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EPSL, 2004, 229/1-2 pp. 31-43 .

A new three-axis vibrating sample magnetometer for continuous high-temperature magnetization measurements : Applications to paleo- and archeointensity determinations. Maxime LE GOFF and Yves GALLET. EPSL, 2004, 229/1-2 pp. 31-43.

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EPSL, 2004, 229/1-2 pp. 31-43 .

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  1. A new three-axis vibrating sample magnetometer for continuous high-temperaturemagnetization measurements : Applications to paleo- and archeointensity determinations Maxime LE GOFF and Yves GALLET EPSL, 2004, 229/1-2 pp. 31-43.

  2. Paleo- and archeointensity studiesare fastidious and often unproductive due to poor data quality • It is possible to make them fasterby measuring the magnetizationat high temperatures

  3. TRIAXE SENSOR

  4. High-temperature version of the Thellier and Thellier method revised by Coe must take into account the thermal dependence of the spontaneous magnetization

  5. High-Temperature Magnetization Measurements Heating Troom to T1 (H=0)

  6. High-Temperature Magnetization Measurements Heating T1 to T2 (H=0)

  7. High-Temperature Magnetization Measurements Cooling to T1 andHeating T1 to T2 (H=0)

  8. High-Temperature Magnetization Measurements Applying Hlab = 70µT

  9. High-Temperature Magnetization Measurements Cooling T2 to T1 (H = 70µT)

  10. High-Temperature Magnetization Measurements Hlab = 0µT

  11. High-Temperature Magnetization Measurements Heating T1 to T2 (H=0)

  12. Two possibilities to derive intensity data T2 = 450°C Ti T1 = 150°C TRM NRM Remaining NRM (1) and TRM (5) fractions between Ti and T2  R ratio Lost NRM (1’) and TRM (5’) fractions between T1 and Ti  R’ ratio R(Ti) = Hlab * 1(Ti) / 5(Ti) R’(Ti) = Hlab * 1’(Ti) / 5’(Ti)

  13. Test on a pseudo NRM acquired in a field of 50µT in the same conditions as the laboratory TRM (Hlab=50 µT)

  14. Ancient NRM : R increasing, R’ much more constant R, R’ (µT) Ti, (°C)

  15. Cooling rate effect R’ must be considered

  16. Correction for the TRM anisotropy

  17. Comparison between archeointensity data obtained from the Thellier and Thellier method revised by Coe and from the Triaxe (Samples from Mesopotamia previously studied by Genevey et al., JGR, 2003)

  18. Selection criteria • A large NRM fraction must be involved • Expected behaviour of R and R’ curves

  19. Example of rejected sample

  20. Archeointensity results from a site of baked bricks from Mesopotamia (Mari, Syria) 6 samples

  21. Comparison between archeointensity results obtained from the Thellier and Thellier and Triaxe methods H (µT) Age (BC)

  22. CONCLUSIONS • The experimental procedure was successfully tested with archeological baked materials. We need now to work on volcanic samples. • Other applications of the Triaxe :- Viscosity at high temperature.- Alteration.- Coupling between different magnetic phases.- etc.

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