein behandelt und exakt gelöst.

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Summary The interpretation-problem of the refraction seismic in a uniaxial inhomogeneous medium is generally treated and exactly solved.

     

3. Das Alter des westnorwegischen Grundgebirges

Zusammenfassung Es wird der Nachweis erbracht, daß es sich bei dem ausgedehnten Kristallingebiet West- und Mittelnorwegens nicht um präkambrisches Grundgebirge handelt, sondern um kaledonisch umgewandeltes und teilweise migmatisiertes Kambrosilur der kaledonischen Geosynklinale. Damit entfällt in tektonischer Hinsicht die Drontheimer Mulde in der bisher angenommenen Form.Außerdem beteiligen sich noch Plutone am Aufbau des Grundgebirges, die jünger als die kaledonischen Hauptfaltungen, aber älter als das Downton sind.Die Faltungsgräben früherer Autoren werden abgelehnt. Zuletzt wird kurz darauf hingewiesen, daß Migmatisierung und die Metamorphose dieses Gebietes sich nicht in großer Tiefe abgespielt haben, sondern bis dicht unter die Faltungsoberfläche gereicht haben müssen.     

Chronologic implications of new Miocene mammals from the Cura-Mallín and Trapa Trapa formations, Laguna del Laja area, south central Chile

Recent work in the central Andean Main Range of Chile near Laguna del Laja (37.5°S, 71°W) has produced the first mammal fossils for the region. Fossils, locally abundant and well preserved, occur patchily across a wide area southeast of the lake. Mammalian remains are derived from generally strongly folded (kilometer-scale) exposures of the locally 1.8 km thick, early to middle Miocene Cura-Mallín Formation; two identifiable specimens have been recovered from the overlying Trapa Trapa Formation as well. Both formations consist primarily of well-stratified (1–5 m thick layers) volcaniclastic and volcanic strata, deposited predominantly in fluviatile systems. The Cura-Mallín Formation is possibly the southern continuation of (or lateral equivalent to) the richly fossiliferous Abanico Formation mapped between 32°S and 36°S. Intensive sampling in a series of localities east and south of Laguna del Laja has yielded diverse faunas, in addition to radioisotopically dateable horizons. The new fossil mammal faunas represent as many as six South American Land Mammal “Ages” (SALMAs). Fossils, together with preliminary ⁴⁰Ar/³⁹Ar radioisotopic dates, ranging from 9 to 20 Ma across the exposed thickness of the Cura-Mallín Formation and into the overlying Trapa Trapa Formation, provide a robust geochronological framework for middle Cenozoic strata in the Laguna del Laja region. The sequence of directly superposed mammalian assemblages at Laguna del Laja is one of the longest in all of South America, rivaled only by the classic Gran Barranca section of Patagonian Argentina. These data illuminate the geological history of the area and its record of mammalian evolution. The potential to isotopically date these diverse faunas with high precision (error ± 0.5 Ma) presents a rare opportunity to calibrate related portions of the SALMA sequence.     

Evolution of a mixed siliciclastic‐carbonate deep‐marine system on an unstable margin: The Cretaceous of the Eastern Greater Caucasus,Azerbaijan

Mixed siliciclastic‐carbonate deep‐marine systems (mixed systems) are less documented in the geological record than pure siliciclastic systems. The similarities and differences between these systems are, therefore, poorly understood. A well‐exposed Late Cretaceous mixed system on the northern side of the Eastern Greater Caucasus, Azerbaijan, provides an opportunity to study the interaction between contemporaneous siliciclastic and carbonate deep‐marine deposition. Facies analysis reveals a Cenomanian–early Turonian siliciclastic submarine channel complex that abruptly transitions into a Mid Turonian–Maastrichtian mixed lobe‐dominated succession. The channels are entrenched in lows on the palaeo‐seafloor but are absent 10 km towards the west where an Early Cretaceous submarine landslide complex acted as a topographic barrier to deposition. By the Campanian, this topography was largely healed allowing extensive deposition of the mixed lobe‐dominated succession. Evidence for irregular bathymetry is recorded by opposing palaeoflow indicators and frequent submarine landslides. The overall sequence is interpreted to represent the abrupt transition from Cenomanian–early Turonian siliciclastic progradation to c. Mid Turonian retrogradation, followed by a gradual return to progradation in the Santonian–Maastrichtian. The siliciclastic systems periodically punctuate a more widely extensive calcareous system from the Mid Turonian onwards, resulting in a mixed deep‐marine system. Mixed lobes differ from their siliciclastic counterparts in that they contain both siliciclastic and calcareous depositional elements making determining distal and proximal environments challenging using conventional terminology and complicate palaeogeographic interpretations. Modulation and remobilisation also occur between the two contemporaneous systems making stacking patterns difficult to decipher. The results provide insight into the behaviour of multiple contemporaneous deep‐marine fans, an aspect that is challenging to decipher in non‐mixed systems. The study area is comparable in terms of facies, architectures and the presence of widespread instability to offshore The Gambia, NW Africa, and could form a suitable analogue for mixed deep‐marine systems observed elsewhere.     

Ein exakter Seismograph

Zusammenfassung Es wird ein exakter Seismograph beschrieben.

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Summary An exact seismograph is described.

     

Pitfalls of geocentricism

The principles of biogeography have little or no direct relevance in an astrobiological context. If a microbial ecosystem exists on one planetary body, its spread to neighbouring planets is controlled by available transfer routes with adequate survival en route and appropriate nutrient and growth conditions on the host planetary body.     

The early-type galaxies NGC 1407 and NGC 1400 – II. Star formation and chemical evolutionary history

We present a possible star formation and chemical evolutionary history for two early-type galaxies NGC 1407 and NGC 1400. They are the two brightest galaxies of the NGC 1407 (or Eridanus-A) group, one of the 60 groups studied as part of the Group Evolution Multi-wavelength Study.
Our analysis is based on new high signal-to-noise ratio spatially resolved integrated spectra obtained at the ESO 3.6-m telescope, out to ∼0.6 (NGC 1407) and ∼1.3 (NGC 1400) effective radii. Using Lick/IDS indices, we estimate luminosity-weighted ages, metallicities and α-element abundance ratios. Colour radial distributions from HST /ACS and Subaru Suprime-Cam multiband wide-field imaging are compared to colours predicted from spectroscopically determined ages and metallicities using single stellar population (SSP) models. The galaxies formed over half of their mass in a single short-lived burst of star formation  (≥100 M_⊙ yr⁻¹)  at redshift z ≥ 5. This likely involved an outside–in mechanism with supernova-driven galactic winds, as suggested by the flatness of the α-element radial profiles and the strong negative metallicity gradients. Our results support the predictions of the revised version of the monolithic collapse model for galaxy formation and evolution. We speculate that, since formation, the galaxies have evolved quiescently and that we are witnessing the first infall of NGC 1400 in the group.