Amazon River discharge estimated from TOPEX/Poseidon altimetry     

Elena A. Zakharova  Alexei V. Kouraev  Anny Cazenave  Frédérique Seyler 《Comptes Rendus Geoscience》2006,338(3):188-196

This paper presents an application of the TOPEX/Poseidon (T/P) satellite altimetry data to estimate river discharge at three sites along the Amazon River. We discuss the methodology to establish empirical relationships between satellite-derived water levels and daily estimations of river discharges based on rating curves and in situ level measurements at gauging stations. Three sites are chosen: Manacapuru (River Solimões), Jatuarana (nearby the confluence of the Solimões and Rio Negro rivers) and Óbidos (Amazon River). We then reconstruct the satellite-based river discharge over a 10-year time span (1992–2002). Comparison between satellite-derived and river discharge at the gauging stations shows that the T/P data can successfully be used for hydrological studies of large rivers, in providing in particular discharge estimates when in situ data are not available. To cite this article: E.A. Zakharova et al., C. R. Geoscience 338 (2006).  相似文献   

Constraints and deception in the isotopic record; the crustal evolution of the west Musgrave Province,central Australia     

Christopher L. Kirkland  R. Hugh Smithies  Ailsa J. Woodhouse  Heather M. Howard  Michael T.D. Wingate  Elena A. Belousova  John B. Cliff  Rosanna C. Murphy  Catherine V. Spaggiari 《Gondwana Research》2013,23(2):759-781

The Hf and Nd isotopic evolution of the Musgrave Province, central Australia, is used to constrain the timing of crust formation and lithospheric organisation of Proterozoic Australia. The dataset from this region challenges two widely held tenets of Hf and Nd isotope systematics, namely; that crust formation events can only be identified as periods when crystallisation ages correspond to model ages, and that linear Hf evolution arrays away from depleted mantle (along crustal Lu/Hf or Sm/Nd slopes) reflect reworking of the same source.Hf isotopes in Musgrave Province zircon crystals indicate two major crust formation events at c. 1900 Ma and at 1600–1550 Ma. Although no juvenile rocks or crystals are known from c. 1900 Ma, radiogenic addition into the crust at this time is required to account for consistent Nd and Hf evolution patterns, which show no indication of an initially heterogeneous source. Oxygen isotopes in zircon grains confirm that much of the c. 1900 Ma Hf isotopic signal is not compromised by mixtures. Furthermore, the correspondence between mantle extraction and the commencement of reworking of Archean material supports new crust generation at c. 1900 Ma and a coupling between lower and upper crustal processes. The c. 1900 Ma timing of juvenile addition is dissimilar to that in the Albany–Fraser and Arunta Orogens and may reflect continental arc development on the margin of a southern continent.The general Hf isotopic evolution trend of the Musgrave Province apparently reflects reworking from a dominant c. 1900 Ma source with some additional unradiogenic and radiogenic input through time. However, in the 1220–1050 Ma interval this apparent isotopic evolution contrasts with geological observations that indicate input of voluminous mantle-derived material. Intracontinental rifts and other regions with sustained very-high temperature crustal recycling processes generate magmatic provinces with extreme HFSE-enrichment. This can have a profound influence on isotopic evolution trends, suppressing typical juvenile addition patterns. Isotopic mixture modelling indicates that a significant volume of mantle derived material can be accommodated within HFSE enriched magmas without diverging isotopic signatures from apparent reworking trends. In the Musgrave Province, the crust had become so HFSE enriched during the prolonged Musgrave Orogeny (1220–1150 Ma) that it was insensitive to mantle input, which is estimated to have been as much as 85% during this event.  相似文献   

U‐Pb Detrital Zircon Analysis – Results of an Inter‐laboratory Comparison     

Jan Košler  Jiří Sláma  Elena Belousova  Fernando Corfu  George E. Gehrels  Axel Gerdes  Matthew S. A. Horstwood  Keith N. Sircombe  Paul J. Sylvester  Massimo Tiepolo  Martin J. Whitehouse  Jon D. Woodhead 《Geostandards and Geoanalytical Research》2013,37(3):243-259

Inter‐laboratory comparison of laser ablation ICP‐MS and SIMS U‐Pb dating of synthetic detrital zircon samples provides an insight into the state‐of‐the art of sedimentary provenance studies. Here, we report results obtained from ten laboratories that routinely perform this type of work. The achieved level of bias was mostly within ± 2% relative to the ID‐TIMS U‐Pb ages of zircons in the detrital sample, and the variation is likely to be attributed to variable Pb/U elemental fractionation due to zircon matrix differences between the samples and the reference materials used for standardisation. It has been determined that ~ 5% age difference between adjacent age peaks is currently at the limit of what can be routinely resolved by the in situ dating of detrital zircon samples. Precision of individual zircon age determination mostly reflects the data reduction and procedures of measurement uncertainty propagation, and it is largely independent of the instrumentation, analytical technique and reference samples used for standardisation. All laboratories showed a bias towards selection of larger zircon grains for analysis. The experiment confirms the previously published estimates of the minimum number of grains that have to be analysed in order to detect minor zircon age populations in detrital samples.  相似文献   

Retreat dynamics of the eastern sector of the British–Irish Ice Sheet during the last glaciation     

David J. A. Evans  David H. Roberts  Mark D. Bateman  Chris D. Clark  Alicia Medialdea  Louise Callard  Elena Grimoldi  Richard C. Chiverrell  Jeremy Ely  Dayton Dove  Colm Ó Cofaigh  Margot Saher  Tom Bradwell  Steven G. Moreton  Derek Fabel  Sarah L. Bradley 《第四纪科学杂志》2021,36(5):723-751

The findings of BRITICE-CHRONO Transect 2 through the North Sea Basin and eastern England are reported. We define ice-sheet marginal oscillation between ~31 and 16 ka, with seven distinctive former ice-sheet limits (L1–7) constrained by Bayesian statistical analysis. The southernmost limit of the North Sea Lobe is recorded by the Bolders Bank Formation (L1; 25.8–24.6 ka). L2 represents ice-sheet oscillation and early retreat to the northern edge of the Dogger Bank (23.5–22.2 ka), with the Garret Hill Moraine in north Norfolk recording a significant regional readvance to L3 at 21.5–20.8 ka. Ice-marginal oscillations at ~26–21 ka resulted in L1, L2 and L3 being partially to totally overprinted. Ice-dammed lakes related to L1–3, including Lake Humber, are dated at 24.1–22.3 ka. Ice-sheet oscillation and retreat from L4 to L5 occurred between 19.7 and 17.3 ka, with grounding zone wedges marking an important transition from terrestrial to marine tidewater conditions, triggered by the opening of the Dogger Lake spillway between 19.9 and 17.5 ka. L6 relates to ice retreat under glacimarine conditions and final ice retreat into the Firth of Forth by 15.8 ka. L7 (~15 ka) represents an ice retreat from Bosies Bank into the Moray Firth.  相似文献   

Evidence for Multistage and Polychronous Alkaline–Ultrabasic Mesozoic Magmatism in the Area of Diamondiferous Placers of the Ebelyakh River Basin (Eastern Slope of the Anabar Shield)     

Malkovets  V. G.  Shatsky  V. S.  Dak  A. I.  Gibsher  A. A.  Yakovlev  I. V.  Belousova  E. A.  Tsujimori  T.  Sobolev  N. V. 《Doklady Earth Sciences》2021,496(1):48-52

Doklady Earth Sciences - New mineralogical and isotope–geochemical data for zircon megacrysts (n = 48) from alluvium of Kholomolokh Creek (a tributary of the Ebelakh River) are reported....  相似文献   

Early Paleozoic accretionary orogens along the Western Gondwana margin     

Sebastián Oriolo  Bernhard Schulz  Silvana Geuna  Pablo DGonzález  Juan E.Otamendi  JiíSláma  Elena Druguet  Siegfried Siegesmund 《地学前缘(英文版)》2021,12(1):109-130

Early Paleozoic accretionary orogens dominated the Western Gondwana margin and were characterized by nearly continuous subduction associated with crustal extension and back-arc basin development.The southwestern margin is represented by Famatinian and Pampean basement realms exposed in South America,both related to the protracted Paleozoic evolution of the Terra Australis Orogen,whereas the northwestern margin is mainly recorded in Cadomian domains of Europe and adjacent regions.However,no clear relationships between these regions were so far established.Based on a compilation and reevaluation of geological,paleomagnetic,petrological,geochronological and isotopic evidence,this contribution focuses on crustal-scale tectonic and geodynamic processes occurring in Western Gondwana accretionary orogens,aiming at disentangling their common Early Paleozoic evolution.Data show that accretionary orogens were dominated by high-temperature/lowpressure metamorphism and relatively high geothermal gradients,resulting from the development of extended/hyperextended margins and bulk transtensional deformation.In this sense,retreating-mode accretionary orogens characterized the Early Paleozoic Gondwana margin,though short-lived pulses of compression/transpression also occurred.The existence of retreating subduction zones favoured mantle-derived magmatism and mixing with relatively young(meta)sedimentary sources in a thin continental crust.Crustal reworking of previous forearc sequences due to trenchward arc migration thus took place through assimilation and anatexis in the arc/back-arc regions.Therefore,retreating-mode accretionary orogens were the locus of Early Paleozoic crustal growth in Western Gondwana,intimately associated with major flare-up events,such as those related to the Cadomian and Famatian arcs.Slab roll back,probably resulting from decreasing convergence rates and plate velocities after Gondwana assembly,was a key factor for orogen-scale geodynamic processes.Coupled with synchronous oblique subduction and crustal-scale dextral deformation,slab roll back might trigger toroidal mantle flow,thus accounting for bulk dextral transtension,back-arc extension/transtension and a large-scale anticlockwise rotation of Gondwana mainland.  相似文献   

Hafnium–Neodymium Isotope Systematics of Carbonatites from the Guli Massif (Maimecha–Kotui Province,Russia)     

Malitch  K. N.  Kogarko  L. N.  Badanina  I. Yu.  Belousova  E. A. 《Doklady Earth Sciences》2018,480(1):652-655

Doklady Earth Sciences - This work presents new data on the Hf-isotope systematics of baddeleyite and the Nd-isotope compositions of calcite carbonatites of the Guli massif, located within the...  相似文献   

An Experimental Study of the Statistics of Temperature Fluctuations in the Atmospheric Boundary Layer     

Elena Costa Frola  Andrea Mazzino  Federico Cassola  Luca Mortarini  Enrico Ferrero 《Boundary-Layer Meteorology》2014,150(1):91-106

A statistical characterization for two-point temperature fluctuations in the planetary boundary layer (PBL) is analyzed and its implications on the long-standing closure problem discussed. Despite the non-triviality of the dynamics of temperature fluctuations, our analysis supports the idea that the most relevant statistical properties can be captured solely in terms of two scaling exponents. They turned out to be weakly dependent on the stability properties of the PBL. Its statistics have been investigated by collecting data from a field experiment carried out in the urban area of Turin (Italy) from January 2007 to March 2008. Our results confirm those from a large-eddy simulation (LES) analysis carried out for the convective PBL with different level of convection. We extend the scenario to the stable PBL, a regime much more difficult to simulate when exploiting LES.  相似文献   

Tide−Tsunami Interaction in Columbia River, as Implied by Historical Data and Numerical Simulations     

Elena Tolkova 《Pure and Applied Geophysics》2013,170(6-8):1115-1126

The East Japan tsunami of 11 March 2011 propagated more than 100 km upstream in the Columbia River. Visual analysis of its records along the river suggests that the tsunami propagation was strongly affected by tidal conditions. A numerical model of the lower Columbia River populated with tides and a downstream current was developed. Simulations of the East Japan tsunami propagating up the tidal river reproduced the observed features of tsunami waveform transformation, which did not emerge in simulations of the same wave propagating in a quiescent-state river. This allows us to clearly attribute those features to nonlinear interaction with the tidal river environment. The simulation also points to possible amplification of a tsunami wave crest propagating right after the high tide, previously deduced from the recordings of the 1964 Alaska tsunami in the river.  相似文献   

Peloids of Crimean salt lakes and the Dead Sea: controls on composition and formation     

Irina Kotova  Elena Kayukova  Sergey Kotov 《Environmental Earth Sciences》2016,75(16):1207

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