共查询到20条相似文献，搜索用时 15 毫秒
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Albert Carozzi 《International Journal of Earth Sciences》1951,39(1):177-195
A new method of sedimentary rocks investigation is proposed. It illustrates by means of curves the variations in both time and space of the main mineral and organic features. By combining them together in a logical way, it is possible to decipher the relations between sedimentation and the different factors governing it: depth, distance to shoreline, direction and strength of marine currents, biological and chemical conditions, tectonics and so on. Finally a paleogeographic classification of lithological facies is obtained.Some examples taken in the Cretaceous of the Swiss High Calcareous Alps are presented. The bathymetrical interpretation of their facies is in close agreement with the results of modern oceanographic investigations which have described in some cases very similar conditions.
Zusammenfassung Eine Interpretationsmethode der Sedimentgesteine wird dargestellt. Mittels Kurven warden die zeitlichen und räumlichen Variationen der wichtigsten mineralogischen und organischen Charaktere ausgedrückt. Die durch diese Kurven gelieferten Angaben werden unter sich in logischer Weise kombiniert und erlauben eine paläogeographische Klassifikation der verschiedenen lithologischen Einheiten. Hiermit ist es möglich, die Verbindungen zwischen der Sedimentation und den verschiedenen Faktoren, welche die letztere beeinflussen, herzustellen: Tiefe, Entfernung von der Küste, Richtung und Stärke der Strömungen, physikalisch-chemische Bedingungen, Tektonik usw. Es werden verschiedene Beispiele aus der helvetischen Kreide dargelegt. Die bathymetrische Interpretation ihrer lithologischen Fazies entspricht den neuesten Arbeiten der Ozeanographie, worin ähnliche aktuelle Bedingungen beschrieben sind.相似文献
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Ruth Fridman 《International Journal of Earth Sciences》1955,43(2):402-405
Résumé L'observation de nombreux sédiments de plage et l'étude de prélèvements effectués au large ont montré que l'île de Ré est actuellement privée de sources importantes de sédiments grossiers étrangers; l'évolution des sables — auxquels succède très rapidement vers le large la vase — ne se poursuit plus que par des transferts littoraux, sur un matériel local, depuis le Flandrien, période à laquelle il faut également rattacher l'importante proportion de grains de quartz au cachet éolien très marqué.L'étude granulométrique, celle des minéraux lourds permettent de séparer en deux stocks différents l'ensemble des sables des dunes et des plages; elles dénotent également des transports d'Ouest en Est. 相似文献
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Samira Adil Mohammed Bouabdellah Fidel Grandia Esteve Cardellach Àngel Canals 《Comptes Rendus Geoscience》2004,336(14):1265-1272
The Bou-Dahar PbZn Mississippi Valley deposits located in the eastern part of the High Atlas Range (Morocco) are hosted by a Liassic reefal complex. Fluid inclusion and ‘crush-leach’ data show that two distinct fluids were involved in the mineralisation deposition: a warmer, more saline fluid (180?°C, NaCl equivalent) and a cooler, less saline fluid (70?°C, 16 wt% equivalent NaCl). Mixing of these two fluids resulted in the precipitation of the ore. The solute composition of the ore-forming brine suggests that the MVT mineralising fluids were probably a mixture of halite-dissolution fluids and evaporated seawater. To cite this article: S. Adil et al., C. R. Geoscience 336 (2004). 相似文献
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Pierre-Jean Combes Bernard Peybernès Marie-José Fondecave-Wallez 《Eclogae Geologicae Helvetiae》2004,97(2):155-174
In the Eastern part of French Pyrenees, the Cucugnan area (Southern Corbières) corresponded during the early/Mid-Paleocene (Danian/Selandian) to a narrow transitional zone between the sea to the South (Pyrenean Paleocene Trough) and the continent (fluvio-palustrine and lacustrine Vitrollian deposits) to the North. To the South, in the North-Pyrenean Zone, the polygenic marine breccias and the associated Dano-Selandian Globigerinid-bearing hemipelagites have been preserved within successive paleokarsts superimposed onto the carbonate substratum (ante-Albian). Four paleosurfaces are recognized, principally filled by marine internal sediments with proximal and distal facies. To the North, in the Sub-Pyrenean Zone, a continental foreland basin is characterized by four formations of variegated Microcodium-bearing marls and channelized conglomerates, separated by erosional paleosurfaces underlining well-marked unconformities. An event correlation (chronodiagrams) between the marine realm to the South and the continental realm to the North is proposed, using the successive paleosurfaces and the lithological sequences (same number within the two realms). Our paleogeographic reconstruction shows, to the North, the Lake of Cucugnan and, to the South, a calcareous mountainous zone broken by the juxtaposition of deep paleocanyons (eroded in a continental context) later converted into rias submitted to marine oscillations. Several palinspastic transects are reconstructed: they show the polyphase control of the Frontal North-Pyrenean Overthrust on the Paleocene sedimentation and the importance of the successive intra-Vitrollian compressions/ transpressions (phase fini-crétacée auct.) inducing, within the two juxtaposed realms, emersions, erosions and karstic features which give a very contrasted paleogeography during a period characterized by plate convergence and creation of steep topographies.Manuscrit reçu le 25 septembre 2003 Révision acceptée le 4 mai 2004 相似文献
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Maurice Dreyfuss 《International Journal of Earth Sciences》1955,43(2):428-431
Résumé Des seuils peu profonds et stables, balayés par des courants (stabiliseuils) séparaient en France pendant le Jurassique supérieur des aires subsidentes où s'accumulaient les sédiments; des récifs coralliens pouvaient s'y développer lorsque la subsidence était comprise entre 30 et 70 m. par zone paléontologique, et constituer alors de véritables barrières: la localisation des régions où la subsidence optima était réalisée est par conséquent un élément essentiel de l'abondance et de la répartition des sédiments calcaires.Les variations locales de la subsidence constituent donc un facteur important de la sédimentation, non seulement au point de vue quantitatif, mais encore en ce qui concerne la nature des dépôts. 相似文献
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Pierre Nicolini 《Mineralium Deposita》1967,2(2):95-101
Résumé Bien que de moindre intérêt économique, le gisement de fer oolithique du Djebel Ank se rapporte au type «Lorraine».Il s'agit d'une minéralisation localisée vers le littoral d'un sillon intracratonique, en marge du domaine géosynclinal et située, comme en Lorraine, dans une séquence lithologique négative, mais à lithofaciès détritiques en Lorraine, chimiques en Tunisie. On note aussi la localisation des grands gisements de phosphates dans les mêmes faisceaux stratigraphiques et dans les mêmes types de séquences que le gisement de fer du Djebel Ank, fer et phosphate présentant une radioactivité du même ordre et étant situés sur le même linéament.
Although the Djebel Ank deposit is of less economic value, it may be correlated to «Lorraine» type. Mineralisation of Djebel Ank is found near the ancient shore line of a intracratonic trench on the border of geosynclinal area. The mineralisations both at Djebel Ank and Lorraine occur in a lithologic negative sequence, although the lithofacies are detridal in Lorraine and chemical in Tunisia. It is important to point out that phosphates and iron in Tunisia occur in the same stratigraphic series and in an identical type of lithologic sequence. Also iron ore is rich in phosphates. It is significant that the iron and phosphate contain same amount of radioactivities. Likewise, phosphate and iron in Tunisia are localized along a common «lineament».相似文献
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Ohne Zusammenfassung
En hommage pour le 70 anniversaire du Professeur Dr.C. W. Correns, les auteurs dedient ce travail, en remerciant l’enseignement qu’ils ont re?u pendant leur séjour au Sedimentpetrographisches
Institut de G?ttingen (1952 et 1955). 相似文献
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《Geodinamica Acta》1998,11(1):1-11
In order to debate of the early Paleozoic paleogeography, the repartition of the Hercynian blocks, today scattered around West-Mediterranean Sea. should be known. This is the case for the end of the Paleozoic (Fig. 1), but not for the beginning; Fig. 6 is drawn with the supposed repartition in the middle of the Carboniferous.In Central and Eastern Pyrenees and surrounding areas (Fig. 1), Upper Ordovician beds rest unconformably upon a thick (4–6 km), dominantly pelitic series known as Lower Paleozoic in the Eastern Pyrenees or Seo Formation in the Central Pyrenees. The metamorphic lower part of this series often lies over metagranilic orthogneisses, which are best interpreted as a Precambrian basement, Panafriean-Cadomian in age. By correlation with fossiliferous series of other areas, the Pyrenean Lower Paleozoic should be mainly Cambrian in age (ranging from Uppermost Proterozoic to Lowermost Ordovician).For the purpose of this paper, the complex lithostratigraphic succession of the Lower Paleozoic of the Eastern Pyrenees, with two groups and seven formations, could be summarized (Fig. 2) by a threefold division, from bottom to top: (i) a pelile-greywacke and carbonate unit, with a conspicuous plagioclasic component and a sodic composition (Uppermost Precambrian to Lowermost Cambrian?): (ii) a sandstone-pelite unit, with lithic sandstones, ending with a carbonate level, well developped in the Central Pyrenees (Lower Cambrian?): (iii) a mudstone-siltstone unit (Middle-Upper Cambrian?). Fossiliferous Lower Cambrian beds which outcrop at Terrades (south of the Eastern Pyrenees) could be a remnant of an allochthon unit which can be compared with the nappe-thrusts of the nearby Southern Montagne Noire.The pelite-greywacke and carbonate unit (Fig. 3) occurs only in the South-Eastern Pyrenees as a south to north transgressive platform bordering a basin extending southwards; not far south of Eastern Pyrenees, a volcanism of “intermediate” type supplied in plagioclasic clasts the greywackes and volcanoclastic deposits. Near the base of the sequence, a bimodal volcanism and synsedimentary faults reflect the extensional context of the basin initiation, the geochemistry of which has been related to back-arc setting. An acidic volcanism developped higher in the sequence (tufs and hypovolcanic bodies). Carbonate levels are numerous, particularly in the lower part of the unit. The upper part of the sequence is an oslistostrome made of polygenic intraformational conglomerates fed from the south: it outlines the transition to the next unit.The sandstone-pelite unit (Fig. 4) rests conformably on the previous one in the Eastern Pyrenees, and is unconformable upon the Precambrian basement to the north (North-Pyrenean massifs) and to the west (Central Pyrenees). It is characterized by arkosic lithic sandstones with clear quartz grains: they originated in the erosion of a granitic basement and/or acidic volcanic rocks. Coarseness of the sandstones and thickness (up to 2–4 km) of the unit increase from south-east to north and west. A carbonate upper level, well developped in the Central Pyrenees, can be correlated with Lower Cambrian limestones from the surrounding areas.The mudstone-siltstone unit (Fig. 5) is defined by the prevalence of mm- to cm- scale alternations of argillaceous mud and silt of a flyschoid type, representing a more basinal sedimentation. A carbonate level, the highest in the series, is intercalated in Ihe lower part ot the unit: above this level, deposits are very homogeneous and thiek (about 2 km). A poorly known formation with pelitcs and sandstones caps the muddy-silty unit: it could be Lower Ordovician in age.Thus, the Pyrenean domain shows the same depositional history as West-Mediterranean area: (i) first, a volcano-sedimentary platform or basin occurs, as in Central Spain. Eastern Pyrenees. Sardinia and axial zone of the Montagne Noire, but not further north; (ii) second, a silicoclastic platform spreads out. which becomes carbonated at the end: (iii) third. Ihe basin deepens and receives fine silicoclaslies. This evolution is not fully accounted for in recent synthesis of Pre-hercynian France or Spain, and it should appear useful for a better understanding of the south French Massif Central geological history. 相似文献
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Aida Ben Hassen Jean Trichet Jean-Robert Disnar Habib Belayouni 《Swiss Journal of Geoscience》2010,103(3):457-473
Paléocène-Early Eocene phosphate outcrop in the Ras-Draâ deposit (Tunisia) comprises alternances of P-rich strata (P2O5 ≥ 18%) and P-poor ones (P2O5 ≤ 2%). In phosphate rich strata, P is concentrated in rounded grains—so-called pellets—(28% ≤ P2O5 ≤ 38%) embedded in a matrix—so-called exogangue—much poorer in P (P2O5 # 7%) than pellets. The study of pellets (whose size lies mainly between 100 and 500 μm), of their surrounding matrix and of poorly phosphatic sediments, interlayered between the phosphatic strata, has been performed by optical microscopy and various chemical analyses, ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectroscopy) and punctual chemical analyses by EDS (Energy Dispersive Spectroscopy). Mineralogical and chemical studies of the Tunisian phosphatic pellets show that the basic mineralogical component of these grains is carbonate-fluor-apatite, or francolite. The structural formula of a representative specimen of francolite in the basin is as follows: (Ca4.63Mg0.13Na0.22)(PO4)2.51(CO3)0.48(OH0.77F0.23). The mineralogy of the constituents of the sediment surrounding pellets comprises carbonates, clays, silica (opal, quartz). Microscopic observations of Ras-Draâ phosphorites, added to geochemical results, establish that pellets are small bodies, allochtonous to their matrix and whose composition is independent of that of this matrix. Fecal cylindrical bodies and subspherical pellets, the latest being supposed to proceed from the fecal bodies by fragmentation, are considered to have been formed by fishes, as P-rich and organic matter-rich faeces. These faeces turn out to be resistant to mechanical dispersion and to chemical diffusion of soluble elements from and in direction of sea water. This closeness is responsible for the strong reducing conditions having prevailed inside and during the pellets diagenesis. 相似文献