Zur Tektonik im westlichen Fichtelgebirge

Zusammenfassung Es wird zu einigen tektonischen Problemen im westlichen Fichtelgebirge (Gradabteilungsblätter Weidenberg und Ebnath) Stellung genommen, wobei andere Deutungsmöglichkeiten zur Diskussion gestellt werden. Vor allem wird eine schichtparallele Verschieferung einer älteren Schiefrigkeit abgelehnt und das Umlaufen der Schieferung am SW-Rand des Fichtelgebirges durch sekundäre Kippungen erklärt.

---

The author expresses his opinion on some tectonic problems in the western Fichtelgebirge (Topographical maps: Gradabteilungsblätter Weidenberg und Ebnath).He proposes different ways of interpretation. Above all he rejects that an older schistosity became again foliated parallel to the strata, and he ascribes the bending of the schistosity on the south-west border of the Fichtelgebirge to secundary tilts.

---

Résumé L'auteur critique quelques problèmes tectoniques qui se posent à l'ouest du Fichtelgebirge. (Tebles topographiques: Gradabteilungsblätter Weidenberg und Ebnath). Il indique d'autres interprétations possibles. Avant tout il réfute qu'une ancienne schistosité au sud-ouest du Fichtelgebirge est attribuée à un basculement secondaire.

---

Fichtelgebirge. .

     

Tectonic and climatic controls on late Quaternary bajada sedimentation along Narmada-Son Fault(NSF),Gujarat,Western India

An alluvial bajada has been recognized along a part of the active Narmada-Son Fault(NSF) and confined by the Karjan River on the eastern side and by the Madhumati River on western side.The bajada sequence exposed along the incised cliffs of various north flowing parallel streams has been studied in their proximal,medial and distal part. The sediments are characterized on the basis of grain size,fabric,sedimentary structures,bed geometry and sorting, and lithologs prepared from the mapped cliff sections.Detailed study of sedimentary characteristics,lithofacies analysis and facies associations indicate that sediments are mainly of three types-sediments that were deposited by debris flows and sediment gravity flows,and as extensive bar deposits.Three major aggredational sequences are recognized.Each sequence is composed of coarsening-upward sequence of proximal facies overlain by fining-upward sequence of distal facies.Coarsening upward sequence record periods of tectonic activity related to uplift along the NSF and fan progradation,whereas fining-upward sequence results from tectonic quiescence periods.The presence of rhizocretions,calcium carbonate nodules and calcite sheets within the basal debris flow and sediment gravity flow indicate semi-arid climate,whereas the formation of pedoginized paleosol indicate relatively wetter climate prevailing in the study area.Tectonic activity along the NSF has played dominant role by controlling the geometry and volume of bajada sediments.Climate is found to be responsible for compositional and temporal distribution of bajada sediments.OSL dating suggests that the bajada sediments were deposited during the later part of late Pleistocene.The incision of the sediments is attributed to uplift due to inversion of the lower Narmada basin during the early Holocene.     

Combating famine by grain storage in Western Sudan

Traditional grain storage used to be an effective mechanism to combat famine in the rural areas of W Sudan. Of late, this mechanism has failed to function and a severe famine took place in 1984–1985. This paper endeavours to highlight this crisis, show the traditional methods of grain storage and point out to ways of retrieving grain storage systems to start again on a less vulnerable basis. An assessment of grain storage requirements under the new conditions where both market and subsistence economy are effective in rural areas is made for the different ecological zones of W Sudan.     

The front of 8 October 1987 — Predictions of three mesoscale models

Summary The forntal passage of 8 October 1987, which was extensively sampled during the first intense observation period of the German Front Experiment, is simulated by aid of three mesoscale models. The results are intercompared and held against the manually and objectively analysed observations of the meso and meso- scales, respectively. The orographic impact is studied by comparing model runs with full and cut-off Alps. Implications regarding similar efforts in the future conclude the paper.With 11 Figures     

Korrelation der Sporenzonen der Oberen Trias und des Jura im Mittleren Orient und in Süddeutschland

Zusammenfassung Bei der sporenstratigraphischen Gliederung des mittleren Mesozoikums im Mittleren Orient konnten vom Nor bis zur Unteren Kreide 6 Sporenzonen unterschieden werden: Unterkreide:Ischyosporites variegatus — Rouseisporites laciniatus — Cicatricosisporites-Zone Malm:Ischyosporites variegatus — Rouseisporites laciniatus-Zone Dogger:Ischyosporites variegatus — Duplexisporites problematicus-Zone Lias:Concavisporites — Duplexisporites problematicus-Zone Rät:Concavisporites — Duplexisporites problematicus — Lophotriletes sangburensis — Ricciisporites tuberculatus-Zone Nor:Concavisporites — Duplexisporites problematicus — Lophotriletes sangburensis — Cyclotriletes oligogranifer-ZoneVergleichende Untersuchungen ergaben, daß diese Sporenzonen auch auf Süddeutschland übertragbar sind und den faunistischen Grenzen entsprechen. Nur die sporenstratigraphische Festlegung der Nor/Rätsowie der Dogger/Malm- und der Malm/Unterkreide-Grenze bedürfen noch der Verifizierung.

---

In the middle Mesozoic of the Middle East 6 spore-assoziations could be distinguished from the Norian to the Lower Cretaceous: Lower Cretaceous:Ischyosporites variegatus — Rouseisporites laciniatus — Cicatricosisporites zone Upper Jurassic:Ischyosporites variegatus — Rouseisporites laciniatus zone Middle Jurassic:Ischyosporites variegatus — Duplexisporites problematicus zone Lower Jurassic:Concavisporites — Duplexisporites problematicus zone Rhaetian:Concavisporites — Duplexisporites problematicus — Lophotriletes sangburensis — Ricciisporites tuberculatus zone Norian:Concavisporites — Duplexisporites problematicus — Lophotriletes sangburensis — Cyclotriletes oligogranifer zone.The interregional validity and the correspondance of these spore zones with the faunistic boundaries could be substantiated in equivalent sequences in Southern Germany. However, the palynological definition of the Norian/Rhaetian, Middle/Upper Jurassic and Jurassic/Cretaceous boundaries have still to be confirmed in other regions since suitable sections have not been available in Southern Germany.

---

Résumé Dans le Mésozoïque moyen du Moyen Orient, six zones de spores peuvent être distinguées du Norien au Crétacé inférieur: Crétacé inférieur: Zone àIschyosporites variegatus — Rouseisporites laciniatus — Cicatricosisporites Jurassique supérieur: Zone àIschyosporites variegatus — Rouseisporites laciniatus Jurassique moyen: Zone àIschyosporites variegatus — Duplexisporites problematicus Jurassique inférieur: Zone àConcavisporites — Duplexisporites problematicus Réthien: Zone àConcavisporites — Duplexisporites problematicus — Lophotriletes sangburensis — Ricciisporites tuberculatus Norien: Zone àConcavisporites — Duplexisporites problematicus — Lophotriletes sangburensis — Cyclotriletes oligogranifer Une étude comparative montre que les mêmes zones de spores existent en Allemagne du sud et qu'elles correspondent aux limites faunistiques. Toutefois, les limites Norien/ Rhétien, Dogger/Malm et Malm/Crétacé inférieur demandent à être vérifiées.

---

- : : Ischyosporites variegatus —Rouseisporites laciniatus — Cicatricosisporites : Ischyosporites variegatus — Rouseisporites laciniatus : Ischyosporites variegatus — Duplexisporites problematicus : Concavisporites — Duplexisporites problematicus : Concavisporites — Duplexisporites problematicus — Lophotriletes sangburensis — Ricciisporites tuberculatus : Concavisporites — Duplexisporites problematicus — Lophotriletes sangburensis — Cyclotriletes oligogranifer. , , . , /, / / .

     

Spatial variations in the progress of land reform in Romania

Romania's socialist agricultural sector has been transformed by a series of measures taken after the revolution of 1989. A new farm structure is emerging out of the restitution provided for under the Land Law of 1991. There are striking spatial variations in different aspects of the privatisation process, especially the contrasting situations between the hill country (with heavy pressure on land) and the plains (where there is much better supply in relation to demand). Very small units of land ownership are being grouped into larger functional units for management by associations which are especially prominent in the main cropping zones. Meanwhile individual smallholdings are predominant in the hill and mountain zones. Despite a desire for owner-occupation, association is often advantageous through efficient deployment of machinery and some 40 percent of land allocated to individual peasants is being worked by some 20,000 associations. However, the situation has not yet stabilised and it is emphasised that small farms should be regarded not simply as agricultural units but as the cores of diversified enterprises characterised increasingly by pluriactivity     

Klimatische Tendenzen und Untersuchungen zur allgemeinen Zirkulation

Zusammenfassung Einige Beobachtungsdaten aus dem Winter 1962/63 werden sowohl in bezug auf neuere als auch auf langfristige klimatische Tendenzen diskutiert. Der Abkühlung der Weltklimate seit etwa 1940 ist bisher praktisch noch nicht viel Beachtung geschenkt worden, obwohl sie die Häufigkeit strengen Winterwetters beeinflußt hat. Dies ist vielleicht teilweise durch die künstliche Erwärmung der Städte zu erklären, die unter starken niedrig liegenden Temperaturinversionen im Winter am wirksamsten ist. Ferner wird über Untersuchungen der Änderungen der allgemeinen atmosphärischen Zirkulation berichtet. Diese zeigen den Mechanismus auf, durch den aufeinanderfolgende langfristige Klimaänderungen zustandegekommen sind: Die Abkühlung in den Jahren von 1300 bis 1600 und die Erwärmung in den Jahren von 1700 bis etwa 1930 werden mit einer Abschwächung beziehungsweise Verstärkung der Zirkulation bzw. mit entsprechenden Änderungen der Wellenlänge der zirkumpolaren Westdrift und einer Durchdringung der höchsten Breiten durch Warmluftzufuhr und Zyklonenzugbahnen in Verbindung gebracht. Eine Umkehr des Trends kann unter Verwendung dieser Zirkulations-Aspekte bereits früher entdeckt werden — schon 30 oder mehr Jahre früher — als durch Untersuchung der Temperaturen in der Arktis und anderswo, der Ausdehnung der Eisbedeckung usw. Es ist wahrscheinlich, daß die Abkühlung und die Zunahme des Eises, die jetzt speziell im europäischen Sektor zu beobachten sind, eine Reaktion darstellen auf die neuere Tendenz zu schwächerer zonaler Zirkulation hin und zu einer Westwärts-Verschiebung des Höhentroges im europäischen Sektor, die eine zunehmende Häufigkeit nördlicher Bodenwinde im Sektor zwischen Grönland und dem Ural begünstigt. Die Eislage in den nördlichen Meeren im Februar 1963 läßt sich nur mit den schlimmsten Jahren des 17. und 18. Jahrhunderts vergleichen.

---

Summary Some figures for winter 1962/63 are examined in relation to both recent and long-term climatic trends. The cooling of world climates since about 1940 has not yet received much notice from the practical point of view, though it has affected the frequency of difficult winter weather. The oversight is perhaps partly explained by the increasing artificial warmth of the cities, which is most effective under strong low-level temperature inversions in winter. Studies of changes in the general atmospheric circulation are described. These show the mechanism by which successive long-term changes of climate have been achieved—cooling from 1300 to 1600 and warming from 1700 to about 1930—was associated respectively with weakening and strengthening circulation and corresponding changes of (a) wavelength in the circumpolar westerlies (b) penetration of the highest latitudes by advected warm air and depression tracks. Reversal of trend is detected earlier, already 30 years or more ago, in these aspects of the circulation than when one examines temperatures in the Arctic and elsewhere, extent of ice etc. It seems probable that the cooling and increase of ice now to be observed particularly in the European sector are a response to the recent trend towards weaker zonal circulation and a westward shift of the upper trough in the European sector which favours increased frequency of northerly surface winds in the sector between Greenland and the Urals. The ice situation on the northern seas in February 1963 appears fully comparable only with the worst years of the 17th and 18th centuries.

---

Résumé On discute ici quelques observations de l'hiver 1962–1963 à la lumière de tendances climatologiques tant récentes qu'à long terme. Jusqu'ici, on n'a pas accordé beaucoup d'attention au refroidissement des climats de notre globe depuis 1930, bien que ce refroidissement ait influencé déjà le nombre des hivers rigoureux. Ce peu d'attention s'explique peutêtre par le chauffage artificiel des villes, chauffage qui est particulièrement efficace au-dessous de fortes inversions thermiques situées en hiver à basse altitude. On rapporte en outre sur des recherches concernant des changements de la circulation atmosphérique générale. Ces changements montrent le mécanisme par lequel les modifications successives du climat à long terme se sont produites. On met le refroidissement des années 1300 à 1600 en relation avec un ralentissement de la circulation et le réchauffement de 1700 à 1930 avec une accélération de cette circulation. On peut faire le même raprochement pour des modifications similaires de la longueur d'ondes du courant circumpolaire d'ouest et la pénétration des afflux d'air chaud et des trajectoires des cyclones aux latitudes les plus grandes. Une inversion de la tendance du climat peut être reconnue bien à l'avance—30 ans et plus—en utilisant ces nouveaux aspects de la circulation, qu'en utilisant les températures de l'arctique et d'ailleurs, l'extension de la calotte glaciaire, ou d'autres critères. Il est probable que le refroidissement et l'augmentation de la glace, visibles actuellement surtout dans le secteur européen, ne sont qu'une réaction aux nouvelles tendances de ralentissement de la circulation zonale et d'un déplacement vers l'ouest du creux dépressionnaire en altitude du secteur européen, ce qui favorise une fréquence accrue des vents du nord au sol entre le Groenland et l'Oural. La position des glaces dans les mers du nord en février 1963 ne peut être comparée qu'aux pires années des 17ème et 18ème siècles.

---

---

Mit 5 Textabbildungen     

Crystal structure model for metavoltine from Sierra Gorda

Summary The crystal structure of metavoltine from Sierra Gorda, Chile, has been solved from photographic X-ray data by the heavy atom method. The space group used wasP3 witha=9.575(5) andc=18.17(1)Å; cell content: K₂Na₆ (Fe ²⁺, Cu, Zn)Fe ₆ ³⁺ (SO₄)₁₂O₂·18H₂O. From the relatively small number and the somewhat poor quality of the X-ray data, the least squares refinement did not give very satisfactory results-especially so for the light atoms. Therefore, steric considerations and information from the Fourier maps were also used when choosing the final atomic coordinates. The salient features of the structure are clusters of Fe ₃ ³⁺ O(H₂O)₃(SO₄)₆ with Fe³⁺ in octahedral coordination, and Fe²⁺(H₂O)₆ octahedra. The Na⁺ ions show octahedral coordination, the K⁺ ions irregular nine coordination.

---

Ein Kristallstrukturmodell für den Metavoltin von Sierra Gorda

Zusammenfassung Die Kristallstruktur des Metavoltins von Sierra Gorda (Chile) wurde aus photographischen Röntgendaten mit der Schweratommethode gelöst. Als Raumgruppe wurdeP3 mita ₀9,575(5) undc ₀=18,17(1) Å verwendet; Zellinhalt K₂Na₆ (Fe ²⁺, Cu, Zn) Fe ₆ ³⁺ (SO₄)₁₂O₂·18H₂O.Wegen der relativ kleinen Zahl und der nicht sehr guten Qualität der Röntgendaten gab die Verfeinerung nach der Methode der kleinsten Quadrate keine sehr guten Ergebnissebesonders nicht für die leichten Atome. Deshalb wurden zur Festlegung der endgültigen Atomkoordinaten auch sterische Überlegungen und Informationen aus Fouriersynthesen herangezogen. Hervorstechende Züge der Struktur sind Gruppen Fe ₃ ³⁺ O(H₂O)₃(SO₄)₆ mit Fe³⁺ in oktaedrischer Koordination sowie Fe²⁺(H₂O)₆-Oktaeder. Die Na⁺-Ionen zeigen oktaedrische Koordination, die K⁺-Ionen unregelmäßige 9-Koordination.

---

---

With 4 Figures     

Suevite of the ries crater,Germany: Source rocks and implications for cratering mechanics

Suevites are impact breccias with a montmorillonitic matrix that contains shocked and unshocked mineral and rock fragments from the crystalline basement, glass inclusions and a small amount of sedimentary clasts. Data are given of the modal composition of fall-out suevites (deposited at isolated points around the crater) and crater suevite (forming a layer below post-impact lake sediments in the crater cavity). Fall-out suevites contain aerodynamically shaped bombs which are absent in crater suevite. Taking into account not only large glass fragments and bombs, but also the finer fractions, the glass content of fall-out and crater suevites amounts to 47 and 29 vol%, respectively. Crystalline clasts in suevites consist of all igneous and metamorphic rock types that constitute the local basement which consists of an upper layer of igneous rocks (mainly granites) and a lower series of gneisses and amphibolite. Based on a collection of 1 200 clasts from 13 suevite occurrences the average crystalline clast population of suevites was determined. Suevites contain on the average 46 % igneous and 54 % metamorphic clasts. In constrast, weakly shocked and unshocked crystalline ejecta of the Ries structure consist of 82 % igneous and 18 % metamorphic rocks. From 138 analyses of crystalline rock samples average compositions of the major rock types were calculated. Comparison of these averages with the average glass composition leads to the conclusion that suevite glasses were formed by shock melting of gneisses in deeper levels of the basement. Suevite matrices consist in most cases of 80 to 90 % montmorillonite, in special cases of celadonite. Chemical analyses are given of some matrices and montmorillonite formulas calculated. It is supposed that montmorillonite was formed by early hydrothermal alteration of rock flour or fine glass particles. In the latter case the original glass content of suevites was higher than at present. Of all ejecta from the Ries crater only crystalline rocks contained in suevites occur in all stages of shock metamorphism up to complete fusion. The overwhelming majority of the ejecta from the sedimentary sequence (about 580 m) show no indications of shock pressures above 10 GPa. The same holds true for crystalline megablocks and breccias around the crater which consist mainly of granites from upper levels of the basement. We assume that the Ries impact can be approximated by a deep-burst model: The projectile penetrated through the sedimentary cover into the basement in such a way that the highest pressures and temperatures developed within the gneiss complex below the upper, predominately granitic layer and that rocks of the sedimentary sequence experienced weak shock compression. Numerical data are given for such a model of the Ries impact on transient crater geometry and volumes of vaporized, melted, shocked and excavated rocks. Fall-out suevites are supposed to have been lifted from the central zone by an expanding plume of vaporized rocks and deposited as fluidized turbulent masses outside the crater whereas the main mass of crater suevite was not removed from the crater cavity.     

Chronostratigraphy and paleoclimatic meaning of cryogenic deformations in the Central European loess

Cryoturbations in loess reflect cold and wet environments but not necessarily permafrost. Only flat bottomed cryoturbations are indicative of it. Outside the permafrost zone they occur during the wet period of the last glaciation: during the early Weichselian, the lower pleniglacial, the end of the middle pleniglacial and the late glacial. Their morphology ist related to the frost susceptibility of the superimposed layers, expressed in form of differential frost heaving, ruled by the drainage quality and the frost susceptibility gradient. Their diagenesis is discussed.