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Depth to the bottom of the magnetic layer, crustal thickness, and heat flow in Africa: Inferences from gravity and magnetic data

Research Abstract

Data from the Earth Gravitational Model (EGM2008) and the Earth Magnetic Anomaly Grid (EMAG2) were used to develop a continental scale crustal thickness model for Africa, and to estimate the depth to the bottom of the magnetic layer (DBML) and the geothermal gradient and heat flow. The results are: (1) the estimated DBML from the magnetic data varies from ~23.0 to ~37.2 km. The shallowest DBML values are located in the northern, eastern, and western parts of the continent, whereas the deepest values are observed in the central and southern regions. (2) The estimated crustal thickness based on gravity data varies from ~29.9 km in the northern and western parts of Africa to ~48.0 km in its southern regions, with an average thickness of 35.1 km for the whole continent. (3) The estimated heat flow varies between high values of 46–59 mW/m2, observed in the northern, eastern, and western regions to low values of ~< 41 mW/m2, observed in the central and southern parts of the continent. (4) The geothermal gradient values vary between 14.5 and 23.6 °C/km (5) The East African rift zone is underlain by shallow DBML characterized by high heat flow values that vary between 42 and 59 mW/m2 (6) The heat flow anomalies in Egypt and Libya may be associated with the zone of the Pelusium megashear system, and it shows heat flow values that vary between 36.3 and 59.0 mW/m2. The current study has taken advantage of the availability of the EGM2008 and EMAG2 datasets to map crustal thickness variations and DBML beneath the continental landmass of Africa.

Research Authors
Ahmed Mohamed, Mohamed Al Deep
Research Date
Research Department
Research Journal
Journal of African Earth Sciences
Research Pages
104204
Research Rank
1
Research Vol
179
Research Year
2021

Optical and electrical properties of amorphous Sb2S3 thin films: Effect of the film thickness‏

Research Abstract

The antimony tri-sulphide (Sb2S3) films were prepared by thermal evaporation technique. Four thicknesses (300, 521, 643 and 789 nm) were investigated. X-ray diffraction (XRD) analysis showed the amorphous structure of Sb2S3 films. Optical analyses revealed that Sb2S3 films exhibited optical energy gap between (1.98–1.16 eV) relaying on the film thickness. The films absorption coefficient was found to be higher than 2 × 104 cm−1(above its related optical energy gap) which makes these films reliable absorbers in photovoltaic applications. Optical constants were analyzed using Swanipole's method. The dark dc conductivity measurements of Sb2S3 thin films were conducted in the temperature range 298–503 K. The conduction mechanize was analyzed via Mott's variable -range hopping in three dimensions model. The correlated conductivity mechanize with increasing film thickness changed from extended

Research Authors
مصطفى إبراهيم عبدالرحمن بودى
Research Date
Research Department
Research Journal
North-Holland
Research Year
2021
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