Transgressive overlap of a turbiditic sequence—priabonian of Ovče Pole,Macedonia     

Milorad D. Dimitrijević  Mara N. Dimitrijević 《Sedimentary Geology》1976,16(3):223-234

Flysch sequences develop normally from pelagic sediments, over a pre-flysch transitional unit, or from a well-developed transgressive base. A different situation has been observed in the western portion of the Upper Eocene flysch basin of Ov?e Pole, Macedonia, where deep-water turbidites appear almost directly over the eroded basement, transgressively overlapping the preexisting submarine relief. These relationships are explained as results of successive phases of subsidence in the basin. The outcrop area, situated between Titov Veles and Gradsko, represented a surface without deposition in the early depositional stages. Later subsidence introduced a turbiditic deposition into the domain without a break in sedimentation. Such cases may occur also in other flysch basins where lateral migration of the main depositional trough took place during the sedimentation.  相似文献   

Evaluating the transferability of monthly water balance models under changing climate conditions     

Ž. Topalović  A. Todorović  J. Plavšić 《水文科学杂志》2020,65(6):928-950

ABSTRACT

Monthly water balance models (MWBMs) are often used for making flow projections under climate change. As such, these models should provide accurate flow simulations; however, they are seldom evaluated in this regard. This paper presents a comprehensive framework intended for the evaluation of the applicability of MWBMs under changing climatic conditions. The framework consists of analyses of consistency in model performance, parameter estimates and simulated water balance components, and a subjective assessment of model transferability. Four MWBMs – abcd, Budyko, GR2M and WASMOD – are used to simulate runoff in the Wimmera catchment affected by the Millennium drought. Although abcd and Budyko slightly outperformed GR2M and WASMOD, none of the models performed well in transfer to the driest period. The greatest variability is detected in simulated groundwater storage and baseflow; thus, these model components should be improved and/or enhanced calibration strategies should be employed to advance the transferability of MWBMs under changing climate.  相似文献   

Hydrogeology Of Slanac Spring,Croatia     

O. Bonacci  F. Fritz  V. Denić < 《Hydrogeology Journal》1995,3(3):31-40

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Heavy metals in sediments—problems concerning determination of the anthropogenic influence. Study in the Krka River estuary,eastern Adriatic coast,Yugoslavia     

Esad Prohić  Mladen Juračić 《Environmental Geology》1989,13(2):145-151

Factors that govern heavy metal concentration in sediments were examined by a combined analytical, geochemical, and geological approach. The constrains encountered in the determination of the anthropogenic influence are exposed. The region examined was the Krka River estuary located in the typical karst region of the eastern Adriatic, Yugoslavia.Sedimentological research revealed that: the Krka River (main water supplier) is almost free of suspended terrigenous material; the main supplier of suspended terrigenous matter of flysch origin is a small torrent-type Gudua Creek, and that this fine grained terrigenous material is sedimented mostly in the central enlarged part of the estuary, the Prokljan Lake.Three different groups of heavy metals were identified in recent sediments. Increased concentrations of nickel and zinc were found in estuarine sediments due to strongnatural enrichment in source rocks. Manganese and chromium were found to benaturally enriched and depleted in surface layer respectively, due to the different postdepositional geochemical behavior. Lead and copper concentrations were found to be increased in surface sediments in the central part of the estuary, apparently from anthropogenic source.  相似文献   

Depositional mechanics of turbulent nuées ardentes (surges) from their grain sizes     

François P Brissette  Jean Lajoie 《Bulletin of Volcanology》1990,53(1):60-66

The ability of turbulent nuées ardentes (surges) to transport coarse pyroclasts has been questioned on the basis that settling velocities of coarse fragments in the deposits are much too high for them to have been supported by turbulence in a dilute gas suspension. A computer model is used to evaluate the settling velocity of pyroclasts in suspensions of varying concentration and temperature. Since suspension of grains in low-concentration surges occurs if the shear velocity exceeds the settling velocity, the shear velocities related to the 16th and 84th percentiles, and the mean of the grain-size distribution are compared in surge deposits of the Vulsini, with the shear velocity necessary to move the coarsest grain on the bed surface (the Shields criterion). The results show that the settling velocities do not vary significantly in gaseous suspensions having volume concentrations lower than 15%, and that an increase in concentration to 25% is not sufficient to decrease the settling velocity of the coarser fraction, if it represents flow shear velocity. It is shown that the settling velocity of the mean grain size (M _z ) best depicts the shear velocity of a dilute turbulent suspension. Applying the results to the May 1902 paroxysmal nuées ardentes of Mount Pelée shows that the estimated mean velocities are well within the observed velocities, and sufficient to support all the clasts in dilute, turbulent suspensions.  相似文献   

Comment on “segmentation and disruption of the East Pacific Rise in the mouth of the Gulf of California” by Peter Lonsdale (Marine Geophysical Researches 17, pp. 323–359, 1995)     

François Michaud  Jean-Yves Royer  Jacques Bourgois  Bernard Mercier De Lepinay 《Marine Geophysical Researches》1996,18(5):597-599

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Age determination and growth of Atlantic redfish (Sebastes marinus and S. mentella): bias and precision of age readers and otolith preparation methods     

Stransky  Christoph; Gudmundsdottir  Sif; Sigurdsson  Thorsteinn; Lemvig  Svend; Nedreaas  Kjell; Saborido-Rey  Fran 《ICES Journal of Marine Science》2005,62(4):655-670

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Probabilistic yielding and cyclic behavior of geomaterials     

Kallol Sett  Boris Jeremić 《国际地质力学数值与分析法杂志》2010,34(15):1541-1559

In this paper, the novel concept of probabilistic yielding is used for 1‐D cyclic simulation of the constitutive behavior of geomaterials. Fokker–Planck–Kolmogorov equation‐based probabilistic elastic–plastic constitutive framework is applied for obtaining the complete probabilistic (probability density function) material response. Both perfectly plastic and hardening‐type material models are considered. It is shown that when uncertainties in material parameters are taken into consideration, even the simple, elastic‐perfectly plastic model captures some of the important features of geomaterial behavior, for example, modulus reduction with cyclic strain, which, deterministically, is only possible with more advanced constitutive models. Furthermore, it is also shown that the use of isotropic and kinematic hardening rules does not significantly improve the probabilistic material response. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Correcting wind‐induced bias in solid precipitation measurements in case of limited and uncertain data     

Vincent Fortin  Charles Therrien  François Anctil 《水文研究》2008,22(17):3393-3402

Automatic precipitation gauges tend to underestimate solid precipitation in the presence of wind. Loss as a function of wind speed is typically evaluated by comparing the gauge with a more accurate measurement made using a double‐fence intercomparison reference gauge (DFIR). For small precipitation events, small errors in the observations can induce large errors in the ‘catch’ ratio, i.e. the ratio of the automatic gauge measurement to the DFIR observation. For this reason, precipitation events of less than 3 mm are typically discarded before performing the regression analysis. This can mean discarding more than 90% of the observations. This paper shows how the method of weighted least squares can be used to perform a regression analysis that can take into account the whole sample to provide a more accurate estimation of the relationship between the catch ratio and the wind speed. This methodology is then used to obtain an adjustment curve for a shielded Geonor T‐200B precipitation gauge in Northern Québec. Copyright © 2008 John Wiley & Sons, Ltd and Her Majesty the Queen in right of Canada.  相似文献   

A relative water-depth model for the Normandy Chalk (Cenomanian–Middle Coniacian,Paris Basin,France) based on facies patterns of metre-scale cycles     

Eric Lasseur  François Guillocheau  Cécile Robin  Franck Hanot  Denis Vaslet  Renaud Coueffe  Didier Neraudeau 《Sedimentary Geology》2009,213(1-2):1-26

A relative water-depth model for the Chalk of the Paris Basin is proposed, based on the lateral variations of the high-frequency metre-scale cycles, which are characteristic features easily identified in the field. The studied outcrops are the Cenomanian–Middle Coniacian cliffs of Normandy. The main result of this study is to highlight the importance of storm activity in the deposition of the Chalk. The relative water-depth model is based on storm-induced shell concentrations observed within the two components of the metre-thick cycles: the depositional interval itself and the top hiatal surface.Six types of shell concentrations are defined, along with seven types of depositional facies making up the depositional units, as well as eight types of hiatal surface. Three cycle associations, differing in their thickness and the amount and type of non-carbonate constituents, can be identified in the Lower to Upper Cenomanian, the Upper Cenomanian to Lower Turonian and the Middle Turonian to Middle Coniacian.A relative water-depth profile model for all these cycles is based on the shell concentrations and a “water-depth equivalence” is proposed between the three cycle associations (lateral “facies” substitution diagram). This model is tested using palaeocological data (irregular echinoids) and by correlating field sections in terms of stacking patterns. Most of the studied deposits accumulated above the storm wave base (upper offshore zone or mid ramp).  相似文献