Anisotropy of magnetic susceptibility (AMS)
of banded iron formations (BIFs) is characterized by high anisotropy and
well-developed bedding-parallel magnetic foliation. Since most previous studies
were focused on palaeomagneism of BIFs and BIF-derived iron ores, little effort
has been made to further understand this special type of AMS for BIFs. A
detailed theoretical analysis, incorporating with the previous experimental
data, is made to understand the formative mechanism of this special anisotropy
for BIFs. The good consistence between the theoretical and experimental results
demonstrates that this type of anisotropy is likely caused by the layered
structure of BIFs, and thus verifies the term of textural anisotropy for BIFs.
Theoretical analysis also shows that in the negligence of the inter-layer
magnetic action BIF’s apparent anisotropy increases with an increase in
intrinsic susceptibility of magnetic layers, but decreases with an increase in
length-to- diameter ratio of the magnetic layer.
References
[1]
James, H.L. (1983) Distribution of Banded Iron-Formation in Space and Time. In: Iron-Formation: Facts and Problems, Elsevier, Amsterdam, 471-490. http://dx.doi.org/10.1016/S0166-2635(08)70053-7
[2]
Tarling, D.H. and Hrouda, F. (1993) The Magnetic Anisotropy of Rocks. Chapman & Hall, London.
[3]
Dunlop, D.J. and Ozdemir, O. (1997) Rock Magnetism. Cambridge University Press, Cambridge.
http://dx.doi.org/10.1017/CBO9780511612794
[4]
Rochette, P., Jackson, M. and Aubourg, C. (1992) Rock Magnetism and the Interpretation of Anisotropy of Magnetic Susceptibility. Reviews of Geophysics, 30, 209-226. http://dx.doi.org/10.1029/92RG00733
[5]
Jahren, C.E. (1963) Magnetic Susceptibility of Bedded Iron Formation. Geophysics, 28, 756-766.
http://dx.doi.org/10.1190/1.1439268
[6]
Clark, D.A. and Schmidt, P. (1986) Magnetic Properties of the Banded-Iron Formations of the Hamersley Group, WA. CSIRO Division of Mineral Physics, AMIRA Report 1638.
[7]
Schmidt, P. and Clark, D.A. (1994) Palaeomagnetism and Magnetic Anisotropy of Proterozoic Banded-Iron Formations and Iron Ores of the Hamersley Basin, Western Australia. Precambian Research, 69, 133-155.
http://dx.doi.org/10.1016/0301-9268(94)90083-3
[8]
Guo, W. (1999) Magnetic Petrophysics and Density Investigations of the Hamersley Province, Western Australia: Implications for Magnetic and Gravity Interpretation. The University of Western Australia, Perth.
[9]
Guo, W.W. (In Press) Mathematical Model of Anisotropy of Magnetic Susceptibility (AMS). Journal of Applied Mathematics and Physics.
[10]
Porath, H. and Chamalaun, F.H. (1968) Palaeomagnetism of Australian Haematite Ore Bodies, II, Western Australia. Geophysical Journal Royal Astronomical Society, 15, 253-264. http://dx.doi.org/10.1111/j.1365-246X.1968.tb00184.x
[11]
Trendall, A.F. (1983) Introduction, in Iron-Formation: Facts and Problems. Elsevier, Amsterdam, 1-12.
http://dx.doi.org/10.1016/S0166-2635(08)70040-9
[12]
Morris, R.C. (1993) Genetic Modelling for Banded Iron-Formation of the Hamersley Group, Pilbara Craton, Western Australia. Precambrian Research, 60, 243-286. http://dx.doi.org/10.1016/0301-9268(93)90051-3
[13]
Guo, W.W. (2010) A Novel Application of Neural Networks for Instant Iron-Ore Grade Estimation. Expert Systems with Applications, 37, 8729-8735. http://dx.doi.org/10.1016/j.eswa.2010.06.043
[14]
Li, M.M., Guo, W., Verma, B., Tickle, K. and O’Connor, J. (2009) Intelligent Methods for Solving Inverse Problems of Backscattering Spectra with Noise: A Comparison between Neural Networks and Simulated Annealing. Neural Computing and Applications, 18, 423-430. http://dx.doi.org/10.1007/s00521-008-0219-x
[15]
Guo, W.W., Li, M.M., Whymark, G. and Li, Z.X. (2009) Mutual Complement between Statistical and Neural Network Approaches for Rock Magnetism Data Analysis. Expert Systems with Applications, 36, 9678-9682.
http://dx.doi.org/10.1016/j.eswa.2008.11.045
