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Volume 3 Issue 3

September 2011

Issue of Open Geosciences

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Open Access September 23, 2011

A commentary on the shape of loess particles assuming a spatial exponential distribution for the cracks in quartz

John Howarth

Page range: 231-234

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Abstract

An important property of loess is a tendency to collapse on loading and wetting (hydroconsolidation) which can have serious consequences worldwide for civil engineering projects. Randomly generated particles are classified according to Zingg shape categories: disc, sphere, blade and rod. This paper differs from the previous by the same author [8] in that a uniform distribution is no longer assumed for the underlying spatial distribution. Randomly placed faults in the quartz mother-rock lead naturally to an exponential distribution for the linear dimension of the basic particle. Monte Carlo processes and analytical formulae are used to calculate the average dimensions for particles in the blade category, into which most loess has been shown to fall.

Open Access September 23, 2011

Partitioning between “wedge-top” river- and wave-dominated successions: an example from the late Tortonian — early Messinian Terravecchia Formation (NW Sicily)

Calogero Gugliotta

Page range: 235-259

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Abstract

Detailed field sedimentological and facies analyses have been performed in the Terravecchia Formation cropping out in NW Sicily, in order to differentiate and describe, for the first time, wave- and river-dominated shallow-marine (deltaic) siliciclastic successions. The latter were deposited filling syntectonic basins, developed between the late Tortonian and early Messinian time, within the wedge-top depozone of the Sicilian Foreland Basin System. It has been observed that river-dominated successions, recording the deposition of small fan-deltas are characterized by fining- to coarsening upward, transgressive-regressive sequences which were mostly deposited filling relatively narrow and often oversupplied basins. These basins were probably located in a proximal sector of the wedge-top depozone, closer to emergent sectors of the chain and probably sheltered from the main marine areas. Wavedominated successions, on the other hand, are characterized by upward fining, mostly transgressive sequences which were deposited filling wider basins open to major marine regions and located in a more distal position of the wedge-top depozone. The documented partitioning between river- and wave-dominated successions, as a function of the position of the sedimentary basin within the wedge-top depozone, is coherent with data from analyses of the deformational patterns of the Terravecchia Formation in this study area. Furthermore, the data here presented could be considered as a preliminary database for future characterization and analysis of siliciclastic reservoirs from Sicilian outcrop analogues.

Open Access September 23, 2011

Engineering-geological and geotechnical investigation for risk assessment

Moufida May, Mahmoud Dlala, Aouicha Bedday

Page range: 260-270

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Abstract

Before construction activities could begin, engineering geological and geotechnical investigations had to be approved in order to establish a map with suitable areas for safe construction. The example used in this study is Tunis City which has complex geology and geomorphology. The risk analysis was based on a large-scale land-suitability map that was prepared using Geographic Information Systems (GIS). The approach used in this study combined physical data with the geotechnical properties of Tunis City. The adopted methodology and analyses were performed to assess the risk of urban expansion and landscape management. Results are presented as a zoning map that shows the suitable area for safe extension of the urban area. The data used and multi-criterion analysis of geotechnical and geological data seems to be useful for similar case studies and the adopted methodology can be used successfully for identifying similar cities for risk assessment.

Open Access September 23, 2011

Geological and geomorphological problems caused by transportation and industry

Lorant David, Zoltan Ilyes, Zoltan Baros

Page range: 271-286

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Abstract

Alterations in topography due to the construction of transport infrastructure and industrial development are the results of rather complex processes. The impact of transport constructions upsetting (topographic) equilibrium is manifested in a relatively narrow strip, and, mostly, through producing abnormally steep slopes, in reducing relief stability. The earthworks for transport routes are themselves also landscape-forming factors whereas in the case of industrial developments, planation is usually mentioned. Topographic changes related to the construction of transport infrastructure and industrial development are discussed historically in this chapter. Among the direct impacts of the first are those related to the construction of Roman and Medieval roads, hollow roads in loess, public roads, motorways, railways, canals, tunnels and airports; while of the second are those of early mining and metallurgy, cellars, sludge reservoirs, slag cones and fly-ash reservoirs, cooling ponds, industrial parks, shopping centres and waste disposal sites. Of the indirect ones, an introduction is given to impacts of surface sealing, changes in runoff, the ‘waterfall effect,’ as well as to environmental impacts under permafrost conditions.

Open Access September 23, 2011

Limitation of petrographic indices in depositional environmental interpretation of coal deposits

Vinay Sahay

Page range: 287-290

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Abstract

Organic petrology based petrographic indices (Tissue Preservation Index and Gelification Index) is a widely utilized tool in the study of depositional palaeoenvironment of coal. Evaluation of these petrographic indices suggests that, at present, utilize only vitrinite/huminite and inertinite macerals to interpret depositional environment of coal. Liptinite group macerals have important depositional environment implications, but liptinite macerals have not been taken into account in earlier petrographic indices (TPI and GI) formulations. This article examines the limitation of TPI and GI, and proposes improved TPI and GI indices, including the liptinite and inertinite macerals having depositional environment significance.

Open Access September 23, 2011

Tracing depositional consequences of environmental radionuclides (137Cs and 210Pb) in Slovenian forest soils

Ryoko Fujiyoshi, Takayuki Yamaguchi, Naoki Takekoshi, Kazumasa Okamoto, Takashi Sumiyoshi, Ivan Kobal, Janja Vaupotič

Page range: 291-301

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Abstract

Depth distribution profiles of environmental radionuclides (137Cs and 210Pb) have been investigated in soil to elucidate the underlying environment of semi-natural temperate deciduous and/or coniferous forest soils in Slovenia (Žirovski vrh, Idrija, Kočevski Rog, Pohorie, Gorišnica and Rakitna). Surface enrichment of both nuclides was observed at all the sites investigated in this study, suggesting that the soils had undergone little natural or anthropogenic disturbance for at least the last several decades. Apparent annual burial rates of 137Cs (0.1–0.2 cm y−−1) were estimated to be about 1.3 times higher than those of 210Pb at individual sites of different lithology, which suggests strong affinity of 210Pb to soil organic matter. Variability of the vertical distribution profiles of these nuclides depends not only on “in situ” pedology but also on geographical and meteorological conditions, especially precipitation and wind direction.

Open Access September 23, 2011

U-Pb ID-TIMS age of the Tiksheozero carbonatite: expression of 2.0 Ga alkaline magmatism in Karelia, Russia

Fernando Corfu, Tamara Bayanova, Vladimir Shchiptsov, Natalia Frantz

Page range: 302-308

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Abstract

The Tiksheozero carbonatite in northern Russian Karelia is a transitional type between alkaline ultramafic — carbonatitic and alkaline gabbroic suites. The complex is dominated by pyroxenite with a variety of subordinate mafic and ultramafic phases and nepheline syenite. Carbonatite occurs in a main central body and in veins. In this study we have obtained a reliable age for the complex by single grain ID-TIMS U-Pb analyses of zircon and baddeleyite. The age of 1999 ± 5 Ma is important because it places the emplacement of the alkaline complexes in the context of craton-wide extension and break-up events which preceded the initiation of a major Paleoproterozoic orogenic cycle. The Paleoproterozoic age also emphasizes the fact that not all members of the Kola alkaline province are of Paleozoic age.

Open Access September 23, 2011

Comparison of recorded rainfall with quantitative precipitation forecast in a rainfall-runoff simulation for the Langat River Basin, Malaysia

Lawal Billa, Hamid Assilzadeh, Shattri Mansor, Ahmed Mahmud, Abdul Ghazali

Page range: 309-317

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Abstract

Observed rainfall is used for runoff modeling in flood forecasting where possible, however in cases where the response time of the watershed is too short for flood warning activities, a deterministic quantitative precipitation forecast (QPF) can be used. This is based on a limited-area meteorological model and can provide a forecasting horizon in the order of six hours or less. This study applies the results of a previously developed QPF based on a 1D cloud model using hourly NOAA-AVHRR (Advanced Very High Resolution Radiometer) and GMS (Geostationary Meteorological Satellite) datasets. Rainfall intensity values in the range of 3–12 mm/hr were extracted from these datasets based on the relation between cloud top temperature (CTT), cloud reflectance (CTR) and cloud height (CTH) using defined thresholds. The QPF, prepared for the rainstorm event of 27 September to 8 October 2000 was tested for rainfall runoff on the Langat River Basin, Malaysia, using a suitable NAM rainfall-runoff model. The response of the basin both to the rainfall-runoff simulation using the QPF estimate and the recorded observed rainfall is compared here, based on their corresponding discharge hydrographs. The comparison of the QPF and recorded rainfall showed R2 = 0.9028 for the entire basin. The runoff hydrograph for the recorded rainfall in the Kajang sub-catchment showed R2 = 0.9263 between the observed and the simulated, while that of the QPF rainfall was R2 = 0.819. This similarity in runoff suggests there is a high level of accuracy shown in the improved QPF, and that significant improvement of flood forecasting can be achieved through ‘Nowcasting’, thus increasing the response time for flood early warnings.

Open Access September 23, 2011

Perspective targeting CuAuMo porphyries of Romanian Carpathians: blind porphyry mineralization and its variable distal expression as vein and skarns

Serban Vlad

Page range: 318-335

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Abstract

Romania has a genuine accumulation of “blind” porphyry CuAuMo systems associated with Cu skarns or AuAg (PbZn) epithermal vein sets. Many such hidden structures were discovered inadvertently during state exploration based on local tradition that Romanian Carpathians are rich in vein and skarn ore types. Notable dichotomy between porphyries associated with peripheral skarns versus epithermal ores is expressed by age (Mesozoic versus Tertiary), precious metal content, alteration types and zoning, shape/size and extension of ore bodies. Preliminary conclusions on metallic/alteration assemblages around porphyries in addition to geophysical information about inferred deep-seated Alpine plutonism promote potential exploration vectors for what will be an increasingly important deposit type in the future.

Open Access September 23, 2011

Investigating vegetation biophysical and spectral parameters for detecting light to moderate grazing effects: a case study in mixed grass prairie

Xiaohui Yang, Xulin Guo

Page range: 336-348

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Abstract

Identifying effective vegetation biophysical and spectral parameters for investigating light to moderate grazing effects on grasslands improves management practices on grasslands. Using mixed grasslands as a case study, this paper compares responses of vegetation biophysical properties and spectral parameters derived from satellite images to grazing intensity, and identifies the suitable biophysical and spectral parameters to detect grazing effects in these areas. Biophysical properties including cover, canopy height and Leaf area index (LAI) were measured in three sites with different grazing managements and one benchmark site in 2008 and 2009 in Grasslands PlaceTypeNational Park and surrounding provincial pastures, Canada. Thirteen vegetation spectral indices, calculated by statistically combining different spectral information, were evaluated. The results indicate that canopy height and the ratio of photosynthetically active vegetation cover to non-photosynthetically active vegetation cover (PV/NPV) showed significant differences between ungrazed and grazed sites. All spectral vegetation indices except the canopy index (CI) show significant differences between grazing treatments. Red-Near infrared (Red-NIR) based vegetation indices, such as Modified Triangular Vegetation Index 1 (MTVI1), Soil-adjusted Vegetation Index (SAVI), are significantly correlated to the PV/NPV. Green/Mid-infrared (Green/MIR) related vegetation indices, i.e. Plant Senescence Reflectance Index (PRSI) and Normalized Canopy Index (NCI), show significant correlation with canopy height. Models based on a linear combination of MTVI1 and SAVI were developed for PV/NPV and PRSI and NCI for canopy height. Models that simulated PV/NPV and canopy height show significant correlations with grazing intensity, suggesting the feasibility of remote sensing to quantify light to moderate grazing effects in mixed grasslands.

About this journal

Open Geosciences is an open access, peer-reviewed journal publishing original research results from all fields of Earth Sciences. The aim of the journal is to become the premier source of high-quality research from all over the world. Open Geosciences is designed to facilitate the exchange of ideas between experienced and young researchers from different countries.

Aims and Scope

Subject areas suitable for publication include, but are not limited to, the following: Atmospheric Sciences, Geology, Geophysics, Geochemistry, Geography, Oceanography and Hydrology, Glaciology, Speleology, Volcanology, Soil Science, Palaeoecology, Geotourism, Geoinformatics, Geostatistics, Geoengineering, and Remote Sensing.