岩石剩余磁化强度的应力效应
THE STRESS EFFECT ON REMANENT MAGNETIZATION OF ROCKS
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摘要: 为模拟构造应力对岩石剩余磁化强度的影响,本研究对六种不同类型的44块岩样进行了应力实验,发现岩石天然剩磁随应力的变化规律比迄今所估计的要复杂得多.作者指出,这些变化可归属于三种类型:在弱不可逆的Ⅰ型效应中,剩磁随应力呈现规则的减小,应力解除后剩磁部分恢复;而在强不可逆的Ⅱ型效应中,应力去除后剩磁大部不恢复;在Ⅲ型效应中,剩磁随应力呈极不规律的变化.进一步的岩石磁学分析表明,不同应力效应的重要原因,在于天然剩磁中的粘滞剩磁的比例不同,微观上取决于磁性矿物成分及其磁畴状态等因素.因此,不能用单一的岩石压磁模式来解释地震压磁效应,须考虑各震源区的不同岩石组成.Abstract: In order to simulate the effect of tectonic stress on the remanent magnetization of rocks,an experiment with 44 samples of 6 types is carried out. The result shows that the nature of the changes of the remanence with the stress is far more complicated than estimated hitherto. The authors suggest that these phenomena could be divided into three types. In the weakly irreversible (typeⅠ) effect the remanence decreases with stress regularly and then is restored to nearly its original value when the stress is completely released. In the strongly irreversible (typeⅡ) effect the remanence is hardly restored when the stress is released. In the irregular (type Ⅲ) effect the remanence shows a very jumble variation with stress. An important reason that these rock samples show such different effects is,according to the results of comprehensive magnetic study on these rocks,the different contents of VRM contained in NRM of the samples,microscopically depending on the magnetic minerals in rocks and their domain states etc. The results imply that to interpret the piezomagnetic effects of earthquakes the sole simple piezomagnetic model of rocks is not enough,while the specific contents of rocks in the seismic regions involved need be considered.
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[1] Ohnaka M. and H. Kinoshita, 1968, Glfect of uniaxial compression on remanent magnetization. J. Geomag,Geoclectr., 20, 93——99.
[2] Revol J., R. Day and M. D. Fuller, 1977. Magnetic behavior of magnetite and rocks stressed to failure——relation to earth quake prediction. Earth Ylanct. Sci. Lezz., 37. 296——306.
[3] Henyey T. L., S. T. Pike and D. F. Palmer, 1978. On the measurement of stress sensitivity of NRM using a cryogenic magnetometers. J. Gcomag. Geoelectr., 30, 607——617
[4] Revol J., R. Day and M. Fuller, 1978. Effect of uniaxial stress upon remancnt magnetization:stress cycling and domain state dependence. J. Gaozttrb. Gcoelectr., 30. 593——605.
[5] Collinson D. W., 1983. Methods in rock magnetism and palacumagnetism, Chapman and llall, London,503pp
[6] Hronda F., 1982. Magnetic anisotropy of racks and its application in geology and geophysics. Gep[justca Surveys, 5, 37——82.
[7] Stacey, F, D., S. K. Banerjee, 1974. The physical principles of rock magnetism. Elrevier, fintsterdum 195pp.
[8] Parry L. G., 1965. Magnetic properties of dispersed magnetite powders. Phil. Mag., 11, 303——312.
[9] Hao Jin——qi, L. G. Parry, G. J. Tuck and F. D. Stacey, 1982. The piezomagnettc effort in rocks: a comparison of measurements in high and low fields. Phys. Earth Planct. Inter., 29, 173——182.
[10] Dunlop D, J., 1981. The rock magnetism of tine particles. Phys. Earth Planet. Inter., 26, 1——26.
[11] Dunlop D. J,1983. Viscous triagnetization of 0.04——100 μm magnetizes. Grnphys. J R. astr. Spc., 74,667——687.
[12] 郝锦绮,1985,唐山地震与震磁效应的最佳观测.地震学报,7,300——313.[1] Ohnaka M. and H. Kinoshita, 1968, Glfect of uniaxial compression on remanent magnetization. J. Geomag,Geoclectr., 20, 93——99.
[2] Revol J., R. Day and M. D. Fuller, 1977. Magnetic behavior of magnetite and rocks stressed to failure——relation to earth quake prediction. Earth Ylanct. Sci. Lezz., 37. 296——306.
[3] Henyey T. L., S. T. Pike and D. F. Palmer, 1978. On the measurement of stress sensitivity of NRM using a cryogenic magnetometers. J. Gcomag. Geoelectr., 30, 607——617
[4] Revol J., R. Day and M. Fuller, 1978. Effect of uniaxial stress upon remancnt magnetization:stress cycling and domain state dependence. J. Gaozttrb. Gcoelectr., 30. 593——605.
[5] Collinson D. W., 1983. Methods in rock magnetism and palacumagnetism, Chapman and llall, London,503pp
[6] Hronda F., 1982. Magnetic anisotropy of racks and its application in geology and geophysics. Gep[justca Surveys, 5, 37——82.
[7] Stacey, F, D., S. K. Banerjee, 1974. The physical principles of rock magnetism. Elrevier, fintsterdum 195pp.
[8] Parry L. G., 1965. Magnetic properties of dispersed magnetite powders. Phil. Mag., 11, 303——312.
[9] Hao Jin——qi, L. G. Parry, G. J. Tuck and F. D. Stacey, 1982. The piezomagnettc effort in rocks: a comparison of measurements in high and low fields. Phys. Earth Planct. Inter., 29, 173——182.
[10] Dunlop D, J., 1981. The rock magnetism of tine particles. Phys. Earth Planet. Inter., 26, 1——26.
[11] Dunlop D. J,1983. Viscous triagnetization of 0.04——100 μm magnetizes. Grnphys. J R. astr. Spc., 74,667——687.
[12] 郝锦绮,1985,唐山地震与震磁效应的最佳观测.地震学报,7,300——313.
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