TY - JOUR A1 - Akal, Cuneyt A1 - Koralay, O. Ersin A1 - Candan, Osman A1 - Oberhänsli, Roland A1 - Chen, Fukun T1 - Geodynamic significance of the early triassic karaburun granitoid (Western Turkey) for the opening history of Neo-Tethys JF - Turkish journal of earth sciences = Türk yerbilimleri dergisi N2 - The Karaburun Peninsula, which is considered part of the Anatolide-Tauride Block of Turkey, contains clastic and carbonate sequences deposited on the northern margin of Gondwana. The Palaeozoic clastic sequence, which is intruded by the Early Triassic granitoid and tectonically overlies a Mesozoic melange sequence, can be divided into three subunits: a lower clastic subunit consisting of a sandstone-shale alternation, an upper clastic subunit consisting of black chert-bearing shales, sandstone and conglomerate, and a Permo-Carboniferous carbonate subunit. The lower Triassic Karaburun I-type granitoid has a high initial Sr-87/Sr-86 ratio (0.709021-0.709168), and low Nd-143/Nd-144 ratio (0.512004-0.512023) and epsilon Nd (-5.34 to -5.70) isotopic values. Geochronological data indicate a crystallization (intrusion) age of 247.1 +/- 2.0 Ma (Scythian). Geochemically, the acidic magmatism reflects a subduction-related continental-arc basin tectonic setting, which can be linked to the opening of the northern branch of Neo-Tethys as a continental back-arc rifting basin on the northern margin of Gondwana. This can be related to the closure through southward subduction of the Palaeotethys Ocean beneath Gondwana. KW - Karaburun KW - Neo-Tethys KW - Palaeo-Tethys KW - diorite KW - Triassic KW - magmatism Y1 - 2011 U6 - https://doi.org/10.3906/yer-1008-1 SN - 1300-0985 VL - 20 IS - 3 SP - 255 EP - 271 PB - Tübitak CY - Ankara ER - TY - JOUR A1 - Wischnewski, Juliane A1 - Mischke, Steffen A1 - Wang, Yongbo A1 - Herzschuh, Ulrike T1 - Reconstructing climate variability on the northeastern Tibetan Plateau since the last Lateglacial - a multi-proxy, dual-site approach comparing terrestrial and aquatic signals JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - A sediment core from a closed basin lake (Lake Kuhai) from the semi-arid northeastern Tibetan Plateau was analysed for its pollen record to infer Lateglacial and post glacial vegetation and climatic change. At Lake Kuhai five major vegetation and climate shifts could be identified: (1) a change from cold and dry to relatively warmer and more moist conditions at 14.8 cal ka BP: (2) a shift to conditions of higher effective moisture and a stepwise warmer climate at 13.6 cal ka BP; (3) a further shift with increased moisture but colder conditions at 7.0 cal ka BP; (4) a return to a significantly colder and drier phase at 6.3 cal ka BP; (5) and a change back to relatively moist conditions at 2.2 cal ka BP. To investigate the response of lake ecosystems to climatic changes, statistical comparisons were made between the lake Kuhai pollen record and a formerly published ostracod and sedimentary record from the same sediment core. Furthermore, the pollen and lacustrine proxies from lake Kuhai were compared to a previously published pollen and lacustrine record from the nearby Lake Koucha. Statistical comparisons were done using non-metric multidimensional scaling and Procrustes rotation. Differences between lacustrine and pollen responses within one site could be identified, suggesting that lacustrine proxies are partly influenced by in-lake or local catchment processes, whereas the terrestrial (pollen) proxy shows a regional climate signal. Furthermore, we found regional differences in proxy response between lake Kuhai and Lake Koucha. Both pollen records reacted in similar ways to major environmental changes, with minor differences in the timing and magnitude of these changes. The lacustrine records were very similar in their timing and magnitude of response to environmental changes; however, the nature of change was at times very distinct. To place the current study in the context of Holocene moisture evolution across the Tibetan Plateau, we applied a five-scale moisture index and average link clustering to all available continuous palaeo-climate records from the Tibetan Plateau to possibly find general patterns of moisture evolution on the Plateau. However, no common regional pattern of moisture evolution during the Holocene could be detected. We assign this to complex responses of different proxies to environmental and atmospheric changes in an already very heterogeneous mountain landscape where minor differences in elevation can cause strong variation in microenvironments. Y1 - 2011 U6 - https://doi.org/10.1016/j.quascirev.2010.10.001 SN - 0277-3791 VL - 30 IS - 1-2 SP - 82 EP - 97 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Pilz, Marco A1 - Parolai, Stefano A1 - Picozzi, Matteo A1 - Zschau, Jochen T1 - Evaluation of proxies for seismic site conditions in large urban areas the example of Santiago de Chile JF - Physics and chemistry of the earth N2 - Characterizing the local site response in large cities is an important step towards seismic hazard assessment. To this regard, single station seismic noise measurements were carried out at 146 sites in the northern part of Santiago de Chile. This extensive survey allowed the fundamental resonance frequency of the sedimentary cover, derived from horizontal-to-vertical (H/V) spectral ratios, to be mapped. By inverting the spectral ratios under the constraint of the thickness of the sedimentary cover, known from previous gravimetric measurements, local S-wave velocity profiles have been retrieved. After interpolation between the individual profiles, the resulting high resolution 3D S-wave velocity model allows the entire area, as well as deeper parts of the basin, to be represented in great detail. Since one lithology shows a great scatter in the velocity values only a very general correlation between S-wave velocity in the uppermost 30 m (v(s)(30)) and local geology is found. Local S-wave velocity profiles can serve as a key factor in seismic hazard assessment, since they allow an estimate of the amplification potential of the sedimentary cover. Mapping the intensity distribution of the 27 February 2010 Maule, Chile, event (Mw = 8.8) the results indicate that local amplification of the ground motion might partially explain the damage distribution and encourage the use of the low cost seismic noise techniques for the study of seismic site effects. KW - Ambient seismic noise KW - H/V ratio KW - Inversion KW - S-wave velocity KW - Site effects Y1 - 2011 U6 - https://doi.org/10.1016/j.pce.2011.01.007 SN - 1474-7065 VL - 36 IS - 16 SP - 1259 EP - 1266 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Donges, Jonathan A1 - Donner, Reik Volker A1 - Rehfeld, Kira A1 - Marwan, Norbert A1 - Trauth, Martin H. A1 - Kurths, Jürgen T1 - Identification of dynamical transitions in marine palaeoclimate records by recurrence network analysis JF - Nonlinear processes in geophysics N2 - The analysis of palaeoclimate time series is usually affected by severe methodological problems, resulting primarily from non-equidistant sampling and uncertain age models. As an alternative to existing methods of time series analysis, in this paper we argue that the statistical properties of recurrence networks - a recently developed approach - are promising candidates for characterising the system's nonlinear dynamics and quantifying structural changes in its reconstructed phase space as time evolves. In a first order approximation, the results of recurrence network analysis are invariant to changes in the age model and are not directly affected by non-equidistant sampling of the data. Specifically, we investigate the behaviour of recurrence network measures for both paradigmatic model systems with non-stationary parameters and four marine records of long-term palaeoclimate variations. We show that the obtained results are qualitatively robust under changes of the relevant parameters of our method, including detrending, size of the running window used for analysis, and embedding delay. We demonstrate that recurrence network analysis is able to detect relevant regime shifts in synthetic data as well as in problematic geoscientific time series. This suggests its application as a general exploratory tool of time series analysis complementing existing methods. Y1 - 2011 U6 - https://doi.org/10.5194/npg-18-545-2011 SN - 1023-5809 VL - 18 IS - 5 SP - 545 EP - 562 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Benmehdi, Sabah A1 - Makarava, Natallia A1 - Benhamidouche, N. A1 - Holschneider, Matthias T1 - Bayesian estimation of the self-similarity exponent of the Nile River fluctuation JF - Nonlinear processes in geophysics N2 - The aim of this paper is to estimate the Hurst parameter of Fractional Gaussian Noise (FGN) using Bayesian inference. We propose an estimation technique that takes into account the full correlation structure of this process. Instead of using the integrated time series and then applying an estimator for its Hurst exponent, we propose to use the noise signal directly. As an application we analyze the time series of the Nile River, where we find a posterior distribution which is compatible with previous findings. In addition, our technique provides natural error bars for the Hurst exponent. Y1 - 2011 U6 - https://doi.org/10.5194/npg-18-441-2011 SN - 1023-5809 VL - 18 IS - 3 SP - 441 EP - 446 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Moradi, Ahmad B. A1 - Carminati, Andrea A1 - Vetterlein, Doris A1 - Vontobel, Peter A1 - Lehmann, Eberhard A1 - Weller, Ulrich A1 - Hopmans, Jan W. A1 - Vogel, Hans-Jörg A1 - Oswald, Sascha T1 - Three-dimensional visualization and quantification of water content in the rhizosphere JF - New phytologist : international journal of plant science N2 - Despite the importance of rhizosphere properties for water flow from soil to roots, there is limited quantitative information on the distribution of water in the rhizosphere of plants. Here, we used neutron tomography to quantify and visualize the water content in the rhizosphere of the plant species chickpea (Cicer arietinum), white lupin (Lupinus albus), and maize (Zea mays) 12 d after planting. We clearly observed increasing soil water contents (h) towards the root surface for all three plant species, as opposed to the usual assumption of decreasing water content. This was true for tap roots and lateral roots of both upper and lower parts of the root system. Furthermore, water gradients around the lower part of the roots were smaller and extended further into bulk soil compared with the upper part, where the gradients in water content were steeper. Incorporating the hydraulic conductivity and water retention parameters of the rhizosphere into our model, we could simulate the gradual changes of h towards the root surface, in agreement with the observations. The modelling result suggests that roots in their rhizosphere may modify the hydraulic properties of soil in a way that improves uptake under dry conditions. KW - extent of rhizosphere KW - modelling KW - neutron tomography KW - rhizosphere hydraulic properties KW - root water uptake KW - soil moisture profile KW - water distribution Y1 - 2011 U6 - https://doi.org/10.1111/j.1469-8137.2011.03826.x SN - 0028-646X VL - 192 IS - 3 SP - 653 EP - 663 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Schlunegger, Fritz A1 - Norton, Kevin P. A1 - Zeilinger, Gerold T1 - Climatic forcing on channel profiles in the eastern cordillera of the Coroico Region, Bolivia JF - The journal of geology N2 - Orographic precipitation has a large impact on channel morphology and rock uplift via a positive feedback to erosion. We show that in the Eastern Cordillera of Bolivia, channel concavities reach their highest values where annual precipitation increases in the downstream direction, exceeding 3000 mm. The steepest channels are upstream of this zone of high concavity, where precipitation rates are <1000 mm yr(-1). Channels exhibit graded forms both upstream and downstream of this transient reach. We conclude that the prolonged effect of orographic erosion and related tectonic uplift is the preservation of channels with extreme concavities in the Eastern Cordillera. Y1 - 2011 U6 - https://doi.org/10.1086/657407 SN - 0022-1376 VL - 119 IS - 1 SP - 97 EP - 107 PB - Univ. of Chicago Press CY - Chicago ER - TY - JOUR A1 - Krause, Rolf Harald A1 - Buse, Joern A1 - Matern, Andrea A1 - Schroeder, Boris A1 - Haerdtle, Werner A1 - Assmann, Thorsten T1 - Eresus kollari (Araneae: Eresidae) calls for heathland management JF - The Journal of arachnology N2 - Northwest Europe's largest heather-dominated sandy habitats are located in the nature reserve Luneburger Heide, Germany. Yet, even these appear to be losing their ability to support some of their stenotopic species such as the ladybird spider, Eresus kollari Rossi 1846, and are thus becoming increasingly important for the preservation of these species. The habitat requirements of this endangered spider species were investigated in order to obtain data that will help stabilize the last remnants of the species' population in northwest Germany. Several heathland habitats were surveyed by pitfall trapping during the mate-search period of the males. Two statistical methods were applied: logistic regression and boosted regression trees (BRT). Both methods showed that three habitat variables are of prime relevance in predicting the occurrence of E. kollari: a) thickness of the organic layer (a negative effect), b) soil temperature at a depth of 10 cm, and c) Calluna cover in the herb layer (both have positive effect). Our results show that choppering (removing above-ground biomass and most of O-layer) and burning are likely appropriate heathland management measures for the conservation of E. kollari. Such measures improve the species' habitat quality by creating a heterogenic (small-scaled) heathland structure with suitable microhabitats. As Calluna heathlands show a clear senescence of the dominant heather, it is essential that those habitat patches be conserved. Further measures, such as transfer experiments, are recommended. KW - Conservation management KW - habitat modeling KW - action plan KW - choppering KW - burning Y1 - 2011 SN - 0161-8202 SN - 1937-2396 VL - 39 IS - 3 SP - 384 EP - 392 PB - American Arachnological Society CY - College Park ER - TY - JOUR A1 - Rivera Villarreyes, C. A. A1 - Baroni, Gabriele A1 - Oswald, Sascha T1 - Integral quantification of seasonal soil moisture changes in farmland by cosmic-ray neutrons JF - Hydrology and earth system sciences : HESS N2 - Soil moisture at the plot or hill-slope scale is an important link between local vadose zone hydrology and catchment hydrology. However, so far only a few methods are on the way to close this gap between point measurements and remote sensing. One new measurement methodology that could determine integral soil moisture at this scale is the aboveground sensing of cosmic-ray neutrons, more precisely of ground albedo neutrons. The present study performed ground albedo neutron sensing (GANS) at an agricultural field in northern Germany. To test the method it was accompanied by other soil moisture measurements for a summer period with corn crops growing on the field and a later autumn-winter period without crops and a longer period of snow cover. Additionally, meteorological data and aboveground crop biomass were included in the evaluation. Hourly values of ground albedo neutron sensing showed a high statistical variability. Six-hourly values corresponded well with classical soil moisture measurements, after calibration based on one reference dry period and three wet periods of a few days each. Crop biomass seemed to influence the measurements only to minor degree, opposed to snow cover which has a more substantial impact on the measurements. The latter could be quantitatively related to a newly introduced field neutron ratio estimated from neutron counting rates of two energy ranges. Overall, our study outlines a procedure to apply the ground albedo neutron sensing method based on devices now commercially available, without the need for accompanying numerical simulations and suited for longer monitoring periods after initial calibration. Y1 - 2011 U6 - https://doi.org/10.5194/hess-15-3843-2011 SN - 1027-5606 VL - 15 IS - 12 SP - 3843 EP - 3859 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Munz, Matthias A1 - Oswald, Sascha A1 - Schmidt, C. T1 - Sand box experiments to evaluate the influence of subsurface temperature probe design on temperature based water flux calculation JF - Hydrology and earth system sciences : HESS N2 - Quantification of subsurface water fluxes based on the one dimensional solution to the heat transport equation depends on the accuracy of measured subsurface temperatures. The influence of temperature probe setup on the accuracy of vertical water flux calculation was systematically evaluated in this experimental study. Four temperature probe setups were installed into a sand box experiment to measure temporal highly resolved vertical temperature profiles under controlled water fluxes in the range of +/- 1.3 md(-1). Pass band filtering provided amplitude differences and phase shifts of the diurnal temperature signal varying with depth depending on water flux. Amplitude ratios of setups directly installed into the saturated sediment significantly varied with sand box hydraulic gradients. Amplitude ratios provided an accurate basis for the analytical calculation of water flow velocities, which matched measured flow velocities. Calculated flow velocities were sensitive to thermal properties of saturated sediment and to temperature sensor spacing, but insensitive to thermal dispersivity equal to solute dispersivity. Amplitude ratios of temperature probe setups indirectly installed into piezometer pipes were influenced by thermal exchange processes within the pipes and significantly varied with water flux direction only. Temperature time lags of small sensor distances of all setups were found to be insensitive to vertical water flux. Y1 - 2011 U6 - https://doi.org/10.5194/hess-15-3495-2011 SN - 1027-5606 VL - 15 IS - 11 SP - 3495 EP - 3510 PB - Copernicus CY - Göttingen ER -