First record of a non-pterodactyloid pterosaur (Reptilia: Archosauria) from Switzerland     

Jean-Paul Billon-Bruyat 《Eclogae Geologicae Helvetiae》2005,98(3):313-317

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元素活动态测量法在鄂尔多斯盆地砂岩型铀矿勘查中的应用     

叶庆森  杨尚海  杨建新 《地质通报》2005,(Z1)

常规化探方法勘查砂岩型铀矿难以奏效。应用深穿透地球化学方法系列中的元素活动态测量法在鄂尔多斯盆地砂岩型铀矿上的试验结果表明,几种U元素活动态在矿体上方都有异常出现,特别是其中的粘土吸附态U含量级别高、异常衬度大。因此,土壤粘土吸附态U测量法是本区化探找铀矿的有效方法;取样深度和取样粒级分别以60～90cm和-120目为宜;采用400m的取样点距基本不影响本区砂岩型铀矿的找矿效果。在盆地东北部应用土壤粘土吸附态U测量法预测了3个有利地段,并在其中1个地段的深部发现了较好的铀矿化。  相似文献   

Comparative research on integrated development of large river basins: a case study of the Yangtze and the Rhone     

LIU Hui  Jean-Paul Bravard  CAI Zongxia  Thierry Sanjuan 《地理学报》2006,16(3):378-382

Since 2001, the French and Chinese researchers have done a cooperative research on the comparison of integrated development of large river basins. The Yangtze River was chosen as a crux of this research and linked with other older river experiments like the Rhone, the Nile and the Mississippi. This research includes not only the environmental issues but also economic and social issues. One special issue journal has been published in French for our research results. Other two collective and comparative books in French and Chinese will be finished at the end of this year. In the future, the comparison should be widened to Italy (the Po), Egypt (the Nile development planning) and the United States (the Mississippi Basin) and we would like to enlarge our research group and want to link up different teams and research projects, in order to get a global understanding of large river regions phenomenon.  相似文献   

东天山觉罗塔格地区夹白山一带晚古生代构造格局及演化     

左国朝  梁广林  陈俊  郑勇  高俊宝  邢德超  李绍雄 《地质通报》2006,(Z1)

研究区早石炭世经历了中天山古陆北缘被动陆缘向活动陆缘沟弧盆体系演化的全过程。阿齐山-雅满苏岛弧带于维宪期发育在广宽陆棚海之上。岛弧为大型背形结构,雅满苏断裂带为火山喷发的主要通道,弧前盆地生成于弧沟间隙部位。晚石炭世早期,弧后区发生扩张作用而塌陷形成向形的边缘盆地。晚石炭世末,北侧康古尔洋区以弧弧对接方式关闭,弧区伴有深成花岗岩浆侵位。早二叠世早期进入松弛阶段,在弧间及弧后南缘产生上叠断陷盆地。晚二叠世右旋走滑变动席卷全区,最后大型造山带与地块之间发生块体右旋滑移错位,由此奠定了现今的盆山构造格局初貌。  相似文献   

DORIS time bias estimated using Jason-1, TOPEX/Poseidon and ENVISAT orbits     

Nikita P. Zelensky  Jean-Paul Berthias  Frank G. Lemoine 《Journal of Geodesy》2006,80(8-11):497-506

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The alkaline–peralkaline granitic post-collisional Tin Zebane dyke swarm (Pan-African Tuareg shield, Algeria): prevalent mantle signature and late agpaitic differentiation     

Zakia Hadj-Kaddour  Jean-Paul Li  geois  Daniel Demaiffe  Renaud Caby 《Lithos》1998,45(1-4):223-243

The Tin Zebane dyke swarm was emplaced at the end of the Pan-African orogeny along a mega-shear zone separating two contrasting terranes of the Tuareg shield. It is located along the western boundary of the Archaean In Ouzzal rigid terrane, but inside the adjacent Tassendjanet terrane, strongly remobilized at the end of the Precambrian. The Tin Zebane swarm was emplaced during post-collisional sinistral movements along the shear zone at 592.2±5.8 Ma (19WR Rb–Sr isochron). It is a dyke-on-dyke system consisting of dykes and stocks of gabbros and dykes of metaluminous and peralkaline granites. All rock types have Sr and Nd isotopic initial ratios (Sr_i=0.7028 and _Nd=+6.2) typical of a depleted mantle source, similar to the prevalent mantle (PREMA) at that period. No crustal contamination occurred in the genesis of the Tin Zebane swarm. Even the samples showing evidence of fluid interaction (essentially alkali mobility) have the same isotopic signature. The peralkaline granites have peculiar geochemical characteristics that mimic subduction-related granites: this geochemical signature is interpreted in terms of extensive differentiation effects due to late cumulates comprising aegirine, zircon, titanite, allanite and possibly fergusonite, separated from the liquid in the swarm itself due to magmatic flow turbulence. The Tin Zebane dyke swarm is thus of paramount importance for constraining the differentiation of mantle products to generate highly evolved alkaline granites without continental crust participation, in a post-collisional setting.  相似文献   

Channel metamorphosis, floodplain disturbance, and vegetation development: Ain River, France     

Richard A. Marston  Jacky Girel  Guy Pautou  Herve Piegay  Jean-Paul Bravard  Chris Arneson 《Geomorphology》1995,13(1-4)

The purpose of this paper is to describe and explain channel metamorphosis of the Ain River in east-central France and the effects of this metamorphosis on floodplain disturbance and vegetation development. The Ain River is a 195 km long stream originating in the Jura Mountains which flows into the Rhône River between Lyon, France, and Geneva, Switzerland. The lower 40 km of the Ain River, beyond the mountain front, are situated in a valley of outwash deposits where the floodplain is 0.2 to 1.2 km wide. A complex mosaic of floodplain landscape units has developed. Maps dating back to 1766 and six sets of aerial photographs dated between 1945 and 1991 were used to document changes in channel pattern. Aerial photos and field surveys were used to compile maps of landscape units based on dominant vegetation life-forms, species, and substrate. Six maps dated between 1945 and 1991 were digitized in ARC/INFO and an overlay was generated to determine the changes in landscape units as related to channel disturbance. Change from a braided to a single-thread meandering channel probably took place in the period 1930–1950. The process of river entrenchment has occurred throughout the Holocene but has accelerated in the present century due to shortening of the river course, construction of lateral embankments, and vegetation encroachment following reservoir construction and cessation of wood-cutting and grazing. The increase in horizontal channel stability coupled with channel entrenchment have decreased floodplain disturbance and lowered the water table by approximately one meter. Pioneer and disturbance-dependent landscape units have experienced a more terrestrial-like succession to an alluvial forest. Abandoned channels have also been replaced by alluvial forests. On poorly drained soils, shrub-swamp communities of willow and hydrophytic herbaceous plants have been replaced by mixed forests of ash, alder, black poplar, and oak. On well drained alluvial soils, ash and oak dominated hardwood forests have declined in favor of mesophytic stands of black poplar. All types of vegetation, but particularly dry grasslands-shrublands, have been cleared for mines, campgrounds, agriculture, and other types of development. Using several measures, landscape diversity decreased between 1945 and 1991.  相似文献   

A generalized combination equation derived from a multi-layer micrometeorological model     

Jean-Paul Lhomme 《Boundary-Layer Meteorology》1988,45(1-2):103-115

The discrete multi-layer model originally devised by Waggoner and Reifsnyder (1968) is used as a theoretical basis to describe the vegetation-atmosphere interaction. Mathematical development of the basic equations yields Ohm's law-type formulae for sensible and latent heat fluxes from which it is possible to derive a combination equation very close in form to Penman-Monteith's equation. A bulk aerodynamic resistance and a bulk stomatal resistance can be defined and expressed in terms of the elementary resistances of the multi-layer model. This new combination equation offers an alternative to the attempts undertaken by Shuttleworth (1976) to unify multi-layer and single-layer approaches.  相似文献   

Pito and Orongo fracture zones: the northern and southern boundaries of the Easter microplate (southeast Pacific)     

Rapanui Scientific Party  J. Francheteau  P. Patriat  J. Segoufin  R. Armijo  M. Doucoure  A. Yelles-Chaouche  J. Zukin  S. Calmant  D.F. Naar  R.C. Searle 《Earth and Planetary Science Letters》1988,89(3-4)

The Easter (Rapanui) microplate is a case example of a large dual spreading center system in a region where the fastest seafloor spreading on Earth is occurring today. Recent theoretical models of the tectonic evolution of dual spreading center systems have explored the effects of shear and rigid rotation on the boundaries and internal structure of microplates but the models must be critically constrained by improved relative motion and structural fabric data sets.During the January 1987 Rapanui expedition on the N/O “Jean Charcot” we conducted a Sea Beam/magnetics/ gravity survey of a portion of the microplate boundaries. The method that was used was to fully map selected portions of the boundaries in order to establish precise structural relationships. The northern terminus of the East Rift or eastern boundary of the microplate is expressed as a series of parallel NW-SE trending valleys including what appears to be, with 5890 m depth, the deepest active rift axis mapped in the Pacific today (Pito Rift).The northern end of the Pito Rift merges with an E-W to 083° narrow band of linear faults interpreted to be a transform fault between the Nazca and Easter (Rapanui) plates.The northern triple junction between the Easter (Rapanui), Nazca and Pacific plates is a RFF type with the two transform faults colinear along an approximately E-W direction.The southwestern boundary of the Easter (Rapanui) microplate is marked by a series of en-echelon offsets, outlined by depressions, which merge into an approximately E-W zone where shear must be predominant.The southern triple junction is a RRF junction with an overlapping ridge system.The structural data acquired during the survey provide strong constraints for kinematic models of the microplate. The structural data need to be combined with crustal age determinations in order to derive a model for the evolution of the microplate.  相似文献   

Regional gravity variations in Europe from superconducting gravimeters   总被引：1，自引：0，他引：1  

David Crossley  Jacques Hinderer  Jean-Paul Boy   《Journal of Geodynamics》2004,38(3-5):325

Recent satellite missions (CHAMP, GRACE) are now returning data on the time variation of the gravity field with harmonic coefficients computed every 4 weeks. The promise is to achieve a sub-microgal accuracy that will define continental mass variations involving large-scale hydrology. With this in mind, we examine the time varying gravity field over central Europe using a limited number of high quality ground-based superconducting gravimeter stations within the Global Geodynamics Project (GGP). Our purpose is to see whether there are coherent signals between the individual stations and to compare the regional component with that predicted from models of continental hydrology. The results are encouraging. We have found, using empirical orthogonal eigenfunctions of the gravity data that a clear annual signal is present that is consistent in phase (low amplitudes in summer) and amplitude (1–3 microgal) with that determined from a large-scale model of land water in connection with global climate modeling. More work is required to define how the gravity field is related to large-scale soil moisture and other mass variations, and we have yet to compare our results to the latest satellite-derived data.  相似文献