Modeling environmental effects on the size-structured energy flow through marine ecosystems. Part 1: The model   总被引：2，自引：3，他引：2  

Olivier Maury  Blaise Faugeras  Yunne-Jai Shin  Jean-Christophe Poggiale  Tamara Ben Ari  Francis Marsac 《Progress in Oceanography》2007,74(4):479-499

This paper presents an original size-structured mathematical model of the energy flow through marine ecosystems, based on established ecological and physiological processes and mass conservation principles. The model is based on a nonlocal partial differential equation which represents the transfer of energy in both time and body weight (size) in marine ecosystems. The processes taken into account include size-based opportunistic trophic interactions, competition for food, allocation of energy between growth and reproduction, somatic and maturity maintenance, predatory and starvation mortality. All the physiological rates are temperature-dependent. The physiological bases of the model are derived from the dynamic energy budget theory. The model outputs the dynamic size-spectrum of marine ecosystems in term of energy content per weight class as well as many other size-dependent diagnostic variables such as growth rate, egg production or predation mortality.In stable environmental conditions and using a reference set of parameters derived from empirical studies, the model converges toward a stationary linear log–log size-spectrum with a slope equal to −1.06, which is consistent with the values reported in empirical studies. In some cases, the distribution of the largest sizes departs from the stationary linear solution and is slightly curved downward. A sensitivity analysis to the parameters is conducted systematically. It shows that the stationary size-spectrum is not very sensitive to the parameters of the model. Numerical simulations of the effects of temperature and primary production variability on marine ecosystems size-spectra are provided in a companion paper [Maury, O., Shin, Y.-J., Faugeras, B., Ben Ari, T., Marsac, F., 2007. Modeling environmental effects on the size-structured energy flow through marine ecosystems. Part 2: simulations. Progress in Oceanography, doi:10.1016/j.pocean.2007.05.001].  相似文献   

Bimodal back-arc alkaline magmatism after ridge subduction: Pliocene felsic rocks from Central Patagonia (47°S)     

Felipe Espinoza  Diego Morata  Mireille Polv  Yves Lagabrielle  Ren C. Maury  Christle Guivel  Joseph Cotten  Herv Bellon  Manuel Surez 《Lithos》2008,101(3-4):191-217

Volumetrically minor microsyenites, alkali microgranite and related trachytic dykes intrude early Pliocene OIB-like alkali basaltic and basanitic flows of the Meseta del Lago Buenos Aires in Central Patagonia (47°S–71°30′W), and occur together with scarce trachytic lava flows. Whole-rock K–Ar ages between 3.98 and 3.08 Ma indicate that the emplacement of these felsic rocks occurred more or less synchronously with that of the post-plateau basaltic sequence that they intrude, during a bimodal mafic–felsic magmatic episode devoid of intermediate compositions. Chemically, these rocks have A₁-type granitoid affinities and are characterized by high silica and alkali contents (60–68 wt.% SiO₂; 8.7–10.8 wt.% Na₂O + K₂O), major and trace elements patterns evidencing evolution by low-pressure fractional crystallization, and Sr and Nd isotopic signatures similar to those of coeval basalts ((⁸⁷Sr/⁸⁶Sr)_o = 0.70488–0.70571; (¹⁴³Nd/¹⁴⁴Nd)_o = 0.512603–0.512645). Nevertheless, some of them have the most radiogenic Sr values ever reported for a magmatic rock in the Meseta and even in the whole Neogene Patagonian Plateau Lavas province ((⁸⁷Sr/⁸⁶Sr)_o = 0.70556–0.70571; (¹⁴³Nd/¹⁴⁴Nd)_o = 0.512603–0.512608). In addition, very high contents of strongly incompatible elements in the most evolved rocks, together with Sr isotopic ratios higher than those of coeval basalts, suggest the occurrence of open-system magmatic processes. Continuous fractional crystallization from a primitive basaltic source, similar to post-plateau coeval basalts, towards alkali granites combined with small rates of assimilation of host Jurassic tuffs (AFC) in a shallow magmatic reservoir, best explains the geochemical and petrographic features of the felsic rocks. Therefore, A₁-type magmatic rocks can be generated by open-system crystallization of deep asthenospheric melts in back-arc tectonic settings.

In Central Patagonia, these  3–4 Ma old alkaline intrusions occur aligned along a  N160–170 trending lineament, the Zeballos Fault Zone, stacking the morphotectonic front of one segment of the Patagonian Cordillera. Intrusion along this fault zone occurred during the onset of a new transtensional or extensional event in the area, related to major regional tectonics occurring in possible relation with the collision of one segment of the Chile Spreading Ridge with the trench.  相似文献   

Clinopyroxene composition as a method of identification of the magmatic affinities of paleo-volcanic series   总被引：3，自引：0，他引：3  

Jacques Leterrier  René C. Maury  Pierre Thonon  Danielle Girard  Michèle Marchal 《Earth and Planetary Science Letters》1982,59(1):139-154

Uranium contents and²³⁴U/²³⁸U activity ratios have been determined for groundwaters from the Lincolnshire Limestone artesian aquifer in eastern England. Changes in the quantitative and isotopic chemistry of the dissolved uranium are explained in terms of a mixing model involving the rapidly moving fissure water and much older water stored in the pore system of this oolitic limestone. The western part of the aquifer, closest to recharge, is dominated by oxidising groundwaters which then enter a reducing zone towards the east, where there is an abrupt decrease in Eh and the chlorinity of the groundwaters begins to increase. Uranium contents in the oxidising zone range from 0.7 to 3.4 μg kg^?1 and²³⁴U/²³⁸U activity ratio of this dissolved uranium is close to unity, the equilibrium value. The uranium content decreases abruptly when the grounwaaters enter the reducing zone, averaging 0.04 μg kg^?1 east of the oxidation/reduction barrier. Simultaneously with the decrease in uranium content, there is an increase in²³⁴U/²³⁸U activity ratio and this ratio increases to a maximum within 7 km of the oxidation/reduction barrier. This increase in activity ratio is attributed to enhanced²³⁴U solution due to²³⁴Th recoil from uraniferous fissure surfaces east of the oxidising zone. The activity ratio of dissolved uranium in the ancient pore waters could in principle reach high values due to²³⁴Th recoil from the oolith surfaces. However, the activity ratio actually declines further east and this can only be explained as a consequence of mixing with pore waters in which the uranium activity ratio is closer to equilibrium.²³⁴Th recoil from the oolith surfaces has probably been inhibited by sealing of the uranium-bearing surfaces in the process of oolith cementation.  相似文献   

Le magmatisme sursaturé infrabréchique du centre du Cantal (Massif Central français)     

N. Vatin-Perignon  R. C. Maury  J. P. Milesi 《Bulletin of Volcanology》1980,43(3):511-525

Silica oversaturated lavas and pyroclastic flows, 9 to 7,5 M.Y. old, have been emplaced during the sinking of the central volcanotectonic caldera of alkalic stratovolcano Cantal. They can be grouped in a non linear fractional crystallisation series ranging from mugearites to rhyolitic trachytes, comenditic trachytes and comendites through benmoreites. Their evolution results mainly from plagioclase fractionation, alkali feldspar and ferromagnesian minerals playing only a restricted role. We consider this oversaturated group, which follows primordial basanitic lavas in the history of the stratovolcano, as the most evolved liquids resulting from differentiation under high water pressures and oxygen fugacities of alkali basic magmas in a great magma chamber. The less evolved liquids (intermediate and basic) would have been emplaced later, building the greatest part of the volcanic pile.  相似文献   

Joint application of satellite remote sensing,ground penetrating radar (GPR) and resistivity techniques for targeting ground water in fractured Ophiolites of South Andaman Island,India     

Shrikant Maury  R. K. Tiwari  S. Balaji 《Environmental Earth Sciences》2016,75(3):237

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Major ion chemistry and quality assessment of the groundwater resources of Nanded tehsil,a part of southeast Deccan Volcanic Province,Maharashtra, India     

Vasant Madhav Wagh  Dipak Baburao Panaskar  Abhay Mukund Varade  Shrikant Vitthal Mukate  Satyajit Kundlik Gaikwad  Ranjitsinh Subhash Pawar  Aniket Avinash Muley  Manesh Laxman Aamalawar 《Environmental Earth Sciences》2016,75(21):1418

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Stratification and synthesis of crop-livestock production system using GIS     

Shrikant Jagtap  Abigail Amissah-Arthur 《GeoJournal》1999,47(4):573-582

Population increases, land-use changes and marketing opportunities are important factors affecting crop-livestock integration particularly with respect to their effect on soil fertility and feed supply for ruminant livestock. As the human population density rises, crop farmers and grazers are finding it profitable to establish contracts for paddocking, and they are reaching agreement on equitable ways to make use of crop residues and take care of livestocks. As the processes of intensification proceed, mixed crop-livestock systems are evolving as the viable and dominant farming system, allowing smallholder farmers to capitalize on the complementarity between crops and livestock. Strategies directed to raise the productivity of specific crop-livestock systems need to consider the stage of development of the target area in relation to intensification and the nature of crop-livestock interactions. Information related to crop and livestock systems in West Africa is currently available from various sources e.g., household surveys, aerial surveys, rural appraisal, experimental etc., and held by different agencies. The approach used in this study shows how such data (biophysical and socioeconomic) can be integrated within a GIS environment and synthesized to identify the evolution of systems across environments and also to identify constraints and potential of the systems. Potential for integrated crop-livestock systems remains untapped and/or knowledge of its existence is unknown for large parts of Nigeria. Using data from 36 case studies and georeferenced data on cropping intensities and livestock population for the entire country, it was possible to predict emerging crop-livestock systems using GIS. Indeed, depending on availability of data, it is now possible to extend a similar approach in other African countries. The potential contribution of this technology is largely unknown in West and Central Africa, where few operational programs use them. Major technological innovations and appropriate government policies have potential to shift the balance in regional developments, if targeted carefully at areas where the right conditions exist. Further research could then target specific areas thus ensuring efficient allocation of resources while policy makers can achieve development goals by directing policies and resources to domains that have the greatest potential. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

A low δLi lower crustal component: Evidence from an alkalic intraplate volcanic series (Chaîne des Puys, French Massif Central)     

Cdric Hamelin  Hans-Michael Seitz  Jean-Alix Barrat  Laure Dosso  Ren C. Maury  Marc Chaussidon 《Chemical Geology》2009,266(3-4):205-217

The intraplate volcanic suite of the Chaîne des Puys (French Massif Central) shows a complete petrologic range, from alkali basalts to trachytes. The significant variations of trace elements and radiogenic isotopes along the series strongly support the occurrence of crustal assimilation associated with fractional crystallization (AFC). The least contaminated basalts are clearly related to a HIMU-type reservoir (²⁰⁶Pb/²⁰⁴Pb > 19.6; ⁸⁷Sr/⁸⁶Sr < 0.7037; ε_Nd > + 4). The behavior of radiogenic isotopes suggests that the most likely crustal contaminants are meta-sediments located in the lower crust.The Li isotopic compositions of the lavas range from high δ⁷Li (> + 7‰) in basalts to lighter values in more evolved lavas (down to δ⁷Li ≈ 0‰). The mantle component, expressed in the least evolved lavas, has a heavy Li isotopic signature, in good agreement with previous δ⁷Li measurements of OIB lavas with HIMU affinities. The evolution of Li isotopic compositions throughout the volcanic series is in agreement with the AFC model suggested by the Sr–Nd–Pb isotopic systems. Although the behavior of Li isotopes during assimilation processes is currently poorly constrained, our calculations suggest that at least a portion of the lower crust beneath the Chaîne des Puys is characterized by a light Li isotopic composition (δ⁷Li < − 5‰).  相似文献   

Samuel Mandel: International Teacher of Hydrogeology     

Shrikant D. Limaye 《Hydrogeology Journal》1997,5(3):124-124

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Atypical hotspot chains: evidence for a secondary melting zone below the Marquesas (French Polynesia)     

Christelle Legendre  Ren C. Maury  Sylvain Blais  Herv Guillou  Joseph Cotten 《地学学报》2006,18(3):210-216

The atypical age/distance to the hotspot relationships observed for the Marquesas linear chain, which present a considerable scatter, are best explained considering (1) a Pacific plate motion of 10.5 cm yr^?1 in the N115°E direction and (2) rejuvenation of volcanism in Ua Huka island. New K–Ar ages show that the main hotspot activity in Ua Huka emplaced successively shield olivine tholeiites and post‐shield alkali basalts between 3.11 ± 0.04 and 2.43 ± 0.04 Ma. Then, after a quiescence period of 1.28 ± 0.06 Myr, two small basanitic volcanoes were emplaced between 1.15 ± 0.02 and 0.763 ± 0.013 Ma. With respect to the main hotspot volcanics, their lavas originated from weaker partial melting rates of a deeper source. Field, petrologic and geochemical arguments are consistent with the existence of a secondary melting zone located c. 140 km downstream the Marquesas hotspot, which produced the rejuvenated volcanics.  相似文献