The Late Cenozoic Eridanos delta system in the Southern North Sea Basin: a climate signal in sediment supply?

ABSTRACT The Eridanos fluvio‐deltaic system, draining most of north‐western Europe, developed during the Late Cenozoic as a result of simultaneous uplift of the Fennoscandian shield and accelerated subsidence in the North Sea Basin. This seismo‐stratigraphic study aims to reconstruct the large‐scale depositional architecture of the deltaic portion of the basin fill and relate it to external controls. A total of 27 units have been recognized. They comprise over 62×10³ km³ in the Southern North Sea Basin alone, and have an average delta surface area of 28×10³ km², which suggests that the size of the drainage area was about 1.1×10⁶ km². Water depth in the depocentre is seen to decrease systematically over time. This trend is interrupted by a deepening phase between 6.5 and 4.5 Ma that can be correlated with the simultaneous occurrence of increased uplift of the Fennoscandian shield, increased subsidence of the Southern North Sea Basin, and a long‐term eustatic highstand. All these observations point to a tectonic control on long‐term average rates of accommodation and supply. Controls on short‐term variations are inferred from variations in rates of sediment supply and bifurcation of the delta channel network. Both rates were initially low under warm, moist, relatively stable climate conditions. The straight wave‐dominated delta front gradually developed into a lobate fluvial‐dominated delta front. Two high‐amplitude sea‐level falls affected the Pliocene units, which are characterized by widespread delta‐front failures. Changes in relative sea level and climate became more frequent from the late Pliocene onward, as the system experienced the effects of glacial–interglacial transitions. Peaks in sedimentation and bifurcation rates were coeval with cold (glacial) conditions. The positive correlation between rates of supply and bifurcation on the one hand, and climate proxies (pollen and δ¹⁸O records) on the other hand is highly significant. The evidence presented in this study convincingly demonstrates the control of climate on time‐averaged sediment supply and channel‐network characteristics, despite the expected nonuniformity and time lags in system response. The presence of a clearly discernible climate signal in time‐averaged sediment supply illustrates the usefulness of integrated seismo‐stratigraphic studies for basin‐wide analysis of delta evolution on geological time scales.     

The construction of self-consistent models for outflowing stellar envelopes

The article presents self-consistent computations of the spherically symmetric envelope of a massive (M=20M _⊙) star whose envelope is flowing outward under the action of continuum radiation pressure. A system of equations describing the out flow for arbitrary optical depth, degree of ionization, and opacity κ are obtained. A numerical solution is obtained for the case of constant κ and degree of ionization via approaching integrations from the singularities and smooth joining in the intermediate region. Asymptotic solutions are found in the vicinity of the sonic point and the singularity at infinity.     

Morphotectonics of the Mongolia-Siberian mountain belt

The mountains of north-eastern Inner Asia comprise the Mongolia-Siberian orogenic belt which has a complex structure. The southern flank of the belt consists of a chain of large domal uplifts. The Baikal rift zone is located on the northern flank. The central segment is composed of zones of linear warping. The tectonic landforms rest on a large domal basement uplift. The morphology of the latter is paragenetically connected with the shape of the asthenolith underlying the belt. The neotectonic zones are also connected with the deep structure elements.The Mongolia-Siberian mountain belt is a group of orogenic forms typical of intracontinental mountain areas.     

Physiologie des Phenolabbaus bei Rhodococcus spec. P1. Teil 2: Untersuchungen zur Regulation des Phenolabbaus

The phenol-degrading system which can be induced in Rhodococcus spec. P 1 brings about the metabolization of phenol via the β-ketoadipate path (ortho-cleavage of catechol). For the more precise characterization of the degradation performance investigations were made into the influences of different carbon sources: glucose, galactose, ribose, arabinose, xylose, acetate, citricacid, mandelic acid, protocatechoic acid, glycerol, tryptophane, phenylalanine and the complex substrate of nutrient broth as well as succinate, catechol and benzoate. Only the three last-named substances show an influence: succinate inhibits only the synthesis of phenol hydroxylase, catechol and benzoate inhibit the synthesis and activity of phenol hydroxylase. As a comparison of the results with literature shows, even at the same path of degradation there are different regulating mechanismus in the different microorganisms.     

Profile measurements in the atmospheric near-surface layer and the use of suitable universal functions for the determination of the turbulent energy exchange

The authors summarize their recent published studies on profile measurements including new universal functions and an error analysis with a particular view to parameterisation above soil and water. Verification of the theoretical results is given using new data of the MESP-81 Tsimlyansk experiment.     

Asthenospheric parameters of dipping plate regions by magnetotelluric investigations

The multifrequency resolving capability of the electromagnetic surface impedance parameter, employed in magnetotelluric investigations, has been examined for an upper mantle model incorporating (1) a deep-seated lithosphere-asthenosphere boundary and (2) preferred orientations of olivine crystals in the lithosphere, usually associated with the subducting plate boundary zones. Numerical results display the quantitative errors in the resolution of various anisotropic and dipping plate conditions. It is found that (1) conductivity anisotropy, particularly with higher dips, causes a significant dispersion in the impedance values and higher resolving power, and (2) variations in the geometrical/physical parameters are reflected predominantly in the phase component of the surface impedance. The study has relevance to the understanding of the electrical nature of materials, its relationship with physical properties and associated geothermal and seismic activities in the dipping plate regions.