Analysis of tectonic structures and excavation induced fractures in the Opalinus Clay,Mont Terri underground rock laboratory (Switzerland)   总被引：1，自引：0，他引：1  

Christophe Nussbaum  Paul Bossart  Florian Amann  Charles Aubourg 《Swiss Journal of Geoscience》2011,104(2):187-210

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Impact of Oyster Farming on Diagenetic Processes and the Phosphorus Cycle in Two Estuaries (Brittany,France)     

Françoise Andrieux-Loyer  Afi Azandegbé  Florian Caradec  Xavier Philippon  Roger Kérouel  Agnès Youenou  Jean-Louis Nicolas 《Aquatic Geochemistry》2014,20(6):573-611

This study aims to compare the impact of oyster cultures on diagenetic processes and the phosphorus cycle in the sediments of the Aber Benoît and the Rivière d’Auray, estuary of Brittany, France. Our results showed clear evidence of the seasonal impact of oyster cultures on sediment characteristics (grain size and organic matter parameters) and the phosphorus cycle, especially in the Aber Benoît. At this site, seasonal variations in sulfide and Fe concentrations in pore waters, as well as Fe–P concentrations in the solid phase, highlighted a shift from a system governed by iron reduction (Reference) to a system governed by sulfate reduction (beneath oyster). This could be partly explained by the increase in labile organic matter (i.e., biodeposits) beneath oysters, whose mineralization by sulfate led to high sulfide concentrations in pore waters (up to 4,475 µmol l^?1). In turn, sulfide caused an enhanced release of phosphate in the summer, as adsorption sites for phosphate decreased through the formation of iron–sulfide compounds (FeS and FeS₂). In the Aber Benoît, dissolved Fe/PO₄ ratios could be used as an indicator of phosphate release into oxic water. Low Fe/PO₄ ratios in the summer indicated higher effluxes of phosphate toward the water column (up to 47 µmol m^?2 h^?1). At other periods, Fe/PO₄ ratios higher than 2 mol/mol indicated very low phosphate fluxes. In contrast, in the Rivière d’Auray, the occurrence of macroalgae, stranding regularly all over the site, clearly masked the impact of oyster cultures on sediment properties and the phosphorus cycle and made the use of Fe/PO₄ ratios more difficult in terms of indicators of phosphate release.  相似文献   

Scale of relief growth in the forearc of the Andes of Northern Chile (Arica latitude, 18°S)     

Fritz Schlunegger  Gerold Zeilinger  Alexandre Kounov  Florian Kober  Bernice Hüsser 《地学学报》2006,18(3):217-223

The stream profiles of rivers of northern Chile reveal two graded segments separated by 20‐km‐long knickzones. Their formation was initiated in the Late Miocene in response to surface uplift of the western flank of the Altiplano. This phase of uplift that was coeval with the shift of deformation from the Altiplano to the sub‐Andean zone caused relief to grow at the scale of the whole drainage basin. Above and beneath these knickzones, the presence of braided channels and the absence of erosion on adjacent pediplains suggest no substantial modification in the local relief. The knickzones, however, show bedrock channels, and fluvial dissection rates have exceeded erosion rates on adjacent pediplains by two orders of magnitudes. Hence, the data imply that the only geomorphic recorders of relief growth are the knickzones that currently transpose the effects of the Late Miocene phase of surface uplift from the coast to the Altiplano.  相似文献   

Rainfall patterns in the Southern Amazon: a chronological perspective (1971–2010)     

Nathan S. Debortoli  Vincent Dubreuil  Beatriz Funatsu  Florian Delahaye  Carlos Henke de Oliveira  Saulo Rodrigues-Filho  Carlos Hiroo Saito  Raquel Fetter 《Climatic change》2015,132(2):251-264

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The current performance of the in situ 14C extraction line at ETH     

Kristina Hippe  Florian Kober  Heinrich Baur  Matthias Ruff  Lukas Wacker  Rainer Wieler 《Quaternary Geochronology》2009,4(6):493-500

We present the new ¹⁴C extraction line at ETH Zürich. This system is designed to extract in situ-produced cosmogenic ¹⁴C from terrestrial quartz samples, and to obtain pure CO₂ gas for analysis with a gas ion source Accelerator Mass Spectrometry (AMS) system. Samples are degassed at 1550–1600 °C without the use of a fluxing agent. Gas purification is achieved by a series of cryogenic traps and passage through hot Ag and Cu wool/mesh. Graphitization and, thus, sample dilution is not required. Tests to determine the CO₂ recovery after gas extraction and cleaning yielded consistently good recovery rates of >99.8% (n = 7). The ¹⁴C blank contribution from the all-metal tubing system is negligible. Our preliminary procedural blank estimate – deriving mostly from the hot extraction furnace – is <5 × 10^{5 14}C atoms. Extraction tests on two quartz samples by stepped-heating show a quantitative separation of atmospheric ¹⁴C at ≤500 °C from the in situ component above 1200 °C. Based on these data, we estimate to achieve a complete ¹⁴C extraction from a quartz sample.  相似文献   

Sea-water/groundwater interactions along a small catchment of the European Atlantic coast     

Florian Einsiedl 《Applied Geochemistry》2012

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Groundwater recharge rates for regional groundwater modelling: a case study using GROWA in the Lower Rhine lignite mining area, Germany     

Frank Herrmann  Christoph Jahnke  Florian Jenn  Ralf Kunkel  Hans-Jürgen Voigt  Jens Voigt  Frank Wendland 《Hydrogeology Journal》2009,17(8):2049-2060

Groundwater recharge rates calculated with the GROWA model have been applied as the recharge boundary condition for the regional groundwater model Rurscholle. This model simulates groundwater dynamics in the Pleistocene aquifers of the Lower Rhine lignite mining area (Germany). GROWA uses an area-differentiated approach to calculate recharge rates depending on runoff-relevant site characteristics, which are represented by a set of baseflow indices. The regional accuracy of the coupled groundwater and GROWA models has been checked using groundwater hydrographs as validation criteria. The results suggest that the current (unadjusted) version of GROWA underestimates the regional groundwater recharge rate by 10–20 mm/yr. The comparative analysis identified areas where recharge calculations could be improved by adjusting the baseflow indices for areas where runoff is dominated by slope, low water-logging and a low degree of sealing. Using the adjusted set of baseflow indices, the mean groundwater recharge rate of the Rurscholle region was modelled as approx. 170 mm/yr. This study highlights the benefit of using a coupled approach and being able to independently calibrate and validate groundwater recharge boundary conditions in regional groundwater models.  相似文献   

Fuzzy characterization of near-earth-asteroids     

Florian Freistetter 《Celestial Mechanics and Dynamical Astronomy》2009,104(1-2):93-102

Due to close encounters with the inner planets, Near-Earth-Asteroids (NEAs) can have very chaotic orbits. Because of this chaoticity, a statistical treatment of the dynamical properties of NEAs becomes difficult or even impossible. We propose a new way to classify NEAs by using methods from Fuzzy Logic. We demonstrate how a fuzzy characterization of NEAs can be obtained and how a subsequent analysis can deliver valid and quantitative results concerning the long-term dynamics of NEAs.  相似文献   

Texture development of polycrystalline anhydrite experimentally deformed in torsion     

Florian Heidelbach  Iona C. Stretton  Karsten Kunze 《International Journal of Earth Sciences》2001,90(1):118-126

A polycrystalline aggregate of anhydrite was deformed in torsion to a maximum shear strain of 8.1 at 700°C and a maximum shear strain rate of 5᎒^-3 s^-1. The crystallographic preferred orientation (CPO or texture) was investigated as a function of shear strain/shear strain rate in a radial profile from the centre to the edge of the sample. A deformation texture developed at shear strains of 1.5-2 (corresponding to shear strain rates of 1 to 1.3᎒^-3 s^-1) and reached a stable position relative to the kinematic frame at a shear strain of 3.7 (2.3᎒^-3 s^-1). Further shear strain only led to a small increase in texture strength but no change in the orientation relative to the kinematic frame. The CPO is very similar to naturally observed textures and can be explained by the activity of the {001}<010> and {012}<121> slip systems. Although independent mechanical data indicate that a change of mechanism from dislocation- to diffusion-controlled creep occurred at a shear strain of approximately 1.5, the texture does not weaken, but rather increases, in strength with higher shear strains.  相似文献   

Water-assisted migmatization of metagraywackes in a Variscan shear zone, Aiguilles-Rouges massif, western Alps   总被引：2，自引：0，他引：2  

Florian Genier  Franois Bussy  Jean-Luc Epard  Lukas Baumgartner 《Lithos》2008,102(3-4):575-597

Migmatitic rocks developed in metagraywackes during the Variscan orogeny in the Aiguilles-Rouges Massif (western Alps). Partial melting took place 320 Ma ago in a 500 m-wide vertical shear zone. Three leucosome types have been recognised on the basis of size and morphology: (1) large leucosomes > 2 cm wide and > 40 cm long lacking mafic selvage, but containing cm-scale mafic enclaves; (2) same as 1 but with thick mafic selvage (melanosome); (3) small leucosomes < 2 cm and < 40 cm) with thin dark selvages (stromatic migmatites). Types 1 + 2 have mineralogical and chemical compositions in keeping with partial melting experiments. But Type 3 leucosomes have identical plagioclase composition (An_19–28) to neighbouring mesosome, both in terms of major- and trace-elements. Moreover, whole-rock REE concentrations in Type 3 leucosomes are only slightly lower than those in the mesosomes, unlike predicted by partial melting experiments. The main chemical differences between all leucosome types can be related to the coupled effect of melt segregation and late chemical reequilibration.

Mineral assemblages and thermodynamic modelling on bulk-rock composition restrict partial melting to  650 °C at 400 MPa. The large volume of leucosome (20 vol.%) thus generated requires addition of 1 wt.% external water. Restriction of extensive migmatization to the shear zone, without melting of neighbouring metapelites, also points to external fluid circulation within the shear zone as the cause of melting.  相似文献