Analyse quantitative des faciès carbonatés et cycles T–R de haute fréquence dans le Barrémien du Prébalkan central (Bulgarie)     

Viara Minkovska  Bernard Peybernès  Pierre Cugny  Todor Nikolov 《Comptes Rendus Geoscience》2004,336(10):931-938

Within the Emerici zone–Barremense zone biostratigraphic interval, the Barremian deposits of Central Fore-Balkan (Lovech–Veliko Tarnovo shelf) consist of a succession of several formations where alternate terrigenous argillaceous/sandy-dominated facies (Kormjansko Fm., Balgarene Fm.) and carbonate-dominated (‘Urgonian’) facies (Krushevo Fm., Emen Fm.). The qualitative and, particularly, quantitative facies analysis of the carbonate successions observed along 13 detailed cross-sections and in one drill hole show the stacking of about 40 fifth-order T–R cycles induced by numerous eustatic jerks contributing to the progressive settlement of this shelf. These high-frequency cycles of about 100 000 years must be regarded as valuable correlation tools for the subsurface hydrocarbon research. To cite this article: V. Minkovska et al., C. R. Geoscience 336 (2004).  相似文献   

Apport de la gravimétrie à l'étude de la structure du bassin des Triffa (Maroc nord-oriental) : implications hydrogéologiques     

Driss Khattach  Pierre Keating  El Mostafa Mili  Touria Chennouf  Pierre Andrieux  Abdellah Milhi 《Comptes Rendus Geoscience》2004,336(16):1427-1432

Various techniques (horizontal and vertical derivatives, upward continuation, Euler deconvolution) have been applied to the gravity data from the Triffa's plain and the north flank of the Beni-Snassen massif to delineate various major geological structures such as faults and basins. These results allow the production of a structural map showing the fault systems for the survey area. This map forms the basis for planning future hydrogeological research in this region. To cite this article: D. Khattach et al., C. R. Geoscience 336 (2004).  相似文献   

Sur trois principes généraux de la Métallogénie et de la recherche minérale     

Pierre Routhier 《Mineralium Deposita》1969,4(2):213-218

Des publications récentes conduisent à insister sur trois démarches, ou trois principes fondamentaux sans lesquels la Métallogénie (comme la Pétrologie) et la recherche minérale ne peuvent progresser. 1. Sortons des «types» connus et posons en principe que tout élément chimique peut se concentrer à diverses étapes du cycle géologique et géochimique; recherchons donc ces concentrations et traquons les par tous les moyens minéralogiques et géochimiques à notre disposition. 2. Récusons la confusion des concepts chronologiques et des concepts spatiaux, et en particulier la superposition totalement erronée d'«épigénétique» et d'«étranger». 3. Tout est hérité d'un passé plus ou moins lointain; principe qui rejoint le premier et nous conduira, dans certains cas favorables, vers des concentrations antérieures.

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Recent publications lead to three steps without which metallogenic and thus petrologic investigations are impossible: 1. We should depart from known types in ore genesis and assume that any element can be enriched during various stages of the geological and geochemical cicle. These enrichments should thus be investigated with all possible methods of mineralogy and geochemistry. 2. We should reject the confusion of terms referring to time and space of ore genesis, especially the completely confused superposition of the terms epigenetic and introduced from the outside. 3. All deposits show signs of inheritance; this leads us back to point one which involves economic accumulations under certain favorable conditions.

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Neuere Veröffentlichungen zeigen die Notwendigkeit, drei Umstände anzuerkennen, ohne die eine petrologische Forschung nicht mehr möglich ist: 1. Wir müssen davon Abstand nehmen, von den bekannten Lagerstätten-Typen zu reden. Richtig ist vielmehr, daß jedes chemische Element in den verschiedenen Etappen des geologischen und geochemischen Geschehens angereichert werden kann; forschen wir also nach diesen Anreicherungen und verfolgen wir sie mit allen mineralogischen und geochemischen Mitteln, die uns zur Verfügung stehen. 2. Wir müssen die Verwirrung der chronologischen und räumlichen Vorstellungen vermeiden, vor allem die vollkommen falsche Überlagerung von epigenetisch und fremd. 3. Alles was wir beobachten, ist das Erbe einer mehr oder weniger fernen Vergangenheit. Nur wenn wir uns ständig über dieses Faktum klar sind, dann können wir unter günstigen Umständen zu frühen Anreicherungen hingeführt werden.

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Petrography and paleo-environment of continental carbonate deposits with particular reference to the upper cretaceous and lower eocene of languedoc (Southern France)     

Pierre Freytet 《Sedimentary Geology》1973,10(1):25-60

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Raman Spectroscopy of Nb,Ta-rich Cassiterite in Beauvoir and Montebras Granites,France     

Wang Rucheng  Wu Jinwei  Dubessy Jean  Monchoux Pierre 《中国地球化学学报》1993,12(4):353-360

Cassiterites from both the Beauvoir and Montebras geanited of France are typically rich in trace elements such as Nb and Ta, and contain quite a number of inclusions of columbite (dominantly manganocolumbite).Two thin sections of cassiterite crystals have been prepared for Raman microprobe analysis).The spectra obtained from different parts of the cassiterites show that the vibra-tion frequency of the A1g peak decreases with increasing Nb ,Ta,Fe and Mn atomic contents.It is worthy to note that a new peak (named the “An peak”) has been reported for the first time in the part with oriented columbite inclusions.The vibration frequency varies from 827 to 830 cm^-1.The presence of th enew peak may be attributed to structural changes of cassiterite due to the excess of Nb and Ta in the lattice and the exsolution of columbite inclusions in cassiterite.  相似文献   

Paper 2. agricultural impacts of and responses to climate change in the Missouri-Iowa-Nebraska-Kansas (MINK) region     

William E. Easterling III  Pierre R. Crosson  Norman J. Rosenberg  Mary S. McKenney  Laura A. Katz  Kathleen M. Lemon 《Climatic change》1993,24(1-2):23-61

The climate of the 1930s was used as an analog of the climate that might occur in Missouri, Iowa, Nebraska and Kansas (the MINK region) as a consequence of global warming. The analog climate was imposed on the agriculture of the region under technological and economic conditions prevailing in 1984/87 and again under a scenario of conditions that might prevail in 2030. The EPIC model of Williamset al. (1984), modified to allow consideration of the yield enhancing effects of CO₂ enrichment, was used to evaluate the impacts of the analog climate on the productivity and water use of some 50 representative farm enterprises. Before farm level adjustments and adaptations to the changed climate, and absent CO₂ enrichment (from 350 to 450 ppm), production of corn, sorghum and soybeans was depressed by the analog climate in about the same percent under both current and 2030 conditions. Production of dryland wheat was unaffected. Irrigated wheat production actually increased. Farm level adjustments using low-cost currently available technologies, combined with CO₂ enrichment, eliminated about 80% of the negative impact of the analog climate on 1984/87 baseline crop production. The same farm level adjustments, plus new technologies developed in response to the analog climate, when combined with CO₂ enrichment, converted the negative impact on 2030 crop production to a small increase. The analog climate would have little direct effect on animal production in MINK. The effect, if any, would be by way of the impact on production of feed-grains and soybeans. Since this impact would be small after on-farm adjustments and CO₂ enrichment, animal production in MINK would be little affected by the analog climate.  相似文献   

Introduction to the Special Section on the Aquatic Climate Change Adaptation Services Program     

Guoqi Han  Pierre Pepin 《大气与海洋》2019,57(1):1-2

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Detection of temporal changes in the spatial distribution of cancer rates using local Moran’s I and geostatistically simulated spatial neutral models   总被引：1，自引：0，他引：1  

Goovaerts P  Jacquez GM 《Journal of Geographical Systems》2005,7(1):137-159

This paper presents the first application of spatially correlated neutral models to the detection of changes in mortality rates across space and time using the local Morans I statistic. Sequential Gaussian simulation is used to generate realizations of the spatial distribution of mortality rates under increasingly stringent conditions: 1) reproduction of the sample histogram, 2) reproduction of the pattern of spatial autocorrelation modeled from the data, 3) incorporation of regional background obtained by geostatistical smoothing of observed mortality rates, and 4) incorporation of smooth regional background observed at a prior time interval. The simulated neutral models are then processed using two new spatio-temporal variants of the Morans I statistic, which allow one to identify significant changes in mortality rates above and beyond past spatial patterns. Last, the results are displayed using an original classification of clusters/outliers tailored to the space-time nature of the data. Using this new methodology the space-time distribution of cervix cancer mortality rates recorded over all US State Economic Areas (SEA) is explored for 9 time periods of 5 years each. Incorporation of spatial autocorrelation leads to fewer significant SEA units than obtained under the traditional assumption of spatial independence, confirming earlier claims that Type I errors may increase when tests using the assumption of independence are applied to spatially correlated data. Integration of regional background into the neutral models yields substantially different spatial clusters and outliers, highlighting local patterns which were blurred when local Morans I was applied under the null hypothesis of constant risk.This research was funded by grants R01 CA92669 and 1R43CA105819-01 from the National Cancer Institute and R43CA92807 under the Innovation in Biomedical Information Science and Technology Initiative at the National Institute of Health. The views stated in this publication are those of the authors and do not necessarily represent the official views of the NCI. The authors also thank three anonymous reviewers for their comments that helped improve the presentation of the methodology.  相似文献   

Giant submarine collapse of a carbonate platform at the Turonian–Coniacian transition: The Ayabacas Formation, southern Peru     

Pierre Callot  Thierry Sempere  Francis Odonne  Emmanuel Robert† 《Basin Research》2008,20(3):333-357

The Ayabacas Formation of southern Peru is an impressive unit formed by the giant submarine collapse of the mid‐Cretaceous carbonate platform of the western Peru back‐arc basin (WPBAB), near the Turonian–Coniacian transition (～90–89 Ma). It extends along the southwestern edge of the Cordillera Oriental and throughout the Altiplano and Cordillera Occidental over >80 000 km² in map view, and represents a volume of displaced sediments of >10 000 km³. The collapse occurred down the basin slope, i.e. toward the SW. Six zones are characterised on the basis of deformational facies, and a seventh corresponds to the northeastern ‘stable’ area (Zone 0). Zones 1–3 display increasing fragmentation from NE to SW, and are composed of limestone rafts and sheets embedded in a matrix of mainly red, partly calcareous and locally sandy, mudstones to siltstones. In contrast, in Zones 4 and 5 the unit consists only of displaced and stacked limestone masses forming a ‘sedimentary thrust and fold system’, with sizes increasing to the southwest. In Zone 6, the upper part of the limestone succession consists of rafts and sheets stacked over the regularly bedded lower part. The triggering of this extremely large mass wasting clearly ensued from slope creation, oversteepening and seismicity produced by extensional tectonic activity, as demonstrated by the observation of synsedimentary normal faults and related thickness variations. Other factors, such as pore pressure increases or lithification contrasts probably facilitated sliding. The key role of tectonics is strengthened by the specific relationships between the basin and collapse histories and two major fault systems that cross the study area. The Ayabacas collapse occurred at a turning point in the Central Andean evolution. Before the event, the back‐arc basin had been essentially marine and deepened to the west, with little volcanic activity taking place at the arc. After the event, the back‐arc was occupied by continental to near‐continental environments, and was bounded to the southwest by a massive volcanic arc shedding debris and tuffs into the basin.  相似文献   

Crustal structure beneath the Mount Cameroon region derived from recent gravity measurements     

Severin Nguiya  Marcelin Mouzong Pemi  Alain Pierre Tokam  Évariste Ngatchou Heutchi  Willy Lemotio 《Comptes Rendus Geoscience》2019,351(6):430-440

In this study, the recent update of the gravity database with new measurements has raised the opportunity of improving the knowledge of the crustal structure beneath the large volcanic system called Mount Cameroon, and its implication in the regional tectonics. The multi-scale wavelet analysis method was applied to highlight the geologic features of the area, and their depths were estimated using the logarithmic power spectrum method. The results reveal a complex crustal structure beneath Mount Cameroon with high variation in the lateral distribution of crustal densities. The upper and lower crusts are intruded by dense materials originating from the mantle with less lateral extension. The trends of Tiko and Ekona faults along the intrusion suggest tectonic activities as deep as 25 km. The difference in mantle composition or temperature between the East and the West of the studied area is clearly seen in detailed wavelet images and agrees with a mantle origin for the Cameroon Volcanic Line.  相似文献