Image Segmentation for Hydrothermal Alteration Mapping Using PCA and Concentration–Area Fractal Model

Information extraction from processed remotely sensed images, in the case of missing initial spectra of pixels, can be a challenge for the users. In such situations, application of conventional methods based on spectral properties of pixels is impractical. We took advantage of the fractal theory for image segmentation of a principal component (PC) image for hydrothermal alteration mapping. The selected input images included short wave infrared bands of ASTER imagery covering the Darrehzar porphyry copper mine and surrounding areas with well-known hydrothermal alteration zones. Hydrothermal alteration like other geological processes can show spatial distribution with fractal properties. Principal component analysis was used to enhance hydrothermal alteration associated with the Darrehzar porphyry copper deposit. None of the resulting PCs were appropriate to portray clearly important alteration types in the study area. The PC1 image, which contains more than 98% of variance of the input bands, was selected for image segmentation using a digital number–area technique based on the established concentration–area fractal model. This technique was proposed based on frequency distributions and spatial correlation and variability of pixel values. The resulting hydrothermal alteration map indicates intense phyllic, weak phyllic, and propylitic as the main alteration types exposed at the surface of the Darrehzar area. In addition, the proposed technique delineated the phyllic zone in the exposed mine pit and a transition zone between inner phyllic and surrounding propylitic alteration zones. Field investigation and sampling in 23 locations including spectral measurements, XRD and thin section studies, confirmed the accuracy of the classified image by the proposed technique.     

Experimental investigation of density current patterns using dynamic fractal analysis

Density currents are caused by a difference in density,though low,of an entering fluid with the ambient fluid.This type of current is two-phased and found on riverbeds or in reservoirs behind dams,and is nonlinear in nature,complex,and sensitive to initial conditions.Fractal geometry is used as a powerful tool for studying complex natural phenomena.Using experimental studies and changes in inlet current conditions,the fractal and multi-fractal analyses of the interface between the density current and the ambient fluid were done.In addition,a search was made to find a possible connection between the nonlinear patterns.According to the results,with an increase in the inlet discharge and inlet density of the current the fractal dimension decreased.Further,the smaller the range of the singularity spectrum diagram was,i.e.,the more it was less than 0.34,the lower the system's tendency was to be multi-fractal,and the system sensitive to large local changes.In the interface between the density current and the ambient fluid,using the fractal dimension-based Richardson number could improve experimental data by 12.4%.Moreover,with an increase in the Richardson number,the Reynolds number of the current decreased.Further,upon considering the fractal dimension,the Reynolds number improved by 23%and a good correlation with a coefficient of determination of 0.76.     

Les granitoı̈des hercyniens post-collisionnels du Maroc oriental : une province magmatique calco-alcaline à shoshonitique

The post-collisional Hercynian granitoids crop out in the easternmost part of the Moroccan Hercynian belt. Petrographical and geochemical studies show a composition similarity in the various granitoids. The granitoids belong to per-aluminous and metaluminous magmatic associations. They have evolved according to a scheme similar to high-K calc-alkaline to shoshonitic associations. To cite this article: H. El Hadi et al., C. R. Geoscience 335 (2003).     

Prediction of Blast-Induced Ground Vibration in a Mine Using Relevance Vector Regression Optimized by Metaheuristic Algorithms

Natural Resources Research - Prediction of ground vibration induced by blasting operations is a crucial challenge to engineers working in surface mines. This study aims to assess the efficiency of...     

Utilization of bituminous limestone ash from EL-LAJJUN area for engineering applications

The following work aims at minimizing the environmental impact of the solid wastes (ash) that is produced after the utilization of the bituminous limestone in thermal power stations and /or retort processes. Limy ash has been prepared from the El-Lajjun bituminous limestone by direct combustion at 1,200, 950, and 525°C respectively. The laboratory tests have been selected with respect to construction needs and possible post construction conditions. Utilization of the various types of ash in the stabilization problematic soils from Jordan as brown soils and the clayey marl has revealed optimum results. The unconfined compressive strength of the parent brown soil and the clayey marl has been raised from 5 kg/cm² to 50 and 25 kg/cm², respectively. The CBR value has been raised from 4.5 to 150% for both problematic soil types. Various mortars and construction elements can be produced at normal room curing temperature without the use of ordinary Portland cement (OPC). Low quality sub-base and base course can be mixed with ash to produce cement treated base (CTB) and roller compacted concrete (RCC) without OPC. Durable pavements, embankments can be constructed with very long life and low cost. CTB and RCC utilizing ash can be used in dam construction instead of normal soil in earth fill dams. The high alkalinity of El-Lajjun ash is considered as a disadvantage to be utilized in normal concrete mixes for structural purposes. Ash only can be mixed with aggregates to produce lean concrete like for blinding purposes to be prepared for foundation activities.     

Challenges in financing public sector low-carbon initiatives: lessons from private finance for a school district in British Columbia,Canada

Governments are major investors in climate change mitigation, but aversion to public indebtedness has led to reliance on private finance to deliver public assets. Compounding this challenge, financing through Energy Service Contracts is ruled out by accounting rules. With public and traditional private funding avenues closed, government departments have sought contracts that do not disclose the full cost of borrowing, such as the Public–Private Partnership (PPP) described in this case study. We unpack the utility contract filed with the provincial regulator to show that circumventing budgetary constraints cost the Delta School Board (DSB) 8.75% per annum on borrowed private funds while public finance would have cost 4%pa. All levels of the public sector are keen to play their role in climate mitigation. Climate policy is about not passing our burden of unbridled fossil fuel use and greenhouse gas emissions to future generations. If we do not exempt public sector capital investments for decarbonization from deficit regulations, we risk passing an unnecessary economic burden to future generations.

Key policy insights

• Transition to a low-carbon economy requires public sector investments that exceed budget deficit regulations and political aversion in many jurisdictions;

• Private–Public Partnerships are currently viewed as the solution to this self-imposed fiscal constraint;

• PPPs without clear performance targets or contractual templates will expose less experienced public sector investors to high costs and emissions above expectations.

     

Preliminary studies on the primary production of north-west Persian Gulf during post-monsoon period

Primary productivity, chlorophyll-a and the euphotic zone depth were determined averagely as 161 mg C (m³ day)^–1, 3.48 mg m^–3 and 6.2 m, respectively, in the north-west Persian Gulf during the post monsoon period in 1975 and 1976.     

Characterization of natural hydrocarbon seepage in the South Caspian Sea off Iran using satellite SAR and geological data

Abstract

Two groups of oil slicks have been repeatedly detected in the Southern Caspian Sea, off Cape Sefidrud and close to the Iranian coast of the sea on the synthetic aperture radar (SAR) images acquired by the Sentinel-1A and Sentinel-1B satellites in April–June 2018. Analysis of the SAR images together with bathymetry, geological and geophysical data in geographic information system showed that these manifestations (oil slicks) visible on the sea surface have natural origin, related to the bottom seepage phenomenon and are associated with existing hydrocarbon system. Oil slicks are concentrated over the continental slope and related to local geological formations of the sedimentary cover having oil deposits related to paleo-delta of Sefidrud River. Our evidence shows that two seeps in this area are active and repeating. It is concluded that the SAR is an excellent tool for monitoring of seepage phenomenon. Moreover, results indicate that the use of remote methods to identify offshore natural oil seeps related to existing active petroleum system can be considered as a well-accepted approach to support oil and gas exploration in frontier areas such as the South Caspian Basin.