Mantle electrical conductivity profile of Niger delta region

作者：Obiora Daniel N^*; Okeke Francisca N; Yumoto K; Agha Stan O

来源：Journal of Earth System Science, 2014, 123(4): 827-835.

DOI：10.1007/s12040-014-0425-0

• Conductivity profile
• Niger delta
• solar quiet day current
• spherical harmonic analysis (SHA)
• mantle
• magnetic data

The mantle electrical conductivity-depth profile of the Niger delta region in Nigeria has been determined using solar quiet day ionospheric current (Sq). The magnetometer data obtained in 2010 from geomagnetic stations installed in Lagos by magnetic dataset (MAGDAS) in 2008 and data from magnetometers installed in some parts of Niger delta by Center for Basic Space Science, University of Nigeria, Nsukka, were employed in this study. Gauss spherical harmonic analysis (SHA) method was used to separate the internal and external field contributions to Sq current system. The result depicted that the conductivity profile rose steadily from about 0.032 S/m at a depth of 89 km to 0.041 S/m at 100 km and 0.09 S/m at 221 km. This high conductivity region agreed with the global seismic low velocity region, the asthenosphere. The conductivity profile continued increasing downward until it got to 0.157 S/m at a depth of about 373 km (close to the base of upper mantle), 0.201 S/m at 784 km and reached 0.243 S/m at a depth of 1179 km at the lower mantle.

• 出版日期2014-6