Evidence for fullerenes in solid bitumen from pillow lavas of Proterozoic age from Mítov (Bohemian Massif, Czech Republic)

Andesitic pillow lavas containing biogenic, solid bitumen (SB) are a constituent of a Neoproterozoic volcanosedimentary sequence (Teplá-Barrandian unit, Bohemian Massif) in the Mítov area of the Czech Republic. A black shale formation that is crosscut by these andesitic basalts is 565 Ma old. Carbon disulfide extracts of two powdered samples of SB contain 0.2 and 0.3 ppm of C₆₀, respectively, as determined by high-pressure liquid chromatography. The peak assignment based on retention time is fully supported by high-resolution electron ionization mass spectrometry (EI-MS). No C₇₀ was detected, nor was C₆₀ found in two other SB samples from this locality. Other investigated carbonaceous samples from Bohemia (coals and anthracites of Upper Paleozoic age and anthraxolite, graphitoids, and graphite of Upper Proterozoic age) did not contain fullerenes at concentrations above the detection limit of 0.01 ppm. The absence of C₆₀ in these samples was confirmed by EI-MS. The proposed mechanism of fullerene formation involves a primary algal phase, generation of a hydrocarbonaceous mixture in the course of thermal evolution of the sedimentary series, and their high-temperature transformation related to the extrusion of basalt. An important feature for fullerene conservation was the enclosure of fullerenes in SB with a structure similar to glasslike carbon, where the fullerene was protected against oxidation.     

Repeated Geodetic Measurements in the West Bohemia Seismoactive Region: Period 1993 - 1996

The western part of the Bohemian Massif is characterized by repeated occurrences of intraplate earthquake swarms. To study surface deformations of this anomalous region, a network covering about 2000 square kilometres for repeated geodetic measurements was established in 1993 - 1994. The positions of the individual points of the network were carefully picked with respect to local tectonic structure and earthquake foci distribution. GPS and precise levelling measurements were performed 1-2 times a year. The GPS data were processed by Bernese GPS software. No tendency to any displacement - either horizontal or vertical - of geological blocks was derived from the geodetic data for the period 1993 - 96. Only displacements of less than 5 mm/year in average could occur in the whole region in that period; larger displacements would have been revealed by our measurements.     

THE IMPORTANCE OF TOPOGRAPHIC CORRECTIONS ON MAGNETOTELLURIC RESPONSE DATA FROM RUGGED REGIONS OF ANATOLIA

Topographic irregularities cause some distortions of magnetotelluric (MT) fields. In the vicinity of a topographic feature, the TM-mode distortion increases with the height and inclination of the slope. It is well-known that TM-mode ( E _⊥) topographic effects are much greater than TE-mode ( E _ı) distortions.   We have made a study of MT anomalies in TM-mode due to two-dimensional topography. In order to reduce these effects, the distortion tensor stripping technique was used. After corrections, the resulting data can be interpreted as if they were obtained over a flat surface and depend only on the subsurface structure. However, this technique sometimes causes some geometrical distortions of the real subsurface structure.   One of our aims is to overcome this failure. We have modified the correction coefficients by considering the actual one-dimensional geology. Model studies showed that our approach is especially useful in removing the terrain effects on complex 2D subsurface structures.   The other purpose of this study is to emphasize the importance of a proper terrain correction for data from sites having mountainous topography over complex geology, e.g. strike-slip faults, suture zones and rift valleys. Some examples of MT data sets collected from the North Anatolian Fault Zone and from the thrust regions of the Western Taurides will be presented.     

Remote sensing detection of atmospheric pollutants by differential absorption LIDAR 510M/SODAR PA2 mobile system

Summary Air pollution problem in the Czech Republic is very complex due to large number of factors as turbulent dispersion and chemical reactions concurring in the status of the PBL. For this 3D distribution of pollutants is a key information that cannot be given by conventional monitoring stations. Combined use of DIAL lidar and sodar can give access to such information. Case studies of air pollutants transport are presented using 3D concentration fields of NO₂ and ozone measured by lidar and meteorological conditions monitored by Doppler Sodar.     

Some Morphological Aspects and Hydrological Characterization of the Tagus Floods in the Santarém Region, Portugal

In Portugal, few studies have been made of the historical floods of the RiverTagus (the longest in the Iberian Peninsula). This fact led to the study of theLower Tagus (Santarém region) using written historical documents,cartographic documents and hydrological data, consisting mainly of waterlevel records. With the support of the historical documents and the analysisof all the maps, it was possible to verify that the human intervention has beenfundamental in the morphological changes of the Tagus' channel. It becameaware that the river changed from a braided to a single channel with alternatebars. From the hydrological data, return periods for the floods were determined,using the Pearson Type 3 distribution. The selection of the most important floods,from 1855 to 1998, enabled to build a ``flood hazard scale' for this region.     

Complete Tertiary exhumation history of the Menderes massif, western Turkey: an alternative working hypothesis

The main exhumation of the Menderes massif, western Turkey, occurred along an originally N‐dipping Datça–Kale main breakaway fault that controlled depositions in the Kale and the Gökova basins during the Oligocene – Early Miocene interval. The isostatically controlled upward bending of the main breakaway fault brings the lower plate rocks to the surface. In the Early Miocene, E–W‐trending N‐ and S‐dipping graben‐bounding faults fragmented the exhumed, dome‐shaped massif. The development of half grabens by rolling master fault hinges has allowed further exhumation of the central Menderes massif. After the Pliocene, high‐angle normal faults cut all of the previous structures. This model suggests that the Menderes massif is a single large metamorphic core complex that has experienced a two‐stage exhumation process.