Archaeomagnetism and archaeomagnetic dating: principles and methods

Abstract

The direction and intensity of the Earth’s magnetic field oscillates in different time-scales. Variations within 1,7X 103 to 1X104 years are referred to as archaeomagnetic variations. They correspond to a part of the geomagnetic secular variation, have an internal origin (in the conductive fluid outer core), and are coherent over regions of ~200.000 km2. The study of the archaeomagnetic variations in different parts of the globe enables the construction of regional master curves. Well-constrained master curves allow the use of archaeomagnetic variations as a dating tool. The archaeomagnetic dating corresponds to the comparison of an archaeomagnetic data obtained from an archaeological artifact or structure to the master curve for the region of interest. In this paper, we present the basis of archaeomagnetism, the mechanisms by which archaeological artifacts, structures and geological material record the ancient magnetic field, and how the magnetic signal is measured and interpreted, as well as the principles of archaeomagnetic dating. Also discussed are the perspectives for archaeomagnetic studies in Brazil and its application as a dating technique in southern South America.