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141.
Doz. Dr. Peter Faupl Prof. Dr. Alexander Tollmann 《International Journal of Earth Sciences》1979,68(1):93-120
Zusammenfassung Im Mittelabschnitt der Nördlichen Kalkalpen (Ostalpen), zwischen den Flüssen Saalach und Traun, in einer streichenden Verbreitung von 50 km, entwickeln sich in der Unterkreide aus den neokomen Aptychenschichten (Schrambachschichten) die terrigenen Gesteine der Roßfeldschichten. In dieser Studie wurde das Profil der Typlokalität am Roßfeld südlich von Salzburg untersucht.Die Unteren Roßfeldschichten bestehen in ihrem tieferen Abschnitt aus einer ca. 175 m mächtigen Mergelgruppe. Darüber folgen 10–15 m dünnbankige Sandsteine, die in eine 70–80 m mächtige, dickbankige Sandsteingruppe übergehen. Die Oberen Roßfeldschichten setzen abrupt mit grobklastischen Gesteinen ein. Die gesamte Schichtfolge zeigt eine Kornvergröberung gegen das Hangende.Eine erste stichprobenartige mikropaläontologische Bearbeitung hat im tieferen Anteil des Profiles gut auswertbare Foraminiferenvergesellschaftungen erbracht, die mit einer Reihe stratigraphisch wertvoller Unterkreidearten das von den Roßfeldschichten dieser Region nach ihrer Ammonitenfauna bekannte Alter Obervalendis—Hauterive bestätigt.Das Profil konnte im Vergleich mit rezenten Faziesverteilungen als eine vorstoßende Serie eines Tiefseerinnen-Environments interpretiert werden. An Subenvironments sind der Bereich der Hauptrinne (= dickbankige Sandsteingruppe), ein beckenwärts gelegener Damm (dünnbankige Sandsteinfazies) und daran anschließend ein submarines Überflutungsgebiet (= Mergelgruppe) zu unterscheiden. Von der Beckenabhangseite her hat sich ein kleinräumiges Fächersystem mit Grobklastika und Slumping-Ablagerungen vorgeschoben Obere Roßfeldschichten).Das terrigene Material der Roßfeldschichten ist durch das Auftreten von Chromspinell und grüner Hornblende in den Schwermineralspektren charakterisiert. Besonders interessant sind vereinzelt vorkommende rotbraune Hornblenden (Kaersutit), welche auf ein Vorkommen von Alkaligesteinen im Liefergebiet Hinweis geben. Die Anlieferung des terrigenen Materials erfolgte von einer südlich gelegenen Provinz, die eine orogeninterne Position innehatte. Die Position entspricht nicht jener des Ultrapienidischen Rückens im Cenoman und zur Zeit der tieferen Gosauschichten.
Arbeit durchgeführt im Rahmen des IGCP-Projektes Mid-Cretaceous Events 73/ I/58. 相似文献
Summary The Lower Cretaceous Roßfeld Formation, which is exposed in the central Northern Calcareous Alps (East Alps) between Saalach river and Traun river over a distance of about 50 km, was studied in a profile in the type locality at the Roßfeld south of Salzburg. The terrigeneous rocks of the Roßfeld Formation arise gradually from the Neocomian Aptychus beds (Schrambachschichten).In its deeper part the Lower Roßfeld Fm. consists of gray marls of about 175 m thickness. Above that 10–15 m thin-bedded sandstones and then 70–80 m thick-bedded ones follow. The Upper Roßfeld Fm. starts abruptly with coarse-grained sediments. The complete sequence is a coarsening-upward unit.As a result of an initial micropaleontological study well evaluable foraminifera associations were found in the lower part of the section. Some stratigraphically significant species of Lower Cretaceous age attest the range from Upper Valanginian to Hauterivian already established by ammonites in this region.According to modern facies distributions the Roßfeld Fm. can be interpreted as a prograding deep sea channel facies. The following subenvironments are observed: The axial channel (= Thick-bedded sandstone group), and a seaward levee (= thin-bedded unit) passing into a submarine overbank facies (= marly unit). At the slopeward side of the channel there was a narrow fan system consisting of coarse-grained components and slump-deposits (= Upper Roßfeld Fm.).The heavy mineral spectra of the terrigeneous material of the Roßfeld Fm. are characterized by the occurrence of chromium spinell and green amphiboles. Very interesting are few reddishbrown amphiboles (kaersutite), which are considered to indicate alkaline rocks in the source area. This source area was lying in the south in an internal position of the East Alpine system. This position was not the same as that of the Ultrapienidic Ridge of Cenomanian or early Gosauian age.
Résumé Dans le partie moyenne des Alpes Calcaires Septentrionales entre les rivières Saalach et Traun, les couches terrigènes de la Formation de Rossfeld se développent à partir de la série marneuse de Schrambach (couches à Aptychus) du Néocomien. Cette étude présente les résultats de l'examen de la localité typique des couches de Rossfeld au sud de Salzburg.Les couches inférieures de Rossfeld sont formées à leur base par des marnes grises d'une épaisseur de 175 m environ. Au-dessus suivent 10–15 m d'un grès en minces bancs qui passe à des grès en gros bancs d'une épaisseur totale de 70–80 m. Les couches supérieures de Rossfeld commencent brusquement avec des sédiments grossiers. La série complète montre une augmentation de la granularité vers le haut.Une étude micropaléontologique préliminaire révèle des faunes à foraminifères à espèces typiques du Crétacé inférieur (Valenginien à Hauterivien) dans la partie inférieure de cette section des couches de Rossfeld.Par comparaison avec des répartitions de facies récentes, on peut interpréter la formation de Rossfeld comme facies d'une série qui s'avance dans la région d'une fossé abyssal. On peut définir les régions spéciales suivantes: Un canal axial avec des grès en gros bancs, une levée du côté du bassin avec des grès en bancs minces et, lié à cela, un terrain de débordement sousmarin avec la série marneuse. Un éventail plus local à matériel détritique plus grossier et avec des structures de slumping s'avançait à partir du flanc du bassin: ce sont les couches supérieures de Rossfeld.Le spectre des minéraux denses de la formation de Rossfeld est caractérisé par l'existence du spinelle chromé et d'amphiboles vertes. Particulièrement intéressantes sont des amphiboles rouge-brun très rares (Kaersutites), lesquelles montreraient l'existence de roches alcalines dans le domaine nourricier. Le matériel détritique a une origine méridionale et provient donc d'une région ayant une position interne dans l'orogène, ce qui ne correspond pas avec la position du seuil ultrapiénidique du crétacé supérieur.
( ), , 50 ( ) . — — . 175 . 10–15 , (70–80 ) . . . , , , , . , , . , . . , — — . — . . - ( ?), , , . , , . .
Arbeit durchgeführt im Rahmen des IGCP-Projektes Mid-Cretaceous Events 73/ I/58. 相似文献
142.
There have been many studies of the retail industry in recent years, and of the impact that retailing has had on the spatial arrangement of urban areas and on consumer behaviour. Little attention has been paid, however, to employment in retailing, which is disturbing in view of its growing importance and its rapidly changing nature and composition. This paper examines the nature of the broad structural changes within the industry, and investigates their spatial consequences through a case study of employment generation within a system of suburban retail centres in Canberra, Australia. It is shown that the evolution of suburban centres, particularly those of a regional variety, has had an important and enriching impact on the suburban labour market. The regional centres are also seen to be the focus of the major structural employment changes currently affecting the retail industry. This has some important implications for urban planning. 相似文献
143.
A conspicuous graben extends for 800 kilometers through El Salvador and western Nicaragua to the Caribbean Sea in northeastern Costa Rica. Like the smaller but structurally similar Semangko and Toba Depressions of northern Sumatra, the trough is clearly related to voluminous volcanic eruptions during Late Tertiary time. In the region around Lakes Managua and Nicaragua, where the depression is best defined and reaches its greatest dimension, a thick series of Tertiary sediments and volcanic rocks provides a means of interpreting the Cenozoic history of the region. Following a long period of intermittent volcanic activity and sedimentation, extensive sheets of andesitic and dacitic ignimbrites were erupted during Late Miocene time from fissure sources which appear to have been located near the now-subsided central portion of the graben. Near the coast, ignimbrites flowed across a flat lagunal shore overwhelming and burying the tropical vegetation and finally coming to rest in shallow water. Unusual textures and chaotic mixtures of pumice with sediments and silicified wood characterize the bases of many of the water-laid ignimbrites. Subsidence of the graben does not appear to have occurred concurrently with the ignimbrite eruptions but followed them closely near the end of the Miocene or the beginning of Pliocene time. Subsequent activity has been confined to relatively smaller eruptions from central vents near the boundary faults of the graben. 相似文献
144.
Norman K. Grant James L. Powell Flora R. Burkholder John V. Walther Max L. Coleman 《Earth and Planetary Science Letters》1976,31(2):209-223
Strontium and oxygen isotope measurements on the alkali basalt-trachyte-phonolite suite of St. Helena show that some of the late-fractionated rocks are enriched in 87Sr and depleted in 18O relative to the older basalts. The data rule out both the formation of the late-fractionated rocks by the partial melting of hydrothermally altered oceanic crust and the contamination of the volcanic rocks by oceanic sediment. It also appears to be incompatible with models based either on the melting of previously fractionated and crystallized liquids in the volcanic pile, or the long-term fractionation of lavas over several millions of years in a sub-volcanic magma chamber.It is concluded that hydrothermal interaction with meteoric water is the most important cause of the 18O depletion. If the interaction occurred at widely differing temperatures, and involved meteoric and seawaters, it might conceivably have caused both the oxygen and strontium isotope heterogeneities. 相似文献
145.
146.
Alexander Roglinov Ludmil Christoskov Reviewer J. Vaněk 《Studia Geophysica et Geodaetica》1977,21(1):11-18
Summary Aki's spectral 2 model[1] is used to estimate the amplitude field at epicentral distances up to 1000 km in the case of an absorption coefficient of seismic waves which varies with distance. Velocity spectra, the periods of the maximum of these spectra and the maximum velocity amplitudes are obtained. The results are compared with[2] and it is shown that the divergence of the amplitude field decreases if a variable absorption coefficient is used. The theoretical results, obtained in this case, approach the results seen in practice. The possibility of determining the limits of epicentral distances, at which the amplitude field may be considered as linear, is given. 相似文献
147.
148.
149.
Graphical Interpretation of Water-Quality Data 总被引:12,自引:0,他引:12
Alexander Zaporozec 《Ground water》1972,10(2):32-43
150.