Errors in measuring the percentage dry weight change of stone tablets

Portland Stone and Monks Park limestone tablets were used to assess weathering loss over a two-year study. Procedures involved in preparing tablets for exposure, attaching them to the exposure frame and reweighing might have influenced weight changes measured. The impact of each stage in the above procedures was tested to assess how much weight loss was generated and how significant the loss was comparing the two stone types and the final loss sustained upon weathering. Although all the procedures seem to produce a statistically insignificant amount of weight loss, the two stone types do respond differently to the procedures. This suggests that stone properties may be important in determining the accuracy with which tablets can be used to assess spatial patterns of weathering.     

Late Cenozoic surface uplift,basaltic volcanism,and incision by the River Tigris around Diyarbakır,SE Turkey

We document the staircase of terraces of the River Tigris in the Diyarbakır area of SE Turkey, in the northern Arabian Platform, and improve control on the ages of these terrace deposits by dating of overlying basalt flows using the unspiked K–Ar technique. These fluvial terraces are formed of polymict gravel, including clasts derived from the Anatolian metamorphic terrane farther north as well as of local basalt. At least 9 Tigris terraces have been recognised so far, the highest of which, ∼200 m above present river level, marks the local transition from stacked deposition to fluvial incision, the timing of which is bounded between the mid Late Miocene and the Middle Pliocene. Our K–Ar dating indicates a hiatus in fluvial incision in the late Early Pleistocene, as basalts dated to 1.22 ± 0.02 and 1.07 ± 0.03 Ma overlie Tigris gravels at very similar levels, ∼60–70 m above the present river. The lower terraces record the subsequent entrenchment of the modern Tigris valley following an increase in incision rates in the early Middle Pleistocene, evident from the disposition of younger basalt, dated to 0.43 ± 0.02 Ma, capping fluvial gravel only ∼21–22 m above the present river level. Numerical modelling can account for the observed uplift history, as the response to coupling between surface processes and induced flow in the lower crust, with the mobile lower-crust thin (∼5–7 km thick), consistent with the known presence of a thick layer of mafic underplating at the base of the crust beneath the Arabian Platform. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Fitness spaces and their potential for visualizing change in the physical landscape

The use of the metaphors of general fitness and N-K spaces can assist in the understanding of the development of the physical landscape. Different modes of change can be viewed as different types of movement in, and distortions of, these phase spaces. Visualized in this manner landscape change can be viewed as both channelized, constrained and random.     

Geochemical characterization, correlation, and optical dating of tephra in alluvial sequences of central western Argentina

The synthesis of paleoclimatic archives provided by loess and alluvial sequences of central Argentina has been hindered by the lack of a cohesive lithostratigraphic framework extending across the Chaco-Pampean plains and catchments of the Rios Desaguadero, Colorado, and Negro. This condition originates in part from the dearth of absolute chronological controls. The occurrence of discrete tephra layers across this region may provide an opportunity to address this deficiency if a tephrochronological framework can be established. The potential of such a project is assessed within the context of a pilot study constrained within alluvial sequences of central western Argentina proximal to potential source vents in the Southern Volcanic Zone. The intersite discrimination and correlation of tephra layers on a geochemical basis is examined, with indirect chronological control for the eruption of each generated by optical dating. Alluvial sediments on either side of each of five tephra units at a type site were dated using the optically stimulated luminescence of fine-silt-sized quartz, thus providing an age control on each tephra (ca. 24,000, 30,000, 32,000, 39,000, and 48,000 yr). The geochemical composition of each tephra was derived. Using these data, tephra layers at other sites in the study area were geochemically analyzed and, in instances of statistical concordance in major oxide structure, correlated to the type site and therefore ascribed ages. This methodology identified a further sixth volcanic event between ca. 24,000 and 30,000 yr not registered by type-site tephras. The extension of this initial tephrochronological framework beyond the alluvial sequences of central western Argentina is encouraged by the occurrence of geochemically distinct tephra verified and dated in this study.     

Timing of Variscan HP-HT metamorphism in the Moldanubian Zone of the Bohemian Massif: U-Pb SHRIMP dating on multiply zoned zircons from a granulite from the Dunkelsteiner Wald Massif, Lower Austria

In an attempt to better constrain the timing of Variscan HP-HT metamorphism in the SE Bohemian Massif we have dated zoned zircons from a garnet-kyanite granulite of granitic composition from the Dunkelsteiner Wald Massif, Lower Austria, by means of sensitive high-resolution ion microprobe (SHRIMP) technique. In order to combine isotopic information with crystal growth textures, CL and BSE images were systematically taken from the dated zircons. A characteristic threefold concentric zoning was found in many zircons. This involves pre-Variscan protolithic cores followed by two distinct metamorphic/anatectic overgrowth shells of Variscan age. The inner overgrowth shell is characterized by a weak CL but bright BSE signal, and yields high contents of uranium (0.1 to 0.2 wt.%). A pooled U-Pb Concordia age for this zone is 342.0?±?3.0?Ma (n?=?11, MSWD?=?0.12). The second, outer, overgrowth shell is always bright in the CL image, dark in the BSE image, and has generally low uranium contents (mostly <500?ppm). A pooled U-Pb Concordia age for this zone is 337.1?±?2.7?Ma (n?=?11, MSWD?=?0.22). These results imply that the Variscan HT crystallisation history of the Moldanubian granulites took place over a period of a few million years and was not an extremely rapid subduction-exhumation process. SHRIMP measurements in the protolithic cores yield a cluster of (sub)concordant ages between ??390 and 460?Ma and a few outliers at higher ages mostly represented by cores in cores. Core domains, which are large, homogeneous and with undisturbed igneous oscillatory zoning, yielded preferentially ages between 430 and 460?Ma. We therefore consider that granitic protolith formation took place at that time. The still older inner cores are interpreted as inherited into the granitic melt.     

Perception of urban retailing environments: An empirical analysis of consumer information and usage fields

This article reports on an empirical analysis of consumer information and usage fields in the city of Eindhoven. The main purposes of this study are to investigate the distance, sectoral and directional biases of these fields, to analyse whether the degree of biases is related to personal characteristics of consumers and to identify the factors of the basis on which a model which predicts the probability that a shopping centre will be known by consumers can be developed. The findings of the study suggest that strong distance, sectoral and directional biases are present in the information and usage fields of consumers and that no systematic relationships exist between these characteristics of information and usage fields and personal variables of consumers. Finally, the present studies suggests that a model which describes the formation of consumer choice sets should include spatial factors such as distance, size, intervening opportunities and direction towards the city centre.