Geologische Beobachtungen an der Küste und auf dem Schelf von Kephallinia (Ionische Inseln)

The largest Ionian island Cephalonia is situated on the edge of the Greek shelf. To the west the slope (20% average) extends to the Ionian fault scarp. This area is characterized by young tectonic activity (last disastrous earthquake in 1953) with dominant N-S and NE-SW fault directions. This paper constitutes the first account of the marine and Quaternary geology of Cephalonia. Late Pleistocene (? Tyrrhen III) red algae-rich limestones - up to 6,5 m thick - with interbedded sand layers transgress steeply folded Plio-Pleistocene and Eocene sediments. In addition, relative sea level changes in Quaternary time are indicated by a submarine platform at ?26 m NN. and 5 elevated shorelines, partly with wave-cut notches and borings, at heights of about 15 m, 45 m, 90 m, 150 m and 190 m, whose correlation with other so-called high-sea-levels of the Mediterranean area is doubtful. Shore- and nearshore sediments mainly consist of eroded coast material and reworked Pliocene which locally crops out on the sea floor, The outer shelf sedimentation is characterized by the deposition of marly foraminiferal ooze which undergoes bioturbation. Because of strong currents the ridge between Cephalonia and Zante is free of recent sediment. A swash mark entirely composed of the tests of sessil foraminiferas (Miniacina miniacea) is described.     

Effects of the Herbicide Metazachlor on Phytoplankton and Periphyton Communities in Outdoor Mesocosms

The effects of the chloroacetanilide herbicide metazachlor have been investigated in outdoor artificial mesocosms. Decreasing phytoplankton densities were caused by the application, however, the communities recovered after 30 to 35 days. Periphyton growth was found to be affected not only by the herbicide application but by the presence of species with different ability to grow on artificial substrates. Zooplankton diversity was small due to low density of ingestible algae species. Oxygen saturation was found to be correlated with the dosage levels of the herbicide in the second half of the study.     

Thermobarometric data from a fossil zircon partial annealing zone in high pressure–low temperature rocks of eastern and central Crete, Greece

A fossil partial annealing zone of fission tracks in zircon is described from high pressure–low temperature (HP–LT) rocks of the Phyllite–Quartzite Unit (PQ) on the island of Crete, Greece. Correlation of regional trends in fission track age populations with independent thermobarometric and microstructural data, and with new experimental annealing results, allows a calibration of this low temperature thermochronological method to a degree hitherto not available from other field examples.The zircon fission track (FT) ages of samples from the PQ across Crete range from original detrital signature through reduced to completely reset. The annealing is the result of a single heating period related to the HP–LT metamorphism with near-peak temperatures lasting for only a few million years some time between 24±1 and 20±1 Ma. In eastern Crete, where rocks have experienced temperatures of 300±50 °C and pressures of 0.8±0.3 GPa, zircon FT ages range from 414±24 to 145±10 Ma. Ages above 300 Ma occur mostly near the east coast of the island in rocks which have not been heated to above ca. 280 °C and probably represent a pre-Variscan source. Track lengths are already indicative of a substantial annealing at this temperature. Most of the zircon FT ages from eastern Crete scatter within error around the stratigraphic age. Samples with apparent zircon FT ages significantly younger than the depositional age are only observed in areas where temperatures exceeded ca. 320 °C. Towards the west, a sudden decrease to very young ages ranging from 17±2 to 18±1 Ma reflects a complete resetting at ca. 350 °C. Short tracks, however, are still observed. Throughout the central and western part of the island, ages are consistently below 22 Ma. Thermobarometric data for this area indicate maximum temperatures of 400±50 °C and pressures of 1±0.3 GPa. Only samples from western Crete, which have been exposed to 400±50 °C, show exclusively long tracks. Consequently, the high temperature limit of the zircon partial annealing zone (ZPAZ) appears to be between 350 and 400 °C.A significant influence of elevated confining pressure on the stability of fission tracks in zircon is ruled out by the results of annealing experiments at 0.5 GPa and at different temperatures, which fit the curves previously obtained by other authors at ambient pressure.     

Impact ejecta exceeding lunar escape velocity

Microrater frequencies caused by fast (? 3 km s^?1) ejecta have been determined using secondary targets in impact experiments. A primary projectile (steel sphere, diam 1.58 mm, mass 1.64 × 10^?2 g) was shot in Duran glass with a velocity of 4.1 km s^?1 by means of a light gas gun. The angular distribution of the secondary crater number densities shows a primary maximum around 25°, and a secondary maximum at about 60° from the primary target surface. The fraction of mass ejected at velocities of ? 3 km s^?1 is only a factor of 7.5 × 10^?5 of the primary projectile mass. A conservative calculation shows that the contribution of secondary microcraters (caused by fast ejecta) to primary microcrater densities on lunar rock surfaces (caused by interplanetary particles) is on the statistical average below 1% for any lunar surface orientation. Calculation of the interplanetary dust flux enhancement caused by Moon ejecta turned out to be in good agreement with Lunar Explorer 35in situ measurements.     

A dense bottom water plume in the western Barents Sea: downstream modification and interannual variability

The generation and downstream modification of a cold dense Arctic shelf water plume were studied with moored current meters, thermistor chains and conductivity/temperature sensors deployed from August 1993 to September 1994 south of the Storfjord in the Svalbard Archipelago. These observations are compared to similar time series from 1991/92. In 1993/94, bottom water with temperatures close to the freezing point drained continuously from Storfjord between March and September with a mean speed of 0.14 m s⁻¹. About 1.5 months after the plume front had left the Storfjord, it reached the shelf break, 150 km away. The plume had increased its width from 15 km to about 35 km, but its thickness of 50 m remained almost constant and it left the shelf edge at a similar speed. The increased volume transport and the change of temperature/salinity properties indicate an entrainment of 110% of ambient Atlantic water into the plume on its way from the production area to the shelf edge.The maximum salinity of the cold plume was 0.2 lower in 1993/94 than in 1991/92, whilst the temperature/salinity-range of the surrounding Atlantic water remained unchanged. Probably as a dynamic consequence, the speed of the plume was considerably lower in 1993/94. The lower salinity of the plume in 1993/94 is a result of both the 30% less ice formation in Storfjord, caused by lower heat flux and less open water, and a lower surface salinity at the beginning of ice formation. During 1993/94, the Storfjord plume was too light to sink below 700 m.     

Interplanetary dust detected by the Cassini CDA Chemical Analyser

During its cruise phase, prior to encountering Jupiter, the Cosmic Dust Analyser (CDA) onboard the Cassini spacecraft returned time of flight mass spectra (TOF MS) of two interplanetary dust particles. Both particles were found to be iron-rich, with possible traces of hydrogen, carbon, nickel, chromium, manganese, titanium, vanadium and minor silicates. Carbon, hydrogen, oxygen and potassium are also present as possible contaminants of the impact target of CDA. Silicates and magnesium do not feature predominantly in the spectra; this is surprising considering the expected dominance of silicate-rich minerals in interplanetary dust particles. The particle masses are and . The corresponding radii ranges for the particles, assuming densities from 7874-2500 kg m⁻³ are 0.7-4 μm and 2.6-6.8 μm, respectively. With the same density assumptions the β values (ratio of radiation pressure to gravitational force) are estimated as 0.027-0.21 and 0.016-0.06 respectively, allowing possible orbits to be calculated. The resulting orbits are bound and prograde with semi-major axes, eccentricities and inclinations in the region of 0.3-1.26 AU, 0.4-1.0 and 0-60° for the first particle and 0.8-2.5 AU, 0.2-0.9 and 0-30° for the second. The more probable orbits within these ranges indicate that the first particle is in an Aten-like orbit, whilst the second particle is in an Apollo-like orbit, despite both grains having very similar, predominantly metallic compositions. Other possible orbital solutions for both particles encompass orbits which more closely resemble those of Jupiter-family comets.     

德国南部索伦霍芬石板印灰岩中翼龙纤维状头骨脊连续矿物化的证据

The Solnhofen Lithographic Limestone and other Upper Jurassic “Solnhofen type” plattenkalks of southeast Germany are famous for pterosaur fossils with soft tissue preservation. Flight membranes, integumentary structures such as pedal scales and bristles as well as pedal webbing are known from these deposits.     

翼龙类翼膜的折叠，褶皱以及物质特性

Preservation of wing membranes in pterosaurs is only reported from a few localities in the world, namely from the Karatau Hills, Kazakhstan (Upper Jurassic), from the Solnhofen Lithographic Limestone, Germany (Upper Jurassic), the Daohugou Beds of China (Upper Jurassic or Lower Cretaceous) and the Crato and Santana Formations, Chapada do Araraipe, NE Brazil (Lower Cretaceous).