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Volume 4 (2020): Edizione 2 (December 2020)

Volume 4 (2020): Edizione 1 (June 2020)

Volume 3 (2019): Edizione 2 (December 2019)

Volume 3 (2019): Edizione 1 (June 2019)

Dettagli della rivista
Formato
Rivista
eISSN
2521-2923
Pubblicato per la prima volta
30 Apr 2019
Periodo di pubblicazione
2 volte all'anno
Lingue
Inglese

Cerca

Volume 4 (2020): Edizione 2 (December 2020)

Dettagli della rivista
Formato
Rivista
eISSN
2521-2923
Pubblicato per la prima volta
30 Apr 2019
Periodo di pubblicazione
2 volte all'anno
Lingue
Inglese

Cerca

6 Articoli
access type Accesso libero

A Study of the Dynamics of Soil Erosion Using Rusle2 Modelling and Geospatial Tool in Edda-Afikpo Mesas, South Eastern Nigeria

Pubblicato online: 05 Jan 2021
Pagine: 56 - 71

Astratto

Abstract

The Revised Universal Soil Loss Equation (RUSLE) was used to study the soil erosion processes in Edda-Afikpo mesas, Lower Cross River watersheds,Nigeria. The mesas occupy an area estimated at 60km2 on a surface relief of about 284m. DEM data, satellite images and basemap of the area were used. Remotely sensed data were ground-truthed through extensive field works. The results show that the process is facilitated by the Trifecta of hill slope hydrology, geology and land use practices. Steep hill Slope of values 78 % at the major hot spots, very fragile, dry and non-plastic sandy soils all aid sediment detachment. Analysis of the index properties which include Liquid Limit(LL) of 25-30,moisture content(w%) of 5.9-7.4,permeability of 1.541x10-3 – 1.636x10-3 cm/s and shear strength of 36-42 KN/m2 predispose the sediments to detachment and erosion. Based on the analysis, the amount of soil loss in the project area is about 1373.79 ton per year. Soil erosivity factor is high at the mesas(5023.83 MJ mm ha−1 h−1 yr−1 - 5069.51 MJ mm ha−1 h−1 yr−1) The sandy layer attain thickness of 50m-60m in places and with high pore pressure development, slope failure are triggered during intense storm events. In terms of vulnerability level in erosion risk, high to very high constitute 4.1% of the watershed which translate to 5.05km2 of the 59km2. The various processes occur simultaneously and are exacerbated by human factors through seasonal bush burning and development along drainage lines. The study reveals that 18.8% of the available land for development is at high to very high risk of erosion. The soil loss model has been validated and the hotspots from the map coincide with the gully sites. The results of this research can therefore be used for conservation and adaptation purposes.

Parole chiave

  • Land use
  • GIS
  • landscape
  • Hydrology
  • soil erosion
  • model
access type Accesso libero

Geology and Petrology of Omzha Block, Zhob Ophiolite, northern Balochistan, Pakistan

Pubblicato online: 05 Jan 2021
Pagine: 72 - 80

Astratto

Abstract

The Zhob Ophiolite is divided into three detached blocks including the Omzha block. The Omzha block is mapped and divided into lithological units such as ultramafic rock, mafic-felsic rock, and volcanic–volcaniclastic–pelagic rocks. These units are quite deformed and mixed up and are associated with one another by thrust faults. Petrography and geochemistry divide them into gabbro, diorite, plagiogranite, pheno-tephrite and trachy-andesite basalt, trachy basalt, chert, limestone, and mudstone. The ultramafic rocks are dominantly serpentinized harzburgite, dunite, and a minor lherzolite. Petrography of peridotite shows that it may be depleted in nature and may have residual after processes such as partial melting and the melt-rock reaction of a lherzolitic source. The gabbroic rocks are less well-developed and highly deformed. They are cross-cut by diorite, plagiogranite and anorthosite’ intrusions. The gabbro may be the plutonic section of Omzha block’ crust while the intermediate-felsic igneous rocks may have formed by the anataxis of crustal gabbro. The volcanic–volcaniclastic–pelagic rocks unit may be corrected with Bagh complex found underneath the Muslim Bagh Ophiolite. The metamorphic sole rocks of Omzha block are highly deformed and dismembered are comprising of metamorphic facies such as amphibolite, quartz-mica schist, and greenschist.

Parole chiave

  • Ophiolitic mélange
  • ultramafic rocks
  • gabbro
  • plagiogranite
  • volcanics- volcaniclastics. metamorphic sole rocks
access type Accesso libero

Land Seismic Multiples Detection and Attenuation In Bornu-Chad Basin, Nigeria

Pubblicato online: 05 Jan 2021
Pagine: 81 - 89

Astratto

Abstract

Three dimensional (3D) seismic survey was acquired and processed in Bornu-Chad basin, Nigeria with the aim of detecting and attenuating multiples to aid proper imaging of the subsurface. The 25.5km2 volume was processed using SeisUp processing software on a 32-Node Cluster Infrastructure (CI) hardware. Considering the imaging objectives and depth of interest of 1.2s-4.5s, the minimum, middle and maximum offsets were set at 500-2300m, 2500-4300m and 4500-7300m respectively. Since the study area comprised of dry open land and swampy Lake Chad, vibroseis and dynamite sources were used respectively. Charge depth was 0m (surface) for vibroseis and 25m dynamite. The dataset was first pre-conditioned, normalized, regularized before application of demultiple process. The detection and demultiple processes based on multiple characteristics of periodicity and velocity discrimination were applied as the multiples have comparable velocity with the primaries. The near-surface reverberations and short-period multiples were attenuated using predictive deconvolution and radon transform algorithms. High resolution radon was performed on post-migrated common-mid-point (CMP) gathers and stacked with 1kmx1km target line velocities. Internal multiples were detected and attenuated using data-driven methodology of extended internal multiple prediction (XIMP). Multiples detected were short, long period and interbed multiples on all frequencies ranges of 0 – 90Hz but useful seismic frequency range was between 20Hz and 70Hz. The frequencies and amplitudes of the primaries and multiples were very comparable, therefore great care was taken in the attenuation processes. The results of this work has produced better seismic section for interpretation of subsurface geology in the study area.

Parole chiave

  • seismic
  • multiple
  • amplitudes
  • detection
  • attenuation
  • Bornu-Chad Basin
  • Nigeria
access type Accesso libero

Sandstone Composition and Provenance of the Nari Formation, Central Kirthar Fold belt, Pakistan

Pubblicato online: 05 Jan 2021
Pagine: 90 - 96

Astratto

Abstract

The Oligocene-Early Miocene Nari Formation is widely distributed in the Kirthar thrust-fold belt. The formation in the study area is mainly consist of sandstone and shale. Field observations and detailed petrographic study reveal that these sandstones are mostly fine to medium grained, subangular to subrounded and poorly to moderately sorted. Detrital grains are dominantly quartz ranging in proportion 36-76%, feldspar 7-17% and lithic grains 1-13%, reflecting that these sandstones are compositionally submature. Quartz is mostly monocrystalline with some polycrystalline grains. Feldspar is dominantly plagioclase (albite) with some alkali feldspar (orthoclase and microcline). Lithic fragments are siltstone, mudstone and chert. Biotite and muscovite are present as accessory minerals. Heavy minerals such as apatite, tourmaline, and zircon are present in trace amount. The QFL diagrams show that the sandstones of the Nari formation are subarkose and lithic subarkose. The QtFL, QmFLt ternary diagrams and paleocurrent direction suggest that the sediments were transported from the Indian shield exposed to the northeast of the Nari Basin.

Parole chiave

  • Petrography
  • Provenance
  • Nari Formation
  • Kirthar Fold Belt
  • Indian Sheild
access type Accesso libero

A Review of Electrical Methods as A Worthy Tool for Mineral Exploration

Pubblicato online: 05 Jan 2021
Pagine: 97 - 100

Astratto

Abstract

This paper focuses on the review of electrical geophysical methods such as electrical resistivity and induced polarization as a technique for mineral exploration. It highlights the general fundamental principles of the electrical methods and result from other investigations. Most rock – forming minerals are insulators, and electrical current is carried through rocks mainly by the passage of ions in pore waters. In light of this, most rocks conduct electricity by electrolytic rather than electronic processes. Since metals and most metallic sulphides conduct electricity efficiently by the flow of electrons, electrical method is efficient and important in environmental investigation especially in areas where metallic objects are the targets and also in the search for sulphide ores. The results from various research showed the applicability of these geophysical ground methods, specially the Induce Polarization method, as a support tool in the identification and selection of exploration targets for test drilling.

Parole chiave

  • Electrical resistivity
  • Induced polarization
  • chargeability
  • sulphide ores
access type Accesso libero

Subsurface Cavity Detection Using Electrical Resistivity Tomography (Ert); A Case Study from Southern Quetta, Pakistan

Pubblicato online: 05 Jan 2021
Pagine: 101 - 105

Astratto

Abstract

Dipole-dipole electrical resistivity tomographic method was applied to investigate the subsurface cavities at Staff Welfare Hospital & School Quetta. A total of 890-meter profile line was covered along five smaller profile lines and fracture zones with maximum 21 meters interval. The cavity system along profile line-1 and 2 was very restricted and had no direct impact on infrastructure while major cavity beneath the building was traced at profile line-3 and line-4 thus constituting a ~20m wide cavity system with 3-4 small interconnected cavities between depths of 7 to 21 meters. This system was also traced at profile line-4 at a depth of 10 meters having a reduced width of 10m. At profile line-5, a few other cavities were detected that proved imperceptible due to limitations in data acquisition. To conclude, the cavity systems traced in profile line-3 and profile line-4 were the most perilous ones and are commonly the foremost reason for building collapse.

Parole chiave

  • Natural disaster
  • Quetta Valley
  • Geophysical Techniques
6 Articoli
access type Accesso libero

A Study of the Dynamics of Soil Erosion Using Rusle2 Modelling and Geospatial Tool in Edda-Afikpo Mesas, South Eastern Nigeria

Pubblicato online: 05 Jan 2021
Pagine: 56 - 71

Astratto

Abstract

The Revised Universal Soil Loss Equation (RUSLE) was used to study the soil erosion processes in Edda-Afikpo mesas, Lower Cross River watersheds,Nigeria. The mesas occupy an area estimated at 60km2 on a surface relief of about 284m. DEM data, satellite images and basemap of the area were used. Remotely sensed data were ground-truthed through extensive field works. The results show that the process is facilitated by the Trifecta of hill slope hydrology, geology and land use practices. Steep hill Slope of values 78 % at the major hot spots, very fragile, dry and non-plastic sandy soils all aid sediment detachment. Analysis of the index properties which include Liquid Limit(LL) of 25-30,moisture content(w%) of 5.9-7.4,permeability of 1.541x10-3 – 1.636x10-3 cm/s and shear strength of 36-42 KN/m2 predispose the sediments to detachment and erosion. Based on the analysis, the amount of soil loss in the project area is about 1373.79 ton per year. Soil erosivity factor is high at the mesas(5023.83 MJ mm ha−1 h−1 yr−1 - 5069.51 MJ mm ha−1 h−1 yr−1) The sandy layer attain thickness of 50m-60m in places and with high pore pressure development, slope failure are triggered during intense storm events. In terms of vulnerability level in erosion risk, high to very high constitute 4.1% of the watershed which translate to 5.05km2 of the 59km2. The various processes occur simultaneously and are exacerbated by human factors through seasonal bush burning and development along drainage lines. The study reveals that 18.8% of the available land for development is at high to very high risk of erosion. The soil loss model has been validated and the hotspots from the map coincide with the gully sites. The results of this research can therefore be used for conservation and adaptation purposes.

Parole chiave

  • Land use
  • GIS
  • landscape
  • Hydrology
  • soil erosion
  • model
access type Accesso libero

Geology and Petrology of Omzha Block, Zhob Ophiolite, northern Balochistan, Pakistan

Pubblicato online: 05 Jan 2021
Pagine: 72 - 80

Astratto

Abstract

The Zhob Ophiolite is divided into three detached blocks including the Omzha block. The Omzha block is mapped and divided into lithological units such as ultramafic rock, mafic-felsic rock, and volcanic–volcaniclastic–pelagic rocks. These units are quite deformed and mixed up and are associated with one another by thrust faults. Petrography and geochemistry divide them into gabbro, diorite, plagiogranite, pheno-tephrite and trachy-andesite basalt, trachy basalt, chert, limestone, and mudstone. The ultramafic rocks are dominantly serpentinized harzburgite, dunite, and a minor lherzolite. Petrography of peridotite shows that it may be depleted in nature and may have residual after processes such as partial melting and the melt-rock reaction of a lherzolitic source. The gabbroic rocks are less well-developed and highly deformed. They are cross-cut by diorite, plagiogranite and anorthosite’ intrusions. The gabbro may be the plutonic section of Omzha block’ crust while the intermediate-felsic igneous rocks may have formed by the anataxis of crustal gabbro. The volcanic–volcaniclastic–pelagic rocks unit may be corrected with Bagh complex found underneath the Muslim Bagh Ophiolite. The metamorphic sole rocks of Omzha block are highly deformed and dismembered are comprising of metamorphic facies such as amphibolite, quartz-mica schist, and greenschist.

Parole chiave

  • Ophiolitic mélange
  • ultramafic rocks
  • gabbro
  • plagiogranite
  • volcanics- volcaniclastics. metamorphic sole rocks
access type Accesso libero

Land Seismic Multiples Detection and Attenuation In Bornu-Chad Basin, Nigeria

Pubblicato online: 05 Jan 2021
Pagine: 81 - 89

Astratto

Abstract

Three dimensional (3D) seismic survey was acquired and processed in Bornu-Chad basin, Nigeria with the aim of detecting and attenuating multiples to aid proper imaging of the subsurface. The 25.5km2 volume was processed using SeisUp processing software on a 32-Node Cluster Infrastructure (CI) hardware. Considering the imaging objectives and depth of interest of 1.2s-4.5s, the minimum, middle and maximum offsets were set at 500-2300m, 2500-4300m and 4500-7300m respectively. Since the study area comprised of dry open land and swampy Lake Chad, vibroseis and dynamite sources were used respectively. Charge depth was 0m (surface) for vibroseis and 25m dynamite. The dataset was first pre-conditioned, normalized, regularized before application of demultiple process. The detection and demultiple processes based on multiple characteristics of periodicity and velocity discrimination were applied as the multiples have comparable velocity with the primaries. The near-surface reverberations and short-period multiples were attenuated using predictive deconvolution and radon transform algorithms. High resolution radon was performed on post-migrated common-mid-point (CMP) gathers and stacked with 1kmx1km target line velocities. Internal multiples were detected and attenuated using data-driven methodology of extended internal multiple prediction (XIMP). Multiples detected were short, long period and interbed multiples on all frequencies ranges of 0 – 90Hz but useful seismic frequency range was between 20Hz and 70Hz. The frequencies and amplitudes of the primaries and multiples were very comparable, therefore great care was taken in the attenuation processes. The results of this work has produced better seismic section for interpretation of subsurface geology in the study area.

Parole chiave

  • seismic
  • multiple
  • amplitudes
  • detection
  • attenuation
  • Bornu-Chad Basin
  • Nigeria
access type Accesso libero

Sandstone Composition and Provenance of the Nari Formation, Central Kirthar Fold belt, Pakistan

Pubblicato online: 05 Jan 2021
Pagine: 90 - 96

Astratto

Abstract

The Oligocene-Early Miocene Nari Formation is widely distributed in the Kirthar thrust-fold belt. The formation in the study area is mainly consist of sandstone and shale. Field observations and detailed petrographic study reveal that these sandstones are mostly fine to medium grained, subangular to subrounded and poorly to moderately sorted. Detrital grains are dominantly quartz ranging in proportion 36-76%, feldspar 7-17% and lithic grains 1-13%, reflecting that these sandstones are compositionally submature. Quartz is mostly monocrystalline with some polycrystalline grains. Feldspar is dominantly plagioclase (albite) with some alkali feldspar (orthoclase and microcline). Lithic fragments are siltstone, mudstone and chert. Biotite and muscovite are present as accessory minerals. Heavy minerals such as apatite, tourmaline, and zircon are present in trace amount. The QFL diagrams show that the sandstones of the Nari formation are subarkose and lithic subarkose. The QtFL, QmFLt ternary diagrams and paleocurrent direction suggest that the sediments were transported from the Indian shield exposed to the northeast of the Nari Basin.

Parole chiave

  • Petrography
  • Provenance
  • Nari Formation
  • Kirthar Fold Belt
  • Indian Sheild
access type Accesso libero

A Review of Electrical Methods as A Worthy Tool for Mineral Exploration

Pubblicato online: 05 Jan 2021
Pagine: 97 - 100

Astratto

Abstract

This paper focuses on the review of electrical geophysical methods such as electrical resistivity and induced polarization as a technique for mineral exploration. It highlights the general fundamental principles of the electrical methods and result from other investigations. Most rock – forming minerals are insulators, and electrical current is carried through rocks mainly by the passage of ions in pore waters. In light of this, most rocks conduct electricity by electrolytic rather than electronic processes. Since metals and most metallic sulphides conduct electricity efficiently by the flow of electrons, electrical method is efficient and important in environmental investigation especially in areas where metallic objects are the targets and also in the search for sulphide ores. The results from various research showed the applicability of these geophysical ground methods, specially the Induce Polarization method, as a support tool in the identification and selection of exploration targets for test drilling.

Parole chiave

  • Electrical resistivity
  • Induced polarization
  • chargeability
  • sulphide ores
access type Accesso libero

Subsurface Cavity Detection Using Electrical Resistivity Tomography (Ert); A Case Study from Southern Quetta, Pakistan

Pubblicato online: 05 Jan 2021
Pagine: 101 - 105

Astratto

Abstract

Dipole-dipole electrical resistivity tomographic method was applied to investigate the subsurface cavities at Staff Welfare Hospital & School Quetta. A total of 890-meter profile line was covered along five smaller profile lines and fracture zones with maximum 21 meters interval. The cavity system along profile line-1 and 2 was very restricted and had no direct impact on infrastructure while major cavity beneath the building was traced at profile line-3 and line-4 thus constituting a ~20m wide cavity system with 3-4 small interconnected cavities between depths of 7 to 21 meters. This system was also traced at profile line-4 at a depth of 10 meters having a reduced width of 10m. At profile line-5, a few other cavities were detected that proved imperceptible due to limitations in data acquisition. To conclude, the cavity systems traced in profile line-3 and profile line-4 were the most perilous ones and are commonly the foremost reason for building collapse.

Parole chiave

  • Natural disaster
  • Quetta Valley
  • Geophysical Techniques

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