Recycled loesses – A micromorphological approach to the determination of local source areas of Weichselian loess

2013 ◽  
Vol 296 ◽  
pp. 241-250 ◽  
Author(s):  
Przemysław Mroczek
Keyword(s):  
Local Source ◽  
Source Areas

scholarly journals Seasonal provenance changes in present-day Saharan dust collected in and off Mauritania

2017 ◽  
Vol 17 (16) ◽  
pp. 10163-10193 ◽  
Author(s):  
Carmen A. Friese ◽  
Johannes A. van Hateren ◽  
Christoph Vogt ◽  
Gerhard Fischer ◽  
Jan-Berend W. Stuut
Keyword(s):  
Environmental Changes ◽  
Saharan Dust ◽  
Local Source ◽  
Trade Wind ◽  
Back Trajectory ◽  
Dust Source ◽  
Western Sahara ◽  
Source Areas ◽  
Source Regions ◽  
Dust Sources

Abstract. Saharan dust has a crucial influence on the earth climate system and its emission, transport and deposition are intimately related to, e.g., wind speed, precipitation, temperature and vegetation cover. The alteration in the physical and chemical properties of Saharan dust due to environmental changes is often used to reconstruct the climate of the past. However, to better interpret possible climate changes the dust source regions need to be known. By analysing the mineralogical composition of transported or deposited dust, potential dust source areas can be inferred. Summer dust transport off northwest Africa occurs in the Saharan air layer (SAL). In continental dust source areas, dust is also transported in the SAL; however, the predominant dust input occurs from nearby dust sources with the low-level trade winds. Hence, the source regions and related mineralogical tracers differ with season and sampling location. To test this, dust collected in traps onshore and in oceanic sediment traps off Mauritania during 2013 to 2015 was analysed. Meteorological data, particle-size distributions, back-trajectory and mineralogical analyses were compared to derive the dust provenance and dispersal. For the onshore dust samples, the source regions varied according to the seasonal changes in trade-wind direction. Gibbsite and dolomite indicated a Western Saharan and local source during summer, while chlorite, serpentine and rutile indicated a source in Mauritania and Mali during winter. In contrast, for the samples that were collected offshore, dust sources varied according to the seasonal change in the dust transporting air layer. In summer, dust was transported in the SAL from Mauritania, Mali and Libya as indicated by ferroglaucophane and zeolite. In winter, dust was transported with the trades from Western Sahara as indicated by, e.g., fluellite.

scholarly journals Determination of the rockfall source in an urban settlement area by using a rule-based fuzzy evaluation

2006 ◽  
Vol 6 (6) ◽  
pp. 941-954 ◽  
Author(s):  
H. Aksoy ◽  
M. Ercanoglu
Keyword(s):  
Field Studies ◽  
Fuzzy Evaluation ◽  
Hazard Map ◽  
Initiation Mechanism ◽  
Urban Settlement ◽  
Rule Based ◽  
Rockfall Hazard ◽  
Source Areas ◽  
The City

Abstract. The evaluation of the rockfall initiation mechanism and the simulation of the runout behavior is an important issue in the prevention and remedial measures for potential rockfall hazards in highway protection, in forest preservation, and especially in urban settlement areas. In most of the studies in the literature, the extent of the rockfall hazard was determined by various techniques basing on the selection of a rockfall source, generally defined as zones of rock bodies having slope angles higher than a certain value, proposed by general practice. In the present study, it was aimed to carry out a rule-based fuzzy analysis on the discontinuity data of andesites in the city of Ankara, Turkey, in order to bring a different and rather systematic approach to determine the source areas for rockfall hazard in an urban settlement, based on the discontinuity and natural slope features. First, to obtain rock source areas (RSAs), data obtained from the field studies were combined with a rule-based fuzzy evaluation, incorporating the altitude difference, the number of discontinuities, the number of wedges and the number of potential slides as the parameters of the fuzzy sets. After processing the outputs of the rule-based fuzzy system and producing the linguistic definitions, it could be possible to obtain potential RSAs. According to the RSA maps, 1.7% of the study area was found to have "high RSA", and 5.8% of the study area was assigned as "medium RSA". Then, potential rockfall hazard map was prepared. At the final stage, based upon the high and medium RSAs, 3.6% of the study area showed "high rockfall potential", while areal distribution of "medium rockfall potential" was found as 7.9%. Both RSA and potential rockfall hazard map were in accordance with the observations performed in the field.

scholarly journals The Tiskilwa Till, a Regional View of its Origin and Depositional Processes

1981 ◽  
Vol 2 ◽  
pp. 176-182 ◽  
Author(s):  
Susan Specht Wickham ◽  
W. Hilton Johnson
Keyword(s):  
Thermal Regime ◽  
Controlling Factor ◽  
Local Source ◽  
Source Areas ◽  
Depositional Processes ◽  
Red Color ◽  
Major Controlling Factor ◽  
Late Wisconsinan

The Tiskilwa Till Member of the Wedron Formation represents deposition by basal melt-outin the marginal area of the Laurentide ice sheetduring the Woodfordian (late-Wisconsinan) in Illinois. Distinctive characteristics include: a very thick, homogeneous till; relatively little ablation till; red color; sandy texture; illite content that is relatively low withrespect to other Woodfordian tills; and the presence of discontinuous basal zones of differing composition.Erosion and entrainment of debris from both distant and local source areas are evident in the Tiskilwa Jill. Basal thermal regime is suggested as a major controlling factor on the location of the zones of entrainment. The debris was homogenized en route to the margin and eventually was deposited as basal melt-out till near the margin. Deposition occurred within an interval of 6 ka or more during the first half of the Woodfordian.

A fast atom bombardment study of the lead isotope ratios in early nineteenth century Niagara Peninsula pottery glazes

1986 ◽  
Vol 64 (3) ◽  
pp. 488-491 ◽  
Author(s):  
Jack M. Miller ◽  
Timothy R. B. Jones ◽  
Tina Kenney ◽  
David W. Rupp ◽  
Brian N. Green ◽  
...  
Keyword(s):  
Nineteenth Century ◽  
Lead Isotope ◽  
Fast Atom Bombardment ◽  
Acid Leaching ◽  
Direct Analysis ◽  
Isotope Ratios ◽  
Local Source ◽  
Lead Isotope Ratios ◽  
Sedimentary Deposits

The application of fast atom bombardment (FAB) mass spectrometry to the determination of lead isotope ratios in nineteenth century pottery glazes from the Niagara Peninsula has been investigated with the aim of determining the source of the lead used in the glazes. Methods of sampling have been compared, including direct analysis of glass chips, analysis of powdered glaze scrapings, analysis of acid extracts of the former, and simple acid leaching of the surface of a piece of pottery. The latter method gave the best results. The FAB data, as obtained on an older mass spectrometer, can distinguish lead from igneous vs. sedimentary deposits, but is not adequate to determine specific mining locations. Although newer FAB instrumentation can narrow this range, the overlap of data from the Niagara Peninsula and England precludes a simple answer to the archeological question as to English vs. Canadian origin of the lead used in the Jordan pottery glazes. However, the data do suggest that the potter used a local source for the lead.

scholarly journals Clay minerals as provenance indicators in continental lacustrine sequences: the Leza Formation, early Cretaceous, Cameros Basin, northern Spain

Clay Minerals ◽  
2005 ◽  
Vol 40 (1) ◽  
pp. 79-92 ◽  
Author(s):  
J. Alonso-Azcárate ◽  
M. Rodas ◽  
J. F. Barrenechea ◽  
J. R. Mas
Keyword(s):  
Clay Mineral ◽  
Source Area ◽  
Local Source ◽  
Northern Spain ◽  
Source Areas ◽  
Kübler Index ◽  
Facies Associations ◽  
Mineral Assemblages ◽  
Cameros Basin

AbstractVariations in clay mineral assemblages, changes in Kübler index (KI), and the chemical composition of chlorites are used to identify source areas in the lacustrine materials in the Lower Cretaceous Leza Limestone Formation of the Cameros Basin, northern Spain. This formation has fairly homogeneous lithological characteristics and facies associations which do not allow for identification and characterization of local source areas. The Arnedillo lithosome of the Leza Limestone Formation contains a clay mineral association (Mg-chlorite, illite and smectite) indicative of its provenance. Chlorite composition and illite KI values indicate that these minerals were formed at temperatures higher than those reached by the Leza Formation which indicates its detrital origin. The similarity in the Mg-chlorite composition between the Arnedillo lithosome and the Keuper sediments of the area indicates that these materials acted as a local source area. This implies that Triassic sediments were exposed, at least locally, at the time of deposition of the Leza Formation. The presence of smectite in the Leza Formation is related to a retrograde diagenesis event that altered the Mg-chlorites in some samples.

scholarly journals Assessment of rockfall hazard on the steep-high slopes: Ermenek (Karaman, Turkey)

2016 ◽  
Author(s):  
Hidayet Taga ◽  
Kıvanç Zorlu
Keyword(s):  
Engineering Properties ◽  
Climatic Effects ◽  
Danger Zone ◽  
Safety Measures ◽  
Rockfall Hazard ◽  
Source Areas ◽  
Rock Bolting ◽  
Northern Side ◽  
The City

Abstract. Ermenek is one of the curious settlement areas because of its topographical features in Karaman (Turkey). The city is located in northern side of the very steep cliffs formed byjointed limestone which are suddenly increased from 1250 m to 1850 m. Moreover, these cliffs having almost 90° slope dip are the main rockfall source areas due to their lithologicalcharacteristics, climatic effects and engineering properties of rock units. Up to now, depending on rockfall events, almost 500 residences were damaged severely, and losses oflives were also recorded in Ermenek. The rockfall phonemon are initiated by discontinuities, lithological changes, weathering and freeze-thaw process in the study area. In this study,extensive fieldwork including determination of location and dimension of hanging, detached and already fallen blocks, a detailed discontinuity survey, description of geological,morphological and topographical characteristics was performed. Besides, rockfall hazard is evaluated by two-dimensional rockfall analyses along 10 profiles. During the rockfallanalyses; run out distance, bounce height, kinetic energy and velocity of various size of blocks for each profiles are determined by using RocFall v4.0 software. The results obtainedfrom rockfall analyses were used to map the areas possible rockfall hazard zones and rockfall source areas were interpreted. According to rockfall analysis, field study and laboratory testing, protective and preventiverecommendations can be suggested for the areas under rockfall threat. But, the most widely- known remedial measures in literature such as trenches, retaining walls (barrier), wiremeshes, cable/streching nets and rock bolting etc. are not sufficient in the study area, due to topographical, atmospheric and lithological features. For these reasons, firstly total evacuation of the danger zone should be applied and then hanging blocks in the reachablelocations can be removed taking safety measures in this area to make it safer for the living people.

scholarly journals Identifying urban sources as cause to elevated grass pollen concentrations using GIS and remote sensing

2012 ◽  
Vol 9 (10) ◽  
pp. 14217-14253 ◽  
Author(s):  
C. A. Skjøth ◽  
P. V. Ørby ◽  
T. Becker ◽  
C. Geels ◽  
V. Schlünssen ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Grass Pollen ◽  
Atmospheric Transport ◽  
Local Scale ◽  
Source Distribution ◽  
Local Source ◽  
Source Areas ◽  
Pollen Concentrations ◽  
Pollen Sources ◽  
The City

Abstract. We examine here the hypothesis that during flowering, the grass pollen concentrations at a specific site reflect the distribution of grass pollen sources within a few kilometres from this site. We perform this analysis on data from a measurement campaign in the city of Aarhus (Denmark) using three pollen traps and by comparing these observations with a novel inventory of grass pollen sources. The source inventory is based on a new methodology developed for urban scale grass pollen sources. The new methodology is believed to be generally applicable for the European area, as it relies on commonly available remote sensing data combined with management information for local grass areas. The inventory has identified a number of grass pollen source areas present within the city domain. The comparison of the measured pollen concentrations with the inventory shows that the atmospheric concentrations of grass pollen in the urban zone reflects the source areas identified in the inventory, and that these pollen sources that are found to affect the pollen levels are located near and within the city domain. The results also show that during days with peak levels of pollen concentrations, there is no correlation between the three urban traps and an operational trap located just 60 km away. This finding suggests that during intense flowering, the grass pollen concentration mirrors the local source distribution, and is thus a local scale phenomenon. Model simulations aiming at assessment of population exposure to pollen levels are therefore recommended to take into account both local sources and local atmospheric transport, and not rely only on describing regional to long-range transport of pollen. The derived pollen source inventory can be entered into local scale atmospheric transport models in combination with other components that simulates pollen release in order to calculate urban scale variations in the grass pollen load. The gridded inventory with a resolution of 14 m is therefore made available as supplementary material to this paper, and the verifying grass pollen observations are in additional available in tabular form.

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