Reconstruction of Late-Quaternary sea- and lake-level changes in a tectonically active marginal basin using seismic stratigraphy: The Gulf of Cariaco,NE Venezuela     

Maarten Van Daele  Aurélien van Welden  Jasper Moernaut  Christian Beck  Franck Audemard  Javier Sanchez  François Jouanne  Eduardo Carrillo  Gustavo Malavé  Andrés Lemus  Marc De Batist 《Marine Geology》2011,279(1-4):37-51

The Gulf of Cariaco is a marginal basin located between the Cariaco Basin and the Paria Gulf, offshore NE Venezuela, along a system of active right-lateral strike-slip faults. It is connected to the Caribbean Sea via a shallow 58-m-deep sill implying that the gulf was disconnected from the global ocean during eustatic lowstands. A dense grid of high-resolution reflection seismic profiles has been used to determine the overall tectonic structure of the gulf and to establish the seismic stratigraphy of its sedimentary infill. Six unconformity-bounded seismic–stratigraphic units were identified in the upper ~ 200 m of the sedimentary infill. Detailed seismic–stratigraphic and seismic-facies analysis allowed defining a series of sedimentary features that can be used as indicators of past sea or lake level in the Gulf of Cariaco: i) delta offlap breaks, ii) evaporites, and iii) erosional unconformities. Using accurate measurements of these various indicators at several locations in the gulf and a simple total subsidence model, a relative sea/lake-level history encompassing the last 130 kyr could be reconstructed. In periods of connection with the open ocean, reconstructed relative sea level correlates well with eustatic sea level. In times of disconnection, distinct lake-level fluctuations occurred, which sometimes resulted in total dessication of the gulf. Lake-level fluctuations appear to correlate with major Heinrich Events, stadials and interstadials. MIS 4, the LGM and the Younger Dryas were thus identified in the Gulf of Cariaco sedimentary record. The last reconnection to the Caribbean Sea occurred during MWP1b (around 11.5 kyr). The very good fit of the Cariaco sea/lake-level curve with the eustatic sea-level curves (both in terms of amplitude and of timing) underscores potential for future paleoclimate research of the sedimentary record contained in this marginal basin, despite its active tectonic setting.  相似文献   

Capability of a regional climate model to simulate climate variables requested for water balance computation: a case study over northeastern France     

Damien Boulard  Thierry Castel  Pierre Camberlin  Anne-Sophie Sergent  Nathalie Bréda  Vincent Badeau  Aurélien Rossi  Benjamin Pohl 《Climate Dynamics》2016,46(9-10):2689-2716

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Scientific Errors in the Fearnside Comments on Greenhouse Gas Emissions (GHG) from Hydroelectric Dams and Response to His Political Claiming   总被引：1，自引：0，他引：1  

Luiz Pinguelli Rosa  Marco Aurélio Dos Santos  Bohdan Matvienko  Elizabeth Sikar  Ednaldo Oliveira Dos Santos 《Climatic change》2006,75(1-2):91-102

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Application of Laser‐Induced Breakdown Spectroscopy and Hyperspectral Images for Direct Evaluation of Chemical Elemental Profiles of Coprolites          下载免费PDF全文

Marco Aurélio Sperança  Francisco Wendel Batista de Aquino  Marcelo Adorna Fernandes  Alejandro Lopez‐Castillo  Renato Lajarim Carneiro  Edenir Rodrigues Pereira‐Filho 《Geostandards and Geoanalytical Research》2017,41(2):273-282

This study demonstrates the application of laser‐induced breakdown spectroscopy (LIBS) and hyperspectral imaging to the investigation of coprolite and fossil samples. Solid samples from the Permian (seven coprolites and one fossil), Cretaceous (one coprolite) and Oligo‐Miocene (two coprolites) periods were directly analysed, and emission spectra from 186 to 1042 nm were obtained in several areas covering coprolite/fossil and rock material. Initial exploratory analyses were performed using principal component analysis with the data set normalised by the norm (Euclidean norm = 1). After identification and selection of emission lines of eleven elements (Al, Ca, Cr, Fe, K, Mg, Mn, Na, Ni, P and Si), the signals were normalised again by the relative intensity of the selected element. Phosphorus was identified mainly in the coprolites, while K and Na were primarily found in the rock material. In several cases, there was a positive correlation between Ca and P. A sample from the Oligo‐Miocene series was also analysed using inductively coupled plasma‐optical emission spectrometry (ICP‐OES) (rock and coprolites were analysed separately). Based on the quantitative results from ICP‐OES, it was confirmed that the tendency was the same as that observed with the results obtained from LIBS directly in the solid sample.  相似文献   

Earthquake imprints on a lacustrine deltaic system: The Kürk Delta along the East Anatolian Fault (Turkey)          下载免费PDF全文

Aurélia Hubert‐Ferrari  Meriam El‐Ouahabi  David Garcia‐Moreno  Ulaş Avşar  Sevgi Altınok  Sabine Schmidt  Nathalie Fagel  M. Namık Çağatay 《Sedimentology》2017,64(5):1322-1353

Deltas contain sedimentary records that are not only indicative of water‐level changes, but also particularly sensitive to earthquake shaking typically resulting in soft‐sediment‐deformation structures. The Kürk lacustrine delta lies at the south‐western extremity of Lake Hazar in eastern Turkey and is adjacent to the seismogenic East Anatolian Fault, which has generated earthquakes of magnitude 7. This study re‐evaluates water‐level changes and earthquake shaking that have affected the Kürk Delta, combining geophysical data (seismic‐reflection profiles and side‐scan sonar), remote sensing images, historical data, onland outcrops and offshore coring. The history of water‐level changes provides a temporal framework for the depositional record. In addition to the common soft‐sediment deformation documented previously, onland outcrops reveal a record of deformation (fracturing, tilt and clastic dykes) linked to large earthquake‐induced liquefactions and lateral spreading. The recurrent liquefaction structures can be used to obtain a palaeoseismological record. Five event horizons were identified that could be linked to historical earthquakes occurring in the last 1000 years along the East Anatolian Fault. Sedimentary cores sampling the most recent subaqueous sedimentation revealed the occurrence of another type of earthquake indicator. Based on radionuclide dating (¹³⁷Cs and ²¹⁰Pb), two major sedimentary events were attributed to the ad 1874 to 1875 East Anatolian Fault earthquake sequence. Their sedimentological characteristics were determined by X‐ray imagery, X‐ray diffraction, loss‐on‐ignition, grain‐size distribution and geophysical measurements. The events are interpreted to be hyperpycnal deposits linked to post‐seismic sediment reworking of earthquake‐triggered landslides.  相似文献   

Modelling the behaviour of a large landslide with respect to hydrogeological and geomechanical parameter heterogeneity   总被引：2，自引：1，他引：2  

Laurent Tacher  Christophe Bonnard  Lyesse Laloui  Aurèle Parriaux 《Landslides》2005,2(1):3-14

Thanks to a sophisticated transient hydrogeological modelling allowing the determination of the pore pressure fields in La Frasse landslide mass during a crisis, it has been possible to model the mechanical behaviour of the slide and obtain results that prove to be similar to the monitored data, in terms of peak velocity, distribution of velocity with time and space and total displacements. Such results are reached only when appropriate constitutive modelling laws are used, and when geotechnical tests supply all the required parameters. The main results concern the potential effect of a drainage system during a crisis, like the one experienced in 1994. It can include vertical boreholes equipped with pumps or drains drilled from a gallery. The draining system reduces horizontal displacements down to 5% of the values modelled during the crisis. This effect, which appears to extend over a large width, will be even more significant if the boreholes discharge the drained water into the gallery, due to its extension in the presently stabilised landslide mass below the active zone. The modelling tools developed for La Frasse landslide thus provide all the necessary information to optimise the drainage scheme.  相似文献   

A Case Study of Spectral and Non‐Spectral Interferences on Copper Isotope Measurements by Multi‐Collector ICP‐MS (Wet Plasma)     

Jérôme C. J. Petit  Aurélien Taillez  Nadine Mattielli 《Geostandards and Geoanalytical Research》2013,37(3):319-335

Mathematical modelling was combined with experimental Cu isotope measurements to demonstrate the effect of the sample matrix in changing the absolute and relative abundances of spectral interferences from Ti and Cr species. This unforeseen non‐spectral effect, evidenced by variable inaccuracies of the different Zn‐normalised Cu isotope ratios, was investigated by comparing real sedimentary samples and artificial solutions intended to match the Cu:Ti:Cr ratios of the real samples after (one or two step) chromatographic processing. Artificial solutions showed positive bias in δ⁶⁵Cu_X/Y with the magnitude depending on (a) the ^6XZn/^6YZn ratio used for normalisation, (b) the Ti/Cu ratio and (c) the transmission coefficient of the TiO species. In contrast, real samples showed different δ⁶⁵Cu_X/Y patterns and displayed a more complex population of Ti and Cr oxides and hydroxides, giving rise to positive and negative inaccuracies that were two to six times higher compared with the artificial samples. The results evidence contrasting behaviour of Ti and Cr when forming polyatomic species in the plasma and stress that artificial solutions may fail to predict how residual elements interact with the analyte/dopant pair during MC‐ICP‐MS analyses. More importantly, the study shows that all Zn isotope ratios do not have the same merit in correcting for mass bias in the presence of matrix elements and should all be monitored to verify the absence of spectral interferences for Cu isotope measurements. In this respect, accurate Cu data could be generally obtained by a two‐step chromatographic purification providing a minimum reduction of ~ 21000 and ~ 3000 times the initial amounts of Ti and Cr, respectively.  相似文献   

Structure,composition, and location of organic matter in the enstatite chondrite Sahara 97096 (EH3)   总被引：1，自引：0，他引：1  

Laurette PIANI  François ROBERT  Olivier BEYSSAC  Laurent BINET  Michèle BOUROT‐DENISE  Sylvie DERENNE  Corentin LE GUILLOU  Yves MARROCCHI  Smail MOSTEFAOUI  Jean‐Noël ROUZAUD  Aurélien THOMEN 《Meteoritics & planetary science》2012,47(1):8-29

Abstract– The insoluble organic matter (IOM) of an unequilibrated enstatite chondrite Sahara (SAH) 97096 has been investigated using a battery of analytical techniques. As the enstatite chondrites are thought to have formed in a reduced environment at higher temperatures than carbonaceous chondrites, they constitute an interesting comparative material to test the heterogeneities of the IOM in the solar system and to constrain the processes that could affect IOM during solar system evolution. The SAH 97096 IOM is found in situ: as submicrometer grains in the network of fine‐grained matrix occurring mostly around chondrules and as inclusions in metallic nodules, where the carbonaceous matter appears to be more graphitized. IOM in these two settings has very similar δ¹⁵N and δ¹³C; this supports the idea that graphitized inclusions in metal could be formed by metal catalytic graphitization of matrix IOM. A detailed comparison between the IOM extracted from a fresh part and a terrestrially weathered part of SAH 97096 shows the similarity between both IOM samples in spite of the high degree of mineral alteration in the latter. The isolated IOM exhibits a heterogeneous polyaromatic macromolecular structure, sometimes highly graphitized, without any detectable free radicals and deuterium‐heterogeneity and having mean H‐ and N‐isotopic compositions in the range of values observed for carbonaceous chondrites. It contains some submicrometer‐sized areas highly enriched in ¹⁵N (δ¹⁵N up to 1600‰). These observations reinforce the idea that the IOM found in carbonaceous chondrites is a common component widespread in the solar system. Most of the features of SAH 97096 IOM could be explained by the thermal modification of this main component.  相似文献   

Impact of long separating distances on the energy production of two interacting wave energy converters     

Aurélien Babarit 《Ocean Engineering》2010,37(8-9):718-729

In this paper, wave farms composed of two either surging or heaving wave energy converters are considered. Using a numerical model which takes into account wave interactions, the impact on the absorbed wave power of the separating distance between the two systems and the wave direction is studied. In regular waves, a modified q_mod factor is introduced and it is found to be more relevant than the usual q factor for identifying this impact. Then, it is shown that, asymptotically, the alteration of the energy absorption due to wave interaction effects decreases with the square root of the distance. This is a slow decay, which leads to a still significant modification of the wave energy absorption at long distance (up to 15% at a distance of 2000 m). In irregular waves, it is shown that constructive and destructive effects compensate each other, particularly when considering the mean annual power. It leads to a smaller impact of the wave interactions on the absorbed energy and shorter distances (smaller than 10% for distances greater than 400 m). Finally, conclusions on if wave interactions should be taken into account or not when designing a wave farm are drawn in function of the distance.  相似文献   

Declutching control of a wave energy converter     

Aurélien Babarit  Michel Guglielmi  Alain H. Clément 《Ocean Engineering》2009,36(12-13):1015-1024

When hydraulic power take off (PTO) is used to convert the mechanical energy of a wave energy converter (WEC) into a more useful form of energy, the PTO force needs to be controlled. Continuous controlled variation of the PTO force can be approximated by a set of discrete values. This can be implemented using either variable displacement pumps or several hydraulic cylinders or several high pressure accumulators with different pressure levels. This pseudo-continuous control could lead to a complex PTO with a lot of components. A simpler way for controlling this hydraulic PTO is declutching control, which consists in switching on and off alternatively the wave energy converter's PTO. This can be achieved practically using a simple by-pass valve. In this paper, the control law of the valve is determined by using the optimal command theory. It is shown that, theoretically when considering a wave activated body type of WEC, declutching control can lead to energy absorption performance at least equivalent to that of pseudo-continuous control. The method is then applied to the case of the SEAREV wave energy converter, and it is shown than declutching control can even lead to a higher energy absorption, both in regular and irregular waves.  相似文献