Chemical denudation in arctic-alpine Latnjavagge (Swedish Lapland) in relation to regolith as assessed by radio magnetotelluric-geophysical profiles     

Achim A. Beylich  Else Kolstrup  Tage Thyrsted  Niklas Linde  Laust B. Pedersen  Lars Dynesius 《Geomorphology》2004,57(3-4):303-319

In Latnjavagge, a 9-km² drainage basin with homogeneous lithology in periglacial northern Swedish Lapland, water balance, water chemistry and radio magnetotelluric geophysical investigations along selected profiles were integrated with assessment of regolith thickness as well as of ground frost conditions within the basin. In combination with direct field observations, the geophysical profiles demonstrated presence of relatively thin regolith in most of the investigated area, yet in some parts, the bedrock was located deeper and locally was not detected at 40-m depth. TDS values of the water were generally very low. The areas that contributed with the lowest ion concentrations were cold and had a thin regolith, whereas there were higher concentrations in water that drained radiation exposed slopes with earlier thaw and thicker regolith. The low resistivities found along the profiles in the geophysical investigations in combination with the relatively higher TDS values found in related runoff and subsurface water samples showed that larger volumes of ice-rich frozen ground were not found along the investigated profiles in late August.  相似文献   

Factors affecting the electrification of wind-driven dust studied with laboratory simulations     

J.P. Merrison  H.P. Gunnlaugsson  M.R. Hogg  M. Jensen  J.M. Lykke  M.Bo Madsen  M.B. Nielsen  P. Nørnberg  T.A. Ottosen  R.T. Pedersen  S. Pedersen  A.V. Sørensen 《Planetary and Space Science》2012,60(1):328-335

The electrification of wind-blown dust grains was studied in a series of laboratory experiments to examine how grain electrification depends on grain size, grain mineralogy, atmospheric composition, atmospheric pressure, and the method of dust dispersal. This work is intended to contribute to a deeper physical understanding of particle electrification on both Mars and Earth. Findings indicate that the amount of electrification per suspended particle generally is independent of dust entrainment process and atmospheric composition. As expected, the electrification process is grain size-dependent, with smaller grains predominantly electrifying negatively. Although there appears to be a weak dependence upon dust mineralogy, this work supports the expectation that dust suspended in the Martian atmosphere will be significantly electrified.  相似文献   

Calibration of the New Certified Reference Materials ERM‐AE633 and ERM‐AE647 for Copper and IRMM‐3702 for Zinc Isotope Amount Ratio Determinations     

Kirsten Moeller  Ronny Schoenberg  Rolf‐Birger Pedersen  Dominik Weiss  Shuofei Dong 《Geostandards and Geoanalytical Research》2012,36(2):177-199

The commonly used, but no longer available, reference materials NIST SRM 976 (Cu) and ‘JMC Lyon’ (Zn) were calibrated against the new reference materials ERM^®‐AE633, ERM^®‐AE647 (Cu) and IRMM‐3702 (Zn), certified for isotope amount ratios. This cross‐calibration of new with old reference materials provides a continuous and reliable comparability of already published with future Cu and Zn isotope data. The Cu isotope amount ratio of NIST SRM 976 yielded δ^65/63Cu values of ?0.01 ± 0.05‰ and ?0.21 ± 0.05‰ relative to ERM^®‐AE633 and ERM^®‐AE647, respectively, and a δ^66/64Zn_IRMM‐3702 value of ?0.29 ± 0.05‰ was determined for ‘JMC Lyon’. Furthermore, we separated Cu and Zn from five geological reference materials (BCR‐2, BHVO‐2, BIR‐1, AGV‐1 and G‐2) using a two‐step ion‐exchange chromatographic procedure. Possible isotope fractionation of Cu during chromatographic purification and introduction of resin‐ and/or matrix‐induced interferences were assessed by enriched ⁶⁵Cu isotope addition. Instrumental mass bias correction for the isotope ratio determinations by MC‐ICP‐MS was performed using calibrator‐sample bracketing with internal Ni doping for Cu and a double spike approach for Zn. Our results for the five geological reference materials were in very good agreement with literature data, confirming the accuracy and applicability of our analytical protocol.  相似文献   

Surface wave effects on water temperature in the Baltic Sea: simulations with the coupled NEMO-WAM model   总被引：1，自引：1，他引：0  

Victor Alari  Joanna Staneva  Øyvind Breivik  Jean-Raymond Bidlot  Kristian Mogensen  Peter Janssen 《Ocean Dynamics》2016,66(8):917-930

  相似文献   

Estimating magnetic dike parameters using a non‐linear constrained inversion technique: an example from the Särna area,west central Sweden     

Majid Beiki  Laust B. Pedersen 《Geophysical Prospecting》2012,60(3):526-538

In this paper, we describe a non‐linear constrained inversion technique for 2D interpretation of high resolution magnetic field data along flight lines using a simple dike model. We first estimate the strike direction of a quasi 2D structure based on the eigenvector corresponding to the minimum eigenvalue of the pseudogravity gradient tensor derived from gridded, low‐pass filtered magnetic field anomalies, assuming that the magnetization direction is known. Then the measured magnetic field can be transformed into the strike coordinate system and all magnetic dike parameters – horizontal position, depth to the top, dip angle, width and susceptibility contrast – can be estimated by non‐linear least squares inversion of the high resolution magnetic field data along the flight lines. We use the Levenberg‐Marquardt algorithm together with the trust‐region‐reflective method enabling users to define inequality constraints on model parameters such that the estimated parameters are always in a trust region. Assuming that the maximum of the calculated g_zz (vertical gradient of the pseudogravity field) is approximately located above the causative body, data points enclosed by a window, along the profile, centred at the maximum of g_zz are used in the inversion scheme for estimating the dike parameters. The size of the window is increased until it exceeds a predefined limit. Then the solution corresponding to the minimum data fit error is chosen as the most reliable one. Using synthetic data we study the effect of random noise and interfering sources on the estimated models and we apply our method to a new aeromagnetic data set from the Särna area, west central Sweden including constraints from laboratory measurements on rock samples from the area.  相似文献   

Comment on “Depth Estimation of Simple Causative Sources from Gravity Gradient Tensor Invariants and Vertical Component” by B. Oru? in Pure Appl. Geophys. 167 (2010), 1259–1272     

Majid Beiki  Laust B. Pedersen 《Pure and Applied Geophysics》2012,169(1-2):275-277

  相似文献   

Interpreting magnetic data by integral moments     

F. Caratori Tontini  L. B. Pedersen 《Geophysical Journal International》2008,174(3):815-824

The use of the integral moments for interpreting magnetic data is based on a very elegant property of potential fields, but in the past it has not been completely exploited due to problems concerning real data. We describe a new 3-D development of previous 2-D results aimed at determining the magnetization direction, extending the calculation to second-order moments to recover the centre of mass of the magnetization distribution. The method is enhanced to reduce the effects of the regional field that often alters the first-order solutions. Moreover, we introduce an iterative correction to properly assess the errors coming from finite-size surveys or interaction with neighbouring anomalies, which are the most important causes of the failing of the method for real data. We test the method on some synthetic examples, and finally, we show the results obtained by analysing the aeromagnetic anomaly of the Monte Vulture volcano in Southern Italy.  相似文献   

On the Fringe of Neoliberalism: residential development in outer suburban Sydney     

Dr Nicole Cook  Kristian Ruming 《The Australian geographer》2008,39(2):211-228

Although there is widespread consensus in human geography that neoliberalism is achieved through the intersection of multiple scales and states, there has been growing emphasis in recent years on the hybrid qualities of neoliberalist-styles of governance. Because hybrid approaches draw attention to the wide range of actors and contradictory agendas underpinning the always uneven expression of neoliberalist projects, they are particularly suited to the identification of residual state capacities in contexts where neoliberalist forms dominate economic and political life. Drawing on two cases of large-scale residential development in New South Wales, namely Warnervale Town Centre on the New South Wales Central Coast and the Australian Defence Industry site at St Marys in Sydney's west, the present paper adopts an hybrid approach in order to identify current state capacities. Through a comparison of both sites, it identifies the potential for socially and ecologically balanced development in the outer suburban context.  相似文献   

Early Cambrian wave-formed shoreline deposits: the Hardeberga Formation,Bornholm, Denmark     

Clemmensen  Lars B.  Glad  Aslaug C.  Pedersen  Gunver K. 《International Journal of Earth Sciences》2017,106(6):1889-1903

International Journal of Earth Sciences - During the early Cambrian, the Danish island Bornholm was situated on the northern edge of the continent Baltica with palaeolatitudes of about 35°S....  相似文献   

Dune deformation in a multi‐directional wind regime: White Sands Dune Field,New Mexico          下载免费PDF全文

Anine Pedersen  Gary Kocurek  David Mohrig  Virginia Smith 《地球表面变化过程与地形》2015,40(7):925-941

As with most dune fields, the White Sands Dune Field in New Mexico forms in a wind regime that is not unimodal. In this study, crescentic dune shape change (deformation) with migration at White Sands was explored in a time series of five LiDAR‐derived digital elevation models (DEMs) and compared to a record of wind direction and speed during the same period. For the study period of June 2007 to June 2010, 244 sand‐transporting wind events occurred and define a dominant wind mode from the SW and lesser modes from the NNW and SSE. Based upon difference maps and tracing of dune brinklines, overall dune behavior consists of crest‐normal migration to the NE, but also along‐crest migration of dune sinuosity and stoss superimposed dunes to the SE. The SW winds are transverse to dune orientations and cause most forward migration. The NNW winds cause along‐crest migration of dune sinuosity and stoss bedforms, as well as SE migration of NE‐trending dune terminations. The SSE winds cause ephemeral dune deformation, especially crestal slipface reversals. The dunes deform with migration because of differences in dune‐segment size, and differences in the lee‐face deposition rate as a function of the incidence angle between the wind direction and the local brinkline orientation. Each wind event deforms dune shape, this new shape then serves as the boundary condition for the next wind event. Shared incidence‐angle control on dune deformation and lee‐face stratification types allows for an idealized model for White Sands dunes. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献