한국광물학회지 (Journal of the Mineralogical Society of Korea)

  • 제26권1호
  • /
  • Pages.19-25
  • /
  • 2013
  • /
  • 1225-309X(pISSN)
  • /
  • 2288-7172(eISSN)
한국광물학회 (The Mineralogical Society of Korea)
권호 표지
DOI QR코드

DOI QR Code

저온변환에 따른 적철석의 자화안정도

Magnetic Stability of Hematite on Low-temperature Magnetic Phase Transition

  • 장수진 (충남대학교 지질환경과학과) ;
  • 유용재 (충남대학교 지질환경과학과)
  • Jang, Sujin (Department of Geology and Earth Environmental Sciences, Chungnam National University) ;
  • Yu, Yongjae (Department of Geology and Earth Environmental Sciences, Chungnam National University)
  • 투고 : 2012.11.28
  • 심사 : 2013.02.05
  • 발행 : 2013.03.31
PDF 다운로드
⟨ 이전 논문 다음 논문 ⟩

초록

지난 10여 년간 미항공우주국 주도로 진행된 화성탐사 연구는 화성 암권의 주요 자성광물임을 적철석으로 판명하였다. 금번 연구에서는 적철석의 열잔류자화와 저온 실온포화잔류자를 이용하여 화성 암권에 존재하는 적철석의 자화안정도 검증을 시도하였다. 적철석의 실온포화잔류자화는 모린변환온도인 260 K를 기점으로 급격히 감소한다. 10 K까지 냉각시킨 적철석 시료를 가열하면 260~265 K에서 자화회복이 발생하며, 잔류자화기억도는 37%이다. 실제 화성지표의 일교차는 모린변환온도를 포함하므로, 화성 지표에서 적철석을 함유하는 암체의 자화는 모린변환에 의한 자화안정도가 고려되어야 한다. 지표용암의 고결과 동시에 생성되는 열잔류자화의 강도는 50 ${\mu}m$ 이하 크기에서 적철석 입자반경에 비례하며 증가한다. 화성의 온도구배가 관측된 적은 없지만, 지구의 온도구배를 기준으로 유추하면 대략 1.5 km 이하의 화성 암권은 모린변환온도와 무관하게 적철석의 자화보유가 상시 가능하다. 따라서 행성의 진화가 멈춰진 대략 40억 년 이전에 존재하던 내부기원의 화성자기장 기록이 화성의 암권에 현재까지 보전되어 화성 암권의 자기이상을 유지해온 것으로 해석된다.

Recent progress in Martian exploration identified hematite as the major candidate for the strong magnetic anomalies observed in Martian lithosphere. In the present study, grain-size dependence of thermoremanent magnetization and low-temperature stability of room-temperature saturation isothermal remanent magnetization (RTSIRM) were monitored using synthetic hematites. For hematite, the antiferromagnetic spin configuration is re-arranged from being perpendicular to the c-axis to be parallel to the c-axis below the Morin transition ($=T_M$). A large fraction of RTSIRM is demagnetized at $T_M$ (= 260 K) during zero-field cooling from 300 K to 10 K. About 37% of the initial RTSIRM is recovered on warming from 10 K to 300 K. Shallow Martian subsurface at 1~2 km depth would experience low-temperature cooling-warming of $T_M$ because average Martian surficial temperature is about 220 K. However in most Martian lithosphere whose temperatures are higher than 260 K, the very stable magnetic memory of hematite could be a contributor to Martian magnetic anomalies.

키워드

참고문헌

  1. Acuna, M.H., Connerney, J.E.P., Wasilewski, P., Lin, R.P., Mitchell, D., Anderson, K.A., Carlson, C.W., McFadden, J., Rene, H., Mazelle, C., Vignes, D., Bauer, S.J., Cloutier, P., and Ness, N.F. (2001) Magnetic field of Mars: Summary of results from the aerobraking and mapping orbits. Journal of Geophysical Research, 106(E10), 23403-23417. https://doi.org/10.1029/2000JE001404
  2. Bhowmik, R.N. and Saravanan, A. (2010) Surface magnetism, Morin transition, and magnetic dynamics in antiferromagnetic hematite nanograins. Journal of Applied Physics, 107, 053916, 1-10.
  3. Chevallier, R. (1951) Proprietes magnetiques de l'oxyde ferrique rhomboedrique hematite. Journal de Physique et le Radium, 12, 172-188. https://doi.org/10.1051/jphysrad:01951001203017200
  4. Dunlop, D.J. and Kletetschka, K. (2001) Multidomain Hematite: A source of planetary magnetic anomalies? Geophysical Research Letters, 28(17), 3345-3348. https://doi.org/10.1029/2001GL013125
  5. Dzyaloshinsky, I. (1958) A thermomagnetic theory of "weak" ferromagnetism of antiferromagnetics. Journal of Physics and Chemistry of Solids, 4, 241-255. https://doi.org/10.1016/0022-3697(58)90076-3
  6. Glotch, T.D. and Christensen, P.R. (2005) Geologic and mineralogic mapping of Aram Chaos: Evidence for a water-rich history. Journal of Geophysical Research, 110, E09006, doi:10.1029/2004JE002389.
  7. Haigh, G. (1957a) The effect of added titanium and aluminium on the magnetic behavior of alpha-ferric oxide. Philosophical Magazine, 2, 505-520. https://doi.org/10.1080/14786435708243840
  8. Haigh, G. (1957b) Observation on the magnetic transition in hematite at 258 K. Philosophical Magazine, 2, 877-890. https://doi.org/10.1080/14786435708242726
  9. Hartstra, R.L. (1982) Some rock magnetic parameters for natural iron-titanium oxides. Ph. D. thesis, 145 pp., Univ. of Utrecht, Utrecht, Netherlands.
  10. Hwang, G.C. and Kim. Y-H. (2011) Structure refinement and equation of state studies of the exsoluted Ilmenite-Hematite. Journal of the Mineralogical Society of Korea, 24(3), 195-204 (in Korean with English abstract). https://doi.org/10.9727/jmsk.2011.24.3.195
  11. Jeong. D., and Yu, Y. (2011) Magnetism of ferric iron oxide and its significance in Martian lithosphere. Journal of the Mineralogical Society of Korea, 24(3), 189-194 (in Korean with English abstract). https://doi.org/10.9727/jmsk.2011.24.3.189
  12. Jeong. G-Y. and Kim S.J. (1990) Iron oxide minerals in the Sancheng Kaolin deposits. Journal of the Mineralogical Society of Korea, 3(2), 79-88 (in Korean with English abstract).
  13. Kim, J.J. and Kim. S.J. (2003) Mineralogy of ferrihydrite and Schwertmannite from the acid mine drainage in the Donghae coal mine area. Journal of the Mineralogical Society of Korea, 16(2), 191-198 (in Korean with English abstract).
  14. Kletetschka, G. and Wasilewski, P.J. (2002) Grain size limit for SD hematite. Physics of the Earth and Planetary Interiors, 129, 173-179. https://doi.org/10.1016/S0031-9201(01)00271-0
  15. Kletetschka, G., Wasilewski, P.J., and Taylor, P.T. (2000) Hematite versus magnetite as the signature for planetary magnetic anomalies. Physics of the Earth and Planetary Interiors, 119, 239-267.
  16. Liu, Q., Barron, V., Torrent, J., Qin. H., and Yu, Y. (2010) The magnetism of micro-sized hematite explained. Physics of the Earth and Planetary Interiors, 183, 387-397. https://doi.org/10.1016/j.pepi.2010.08.008
  17. Maher, B.A. and Dennis, P.F. (2001) Evidence against dust-mediated control of glacial-interglacial changes in atmosphere $CO_2$. Nature, 411, 176-180. https://doi.org/10.1038/35075543
  18. Morin, F.J. (1950) Magnetic susceptibility of hematite with added titanium. Physical Review, 78, 819-820.
  19. Morrish, A.H., Johnston, G.B., and Curry, N.A. (1963) Magnetic transition in pure and Ga doped hematite. Physics Letters, 7, 177-178. https://doi.org/10.1016/0031-9163(63)90372-X
  20. Muench, G.J., Arajs, S., and Matijevic, E. (1985) The Morin transition in small hematite particles. Physica Status Solidi A, 92, 187-192. https://doi.org/10.1002/pssa.2210920117
  21. Neel, L. (1949) Essai d'imterpretation des proprietes magnetiques du sesquioxyde de fer rhomboedrique. Annals of Physics, 4, 249-268.
  22. Neel, L. and Pauthenet, R. (1952) Etude thermomagnetique d'un monocristal de hematite. Comptes Rendus de l'Academie des Sciences, 234, 2172-2174.
  23. Ozdemir, O. and Dunlop, D.J. (2005) Thermoremanent magnetization of multidomain hematite. Journal of Geophysical Research, 110, B09104, doi:10.1029/ 2005JB003820.
  24. Ozdemir, O. and Dunlop, D.J. (2006) Magnetic memory and coupling between spin-canted and defect magnetism in hematite. Journal of Geophysical Research, 111, B12S03, doi:10.1029/2006JB004555.
  25. Ozdemir, O., Dunlop, D.J., and Berquo, T.S. (2008) Morin transition in hematite: Size dependence and thermal hysteresis. Geochemistry Geophysics Geosystems, 9(10), Q10Z01, doi:10.1029/2008GC002110.
  26. Ozima, M. and Funaki, M. (2001) Magnetic properties of hemoilmenite single crystals in Haruna dacite pumice revealed by the Bitter technique, with special reference to self-reversal of thermoremanent magnetization. Earth Planets Space, 53, 111-119. https://doi.org/10.1186/BF03352368
  27. Purucker, M., Ravat, D.T., Frey, H.V., Voorhies, C.V., Sabaka, T., and Acuna, M.H. (2000) An altitudenormalized magnetic map of Mars and its interpretation. Geophysical Research Letters, 27, 2449-2452. https://doi.org/10.1029/2000GL000072
  28. Schubert, G., Russell, C.T., and Moore, W.B. (2000) Timing of the Martian dynamo. Nature, 408, 666-667. https://doi.org/10.1038/35047163
  29. Verwey, E.J.W. (1939) Electronic conduction of magnetite and its transition point at low temperatures. Nature, 144, 327-328.
  30. Yamazaki, T. and Ioka, N. (1997) Environmental rockmagnetism of pelagic clay: Implications for Asian eolian input to the North Pacific since the Pliocene. Paleoceanography, 12, 111-124. https://doi.org/10.1029/96PA02757