Experimental Conductivity of Partial Melt Granite at High Temperature and Pressure
-
摘要: 大地电磁测深结果显示青藏高原中上地壳存在高导层，而花岗岩是地壳岩石的主要组成部分，在地壳演化过程中发挥着重要作用。在高温高压下开展花岗岩部分熔融时电导率实验对认识青藏高原地壳电性结构及地壳演化过程具有重要意义。在0.5～2.0 GPa压力、773～1 373 K温度条件下测量花岗岩的电导率。实验结果表明：在温度为773～1 223 K时，样品的活化焓为1.01～1.09 eV；在温度为1 223～1 373 K时，样品的活化焓为2.16～2.97 eV。不同温度段内活化焓的变化可能与花岗岩样品中黑云母的脱水熔融有关，推断花岗岩部分熔融时导电机制为离子导电，Na+起主导作用。将实验测得的电导率与西藏高导层地壳温度背景结合发现：在973～1 223 K范围内实验电导率值在0.016～0.310 S/m范围内，与大地电磁测深数据吻合较好，表明西藏地壳高导层的成因与花岗岩部分熔融关系较为密切。Abstract: Magnetotelluric (MT) surveys reveal that high conductivity layer appear in the upper crust beneath Tibet. Granite is the main rocks composed of upper crust, playing an important role in the process of crustal evolution. Electrical conductivity of granite during partial melting is of great significance to understanding the conductivity structure of Tibetan Plateau crust and the crustal evolution process. Electrical conductivity of granite collected from the Tibet was conducted under the conditions of 0.5－2.0 GPa and 773－1 373 K. The activation enthalpies of 1.01－1.09 eV and 2.16－2.97 eV are derived from 773 to 1 223 K and from 1 223 to 1 373 K, respectively. The change of activation enthalpy in different temperature zones may be related to the partial melting of granite induced by the biotite dehydration. Combining the experimental results and geothermal gradient of Tibet, we found that the experimental conductivity values fell between 0.016 S/m and 0.310 S/m in the temperature range of 973－1 223 K, which was in good agreement with the magnetotelluric sounding data. This may indicate that there is a close relationship between the genesis of the high conductivity layer and the partial melting of granite.
-
Key words:
- high temperature and high pressure /
- conductivity /
- granite /
- partial melting
-
图 1 样品高压电导率测量组装示意图
Figure 1. Sample assembly for high pressure conductivity measurement
图 2 压强1.0 GPa、温度773 ～1 373 K条件下花岗岩样品相角和模随频率的变化
Figure 2. Respectively changes of phase angle and modulus of impedance as the function of frequency for granite at 1.0 GPa and 773－1 373 K
图 3 1.0 GPa、773～1 373 K条件下样品的复阻抗谱
Figure 3. Complex impedance spectra of the samples at 1.0 GPa and 773－1 373 K
图 4 0.5～2.0 GPa压强下电导率随温度的变化
Figure 4. Electrical conductivity as the function of temperatures at 0.5－2.0 GPa
图 5 高压实验前（a）、后（b）样品的扫描电镜图像
Figure 5. Images of scanning electron microscope for the samples before (a) and after (b) the experiment
图 6 花岗岩电导率实验结果对比
Figure 6. Comparison of the conductivity results in this work with previous data
图 7 基于实验室电导率模型与大地电磁结果对比
Figure 7. Comparison of laboratory-based conductivity profile established with the result of the upper crust derived from MT conductivity model
表 1 花岗岩样品的矿物成分及含量
Table 1. Compositions of the minerals in granite
Compounds Content/% Quartz K-feldspar Albite Biotite Na2O 0.008 0.774 10.887 0.319 MgO 0.002 0 0 2.694 Al2O3 0.113 18.771 22.019 20.368 SiO2 97.196 67.117 65.805 40.506 SrO 0.288 0.639 0.240 0 K2O 0.026 15.175 0.144 8.342 CaO 0.016 0.003 1.550 0.084 MnO 0.023 0.072 0 0.470 FeO 0.087 0.096 0.016 24.901 TiO2 0.069 0.103 0 2.147 Total 97.828 102.750 100.661 99.831 
下载: 导出CSV
表 2 不同压力下花岗岩样品电导率的Arrhenius关系拟合参数
Table 2. Fitting parameters of Arrhenius relationship of the conductivity of granite samples under different pressures
p/GPa T/K lg $\sigma $0/(S·m−1) ΔH/eV 0.5 773－1 223 3.53 ± 0.08 1.01 ± 0.01 1 223－1 373 11.66 ± 1.00 2.97 ± 0.26 1.0 773－1 223 3.82 ± 0.09 1.09 ± 0.02 1 223－1 373 8.38 ± 0.63 2.16 ± 0.16 2.0 773－1 223 3.64 ± 0.09 1.06 ± 0.02 1 223－1 373 8.22 ± 0.59 2.21 ± 0.13
下载: 导出CSV
-
[1] LAŠTOVIČKOVÁ M. A review of laboratory measurements of the electrical conductivity of rocks and minerals [J]. Physics of the Earth and Planetary Interiors, 1991, 66(1/2): 1–11. doi: 10.1016/0031-9201(91)90099-4 [2] YANG X Z, KEPPLER H, MCCAMMON C, et al. Effect of water on the electrical conductivity of lower crustal clinopyroxene [J]. Journal of Geophysical Research: Solid Earth, 2011, 116(B4): B04208. doi: 10.1029/2010JB008010 [3] HUANG X G, XU Y S, KARATO S I. Water content in the transition zone from electrical conductivity of wadsleyite and ringwoodite [J]. Nature, 2005, 434(7043): 746–749. doi: 10.1038/nature03426 [4] ARORA B R, UNSWORTH M J, RAWAT G. Deep resistivity structure of the northwest Indian Himalaya and its tectonic implications [J]. Geophysical Research Letters, 2007, 34(4): L04307. doi: 10.1029/2006GL029165 [5] CALDWELL W B, KLEMPERER S L, RAI S S, et al. Partial melt in the upper-middle crust of the northwest Himalaya revealed by Rayleigh wave dispersion [J]. Tectonophysics, 2009, 477(1/2): 58–65. doi: 10.1016/j.tecto.2009.01.013 [6] WEI W B, UNSWORTH M, JONES A, et al. Detection of widespread fluids in the Tibetan crust by magnetotelluric studies [J]. Science, 2001, 292(5517): 716–719. doi: 10.1126/science.1010580 [7] GUO Z F, WILSON M. The Himalayan leucogranites: constraints on the nature of their crustal source region and geodynamic setting [J]. Gondwana Research, 2012, 22(2): 360–376. doi: 10.1016/j.gr.2011.07.027 [8] SEARLE M P, COTTLE J M, STREULE M J, et al. Crustal melt granites and migmatites along the Himalaya: melt source, segregation, transport and granite emplacement mechanisms [J]. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 2010, 100(1/2): 219–233. doi: 10.1017/S175569100901617X [9] STREULE M J, SEARLE M P, WATERS D J, et al. Metamorphism, melting, and channel flow in the Greater Himalayan Sequence and Makalu leucogranite: constraints from thermosbarometry, metamorphic modeling, and U-Pb geochronology [J]. Tectonics, 2010, 29(5): TC5011. doi: 10.1029/2009TC002533 [10] OLHOEFT G R. Electrical properties of granite with implications for the lower crust [J]. Journal of Geophysical Research: Solid Earth, 1981, 86(B2): 931–936. doi: 10.1029/JB086iB02p00931 [11] SHANOV S, YANEV Y, LASTOVICKOVA M. Temperature dependence of the electrical conductivity of granite and quartz-monzonite from South Bulgaria: geodynamic inferences [J]. Journal of the Balkan Geophysical Society, 2000, 3(2): 13–19. [12] 柳江琳, 白武明, 孔祥儒, 等. 高温高压下花岗岩、玄武岩和辉橄岩电导率的变化特征 [J]. 地球物理学报, 2001, 44(4): 528–533. doi: 10.3321/j.issn:0001-5733.2001.04.011LIU J L, BAI W M, KONG X R, et al. Electrical conductivity of granite, basalt and pyroxene peridotite under high temperature-high pressure conditions [J]. Chinese Journal of Geophysics, 2001, 44(4): 528–533. doi: 10.3321/j.issn:0001-5733.2001.04.011 [13] 郭颖星, 王多君, 周永胜, 等. 青藏高原南部花岗岩电导率研究及地球物理应用 [J]. 中国科学: 地球科学, 2017, 60(8): 1522–1532. doi: 10.1007/s11430-016-9046-7GUO Y X, WANG D J, ZHOU Y S, et al. Electrical conductivities of two granite samples in southern Tibet and their geophysical implications [J]. Science China:Earth Sciences, 2017, 60(8): 1522–1532. doi: 10.1007/s11430-016-9046-7 [14] GUO X, ZHANG L, SU X, et al. Melting inside the Tibetan crust? Constraint from electrical conductivity of peraluminous granitic melt [J]. Geophysical Research Letters, 2018, 45(9): 3906–3913. doi: 10.1029/2018GL077804 [15] CHEN J Y, GAILLARD F, VILLAROS A, et al. Melting conditions in the modern Tibetan crust since the Miocene [J]. Nature Communications, 2018, 9(1): 3515. doi: 10.1038/s41467-018-05934-7 [16] 王多君, 易丽, 谢鸿森, 等. 交流阻抗谱法及其在地球深部物质科学中的应用 [J]. 地学前缘, 2005, 12(1): 123–129. doi: 10.3321/j.issn:1005-2321.2005.01.016WANG D J, YI L, XIE H S, et al. Impedance spectroscopy and its application to material science of the Earth's interior [J]. Earth Science Frontiers, 2005, 12(1): 123–129. doi: 10.3321/j.issn:1005-2321.2005.01.016 [17] DAI L D, KARATO S I. Electrical conductivity of wadsleyite at high temperatures and high pressures [J]. Earth and Planetary Science Letters, 2009, 287(1/2): 277–283. doi: 10.1016/j.jpgl.2009.08.012 [18] XIE H S, ZHOU W G, ZHU M X, et al. Elastic and electrical properties of serpentinite dehydration at high temperature and high pressure [J]. Journal of Physics: Condensed Matter, 2002, 14(44): 11359–11363. doi: 10.1088/0953-8984/14/44/482 [19] DUBA A. Electrical conductivity of olivine [J]. Journal of Geophysical Research, 1972, 77(14): 2483–2494. doi: 10.1029/JB077i014p02483 [20] ROBERTS J J, TYBURCZY J A. Frequency dependent electrical properties of dunite as functions of temperature and oxygen fugacity [J]. Physics and Chemistry of Minerals, 1993, 19(8): 545–561. doi: 10.1007/BF00203054 [21] 徐有生. 地幔矿物岩石的电导率研究进展 [J]. 地学前缘, 2000, 7(1): 229–237. doi: 10.3321/j.issn:1005-2321.2000.01.022XU Y S. A review on the electrical conductivity of mantle minerals and rocks [J]. Earth Science Frontiers, 2000, 7(1): 229–237. doi: 10.3321/j.issn:1005-2321.2000.01.022 [22] NI H W, HUI H J, STEINLE-NEUMANN G. Transport properties of silicate melts [J]. Reviews of Geophysics, 2015, 53(3): 715–744. doi: 10.1002/2015RG000485 [23] GAILLARD F. Laboratory measurements of electrical conductivity of hydrous and dry silicic melts under pressure [J]. Earth and Planetary Science Letters, 2004, 218(1/2): 215–228. doi: 10.1016/S0012-821X(03)00639-3 [24] LAUMONIER M, GAILLARD F, SIFRE D. The effect of pressure and water concentration on the electrical conductivity of dacitic melts: implication for magnetotelluric imaging in subduction areas [J]. Chemical Geology, 2015, 418: 66–76. doi: 10.1016/j.chemgeo.2014.09.019 [25] JAMBON A. Tracer diffusion in granitic melts: experimental results for Na, K, Rb, Cs, Ca, Sr, Ba, Ce, Eu to 1 300 ℃ and a model of calculation [J]. Journal of Geophysical Research: Solid Earth, 1982, 87(B13): 10797–10810. doi: 10.1029/JB087iB13p10797 [26] GUO X, ZHANG L, BEHRENS H, et al. Probing the status of felsic magma reservoirs: constraints from the P-T-H2O dependences of electrical conductivity of rhyolitic melt [J]. Earth and Planetary Science Letters, 2016, 433: 54–62. doi: 10.1016/j.jpgl.2015.10.036 [27] POMMIER A, GAILLARD F, PICHAVANT M, et al. Laboratory measurements of electrical conductivities of hydrous and dry Mount Vesuvius melts under pressure [J]. Journal of Geophysical Research: Solid Earth, 2008, 113(B5): B05205. doi: 10.1029/2007JB005269 [28] 黄晓葛, 白武明, 周文戈. 高温高压下黑云斜长片麻岩的电性研究 [J]. 高压物理学报, 2008, 22(3): 237–244. doi: 10.3969/j.issn.1000-5773.2008.03.003HUANG X G, BAI W M, ZHOU W G. Experimental study on electrical conductivity of biotite-and plagioclase-bearing gneiss at high temperature and high pressure [J]. Chinese Journal of High Pressure Physics, 2008, 22(3): 237–244. doi: 10.3969/j.issn.1000-5773.2008.03.003 [29] SKJERLIE K P, JOHNSTON A D. Fluid-absent melting behavior of an F-rich tonalitic gneiss at mid-crustal pressures: implications for the generation of Anorogenic Granites [J]. Journal of Petrology, 1993, 34(4): 785–815. doi: 10.1093/petrology/34.4.785 [30] GARDIEN V, THOMPSON A B, GRUJIC D, et al. Experimental melting of biotite+plagioclase+quartz+muscovite assemblages and implications for crustal melting [J]. Journal of Geophysical Research: Solid Earth, 1995, 100(B8): 15581–15591. doi: 10.1029/95JB00916 [31] 吴宗絮, 邓晋福, WYLLIE P J. 冀东黑云母片麻岩在1 GPa压力下脱水熔融实验 [J]. 地质科学, 1995(1): 12–18.WU Z X, DENG J F, WYLLIE P J, et al. Dehydration-melting experiment of the biotite-gneiss, eastern Hebei, at 1 GPa pressure [J]. Scientia Geologica Sinica, 1995(1): 12–18. [32] 杨晓松, 金振民, HUENGES E, et al. 高喜马拉雅黑云斜长片麻岩脱水熔融实验: 对青藏高原地壳深熔的启示 [J]. 科学通报, 2001, 46(10): 867–871. doi: 10.1007/BF02900441YANG X S, JIN Z M, HUENGES E, et al. Dehydration and melting experiment of high Himalayan biotite and plagioclase bearing gneiss: implications for deep crustal melting on the Tibetan plateau [J]. Chinese Science Bulletin, 2001, 46(10): 867–871. doi: 10.1007/BF02900441 [33] PHAM V N, BOYER D, THERME P, et al. Partial melting zones in the crust in southern Tibet from magnetotelluric results [J]. Nature, 1986, 319(6051): 310–314. doi: 10.1038/319310a0 [34] BROWN L D, ZHAO W J, NELSON K D, et al. Bright spots, structure, and magmatism in southern Tibet from INDEPTH seismic reflection profiling [J]. Science, 1996, 274(5293): 1688–1690. doi: 10.1126/science.274.5293.1688 [35] UNSWORTH M J, JONES A G, WEI W, et al. Crustal rheology of the Himalaya and Southern Tibet inferred from magnetotelluric data [J]. Nature, 2005, 438(7064): 78–81. doi: 10.1038/nature04154 [36] NELSON K D, ZHAO W J, BROWN L D, et al. Partially molten middle crust beneath southern Tibet: synthesis of project INDEPTH results [J]. Science, 1996, 274(5293): 1684–1688. doi: 10.1126/science.274.5293.1684 [37] SPRATT J E, JONES A G, NELSON K D, et al. Crustal structure of the India-Asia collision zone, southern Tibet, from INDEPTH MT investigations [J]. Physics of the Earth and Planetary Interiors, 2005, 150(1/2/3): 227–237. doi: 10.1016/j.pepi.2004.08.035 [38] 魏文博, 金胜, 叶高峰, 等. 西藏高原中、北部断裂构造特征: INDEPTH(Ⅲ)-MT观测提供的依据 [J]. 地球科学, 2006, 31(2): 257–265. doi: 10.3321/j.issn:1000-2383.2006.02.017WEI W B, JIN S, YE G F, et al. Features of the faults in center and North Tibetan Plateau: based on results of INDEPTH (Ⅲ)-MT [J]. Earth Science, 2006, 31(2): 257–265. doi: 10.3321/j.issn:1000-2383.2006.02.017 [39] FU H F, ZHANG B H, GE J H, et al. Thermal diffusivity and thermal conductivity of granitoids at 283-988 K and 0.3-1.5 GPa [J]. American Mineralogist, 2019, 104(11): 1533–1545. doi: 10.2138/am-2019-7099 [40] HACKER B R, RITZWOLLER M H, XI E J. Partially melted, mica-bearing crust in Central Tibet [J]. Tectonics, 2014, 33(7): 1408–1424. doi: 10.1002/2014TC003545 [41] MECHIE J, SOBOLEV S V, RATSCHBACHER L, et al. Precise temperature estimation in the Tibetan crust from seismic detection of the α-β quartz transition [J]. Geology, 2004, 32(7): 601–604. doi: 10.1130/G20367.1 [42] WANG Q, HAWKESWORTH C J, WYMAND, et al. Pliocene-Quaternary crustal melting in central and northern Tibet and insights into crustal flow [J]. Nature Communications, 2016, 7: 11888. doi: 10.1038/ncomms11888 [43] WANG C Y, CHEN W P, WANG L P. Temperature beneath Tibet [J]. Earth and Planetary Science Letters, 2013, 375: 326–337. doi: 10.1016/j.jpgl.2013.05.052 -
下载:
点击查看大图
图(7) / 表(2)
计量
- 文章访问数: 7269
- HTML全文浏览量: 2487
- PDF下载量: 38
