ESR,U-series and paleomagnetic dating of Gigantopithecus fauna from Chuifeng Cave,Guangxi, southern China     

Qingfeng Shao  Wei Wang  Chenglong Deng  Pierre Voinchet  Min Lin  Antoine Zazzo  Eric Douville  Jean-Michel Dolo  Christophe Falguères  Jean-Jacques Bahain 《Quaternary Research》2014

Several Gigantopithecus faunas associated with taxonomically undetermined hominoid fossils and/or stone artifacts are known from southern China. These faunas are particularly important for the study of the evolution of humans and other mammals in Asia. However, the geochronology of the Gigantopithecus faunas remains uncertain. In order to solve this problem, a program of geochronological studies of Gigantopithecus faunas in Guangxi Province was recently initiated. Chuifeng Cave is the first studied site, which yielded 92 Gigantopithecus blacki teeth associated with numerous other mammalian fossils. We carried out combined ESR/U-series dating of fossil teeth and sediment paleomagnetic studies. Our ESR results suggest that the lower layers at this cave can be dated to 1.92 ± 0.14 Ma and the upper layers can be dated to older than 1.38 ± 0.17 Ma. Correlation of the recognized magnetozones to the geomagnetic polarity timescale was achieved by combining magnetostratigraphic, biostratigraphic and ESR data. The combined chronologies establish an Olduvai subchron (1.945–1.778 Ma) for the lowermost Chuifeng Cave sediments. We also analyzed the enamel δ¹³C values of the Gigantopithecus faunas. Our results show that southern China was dominated by C₃ plants during the early Pleistocene and that the Gigantopithecus faunas lived in a woodland-forest ecosystem.  相似文献   

Pollen‐based biome reconstructions for Colombia at 3000, 6000, 9000, 12 000, 15 000 and 18 000 14C yr ago: Late Quaternary tropical vegetation dynamics     

Robert Marchant  Hermann Behling  Juan‐Carlos Berrio  Antoine Cleef  Joost Duivenvoorden  Henry Hooghiemstra  Peter Kuhry  Bert Melief  Elisabeth Schreve‐Brinkman  Bas Van Geel  Thomas Van der Hammen  Guido Van Reenen  Michael Wille 《第四纪科学杂志》2002,17(2):113-129

Colombian biomes are reconstructed at 45 sites from the modern period extending to the Last Glacial Maximum (LGM). The basis for our reconstruction is pollen data assigned to plant functional types and biomes at six 3000‐yr intervals. A reconstruction of modern biomes is used to check the treatment of the modern pollen data set against a map of potential vegetation. This allows the biomes reconstructed at past periods to be assessed relative to the modern situation. This process also provides a check on the a priori assignment of pollen taxa to plant functional types and biomes. For the majority of the sites, the pollen data accurately reflect the potential vegetation, even though much of the original vegetation has been transformed by agricultural practices. At 18 000 ¹⁴C yr BP, a generally cool and dry environment is reflected in biome, assignments of cold mixed forests, cool evergreen forests and cool grassland–shrub; the latter extending to lower altitudes than presently recorded. This signal is strongly recorded at 15 000 and 12 000 ¹⁴C yr BP, the vegetation at these times also reflecting a relatively cool and dry environment. At 9000 ¹⁴C yr BP there is a shift to biomes thought to result from slightly cooler environmental conditions. This trend is reversed by 6000 ¹⁴C yr BP; most sites, within a range of different environmental settings, recording a shift to more xeric biome types. There is an expansion of steppe and cool mixed‐forest biomes, replacing tropical dry forest and cool grassland–shrub biomes, respectively. These changes in biome assignments from the modern situation can be interpreted as a biotic response to mid‐Holocene climatic aridity. At 3000 ¹⁴C yr BP the shift is mainly to biomes characteristic of slightly more mesic environmental conditions. There are a number of sites that do not change biome assignment relative to the modern reconstruction, although the affinities that these sites have to a specific biome do change. These ‘anomalies’ are interpreted on a site‐by‐site basis. Spatially constant, but differential response of the vegetation to climatic shifts are related to changes in moisture sources and the importance of edaphic controls on the vegetation. The Late Quaternary reconstruction of large‐scale vegetation dynamics in Colombia allows an understanding of the environmental controls on these to be developed. In particular, shifts in the character of the main climatic systems that influence Colombian vegetation are described. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

IR band intensities of DC₃N and HC₃N: Implication for observations of Titan's atmosphere     

Yves Bénilan  Antoine Jolly  Jean-Claude Guillemin 《Planetary and Space Science》2006,54(6):635-640

We have obtained the infrared spectra and the corresponding absolute band intensities for two HC₃N isotopomers: DC₃N and HC₃¹⁵N. Our results for DC₃N are in good agreement with previous measurements except for the ν₂ and ν₃ stretching modes. For HC₃¹⁵N, this study is the first including intensity measurements.We have also studied the possible detection of these isotopomers in Titan's atmosphere using the CIRS spectrograph onboard the Cassini spacecraft. Our simulation of the expected spectra shows that for a signal-to-noise ratio better than 100, the ¹⁵N isotopomer of HC₃N could be detected. But, further study of HC₃N hot bands are needed since some of them overlap the HC₃¹⁵N Q-branch.  相似文献   

Status of the eLISA on table (LOT) electro-optical simulator for space based,long arms interferometers     

Pierre Grüning  Hubert Halloin  Pierre Prat  Sylvain Baron  Julien Brossard  Christelle Buy  Antoine Petiteau  Gerhard Heinzel  Iouri Bykov 《Experimental Astronomy》2015,39(2):281-302

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Can the optical very large array be coupled with the JNLT?     

Isabelle Bosc  Denis Mourad  Antoine Labeyrie 《Astrophysics and Space Science》1989,160(1-2):355-360

Coupling the JNLT with the Keck telescope is of considerable interest. Further enhancement may be possible with auxiliary small telescopes, as planned for ESO's VLT. Current plans for installing the optical very large array at Mauna Kea provide opportunities for extra OVLA telescopes near the JNLT.A coudé field slicer is proposed for interferometric observing of a reference star together with the main object. Additions to the JNLT coudé spectrograph are also suggested for use as a speckle camera with multiple spectral channels.Paper presented at the Symposium on the JNLT and Related Engineering Developments, Tokyo, November 29–December 2, 1988.  相似文献   

Conditioning Surface-Based Geological Models to Well and Thickness Data   总被引：2，自引：1，他引：1  

Antoine Bertoncello  Tao Sun  Hongmei Li  Gregoire Mariethoz  Jef Caers 《Mathematical Geosciences》2013,45(7):873-893

Geostatistical simulation methods aim to represent spatial uncertainty through realizations that reflect a certain geological concept by means of a spatial continuity model. Most common spatial continuity models are either variogram, training image, or Boolean based. In this paper, a more recent spatial model of geological continuity is developed, termed the event, or surface-based model, which is specifically applicable to modeling cases with complex stratigraphy, such as in sedimentary systems. These methods rely on a rule-based stacking of events, which are mathematically represented by two-dimensional thickness variations over the domain, where positive thickness is associated with deposition and negative thickness with erosion. Although it has been demonstrated that the surface-based models accurately represent the geological variation present in complex layered systems, they are more difficult to constrain to hard and soft data as is typically required of practical geostatistical techniques. In this paper, we develop a practical methodology for constraining such models to hard data from wells and thickness data interpreted from geophysics, such as seismic data. Our iterative methodology relies on a decomposition of the parameter optimization problem into smaller, manageable problems that are solved sequentially. We demonstrate this method on a real case study of a turbidite sedimentary basin.  相似文献   

Specialization for amphibiosis in Brachyodus onoideus (Artiodactyla, Hippopotamoidea) from the Early Miocene of France     

Maeva J. Orliac  Pierre-Olivier Antoine  Anne-Lise Charruault  Sophie Hervet  Frédéric Prodeo  Francis Duranthon 《Swiss Journal of Geoscience》2013,106(2):265-278

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A new patchwork simulation method with control of the local-mean histogram   总被引：3，自引：3，他引：0  

Corentin Faucher  Antoine Saucier  Denis Marcotte 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(1):253-273

We present a new stochastic simulation method that builds two-dimensional images by assembling together square image pieces called blocks. The blocks are taken from a reference image. Our method, called patchwork simulation method (PSM), enforces pattern continuity in the image. Moreover, PSM allows to control the image local-mean histogram. This histogram bin-frequencies can be set to user-defined target values that may differ from the reference image local-mean histogram. This flexibility enhances the PSM generality by enlarging the set of all possible simulations. The local-mean histogram control is achieved by adjusting suitably the transition probabilities that associate a new block to an existing neighborhood in the partly simulated image. For several types of synthetic images and one polymer blend image, we show that PSM reproduces faithfully the reference image visual appearance (i.e. patterns are correctly shaped) and that simulated images are statistically compatible with the target local-mean histogram. Moreover, we show that our method has the ability to produce simulations that respect conditional hard data as well as a target local-mean histogram.  相似文献   

Estimation de la température maximale d'enfouissement du Toarcien et du Callovo-Oxfordien au centre du bassin de Paris par les marqueurs organiques     

Cédric Ménétrier  Marcel Élie  Luis Martinez  Antoine Le Solleuz  Jean-Robert Disnar  Cécile Robin  François Guillocheau  Christophe Rigollet 《Comptes Rendus Geoscience》2005,337(15):1323-1330

The thermal history of the central part of the Paris basin is reconstructed using C₃₁ hopane $\mathrm{S}/\mathrm{R}$ isomerisation ratios and organic matter transformation ratios measured on Lower Toarcian and Callovo-Oxfordian samples. Maximum burial palaeotemperatures range between 90 and 115?°C for the Toarcian shales, and between 75 and 95?°C for the Callovo-Oxfordian samples, from the East to the centre of the basin, respectively. The amount of Late Cretaceous erosion was evaluated to be between ca. 400 to 600 m in the eastern part of the studied area and 100 to 300 m in the centre of the basin. To cite this article: C. Ménétrier et al., C. R. Geoscience 337 (2005).  相似文献   

Galileo civil signal modulations     

Emilie Rebeyrol  Olivier Julien  Christophe Macabiau  Lionel Ries  Antoine Delatour  Laurent Lestarquit 《GPS Solutions》2007,11(3):159-171

Spectrum limitations for navigation systems require that the various navigation signals broadcast by the Galileo system must be combined and must utilize bandwidth-efficient modulations. At the L1 band, one of the most important questions is how to combine all the Open Service signals and the Public Regulated Service signal at the payload level, while maintaining good performance at reception. The Interplex modulation, a particular phase-shifted-keyed/phase modulation (PSK/PM), was chosen to transmit these signals because it is a constant-envelope modulation, thereby allowing the use of saturated power amplifiers with limited signal distortion. The Interplex modulation was also taken as baseline at the E6 band to transmit the three channels and the services associated on the same carrier frequency. At the E5 band, the modulation must combine two different services on a same constant envelope composite signal, while keeping the simplicity of a BOC implementation. The constant envelope Alternate Binary Offset Carrier (ALTBOC) modulation was chosen as the solution to transmit the Galileo E5 band signal. The main objective of this paper is to study these Galileo modulations. After the introduction, the E5 band signals are described, followed by the Alternate BOC modulation which has been chosen to transmit them. The second part describes the general formulation of the Interplex modulation and its key parameters for an optimal multiplexing of the Galileo L1 band signals. Since the Galileo Open Service signals at the L1 band are still not yet completely specified, different test cases are considered and their impact on the resulting choice for the Interplex modulation parameters is exposed.  相似文献