Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
After Jurassic rifting, numerous carbonate platforms (i.e., the Orizaba, Cordoba and Golden Lane-Tuxpan platforms) developed during the Lower and Middle Cretaceous episode of thermal subsidence along the western passive margin of the Gulf of Mexico, with intervening basinal domains (i.e., the Tampico-Misantla, Zongolica, Veracruz and Deep Gulf of Mexico - DGM - basins).;During the Late Cretaceous-Paleocene, the east-verging Sierra Madre Oriental thrust belt developed, resulting in tectonic uplift and unroofing of the allochthonous units (i.e. tectonic units made up of former Orizaba and Cordoba platforms and Zongolica Basin series). This new topography provided also an important source of clastics to feed the adjacent foredeep, where coeval tectonic loading accounted for the bending of the foreland lithosphere. However, shallow water facies or even emersion persisted until the Eocene in the forebulge area (at the present location of the Golden Lane), preventing locally the clastics to reach the DGM. This topographic barrier was ultimately bypassed by the clastics only during the Oligocene and Neogene, once (1) the prograding clastic wedge had exceeded accommodation, and (2) the long lasting thermal subsidence of the passive margin could overpass the effect of the bending and force the former bulge to sink.;Numerous paleo-thermo-meters (Tmax, Ro), paleo-thermo-barometers (fluid inclusions), PVT and coupled forward kinematic and thermal modeling have been used to calibrate and date the progressive unroofing of the thrust belt. Coupled tectonic and sedimentologic modeling was applied in the foreland to predict the distribution of sand versus shale ratios in the Oligocene to Plio-Quaternary clastic sedimentary wedge of the passive margin, where gravitational gliding of post-Eocene series occurred during the Neogene along major listric faults.;Mantle dynamics are advocated as the main process accounting for post-orogenic uplift and regional tilting of the basement, which initiated a massive transfer of sediments from the Cordillera towards the Gulf of Mexico, from Oligocene onward, resulting in a destabilization and gravitational collapse of the western slope of the Gulf of Mexico in Neogene times.
ISSN: 0040-1951

hal-00445248
https://hal.archives-ouvertes.fr/hal-00445248
DOI : 10.1016/j.tecto.2009.04.012

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Studies of paleomagnetic fields during polarity transitions recorded over the past few million years frequently suggest a configurational persistence consistent with long-lived mantle control over the pattern of flux emanating from Earth's fluid core. Fundamental to an understanding of the core-mantle dynamics involved is the question of the spatial-temporal nature of the physical conditions at the base of the mantle that may be responsible. Our analysis of the field during a mid-Cenozoic, reverse-to-normal (R-N) polarity change, recorded in a continuous sequence of lava flows in southeastern Queensland, Australia, provides strong evidence that the time span over which local mantle features retain such an influence is far longer than had thus far been observed. Specifically. the reversal is dominated by two sequential groupings of transitional magnetic vector directions, each associated with a clustering of virtual geomagnetic poles (VGPs) at locations common to several more youthful reversal datasets from about the globe. Our Ar-40/Ar-39 age determinations indicate that these Australian lavas erupted 25.56 +/- 0.48 Ma, strongly suggesting that the characteristic time for invariant control by the mantle over flux emerging from the outer core is at least on order of a few tens of Myr. The availability of transitional paleomagnetic data from still earlier times within the Cenozoic may further delineate this duration and, perhaps, provide a means to track changes in the pattern of long-standing concentrations of magnetic flux at the core-mantle boundary. (C) 2008 Elsevier B.V. All rights reserved.
ISSN: 0031-9201

hal-00411919
https://hal.archives-ouvertes.fr/hal-00411919
DOI : 10.1016/j.pepi.2008.07.012

Éditeur(s) : HAL CCSD Elsevier
Résumé :  
Classifying species by shared life-history traits is important if common ecological response groups are to be identified among different species. We investigated how habitat area, local and regional factors shape plant communities in small isolated closed depressions, and how the species richness is related to the interplay between environmental factors and specific life-history trait combinations. In Central-Western Europe, 169 closed depressions were completely Surveyed for plant presence in two highly contrasted landscapes (forested and open landscapes). All species were clustered into 9 Emergent Groups based oil 10 life-history traits related to plant dispersal, establishment and persistence. Habitat areas were related to species presence using logistic regressions. Most Emergent Groups were more area-dependent in open than in forested landscapes, owing to heterogeneous light levels in forest weakening the species-area relationship. In open landscapes, Floating Hydrophytes were severely underrepresented in very small depressions, owing to the absence of waterfowl poulation. Local environmental and regional factors were related to species richness using Generalized Linear Models. In open landscapes, local environmental factors such as water conductivity or soil productivity are respectively the main predictors. In forested landscapes, the abundance of most Emergent Groups Was better predicted by regional factors, i.e., habitat connectivity and distance to the forest edge. Forested landscapes strongly impeded the closed depressions' colonization by the less mobile Emergent Groups Such as Large-seeded Perennials.
ISSN: 1146-609X

hal-01032144
https://hal.archives-ouvertes.fr/hal-01032144
DOI : 10.1016/j.actao.2009.02.002

Éditeur(s) : HAL CCSD American Chemical Society
Résumé : International audience
Chlordecone is an organochlorine pesticide that was extensively used in the French West Indies to fight weevils in banana plantations from 1973 to 1993. This has led to a persistent pollution of the environment and to the contamination of the local population for several decades with effects demonstrated on human health. Chlordecone accumulates mainly in the liver where it is known to potentiate the action of hepatotoxic agents. However, there is currently no information on its in situ localization in the liver. We have thus evaluated a matrix-assisted laser desorption ionization (MALDI) imaging quantification method based on labeled normalization for the in situ localization and quantification of chlordecone. After validating the linearity and the reproducibility of this method, quantitative MALDI imaging was used to study the accumulation of chlordecone in the mouse liver. Our results revealed that normalized intensities measured by MALDI imaging could be first converted in quantitative units. These quantities appeared to be different from absolute quantities of chlordecone determined by gas chromatography (GC), but they were perfectly correlated (R(2) = 0.995). The equation of the corresponding correlation curve was thus efficiently used to convert quantities measured by MALDI imaging into absolute quantities. Our method combining labeled normalization and calibration with an orthogonal technique allowed the in situ absolute quantification of chlordecone by MALDI imaging. Finally, our results obtained on the pathological mouse liver illustrate the advantages of quantitative MALDI imaging which preserves information on in situ localization without radioactive labeling and with a simple sample preparation.
ISSN: 0003-2700

hal-01118103
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01118103
PUBMED : 24837422
DOI : 10.1021/ac500313s

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
Iran is an active continental domain accommodating the convergence between the Arabia and Eurasia plates. In northwestern Iran, deformation between the Central Iranian block and the Caucasus domain is mainly accommodated by right lateral strike-slip on the Tabriz fault. Cities and villages, including the city of Tabriz, have been destroyed by several strong historical earthquakes (M similar to 7). In this study, we compare the slip-rates estimated from geodetic measurements (radar interferometry and UPS) with those determined by dating a geomorphological offset of an alluvial fan along the Tabriz fault. The GPS measurements along two profiles normal to the Tabriz fault suggest a slip-rate of 7.3 +/- 1.3 mm yr(-1). The persistent scatterer radar interferometry analysis of Envisat satellite archives from 2003 to 2010 shows a velocity gradient (6 +/- 3 mm yr(-1)) across the Tabriz fault in agreement with GPS results. Moreover, it reveals that most of the area located south of the Tabriz fault is affected by subsidence, and that some sections of the fault probably act as barriers to fluid migration which may have an impact on its mechanical behaviour. West of Tabriz morphotectonic investigations on an alluvial fan surface show a right-lateral cumulative offset of 320 +/- 40 m Luminescence analyses of the coarse matrix alluvial fan deposits provide an age of 46 +/- 3 ka. This yields a slip-rate comprised between 6.5 and 7.3 mm yr(-1) along this segment. These results suggest that the Late Quaternary slip-rate is in agreement with the present-day slip-rate estimated by geodetic measurements, showing no slip-rate changes during the past 45 000 yr. Short-term variations within the 45 000 yr related to temporal earthquake clustering over few seismic cycles cannot be ruled out, but if they exist, they do not affect the geodetic and the geomorphological estimates. This study is in agreement with previous ones suggesting that long-term slip-rates (i.e. averaged over several tens of seismic cycles) are consistent with geodetic estimated slip-rates (i.e. extrapolated from few years of interseismic observations), and suggests that perturbations of fault slip-rates are related to variations over few seismic cycles.
ISSN: 0956-540X

hal-00844695
https://hal.archives-ouvertes.fr/hal-00844695
https://hal.archives-ouvertes.fr/hal-00844695v2/document
https://hal.archives-ouvertes.fr/hal-00844695/file/rizza2013.pdf
DOI : 10.1093/gji/ggt041

Éditeur(s) : HAL CCSD Wiley
Résumé : Question: To establish a habitat classification based on functional group co-occurrence that may help the drawing up of conservation plans. Location: Riverine forest fragments in the Grand-duché de Luxembourg, Europe. Methods: Forest fragments were surveyed for their abundance of vascular plants. These were clustered into emergent groups according to 14 life-traits related 10 plant dispersal, establishment and persistence. Forest fragments were classified according to similar distribution of the identified emergent groups. Environmental factors were related to the emergent group richness in each forest type using generalized linear models. Results: Contrary to former species centred classification, only two groups of forests, each with clearly different emergent group composition and conservation requirements. Were detected: (1) swamp forests characterized by anemogamous perennials, annuals and hydrochorous perennials and (2) moist forests characterized by barochorous perennials, small geophytes and zoochorous phanerophytes. From a conservation point of view, priority should he given to large swamp forest with intact flooding regimes his is in accordance with the high wind and water dispersal capacities of their typical emergent groups. For the moist forests. conservation priorities should he high forest connectivity and historical continuity since dispersal and establishment of their characteristic emergent groups arc highly limited. Conclusions: The described methodology, situated at an intermediate integration level between the individual species and whole community descriptors. takes advantage of both conservation plans built for single species and the synthetic power of bread ecological measures.
ISSN: 1402-2001

hal-01031884
https://hal.archives-ouvertes.fr/hal-01031884

Éditeur(s) : HAL CCSD Elsevier
Résumé : We present comparative field studies in folded areas (Southern France. Moroccan Western Atlas and Abruzzo, Italy) giving new insights into fracture distribution within folded rocks of the shallow brittle crust. We show that the curvature in folds formed in brittle mechanical units is usually accommodated by multiple "dip-domain boundaries" (appearing as curvature discontinuities at fold scale) corresponding to relatively narrow and dense fracture zones, striking parallel or slightly oblique to the fold axis. They separate "dip-domains" where curvature is absent or moderate. It is shown that the dip-domain boundaries (which are obvious in the case of kink folds or box-fold anticlines) are currently present as multiple subtle hinges even when the curvature appears continuous at first sight. The nature of dip-domain boundaries is studied, they often cut through the whole thickness of the mechanical units Their internal structure varies, and a non-exhaustive typology is proposed For each type, an interpretative kinematic scenario shows how the dip-domain boundaries could initiate and develop. We suggest two kinds of origins (1) they could correspond to the reactivation of inherited, along-strike fracture zones (opening-mode fracture concentrations such as big joints, fracture corridors. Inherited faults, etc), (2) they could be created as mechanical instabilities during the fold formation (syn-folding origin), in particular through small reverse faults. In both cases, early zones of weakness localize the dip-domain boundaries, and control the Increase in curvature in association with increasing fracture density within the boundary. Because they represent well-defined vertically and axially persistent sub-seismic fracture zones generally limited to the thickness of the folded unit, dip-domain boundaries could enhance the axial permeability of folded and fractured reservoirs.
ISSN: 0191-8141

hal-00512651
https://hal.archives-ouvertes.fr/hal-00512651
DOI : 10.1016/j.jsg.2010.03.002

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
This paper provides a synthesis of current data and interpretations on the crustal structure of the Pyrenean-Cantabrian orogenic belt, and presents new tectonic models for representative transects. The Pyrenean orogeny lasted from Santonian (~84 Ma) to early Miocene times (~20 Ma), and consisted of a spatial and temporal succession of oceanic crust/exhumed mantle subduction, rift inversion and continental collision processes at the Iberia-Eurasia plate boundary. A good coverage by active-source (vertical-incidence and wide-angle reflection) and passive-source (receiver functions) seismic studies, coupled with surface data have led to a reasonable knowledge of the present-day crustal architecture of the Pyrenean-Cantabrian belt, although questions remain. Seismic imaging reveals a persistent structure, from the central Pyrenees to the central Cantabrian Mountains, consisting of a wedge of Eurasian lithosphere indented into the thicker Iberian plate, whose lower crust is detached and plunges northwards into the mantle. For the Pyrenees, a new scheme of relationships between the southern upper crustal thrust sheets and the Axial Zone is here proposed. For the Cantabrian belt, the depth reached by the N-dipping Iberian crust and the structure of the margin are also revised.The common occurrence of lherzolite bodies in the northern Pyrenees and the seismic velocity and potential field record of the Bay of Biscay indicate that the precursor of the Pyrenees was a hyperextended and strongly segmented rift system, where narrow domains of exhumed mantle separated the thinned Iberian and Eurasian continental margins since the Albian-Cenomanian. The exhumed mantle in the Pyrenean rift was largely covered by a Mesozoic sedimentary lid that had locally glided along detachments in Triassic evaporites. Continental margin collision in the Pyrenees was preceded by subduction of the exhumed mantle, accompanied by the pop-up thrust expulsion of the off-scraped sedimentary lid above. To the west, oceanic subduction of the Bay of Biscay under the North Iberian margin is supported by an upper plate thrust wedge, gravity and magnetic anomalies, and 3D inclined sub-crustal reflections. However, discrepancies remain for the location of continent-ocean transitions in the Bay of Biscay and for the extent of oceanic subduction. The plate-kinematic evolution during the Mesozoic, which involves issues as the timing and total amount of opening, as well as the role of strike-slip drift, is also under debate, discrepancies arising from first-order interpretations of the adjacent oceanic magnetic anomaly record.
ISSN: 0040-1951

insu-01683989
https://hal-insu.archives-ouvertes.fr/insu-01683989
https://hal-insu.archives-ouvertes.fr/insu-01683989/document
https://hal-insu.archives-ouvertes.fr/insu-01683989/file/teixell-tectono-2018.pdf
DOI : 10.1016/j.tecto.2018.01.009

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : The analysis of fine-scale spatial genetic structure (FSGS) within populations can provide insights into eco-evolutionary processes. Restricted dispersal and locally occurring genetic drift are the primary causes for FSGS at equilibrium, as described in the isolation by distance (IBD) model. Beyond IBD expectations, spatial, environmental or historical factors can affect FSGS. We examined FSGS in seven African and Neotropical populations of the late-successional rain forest tree Symphonia globulifera L. f. (Clusiaceae) to discriminate the influence of drift-dispersal vs. landscape/ecological features and historical processes on FSGS. We used spatial principal component analysis and Bayesian clustering to assess spatial genetic heterogeneity at SSRs and examined its association with plastid DNA and habitat features. African populations (from Cameroon and São Tomé) displayed a stronger FSGS than Neotropical populations at both marker types (mean Sp = 0.025 vs. Sp = 0.008 at SSRs) and had a stronger spatial genetic heterogeneity. All three African populations occurred in pronounced altitudinal gradients, possibly restricting animal-mediated seed dispersal. Cyto-nuclear disequilibria in Cameroonian populations also suggested a legacy of biogeographic history to explain these genetic patterns. Conversely, Neotropical populations exhibited a weaker FSGS, which may reflect more efficient wide-ranging seed dispersal by Neotropical bats and other dispersers. The population from French Guiana displayed an association of plastid haplotypes with two morphotypes characterized by differential habitat preferences. Our results highlight the importance of the microenvironment for eco-evolutionary processes within persistent tropical tree populations.
ISSN: 1932-6203

hal-01608324
https://hal.archives-ouvertes.fr/hal-01608324
DOI : 10.1371/journal.pone.0182515
PRODINRA : 403154
PUBMED : 28771629

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
P>The Strait of Hormuz area is a transition zone between the continental collision of the Zagros (west) and the subduction of an oceanic part of the Arabian Plate beneath the Makran wedge (east). Geology and recent GPS measurements indicate that about 15 mm yr-1 of relative motion in N10 degrees E direction is accommodated by two major fault systems: (1) the NNW-trending Minab-Zendan-Palami (MZP) fault system that connects the Main Zagros Thrust (MZT) to the inner Makran thrust system and the Frontal subduction thrust and (2) the N-trending Sabzevaran-Kahnuj-Jiroft (SKJ) fault system that bounds the Jazmurian depression to the west. We use dense GPS measurements along four transects across these fault systems in order to determine the strains spatial distribution. The northern GPS transect confirms the total fault slip rates for both fault systems estimated by the tectonic analyses (about 10 and 7.3 mm yr-1 in N10 degrees direction across the MZP and SKJ fault systems, respectively). For both fault systems, the elastic deformation spreads over shear zones that are several tens of kilometres wide. However, transects located close to latitude 27 degrees N reveal a much narrower shear zone (similar to 10 km) for the MZP fault system. Moreover, we confirm that most of the present-day strain is transferred towards the frontal subduction thrust rather than towards the inner Makran thrusts. In order to complement this new GPS velocity field with spatially dense measurements, we processed a set of ERS radar images by the radar interferometry (InSAR) technique. We used both a 'stacking' and a 'persistant-scatterers' approach to differentiate the ground deformation signal which spatial gradient is expected to be very low, from the atmospheric signal. Results from these interferograms appear to be relatively in agreement with the GPS-determined strain distribution. Nevertheless, they confirm the absence of any superficial creep behaviour since no sharp discontinuity on interferometric phase can be noted on any interferogram. Finally, we use a purely kinematic 'block model' inversion process to calculate slip rates and locking depths for each fault system from our GPS measurements. These models suggest that the relative quiescence over the last 200 yr has certainly produced a slip deficit as high as 2 m. So, we may wonder if the MZP fault system is not late in the interseismic phase of its earthquake cycle.
ISSN: 0956-540X

hal-00429386
https://hal.archives-ouvertes.fr/hal-00429386
DOI : 10.1111/j.1365-246X.2009.04321.x

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The replenishment and persistence of marine species is contingent on dispersing larvae locating suitable habitatand surviving to a reproductive stage. Pelagic larvae rely on environmental cues to make behavioural decisionswith chemical information being important for habitat selection at settlement. We explored the sensory worldof crustaceans and fishes focusing on the impact anthropogenic alterations (ocean acidification, red soil, pesti-cide) have on conspecific chemical signals used by larvae for habitat selection. Crustacean (Stenopus hispidus)and fish (Chromis viridis) larvae recognized their conspecifics via chemical signals under control conditions. Inthe presence of acidified water, red soil or pesticide, the ability of larvae to chemically recognize conspecificcues was altered. Our study highlights that recruitment potential on coral reefs may decrease due to anthropo-genic stressors. If so, populations of fishes and crustaceans will continue their rapid decline; larval recruitmentwill not replace and sustain the adult populations on degraded reefs
ISSN: 0025-326X

hal-01491052
https://hal-univ-perp.archives-ouvertes.fr/hal-01491052
DOI : 10.1016/j.marpolbul.2016.08.083

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Ecological signs of Earth's biosphere forewarn an alarming trajectory towards a global mass-extinction. Assessing species performance and susceptibilities to decline is essential to comprehend and reverse this trend. Yet it is challenging, given difficulties associated with quantifying individual and population processes that are variable across time, space, and life-stages. We describe a new approach to estimating and comparing species performances that combines empirical data, a novel theoretical consideration of population dynamics, and modern statistics. Our approach allows for a more realistic continuous representation of individual performances along development stages while taking into account non-linearity, and natural variability as captured by spatio-temporally replicated observations. We illustrate its application in a coral meta-assemblage composed of populations of the three major reef-building taxa Acropora, Pocillopora, Porites. Using a unique set of highly replicated observations of individual coral dynamics under various environmental conditions, we show how taxa differ in their investment in recruitment and size-specific aptitude for growth and survival, notably through different use of clonal shrinkage, fragmentation, fission, and fusion processes. Our results reveal contrasting life-history trade-offs among taxa which, along with differing patterns of density-dependent recruitment, modulate species responses to decline. These differences in coral life history traits reflect opposing life-strategies, imply regulation at differing life-stages, and explain divergence in species trajectories. Our findings indicate a high potential for resilience in Pocillopora and Porites populations, thanks respectively to a sustained recruitment that promotes demographic elasticity through replacement of individuals, and a steady resistance to mortality which confers persistence through lingering of individuals. Resilience in Acropora appears more arbitrary, given high susceptibility to perturbations and dependency of recruitment on presence of established local populations. We identify management actions that can complement Acropora's life history and benefit recovery of its populations following mortality events. Our regression-modelling approach to quantifying and comparing species performances in different population processes is applicable to all taxa, as illustrated even those with complex clonal life histories, and can be implemented at wide spatio-temporal and taxonomic coverage. It can promote more accurate representation of species dynamics in both descriptive and predictive modelling approaches. The semi-parametric contrast curve method we develop facilitates comparing response variables along continuous explicative metrics while accounting for multiple sources of complexity in empirical data. It should widely benefit investigations in ecology and quantitative science.
ISSN: 1476-945X

hal-01212337
https://hal-univ-perp.archives-ouvertes.fr/hal-01212337
DOI : 10.1016/j.ecocom.2015.07.003

Éditeur(s) : HAL CCSD
Résumé : Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models.
ISSN: 1476-4687

hal-01204223
https://hal.archives-ouvertes.fr/hal-01204223
DOI : 10.1038/nature14283
PRODINRA : 294797
PUBMED : 25788097