TRANSALP—deep crustal Vibroseis and explosive seismic profiling in the Eastern Alps

The TRANSALP consortium, comprising institutions from Italy, Austria and Germany, carried out deep seismic reflection measurements in the Eastern Alps between Munich and Venice in 1998, 1999 and 2001. In order to complement each other in resolution and depth range, the Vibroseis technique was combined with simultaneous explosive source measurements. Additionally, passive cross-line recording provided three-dimensional control and alternative north–south sections. Profits were obtained by the combination of the three methods in sectors or depths where one method alone was less successful.The TRANSALP sections clearly image a thin-skinned wedge of tectonic nappes at the northern Alpine front zone, unexpected graben or half-graben structures within the European basement, and, thick-skinned back-thrusting in the southern frontal zone beneath the Dolomite Mountains. A bi-vergent structure at crustal scale is directed from the Alpine axis to the external parts. The Tauern Window obviously forms the hanging wall ramp anticline above a southward dipping, deep reaching reflection pattern interpreted as a tectonic ramp along which the Penninic units of the Tauern Window have been up-thrusted.The upper crystalline crust appears generally transparent. The lower crust in the European domain is characterized by a 6–7 km thick laminated structure. On the Adriatic side the lower crust displays a much thicker or twofold reflective pattern. The crustal root at about 55 km depth is shifted around 50 km to the south with respect to the main Alpine crest.     

Crustal structure of the Eastern Alps along the TRANSALP profile from wide-angle seismic tomography

The objective of the TRANSALP project is an investigation of the Eastern Alps with regard to their deep structure and dynamic evolution. The core of the project is a 340-km-long seismic profile at 12°E between Munich and Venice. This paper deals with the P-wave velocity distribution as derived from active source travel time tomography. Our database consists of Vibroseis and explosion seismic travel times recorded at up to 100 seismological stations distributed in a 30-km-wide corridor along the profile. In order to derive a velocity and reflector model, we simultaneously inverted refractions and reflections using a derivative of a damped least squares approach for local earthquake tomography. 8000 travel time picks from dense Vibroseis recordings provide the basis for high resolution in the upper crust. Explosion seismic wide-angle reflection travel times constrain both deeper crustal velocities and structure of the crust–mantle boundary with low resolution. In the resulting model, the Adriatic crust shows significantly higher P-wave velocities than the European crust. The European Moho is dipping south at an angle of 7°. The Adriatic Moho dips north with a gentle inclination at shallower depths. This geometry suggests S-directed subduction. Azimuthal variations of the first-break velocities as well as observations of shear wave splitting reveal strong anisotropy in the Tauern Window. We explain this finding by foliations and laminations generated by lateral extrusion. Based on the P-wave model we also localized almost 100 local earthquakes recorded during the 2-month acquisition campaign in 1999. Seismicity patterns in the North seem related to the Inn valley shear zone, and to thrusting of Austroalpine units over European basement. The alignment of deep seismicity in the Trento-Vicenza region with the top of the Adriatic lower crust corroborates the suggestion of a deep thrust fault in the Southern Alps.     

Kriterien für die anwendung des ertelschen erhaltungssatzes in ionisierten bzw. viskosen medien

Zusammenfassung Es wird gezeigt, dass für ein Gasgemisch, das geladene Komponenten enthält und von einem divergenzfreien und stationären Magnetfeld durchsetzt wird, für eine geladene Komponente (Ionen oder freie Elektronen) näherungsweise der Ertelsche Erhaltungssatz gilt, falls unter bestimmten Voraussetzungen das Verhältnis der Reibungskraft (innere) zur magnetischen Feldkraft sehr klein verbleibt. Weiter wurde nachgewiesen, dass derselbe Erhaltungssatz näherungsweise auch für ein viskoses Medium gilt, falls die Reynoldszahl (Verhältnis der Trägheitskraft zur Reibungskraft (innere)) sehr gross ist. Dies ist bei einem turbulenten Medium der Fall.

---

Summary It is shown that in a gas mixture containing charged constituents (ions and free electrons) the conservation theorem of Ertel is valid on certain conditions for one of the charged constituent if the ratio of the friction force between the neutral and charged constituents to the magnetic force is small. The same conservation theorem is also valid for a viscous fluid if the Reynoldsnumber (ratio of inertial force to the viscous force) is large.

     

Der orographische Einfluss der Alpen auf eine westliche Höhenströmung

Zusammenfassung In der vorliegenden Arbeit wurde der orographische Einfluss der Alpen auf eine westliche Höhenströmung untersucht. Dabei hat sich herausgestellt, dass bei westlicher Anströmung des Alpenmassivs die Luftpartikelchen nach rechts abgelenkt werden. Durch einen Radiosondenvergleich zwischen Payerne und Zagreb in 500 mb konnte diese von der Theorie her aufgestellte Forderung bekräftigt werden.

---

Summary The author investigates the orographic influence of the chain of the Alps on a westerly upper air stream. The theory shows that air particles are deflected to the right, if they come with a westerly stream of air. A comparison between the 500 mb winds of Payerne (Switzerland) and Zagreb (Yugoslavia) could confirm this theory.

---

---

Diese Arbeit stellt den Beitrag FRP Alpenwetter Nr. 2/64 eines vom Österreichischen Forschungsrat subventionierten Forschungsvorhabens dar.     

Post-drilling destabilization of temperature profile in borehole Yaxcopoil-1, Mexico

As part of the International Continental Scientific Drilling Program (ICDP), the 1.5-km-deep borehole Yaxcopoil-1, located in the Chixculub meteor impact structure in Mexico, has undergone further study after drilling operations ceased. Temperature logs were repeated ten times at intervals 0.3–0.8, 15, 24 and 34 months after borehole shut-in. The logs bear a distinct signature of transient heat transfer by groundwater flow manifested by a gradual distortion of the linear temperature profile when a cold wave of 0.8–1.6°C amplitude was detected propagating downward from 145 to 312 m at a rate of 4–6 m/month. To understand the nature of this moving anomaly, a 20-day monitoring of the cold wave was carried out at a depth of 307 m that showed further cooling of 0.6°C during the first 16 days of the passage followed by temperature stabilisation. As an explanation of this unusual phenomenon, a theory is proposed, whereby the drilling mud has accumulated within the overlying and cooler highly porous and permeable karstic rocks during the drilling and migrates downward. The observed migration rate suggests a permeability higher than 10^?11 m². This indicates a high vulnerability to contamination of the only freshwater aquifer in the Yucatan region.     

The responses of different ethnic groups in the Sudan to rural-urban migration

The ethnic identities of the various population groups in the Sudan are a product of their specific natural and social environments. The migration of these groups to the towns, especially to Greater Khartoum, involves a drastic change of cultural norms and values. However, the capability of change and the subsequent results are strongly conditioned by the specific background of each ethnic group and by the conditions in its area of origin. This is being proved by a comparative study on three ethnic groups in the Sudan: the Nuba, the Zaghawa and the Hadandawa.     

The eastern continuation of the Cadomian orogen: U–Pb zircon evidence from Saxo-Thuringian granitoids in south-western Poland and the northern Czech Republic

We report U–Pb single zircon ages from three pre-Variscan granitoids in the NE part of the Bohemian Massif. The Platerówka granodiorite from the Lausitz-Izera Unit, the Polish Sudetes, has been dated at 533±9 Ma. The Bitouchov granite form the SW part of the South Krkonoe Unit, the Czech Sudetes, gave an age of 540+11/–10 Ma, and the Wdroe granodiorite in the Fore-Sudetic Block yielded 548±9 Ma. All these latest Vendian/Early Cambrian granitoids represent the post-tectonic expression of a late Proterozoic Cadomian orogenic cycle and demonstrate the eastward extent of the Cadomian basement into the Variscan orogen. Granodiorites of similar age have so far been reported from Brittany and especially from the Saxo-Thuringian Terrane to the NE and SW of the Elbe Fault Zone. We conclude that the Saxo-Thuringian Terrane extends across the Elbe and Sudetic Marginal Fault Zones into the Fore-Sudetic Block.     

Revision of the Clam Shrimp Genus Magumbonia from the Upper Jurassic of the Luanping Basin,Hebei,Northern China

The diverse clam shrimp Nestoria-Keratestheria fauna is widely distributed in the Dabeigou Formation in northern Hebei and eastern Inner Mongolia of China.Its important component genus Magumbonia from the Dabeigou Formation in the Luanping Basin,northern Hebei,China,is revised on the basis of a scanning electron microscope (SEM) examination of the type species M.jingshangensis Wang,1984,which revealed morphological features not recognized previously.These include coarse reticulation on the umbo and promi...     

Einige Probleme des Variszikums von Neo-Europa

The Periadriatic Lineament and its possible extension, the Balatonline, on the one hand and the Balcan-Dinaric Lineament and its continuation (?) the Zagreb-line, on the other hand, separate an outer-region, characterized by clastic, terrestrical Upper Carboniferous and Permian strata, from a marine Inner-region. This Inner-region includes the Southern Alps, the Dinarides, and the ?Igoler“-trough. The aforementioned lineaments were not evident during the Lower Paleozoic, whereas in the Upper Paleozoic (after the Variscan orogenese) a clear separation of the two areas can be seen. As a consequence of the overlapping of the marine sequence into the regions north of the Periadriatic lineaments during the Triassic, the contrast between outer- and inner-regions are agained wiped out. For a full understanding of these facts, significant details are still missing. Above all it is important to find a solution for several still unanswered questions: how far the outer region is still a part of the paleomagnetic “Stabile Europe”; how far the metamorphic development within the region of the Balcan Peninsula, the Pannonic Basin and the Karpates can be compared with the ideas (supported by isotopic-geological dates) of the metamorphic development on both sides of the Insubric line and also how far the Dinaric Ophiolite zones are remains of a Paleothetys. Only when these questions are answered will it be possible to insert the Variscan area into the discussion of plate-tectonics within the Neo-European region.