Open Access

Improvement of the secular variation curve of the geomagnetic field in Egypt during the last 6000 years

Earth, Planets and Space201451:BF03351606

DOI: 10.1186/BF03351606

Received: 14 July 1999

Accepted: 1 November 1999

Published: 20 June 2014

Abstract

A total of 115 ceramic specimens out of 41 samples from 9 archeological sites in Giza, Fayoum, Benisuef, El Minia, Malawy, and Sohag were collected. They represent 14 well-determined ages covering the last 6000 years. Rock magnetic properties such as Curie temperature and hysteresis loops have been measured for these samples to identify the magnetic carrier; it is found to be fine-grained magnetite. All specimens were investigated using the classic Thellier double heating technique (Thellier and Thellier, 1959) and the modification after Odah et al. (1995) to obtain the paleointensity data. These paleointensities and the previous results of Odah et al. (1995) were used to improve the secular variation curve of the geomagnetic field in Egypt for the last 6000 years. This curve shows a maximum of 72.8 µT at about 250 AD and a minimum of 33 µT at about 3500 BC. It also shows a general decrease of the magnetic moment during the last 2000 years.