Mg/Ca-paleothermometry in the western Mediterranean Sea on planktonic foraminifer species Globigerina bulloides: Constraints and implications     

Soumaya Boussetta  Nejib Kallel  Franck Bassinot  Laurent Labeyrie  Jean-Claude Duplessy  Nicolas Caillon  Fabien Dewilde  Hélène Rebaubier 《Comptes Rendus Geoscience》2012,344(5):267-276

We generated a high-resolution SST_Mg/Ca record for the surface-dwelling planktonic foraminifera Globigerina bulloides from the core MD99-2346 collected in the Gulf of Lion, and compared it to that obtained using modern analogue techniques applied to fossil foraminiferal assemblages (SST_MAT). The two temperature records display similar patterns during the last 28,000 years but the SST_Mg/Ca estimates are several degrees warmer (∼ +4 °C) than SST_MAT. The temperature shift between SST_Mg/Ca and SST_MAT remained relatively constant over time. This seems to exclude a bias on the Mg/Ca record associated with salinity or secondary Mg-rich calcite encrustation on the foraminiferal tests during early diagenesis. Therefore, anomalously high Mg/Ca suggests either: (1) the empirical equation for G. bulloides of Elderfield and Ganssen (2000) is incorrect; or (2) there is a specific Mediterranean genotypes of G. bulloides for which a specific Mg/Ca-temperature calibration is needed.  相似文献   

Upper-Ocean Lateral Heat Transports in the Ni?o3.4 Region and Their Connection with ENSO     

He ZHAO  Tongwen WU  Laurent Z.X.LI  Fanghua WU  Weihua JIE  Xiangwen LIU  Ronghua ZHANG  Chengjun XIE 《Journal of Meteorological Research》2022,(2):360-373,中插28-中插35

In the Ni?o3.4 region (tropical Pacific, 5°S–5°N, 170°–120°W), sea surface temperature (SST) changes are highly correlated with temperature variations in the up...  相似文献   

Compressibility of Ca3Al2Si3O12 perovskite up to 55 GPa     

Steeve Gréaux  Denis Andrault  Laurent Gautron  Nathalie Bolfan-Casanova  Mohamed Mezouar 《Physics and Chemistry of Minerals》2014,41(6):419-429

Compressibility of perovskite-structured Ca₃Al₂Si₃O₁₂ grossular (GrPv) was investigated at high pressure and high temperature by means of angle-dispersive powder X-ray diffraction using a laser-heated diamond anvil cell. We observed the Pbnm orthorhombic distortion for the pure phase above 50 GPa, whereas below this pressure, Al-bearing CaSiO₃ perovskite coexists with an excess of corundum. GrPv has a bulk modulus (K ₀ = 229 ± 5 GPa; \(K_{0}^{{\prime }}\) fixed to 4) almost similar to that reported for pure CaSiO₃ perovskite. Its unit-cell volume extrapolated to ambient conditions (V ₀ = 187.1 ± 0.4 Å³) is found to be ~2.5 % larger than for the Al-free phase. We observe an increasing unit-cell anisotropy with increasing pressure, which could have implications for the shear properties of Ca-bearing perovskite in cold slabs subducted into the Earth’s mantle.  相似文献   

Effect of management measures on glass eel escapement     

Beaulaton  Laurent; Briand  Cedric 《ICES Journal of Marine Science》2007,64(7):1402-1413

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Role of Anthropogenic Climate Change in Autumn Drought Trend over China from 1961 to 2014     

Xuyu ZHANG  Jinhua YU  Laurent Z.X.LI  Wei LI 《Journal of Meteorological Research》2022,(2):251-260

Understanding the impact of anthropogenic climate change on drought is of great significance to the prevention of its adverse effects. Two drought indices, stan...  相似文献   

A space Fresnel Imager for ultra-violet astrophysics: example on accretion disks     

Truswin Raksasataya  Ana-Ines Gomez de Castro  Laurent Koechlin  Jean-Pierre Rivet 《Experimental Astronomy》2011,30(2-3):183-194

The Fresnel Diffractive Imager concept is proposed for space borne astronomical imaging at Ultra-Violet wavelengths, using diffractive focalization. The high angular resolution and high dynamic range provided by this new concept makes it an ideal tool to resolve circumstellar structures such as disks or jets around bright sources, among them, pre-main sequence stars and young planetary disks. The study presented in this paper addresses the following configuration of Fresnel diffractive imager: a diffractive array 4 m large, with 696 Fresnel zones operating in the ultra-violet domain. The diffractive arrays are opaque foils punched with a large number of void subapertures with carefully designed shapes and positions. In the proposed space missions, these punched foils would be deployed in space. Depending on the size of the array and on the working spectral band, the focal length of such imagers will range from a few kilometers to a few tens of kilometers. Thus, such space mission requires a formation flying configuration for two satellites around the L2 Sun-Earth Lagragian point. In this article, we investigate numerically the potential of Fresnel arrays for imaging circumstellar dust environments. These simulations are based upon simple protostellar disk models, and on the computed optical characteristics of the instrument. The results show that protoplanetary disks at distances up to a few thousand parsecs can be successfully studied with a 4 m aperture Fresnel imager in the UV.  相似文献