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Supermagnetic enhancement, superparamagnetism, and archaeological soils
Author(s) -
Peters Clare,
Thompson Roy
Publication year - 1999
Publication title -
geoarchaeology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 44
eISSN - 1520-6548
pISSN - 0883-6353
DOI - 10.1002/(sici)1520-6548(199906)14:5<401::aid-gea3>3.0.co;2-a
Subject(s) - superparamagnetism , ferrimagnetism , hysteresis , geology , rock magnetism , environmental magnetism , materials science , remanence , sediment , single domain , bedrock , magnetic hysteresis , mineralogy , grain size , magnetic mineralogy , magnetic domain , condensed matter physics , geomorphology , magnetization , magnetic field , physics , quantum mechanics
A range of mineral magnetic measurements have been carried out on archaeological sediments from Orkney and Cyprus. In a soil profile from Orkney, a magnetic enhancement factor of over 200 is observed in susceptibility data between the bedrock and a Norse sediment. The magnetic enhancement is associated with an increase in superparamagnetic grains probably caused by burning. Until now it has proved difficult to confirm the presence of superparamagnetic grains in natural samples using room temperature magnetic measurements. However, clear differences are to be found between the hysteresis loops of various magnetic domain states, including superparamagnetism. An algorithm has been developed to unmix hysteresis loops in terms of constituent domain states of ferrimagnetic iron oxides. Unmixing 128 hysteresis loops of archaeological sediments has shown that the dominant domain state in all sediments is superparamagnetic. Remarkably uniform superparamagnetic grain sizes of between 80 and 95 Å were found for all 128 sediments. © 1999 John Wiley & Sons, Inc.