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11.
Fanny Cattani Barbara A. Cohen Cameron M. Mercer Agnes J. Dahl 《Meteoritics & planetary science》2023,58(4):591-611
Several laboratories have been investigating the feasibility of in situ K-Ar dating for use in future landing planetary missions. One drawback of these laboratory demonstrations is the insufficient analogy of the analyzed analog samples with expected future targets. We present the results obtained using the K-Ar laser experiment (KArLE) on two old and K-poor chondritic samples, Pułtusk and Hvittis, as better lunar analogs. The KArLE instrument uses laser ablation to vaporize rock samples and quantifies K content by laser-induced breakdown spectroscopy (LIBS), Ar by quadrupole mass spectrometry (QMS), and ablated mass by laser profilometry. We performed 64 laser ablations on the chondrites to measure spots with a range of K2O and Ar content and used the data to construct isochrons to determine the chondrite formation age. The KArLE isochron ages on Pułtusk and Hvittis are 5059 ± 892 Ma and 4721 ± 793 Ma, respectively, which is within the uncertainty of published reference ages, and interpreted as the age of their formation. The uncertainty (2σ) on the KArLE ages obtained in this study is better than 20% (18% for Pułtusk and 17% for Hvittis). The precision, which compares our obtained ages to the reference ages, is also better than 20% (11% for Pułtusk and 4% for Hvittis). These results are encouraging for understanding the limits of this technique to measure ancient planetary samples and for guiding future improvements to the instrument. 相似文献
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Fanny Chenillat Peter J. S. Franks Xavier Capet Pascal Rivière Nicolas Grima Bruno Blanke Vincent Combes 《Ocean Dynamics》2018,68(7):761-777
The California Current System (CCS) is an eastern boundary upwelling system characterized by strong eddies that are often generated at the coast. These eddies contribute to intense, long-distance cross-shelf transport of upwelled water with enhanced biological activity. However, the mechanisms of formation of such coastal eddies, and more importantly their capacity to trap and transport tracers, are poorly understood. Their unpredictability and strong dynamics leave us with an incomplete picture of the physical and biological processes at work, their effects on coastal export, lateral water exchange among eddies and their surrounding waters, and how long and how far these eddies remain coherent structures. Focusing our analysis on the southern part of the CCS, we find a predominance of cyclonic eddies, with a 25-km radius and a SSH amplitude of 6 cm. They are formed near shore and travel slightly northwest offshore for ~?190 days at ~?2 km day?1. We then study one particular, representative cyclonic eddy using a combined Lagrangian and Eulerian numerical approach to characterize its kinematics. Formed near shore, this eddy trapped a core made up of ~?67% California Current waters and ~?33% California Undercurrent waters. This core was surrounded by other waters while the eddy detached from the coast, leaving the oldest waters at the eddy’s core and the younger waters toward the edge. The eddy traveled several months as a coherent structure, with only limited lateral exchange within the eddy. 相似文献
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Maryline Moulin Daniel Aslanian Mikael Evain Anglique Leprêtre Philippe Schnurle Fanny Verrier Joseph Thompson Philippe De Clarens Sylvie Leroy Nuno Dias 《地学学报》2020,32(3):205-214
The Natal Valley, offshore Mozambique, is a key area for understanding the evolution of East Gondwana. Within the scope of the integrated multidisciplinary PAMELA project, we present new wide‐angle seismic data and interpretations, which considerably alter Geoscience paradigms. These data reveal the presence of a 30‐km‐thick crust that we argue to be of continental nature. This falsifies all the most recent palaeo‐reconstructions of the Gondwana. This 30‐km‐thick continental crust 1,000 m below sea level implies a complex history with probable intrusions of mantle‐derived melts in the lower crust, connected to several occurrences of magmatism, which seems to evidence the crucial role of the lower continental crust in passive margin genesis. 相似文献
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Fanny Houlbrèque Malcolm McCulloch Brendan Roark Anders Meibom Graham Mortimer Robert Dunbar 《Geochimica et cosmochimica acta》2010,74(8):2380-2395
The deep-sea coral, Enallopsammia rostrata, a member of the Dendrophylliidae family, is a major structure-forming species that creates massive dendroid colonies, up to 1 m wide and 0.5 m tall. Living colonies of E. rostrata have been collected using the PISCES submersibles from three locations from 480 to 788 m water depth in the Line Islands (∼160°W) in the Equatorial Pacific. We have applied to these colonies a high sensitivity, low blank technique to determine U-series ages in small quantities (70 ± 15 mg) of modern and near modern calcareous skeletons using MC-ICP-MS (Multi-collector Inductively Coupled Plasma Mass Spectrometer). The application of this method to living slow-growing colonies from a range of sites as well as the observations of axial growth patterns in thin sections of their skeletons offer the first expanded and well constrained data on longevity, growth pattern and mean growth rates in E. rostrata. Absolute dated specimens indicate life spans of colonies ranging from 209 ± 8 yrs to 605 ± 7 yrs with radial growth rates from 0.012 to 0.072 mm yr−1 and vertical extension rates from 0.6 to 1.9 mm yr−1. The linear growth rates reported here are lower than those reported for other deep-sea scleractinian corals (Lophelia pertusa and Madrepora oculata). The U-series dating indicates that the growth ring patterns of E. rostrata are not consistent with annual periodicity emphasizing the importance of absolute radiometric dating methods to constrain growth rates. Slow accretion and extreme longevity make this species and its habitat especially vulnerable to disturbances and impacts from human activities. This dating method combined with observation of growth patterns opens up new perspectives in the field of deep-sea corals since it can provide quantitative estimates of growth rates and longevity of deep-sea corals in general. 相似文献
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In the three-body problem, where two bodies are punctual and the third is rigid, we prove the existence of some relative equilibrium
configurations where the rigid body is either an homogeneous ball, an oblate or an elongated ball. In particular, we found
conditions of relative equilibrium of Euler and Lagrange type and several families of relative equilibrium configurations,
where the triangle of the two punctual bodies and the mass center of the rigid body is isosceles or having unequal sides.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Costa Alexandre C. Dupont Fanny Bier George van Oel Pieter Walker David W. Martins Eduardo S. P. R. 《Hydrogeology Journal》2023,31(3):751-769
Particularly in arid and semiarid areas, more and more populations rely almost entirely on imported water. However, the extent to which intentional discharge into transiting river systems and unintentional leakage may be augmenting water resources for communities along and down gradient of the water transfer scheme has not previously been subject to research. The objective of this study was to assess both the potential of a large-scale water transfer (WT) scheme to increase groundwater availability by channel transmission losses in a large dryland aquifer system (2,166 km²) in Brazil, and the capability of the receiving streams to transport water downstream under a prolonged drought. An integrated surface-water/groundwater model was developed to improve the estimation of the groundwater resources, considering the spatio-temporal variability of infiltrated rainfall for aquifer recharge. Aquifer recharge from the WT scheme was simulated under prolonged drought conditions, applying an uncertainty analysis of the most influential fluxes and parameters. The annual recharge (66 mm/year) was approximately twice the amount of water abstracted (1990–2016); however, the annual recharge dropped to 13.9 mm/year from 2012 to 2016, a drought period. Under similar drought conditions, the additional recharge (6.89 × 106 m³/year) from the WT scheme did not compensate for the decrease in groundwater head in areas that do not surround the receiving streams. Actually, the additional recharge is counteracted by a decrease of 25% of natural groundwater recharge or an increase of 50% in pumping rate; therefore, WT transmission losses alone would not solve the issue of the unsustainable management of groundwater resources.
相似文献19.
Fanny Lasry Isabelle Coll Sylvain Fayet Maxime Havre Robert Vautard 《Journal of Atmospheric Chemistry》2007,57(2):107-134
In Europe, in case of the observation or the forecast of a photochemical event, punctual and local reductions in anthropogenic
emissions can be triggered at the regional scale. Although the necessity for the establishment of such measures appears to
be justified by bad air quality records over large European cities, individual short-term action plans (STAPs) have been blindly
elaborated by regional authorities. Moreover, as they impose industrial and road traffic emission restrictions, these measures
have an elevated economical cost. It is consequently crucial to determine their efficiency and potential for ozone peak reduction.
The study presented in this paper aims to draw up an expertise on standard European STAPs, through the example of a French
Mediterranean city. The objective is to determine and investigate the impact of current STAPs on ozone peak formation and
to test ways to optimise their efficiency. In this frame, a set of emission scenarios has been elaborated and tested with
the chemistry-transport model CHIMERE on the Berre–Marseille area. Simulations have shown that the tested action plans are
not sufficient to eradicate severe ozone peaks and that more drastic restrictions on emissions are required to significantly
affect ozone plumes. However, results also showed that the potential for ozone reduction remains small, with a maximum impact
of only 5 ppbv for feasible STAPs. Finally, a temporal analysis of the ozone-emission relationship was engaged in order to
optimise their application. 相似文献