Regional and local variations in the emerging economic landscape of the new German Länder     

Philip N. Jones  Trevor Wild 《Applied geography (Sevenoaks, England)》1997,17(4):283-299

Events in eastern Germany since 1989 pose major challenges for geographical interpretation. This paper examines the spatial impacts of the post-unification economic and social upheavals in the new Länder. Using unemployment rates as a key indicator of regional differentiation, spatial variability within the new Länder is examined in terms of two fundamental dimensions. First, the relationship with former patterns of economic specialization is explored, and secondly, the effects of basic geographical properties such as settlement structure, location and peripherality. Prominent regional polarities are described, notably between major agglomeration cores and rural residuals, and between ‘bridgehead’ locations and less-accessible districts. Within this context the paper then identifies some ‘green shoots’ of recovery and new growth. It concludes by emphasizing the importance of incorporating sub-regional variations into any new framework of regional policy.  相似文献   

Geochemical characteristics of lavas from Broken Ridge, the Naturaliste Plateau and southernmost Kerguelen Plateau: Cretaceous plateau volcanism in the southeast Indian Ocean   总被引：3，自引：0，他引：3  

J. J. Mahoney  W. B. Jones  F. A. Frey  V. J. M. Salters  D. G. Pyle  H. L. Davies 《Chemical Geology》1995,120(3-4):315-345

Lavas from several major bathymetric highs in the eastern Indian Ocean that are likely to have formed as Early to Middle Cretaceous manifestations of the Kerguelen hotspot are predominantly tholeiitic; so too are glass shards from Eocene to Paleocene volcanic ash layers on Broken Ridge, which are believed to have come from eruptions on the Ninetyeast Ridge. The early dominance of tholeiitic compositions contrasts with the more recent intraplate, alkalic volcanism of the Kerguelen Archipelago. Isotopic and incompatible-element ratios of the plateau lavas are distinct from those of Indian mid-ocean ridge basalts; their Nd, Sr, ²⁰⁷Pb/²⁰⁴Pb and isotopic ratios overlap with but cover a much wider range than measured for more recent oceanic products of the Kerguelen hotspot (including the Ninetyeast Ridge) or, indeed, oceanic lavas from any other hotspot in the world. Samples from the Naturaliste Plateau and ODP Site 738 on the southern tip of the Kerguelen Plateau are particularly noteworthy, with ε_Nd(T) = − 13 to −7, (⁸⁷Sr/⁸⁶Sr)_T=0.7090 to 0.7130 and high ²⁰⁷Pb/²⁰⁴Pb relative to ²⁰⁶Pb/²⁰⁴Pb. In addition, the low-ε_Nd(T) Naturaliste Plateau samples are elevated in SiO₂ (> 54 wt%). In contrast to “DUPAL” oceanic islands such as the Kerguelen Archipelago, Pitcairn and Tristan da Cunha, the plateau lavas with extreme isotopic characteristics also have relative depletions in Nb and Ta (e.g., Th/Ta, La Nb > primitive mantle values); the lowest ε_Nd(T) and highest Th/Ta and La Nb values occur at sites located closest to rifted continental margins. Accepting a Kerguelen plume origin for the plateau lavas, these characteristics probably reflect the shallow-level incorporation of continental lithosphere in either the head of the early Kerguelen plume or in plume-derived magmas, and suggest that the influence of such material diminished after the period of plateau construction. Contamination of asthenosphere with the type of material affecting Naturaliste Plateau and Site 738 magmatism appears unlikely to be the cause of low-²⁰⁶Pb/⁰⁴Pb Indian mid-ocean ridge basalts. Finally, because isotopic data for the plateaus do not cluster or form converging arrays in isotope-ratio plots, they provide no evidence for either a quickly evolving, positive ε_Nd, relatively high-²⁰⁶Pb/²⁰⁴Pb plume composition, or a plume source dominated by mantle with ε_Nd of −3 to 0.  相似文献   

A quantitative methodology to extract regional magnetotelluric impedances and determine the dimension of the conductivity structure   总被引：1，自引：0，他引：1  

R. W. Groom  R. D. Kurtz  A. G. Jones  D. E. Boerner 《Geophysical Journal International》1993,115(3):1095-1118

A methodology to determine quantitatively the dimensionality of the dominant conducting structures and the resolution of the structural parameters in magnetotelluric data is presented. In addition, the method recovers the regional impedance responses when the regional structure can be characterized, at least approximately, as 1- or 2-D. The methodology is based upon three general models of the MT tensor, each of which has a distinct parameterization and physical interpretation. A weighted statistical residual describes quantitatively the fit of the model response to the data within the scatter of the measured data and hence permits: (1) tests of dimensionality, (2) determination of the appropriate strike angle, and (3) recovery of the regional responses.
The method has been tested extensively with synthetic data and proven to be successful. These synthetic studies give insight into the different physical parameterizations and the stability of the parameters determined. We describe and illustrate some of these synthetic studies. With field data, the methodology is not always as straightforward, but its application to a great many sites has proven valuable. Data from two closely spaced sites, which are both affected by strong but very different 3-D effects, are analysed to illustrate the geological significance of the results. The analyses reveal and recover regional responses within the data which indicate the presence of electrical anisotropy located deep in the crust and upper mantle. Analyses of the entire data set, of which these two form a part, confirm this finding.  相似文献   

Application of metal zoning to gold exploration in porphyry copper systems: reply to the comments of G.V. Albino     

Brian K. Jones 《Journal of Geochemical Exploration》1993,48(3)

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Shear strength analysis of grouted coal waste materials to improve mine outslope stability: a laboratory analysis     

J. R. Jones  T. E. Ackman 《Geotechnical and Geological Engineering》1990,8(3):227-240

Summary Slope stability problems exist within the Appalachian Basin as a result of the emplacement of coal mine waste materials on mine outslopes. Prevention or elimination of slope instability problems can be costly. In an attempt to test alternative methods of slope stabilization, the United States Bureau of Mines determined some physical characteristics and shear strengths of ungrouted and polyurethenegrouted samples of coal refuse, coal spoil and natural soils collected at a number of mine outslope sites in Pennsylvania and West Virginia. The particle size distribution, per cent field porosity, per cent field water content and shear strengths of the materials were determined in the laboratory. Fifty drained direct shear strength tests were performed with the sample materials using a 0.06 m³ shear box. Tests were done at field moisture, 100% saturation and grout-infused conditions. Normal loads of 103 kN m^–2, 206 kN m^–2 and 416 kN m^–2 were used. The grout-infused tests generally showed strength increases. An infinite slope model was used to demonstrate the potential effectiveness ofin situ grouting for a variety of field slope conditions. This modelling suggests thatin situ grouting has the potential of stabilizing slopes of up to 35° at depths of 14 m for refuse material and 30° at depths of 5 m for spoil and soil materials. The validity of these increases in material strength by grout injection will require field testing for confirmation.  相似文献   

Core-mantle interactions     

K. D. Aldridge  J. Bloxham  V. Dehant  D. Gubbins  R. Hide  J. Hinderer  K. A. Hutcheson  D. Jault  C. A. Jones  H. Legros  J. -L. Le Mouël  D. Lloyd  J. M. Wahr  K. A. Whaler  K. Zhang 《Surveys in Geophysics》1990,11(4):329-353

Several aspects of core-mantle interactions were considered during a Royal Astronomical Society Discussion Meeting on 12th May 1989, including modelling the geomagnetic field at the core surface, the morphology of the field between 1600 and 1820 AD, dynamo theory, Taylor's constraint, fluid motions at the top of the core that reproduce the observed secular variation, pressure coupling between the core and mantle and its geophysical consequences, topographic core-mantle coupling, angular momentum transfer at the core-mantle interface, the detection and implications of core oscillations, particularly those with associated fluctuations in the Earth's rotation rate, and the seismological determination of the core-mantle boundary topography from lateral inhomogeneities in the mantle.  相似文献   

Liquidas phase relationships in the system CaAl2Si2O8-NaAlSi3O8-KAlSi3O8-NaAlSiO4-KAlSiO4 atP(H2O)=5 kb     

Rhian H. Jones  W. S. MacKenzie 《Contributions to Mineralogy and Petrology》1989,102(1):78-92

Liquidus phase equilibria have been determined in the system CaAl₂Si₂O₈-NaAlSi₃O₈-KAlSi₃O₈-NaAlSiO₄-KAlSiO₄ (An-Ab-Or-Ne-Ks) at a pressure of water of 5 kb, for low anorthite contents. The main effects of increasing anorthite content on phase relationships in the system Ab-Or-Ne-Ks include the expansion of the plagioclase stability field towards the potassium-rich part of the system, and an accompanying contraction of the alkali feldspar, leucite, nepheline and kalsilite stability fields; and an increase in liquidus temperatures throughout most of the compositional range. Two quaternary invariant points have been identified in the system, one a reaction point between the fields of alkali feldspar, plagioclase, nepheline and kalsilite at approximately An₄, and the other probably a quaternary eutectic between the fields of alkali feldspar, plagioclase, leucite and kalsilite at approximately An₆. A shallow minimum trough in liquidus temperatures occurs on the two-feldspar surface, and this would be expected to control the paths of liquids cooling under equilibrium conditions. Phase relationships in this quaternary system have been applied to the interpretation of the histories of the potassium-rich rocks of the Roman Volcanic Region, Italy. Differentiation of the phonolitic series in this region may have occurred by two-feldspar fractionation.  相似文献   

The three faces of geological computer contouring     

Thomas A. Jones 《Mathematical Geology》1989,21(3):271-283

Three aspects of successful contouring with the computer are geologic interpretation, data, and the program or algorithm. All of these are important and must be considered jointly to combine good procedures with appropriate software, but interpretation is a critical requirement for mapping geologic variables. Several acceptable, though different, maps could be drawn with a given program and set of observations, so the map that best honors geologic concepts and interpretation is most desirable. Many computer-mapping projects are flawed because one of these three aspects is ignored.This paper points out how data handling and choice of an algorithm should be affected by geologic knowledge and interpretation, including: (a) data consisting of mixtures of populations should be handled with special methods, (b) the algorithm should allow calculation of values beyond the range of observed values, (c) mapping thickness of a unit that pinches out requires projection to negative values and special handling of zero-thickness data, and (d) mapping structure on two related horizons requires that the surfaces be dealt with jointly.  相似文献   

Anomalous isotopic compositions of Sr,Ar and O in the Mesozoic diabase dikes of Liberia,West Africa     

Renée Mauche  Gunter Faure  Lois M. Jones  Jochen Hoefs 《Contributions to Mineralogy and Petrology》1989,101(1):12-18

The Mesozoic diabase dikes of Liberia are tholeiites whose ⁸⁷Sr/⁸⁶Sr and ⁸⁷Rb/⁸⁶Sr ratios scatter widely on the Rb-Sr isochron diagram. The problem is attributed to differences in the initial ⁸⁷Sr/⁸⁶Sr ratios of these rocks which range from 0.70311 to 0.70792, assuming a uniform age of 186 Ma for the dikes and using (⁸⁷Rb)=1.42 × 10^–11y^–1. The range of values is similar to that observed in the Mesozoic basalt flows and dikes of other Gondwana continents.New whole-rock K-Ar dates confirm previous conclusions that the diabase dikes in the Liberian and Pan-African age provinces of Liberia absorbed extraneous ⁴⁰Ar after intrusion. Only the dikes in the Paynesville Sandstone have K-Ar dates that range from 117 Ma to 201 Ma and may not contain extraneous ⁴⁰Ar. However, dikes from all three age provinces of Liberia have elevated initial ⁸⁷Sr/⁸⁶Sr ratios. These results indicate that contamination with radiogenic ⁸⁷Sr occurred primarily before intrusion of the magma whereas the addition of extraneous ⁴⁰Ar occurred after emplacement and reflects the age and mineral composition of the country rock.The ¹⁸O values of the Liberian diabase range from +5.6/% to +9.10/% and correlate positively with initial ⁸⁷Sr/⁸⁶Sr ratios. The data can be modeled by fractional crystallization and simultaneous assimilation of crustal rocks by the magma. However, samples containing amphibole and biotite replacing pyroxene deviate from the Sr-O isotope trajectories of the model and appear to have been depleted in ¹⁸O and enriched in ⁸⁷Sr by interactions with groundwater at high temperature.Laboratory for Isotope Geology and Geochemistry Contribution No. 76  相似文献   

Concentration fluctuation data from dispersion experiments carried out in stable and unstable conditions     

Nils Mole  C. D. Jones 《Boundary-Layer Meteorology》1994,67(1-2):41-74

Experiments have been carried out to investigate the dispersion of plumes at short range in the atmospheric boundary layer during stable and unstable conditions. The experiments and measurement system are described, and the results are compared with those of previous experiments. The slow meandering under stable conditions found by Mylne (1992) is not present here (probably because of topographic effects), so the plume is present on the mean centreline more often, and timescales are shorter, under stable conditions. Associated with this, statistics during stable conditions exhibit greater stability to changes in total sampling time. Intensity is found to be greater under unstable conditions, but there do not appear to be large differences in the shape of the probability density function between stable and unstable conditions. The intermittency is calculated using several variations on the conventional definition. The values obtained vary substantially according to which definition is used (although they are always higher in the stable than in the unstable experiments), demonstrating the sensitivity to both the precise definition and to measurement system characteristics. It is shown that even at very short range the mean and variance of concentration are determined almost entirely by the fluid not emanating from the source. Thus the partition between source and non-source fluid suggested by Chatwin and Sullivan (1989), while providing a more scientifically sound definition of intermittency, does not have an obvious direct practical application.  相似文献