Overview on the middle to upper Jurassic sedimentary succession of Gangta Bet in the Kachchh basin,western India,with special emphasis on its lithostratigraphy,biostratigraphy, and palaeoenvironment

The Jurassic succession of Gangta Bet in the Kachchh basin of western India comprises around 130 m of mostly siliciclastic rocks. The strata belong to the Gangta Member of the Gadhada Formation and are herein sub-divided into four units: the Gangta sandstone beds, the lower silty sandstone beds, the upper silty sandstone beds, and the Gangta ammonite beds. These units can be separated by three marker horizons: the Brachiopod bed, the Gangta Conglomerate Bed, and the Gervillella Bed. Ammonites indicate an Oxfordian age for the upper half of the succession, but the scarcity of identifiable fossils in its basal part so far prevented precise biostratigraphic assignments. The shallow-water sediments can be interpreted as parasequences as a result of minor sea-level changes. Deposition took place close to the palaeo-coastline at water depths around the fair-weather wave-base.     

Heavy metal distribution in karst soils from Croatia and Slovakia

With the use of the optimised three-step BCR sequential-extraction procedure it was possible to assess the mobility of selected elements in soil profiles from Croatian and Slovakian karst terrains. The soils in the Croatian karst were enriched in Cr, Ni, V, Mn, Cu, Cd and Mo, while soils from the Slovak Karst had high Pb and Zn concentrations. It was determined that the elements were most readily mobilised from the topsoil and the degree of mobility decreased with depth. Cr and Ni were mainly bound to the residual fraction, and Pb in the oxidisable fraction. Cu mobility was high in samples treated with agrochemicals throughout the soil profile.     

Photoelectric observations of CPM stars in theBVRI system

Summary A photometric program to estimate the frequency of close unresolved companions in visual binary systems has been developed. The sensitivity of the detection depends on the accuracy of the differential photometric measurements of binary components. Unresolved companions up to seven magnitudes fainter than the primary are detectable in theBVRI photometric system. Presented by K. D. Rakos.     

Simulation of stiff massless tethers

A model is developed and an algorithm presented for the time simulation of low-tension tethers with torsional and bending stiffness. Computational performance is extremely good owing to the neglect of all inertial terms, and quaternions enable arbitrary deflections. A first example verifies the accuracy of the program, and a second illustrates tether behavior during a complex maneuver.     

Infrared,Raman, and cathodoluminescence studies of impact glasses

Abstract— We studied the infrared reflectance (IR), Raman, and cathodoluminescence (CL) spectroscopic signatures and scanning electron microscope‐cathodoluminescence (SEM‐CL) images of three different types of impact glasses: Aouelloul impact glass, a Muong Nong‐type tektite, and Libyan desert glass. Both backscattered electron (BSE) and CL images of the Muong Nong‐type tektite are featureless; the BSE image of the Libyan desert glass shows only weak brightness contrasts. For the Aouelloul glass, both BSE and CL images show distinct brightness contrast, and the CL images for the Libyan desert glass show spectacular flow textures that are not visible in any other microscopic method. Compositional data show that the SiO₂ composition is relatively higher and the Al₂O₃ content is lower in the CL‐bright areas than in the CL‐dark regions. The different appearance of the three glass types in the CL images indicates different peak temperatures during glass formation: the tektite was subjected to the highest temperature, and the Aouelloul impact glass experienced a relatively low formation temperature, while the Libyan desert glass preserves a flow texture that is only visible in the CL images, indicating a medium temperature. All IR reflectance spectra show a major band at around 1040 to 1110 cm^?1 (antisymmetric stretching of SiO₄ tetrahedra), with minor peaks between 745 and 769 cm^?1 (Si‐O‐Si angle deformation). Broad bands at 491 and 821 cm^?1 in the Raman spectra in all samples are most likely related to diaplectic glass remnants, indicating early shock amorphization followed by thermal amorphization. The combination of these spectroscopic methods allows us to deduce information about the peak formation temperature of the glass, and the CL images, in particular, show glass flow textures that are not preserved in other more conventional petrographic images.     

The occultation of AG+29°398 by 93 Minerva

The occultation of AG+29°398 by 93 Minerva on 22 November 1982 was successflly observed at 10 sites. The data are best fitted by a circular limb profile having a diameter of 170.8 ± 1.4 km, a value that agrees well with the published radiometric diameter for this asteriod. However, evidence of significant departure from a spherical shape is found in the occultation observations and in photometric measurements of Minerva made at Lowell Observatory over several months. Additional observations are needed to specify definitively the three-dimensional figure of Minerva.     

A generalization of Hopf's bifurcation problem

The topic presented here is not really a topic of celestial mechanics, because a dissipative system is considered, and dissipative systems do not occur in celestial mechanics at least if drag is not taken into account. Only in the theoretical background of Baumgarte-Stiefel stabilization dissipative systems become important. The only justification is that, in order to establish the result, a tool, namely the method of averaging, is used here which is a good tool for many problems of celestial mechanics too.Proceedings of the Sixth Conference on Mathematical Methods in Celestial Mechanics held at Oberwolfach (West Germany) from 14 to 19 August, 1978.