Rock magnetic property and paleointensity determination on historical Santorini lava flows

Simo Spassov, Jean Pierre Valet, Despina Kondopoulou, Irene Zananiri, Lluís Casas, Maxime Le Goff

Research output: Contribution to journalArticleResearchpeer-review

8 Citations (Scopus)

Abstract

Eight historical dacitic lava flows from Santorini with ages between 46 A.D. and 1950 A.D. (four of them within the past century) have been subjected to detailed rock magnetic analyses and various experiments of absolute paleointensity. Thermomagnetic measurements and acquisition of isothermal magnetization have revealed the presence of two physically distinct magnetic phases with Curie temperatures of 280°C and 500°C. In most of the samples, the second phase does not play a prominent role for the characteristic remanent magnetization, which is dominated by titanomagnetite. Magnetostatic interaction is very limited and does not considerably change upon heating. Back-field curve spectra indicate a good thermochemical stability of these dacitic lava samples, which is also supported by the absence of noticeable changes in the remanent coercive force prior heating to 450°C. Hysteresis measurements show typical pseudo-singledomain behavior without noticeable superparamagnetism. Such characteristics were favorable to conduct and to test the most widely used experimental approaches for absolute paleointensity determination. Despite a success rate of 38%, the microwave technique has provided rather scattered within-flow determinations. The results obtained from approaches involving alternating field demagnetization were biased by considerable differences between the NRM and the TRM coercive force spectra. We have also noticed that most determinations obtained by microwave heating differ from the historical field value at the site for the most recent flows. Last, techniques involving double-heating protocols were successful due to a dominant low Curie temperature phase with a narrow grain size distribution. The results were characterized by low dispersion and were found in good agreement with the historical field. Copyright 2010 by the American Geophysical Union.
Original languageEnglish
Article numberQ07006
JournalGeochemistry, Geophysics, Geosystems
Volume11
DOIs
Publication statusPublished - 1 Jul 2010

Keywords

  • Greece
  • Paleointensity
  • Rock magnetism
  • Santorini
  • Subaerial volcanics

Fingerprint Dive into the research topics of 'Rock magnetic property and paleointensity determination on historical Santorini lava flows'. Together they form a unique fingerprint.

Cite this