Korean Journal of Mineralogy and Petrology (광물과 암석)

The Petrological Society of Korea & The Mineralogical Society of Korea (한국암석학회 & 한국광물학회)
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Lattice Preferred Orientation(LPO) and Seismic Anisotropy of Amphibole in Gapyeong Amphibolites

경기육괴 북부 가평 지역에 분포하는 각섬암 내부 각섬석의 격자선호방향(LPO)과 지진파 비등방성

  • Kim, Junha (School of Earth and Environmental Sciences, Seoul National University) ;
  • Jung, Haemyeong (School of Earth and Environmental Sciences, Seoul National University)
  • 김준하 (서울대학교 지구환경과학부) ;
  • 정해명 (서울대학교 지구환경과학부)
  • Received : 2020.06.16
  • Accepted : 2020.08.04
  • Published : 2020.09.30
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Abstract

The seismic properties in the crust are affected by the lattice preferred orientation(LPO) of major minerals in the crust. Therefore, in order to understand the internal structure of the crust using seismic data, information on the LPO of the major constituent minerals and the seismic properties of major rocks in a specific region are needed. However, there is little research on the LPOs of minerals in the crust in Korea. In this study, we collected amphibolites from two outcrops in Wigokri, Gapyeong, located in the nothern portion of Gyeonggi Massif, and we measured the LPOs of major minerals of amphibolite, especially amphibole and plagioclase through EBSD analysis, and calculated seismic properties of amphibolite. Two types of LPOs of amphibole, which are defined as type I and type IV, were observed in the two outcrops of Gapyeong amphibolites, respectively. In the case of amphibolites with the type I LPO of amphibole, large seismic anisotropy of both P- and S-wave was observed, while in the amphibolites with the type IV LPO of amphibole, small seismic anisotropy was observed. This is consistent with previous experimental results. The polarization direction of the fast S-wave was aligned subparallel to the lineation regardless of the LPO types of amphibole. The seismic anisotropy observed in Gapyeong is expected to be helpful to interpret the structure and seismic data within the crust in Gyeonggi Massif.

지각내부에서의 지진파 전파 특성은 지각의 주요 구성광물들의 격자선호방향에 크게 영향을 받는다. 따라서 지진파 전파속도자료를 이용해 지구내부구조를 해석하기 위해서는 해당 지역의 주요 구성 광물들의 격자선호방향과 이를 이용해 계산된 암석별 지진파 전파속도 특성 자료가 필요하다. 하지만 국내의 암석과 광물의 격자선호방향에 대한 연구는 거의 없는 상황이다. 이번 연구에서는 경기육괴 북부에 위치한 가평 위곡리 일대의 두 각섬암체에서 각섬암을 채취하여, 각섬암 내부의 주요 광물들, 특히 각섬석과 사장석의 격자선호방향을 전자현미경/후방산란전자회절 기기를 통해 분석하고, 이를 이용해 가평지역 각섬암에서 나타나는 지진파 전파속도 특성을 계산하였다. 분석결과 가평 위곡리 일대 두 개의 각섬암체에서 각각 type I과 type IV로 정의된 두 가지 타입의 각섬석 격자선호방향이 관찰되었다. 사장석은 비교적 약한 격자선호방향을 보여주었다. Type I 각섬석 격자선호방향이 관찰된 각섬암에서는 큰 지진파 비등방성이 관찰되었으나, type IV 각섬석 격자선호방향이 관찰된 각섬암에서는 작은 지진파 비등방성이 관찰되었다. 이것은 이전의 실험결과와 일치하는 결과이다. 빠른 S파의 편파방향은 각섬석의 격자선호방향에 관계없이 선구조방향에 평행하게 나타났다. 가평지역의 각섬암에서 관찰된 이러한 지진파 전파 특성은 경기육괴 지각 내부의 구조와 지진파 자료를 해석하는데 도움을 줄 수 있을 것으로 기대된다.

Keywords

References

  1. Abalos, B., 1997, Omphacite fabric variation in the Cabo Ortegal eclogite (NW Spain): Relationships with strain symmetry during highpressure deformation. Journal of Structural Geology, 19(5), 621-637. https://doi.org/10.1016/S0191‐8141(97)00001‐1.
  2. Aleksandrov, K.S. and Ryzhova, T.V., 1961, The elastic properties of rock forming minerals, pyroxenes and amphiboles. Bull. Acad. Sci. USSR Geophys. Ser, 871(875), 1339-1344.
  3. Aleksandrov, K.S., Alchikov, U.V., Belikov, B.P., Zaslavskii, B.I. and Krupnyi, A. I. 1974, Velocities of elastic waves in minerals at atmospheric pressure and increasing precision of elastic constants by means of EVM (in Russian). Izv. Acad. Sci. URSS, Geol. Ser., 10, 15-24.
  4. Almqvist, B.S. and Mainprice, D., 2017, Seismic properties and anisotropy of the continental crust: predictions based on mineral texture and rock microstructure. Reviews of Geophysics, v. 55, no. 2, p. 367-433. https://doi.org/10.1002/2016RG000552
  5. Aspiroz, M.D., Lloyd, G. and Fernandez, C., 2007, Development of lattice preferred orientation in clinoamphiboles deformed under low-pressure metamorphic conditions. A SEM/EBSD study of metabasites from the Aracena metamorphic belt (SW Spain). Journal of Structural Geology, v. 29, no. 4, p. 629-645. https://doi.org/10.1016/j.jsg.2006.10.010
  6. Barruol, G. and Kern, H., 1996, Seismic anisotropy and shear-wave splitting in lower-crustal and upper-mantle rocks from the Ivrea Zone-experimental and calculated data. Physics of the Earth and Planetary Interiors, v. 95, no. 3-4, p. 175-194. https://doi.org/10.1016/0031-9201(95)03124-3
  7. Bass, J.D., 1989, Elasticity of grossular and spessartite garnets by Brillouin spectroscopy. Jounal of Geophysical Research: Solid Earth, 94(B6), 7621-7628. https://doi.org/10.1029/JB094iB06p07621
  8. Berger, A. and Stünitz, H., 1996, Deformation mechanisms and reaction of hornblende: examples from the Bergell tonalite (Central Alps). Tectonophysics, v. 257, no. 2, p. 149-174. https://doi.org/10.1016/0040-1951(95)00125-5
  9. Birch, F., 1960, The velocity of compressional waves in rocks to 10 kilobars: 1. Journal of Geophysical Research, v. 65, no. 4, p. 1083-1102. https://doi.org/10.1029/JZ065i004p01083
  10. Cao, S., Liu, J. and Leiss, B., 2010, Orientation-related deformation mechanisms of naturally deformed amphibole in amphibolite mylonites from the Diancang Shan, SW Yunnan, China. Journal of Structural Geology, 32, 606-622. https://doi.org/10.1016/j.jsg.2010.03.012
  11. Crampin, S., 1981, A review of wave motion in anisotropic and cracked elastic-media. Wave motion, v. 3, no. 4, p. 343-391. https://doi.org/10.1016/0165-2125(81)90026-3
  12. Getsinger, A., Hirth, G., Stünitz, H. and Goergen, E., 2013, Influence of water on rheology and strain localization in the lower continental crust. Geochemistry, Geophysics, Geosystems, v. 14, no. 7, p. 2247-2264. https://doi.org/10.1002/ggge.20148
  13. Getsinger, A. and Hirth, G., 2014, Amphibole fabric formation during diffusion creep and the rheology of shear zones. Geology, 42, 535-538. https://doi.org/10.1130/G35327.1
  14. Gifkins, R.C., 1970. Optical Microscopy of Metals. American Elsevier.
  15. Helmstaedt, H., Anderson, O.L., and Gavasci, A.T., 1972, Petrofabric studies of eclogite, spinel‐Websterite, and spinel-lherzolite Xenoliths from kimberlite‐bearing breccia pipes in southeastern Utah and northeastern Arizona. Journal of Geophysical Research (1896‐1977), 77(23), 4350-4365. https://doi.org/10.1029/JB077i023p04350
  16. Imon, R., Okudaira, T. and Kanagawa, K., 2004, Development of shape-and lattice-preferred orientations of amphibole grains during initial cataclastic deformation and subsequent deformation by dissolution-precipitation creep in amphibolites from the Ryoke metamorphic belt, SW Japan. Journal of Structural Geology, v. 26, no. 5, p. 793-805. https://doi.org/10.1016/j.jsg.2003.09.004
  17. Jeong, H., Kang, S. and Roh, Y., 2016, Types and Characteristics of Fibrous Serpentine Minerals Occurred in Serpentinite in Hongseong and Gapyeong. Economic and Environmental Geology, v. 49, no. 1, p. 1-11. https://doi.org/10.9719/EEG.2016.49.1.1
  18. Ji, S., Salisbury, M.H. and Hanmer, S., 1993, Petrofabric, Pwave anisotropy and seismic reflectivity of high-grade tectonites. Tectonophysics, v. 222, no. 2, p. 195-226. https://doi.org/10.1016/0040-1951(93)90049-P
  19. Ji, S., Shao, T., Michibayashi, K., Long, C., Wang, Q., Kondo, Y., Zhao, W., Wang, H. and Salisbury, M. H., 2013, A new calibration of seismic velocities, anisotropy, fabrics, and elastic moduli of amphibole‐rich rocks. Journal of Geophysical Research: Solid Earth, v. 118, no. 9, p. 4699-4728. https://doi.org/10.1002/jgrb.50352
  20. Jung, H., 2012, Rock deformation and formation of LPO of minerals in the upper mantle: implications for seismic anisotropy. Journal of the Petrological Society of Korea, v. 21, p. 229-241. https://doi.org/10.7854/JPSK.2012.21.2.249
  21. Jung, H., 2017, Crystal preferred orientations of olivine, orthopyroxene, serpentine, chlorite, and amphibole, and implications for seismic anisotropy in subduction zones: a review, Geosciences Journal, 21, 985-1011. https://doi.org/10.1007/s12303-017-0045-1
  22. Jung, H. and Karato, S., 2001, Water-induced fabric transitions in olivine. Science, 293, 1460-1463. https://doi.org/10.1126/science.1062235
  23. Jung, H., Katayama, I., Jiang, Z., Hiraga, T., and Karato, S., 2006, Effect of water and stress on the lattice-preferred orientation of olivine. Tectonophysics, 421, 1-22. https://doi.org/10.1016/j.tecto.2006.02.011
  24. Kern, H., Popp, T., Gorbatsevich, F., Zharikov, A., Lobanov, K. and Smirnov, Y.P., 2001, Pressure and temperature dependence of Vp and Vs in rocks from the superdeep well and from surface analogues at Kola and the nature of velocity anisotropy. Tectonophysics, v. 338, no. 2, p. 113-134. https://doi.org/10.1016/S0040-1951(01)00128-7
  25. Kim, J. and Jung, H., 2019, New Crystal Preferred Orientation of Amphibole Experimentally Found in Simple Shear. Geophysical Research Letters, 46.
  26. Kim, J.Y., 1989, A study on Metamorphism of the Metamorphic Rocks in the Central Part of Gyeonggi Massif. Ph. D. dissertation, Seoul National University.
  27. Kim, O., Kim, S., Hwa, Y. and Park, B., 1974, Explanatory Text of the Geological Map of Gapyeong Sheet: 6727-III, Scale 1: 5000. Geological and Mineral Institute of Korea, p. 1-26.
  28. Ko, B. and Jung, H., 2015, Crystal preferred orientation of an amphibole experimentally deformed by simple shear. Nature communications, v. 6.
  29. Kong, F., Wu, J., Liu, K.H., and Gao, S.S., 2016, Crustal anisotropy and ductile flow beneath the eastern Tibetan Plateau and adjacent areas. Earth and Planetary Science Letters, 442, 72-79. https://doi.org/10.1016/j.epsl.2016.03.003
  30. Kumazawa, M., Helmstaedt, H., and Masaki, K., 1971. Elastic properties of eclogite xenoliths from diatremes of the East Colorado Plateau and their implication to the upper mantle structure. Journal of Geophysical Research, 76(5), 1231-1247. https://doi.org/10.1029/ JB076i005p01231
  31. Lamarque, G., Bascou, J., Maurice, C., Cottin, J.-Y., Riel, N. and Menot, R.-P., 2016, Microstructures, deformation mechanisms and seismic properties of a Palaeoproterozoic shear zone: The Mertz shear zone, East-Antarctica. Tectonophysics, v. 680, p. 174-191. https://doi.org/10.1016/j.tecto.2016.05.011
  32. Lee, K.J. and Cho, M., 1992, Metamorphism of the Gyeonggi Massif in the Gapyeong-Cheongpyeong area. The Journal of the Petrological Society of Korea, v. 1, no. 1, p. 1-24.
  33. Lee, S., Kim, B., So, C. and Sin, M., 1974, Explanatory Text of the Geological Map of Yongduri Sheet (1: 50,000). Geological and Mineralogical Institute of Korea.
  34. Lee, S.R., Cho, M., Hwang, J.H., Lee, B.-J., Kim, Y.-B. and Kim, J. C., 2003, Crustal evolution of the Gyeonggi massif, South Korea: Nd isotopic evidence and implications for continental growths of East Asia. Precambrian Research, v. 121, no. 1-2, p. 25-34. https://doi.org/10.1016/S0301-9268(02)00196-1
  35. Llana-Fúnez, S. and Brown, D., 2012, Contribution of crystallographic preferred orientation to seismic anisotropy across a surface analog of the continental Moho at Cabo Ortegal, Spain. Geological Society of America Bulletin, v. 124, no. 9-10, p. 1495-1513. https://doi.org/10.1130/B30568.1
  36. Mainprice, D., 1990, A FORTRAN program to calculate seismic anisotropy from the lattice preferred orientation of minerals. Computers & Geosciences, v. 16, no. 3, p. 385-393. https://doi.org/10.1016/0098-3004(90)90072-2
  37. Mainprice, D. and Nicolas, A., 1989, Development of shape and lattice preferred orientations: application to the seismic anisotropy of the lower crust. Journal of Structural Geology, v. 11, no. 1-2, p. 175-189. https://doi.org/10.1016/0191-8141(89)90042-4
  38. McSkimin, H. J., Andreatch Jr, P., and Thurston, R. N. L., 1965, Elastic moduli of quartz versus hydrostatic pressure at 25 and- $195.8^{\circ}C$. Journal of Applied Physics, 36(5), 1624-1632. https://doi.org/10.1063/1.1703099
  39. Panozzo, R., 1984, Two-dimensional strain from the orientation of lines in a plane. Journal of Structural Geology, 6(1-2), 215-221. https://doi.org/10.1016/0191-8141(84)90098-1
  40. Park, M. and Jung, H., 2019, Relationships between eclogite-facies mineral assemblages, deformation microstructures, and seismic properties in the Yuka Terrane, North Qaidam ultrahigh-pressure metamorphic belt, NW China. Journal of Geophysical Research: Solid Earth, 124.
  41. Pearce, M.A., Wheeler, J. and Prior, D.J., 2011, Relative strength of mafic and felsic rocks during amphibolite facies metamorphism and deformation. Journal of Structural Geology, v. 33, no. 4, p. 662-675. https://doi.org/10.1016/j.jsg.2011.01.002
  42. Savage, M.K., 1999, Seismic anisotropy and mantle deformation: what have we learned from shear wave splitting? Reviews of Geophysics, 37, 65-106. https://doi.org/10.1029/98RG02075
  43. Siegesmund, S., Takeshita, T. and Kern, H., 1989, Anisotropy of Vp and Vs in an amphibolite of the deeper crust and its relationship to the mineralogical, microstructural and textural characteristics of the rock. Tectonophysics, v. 157, no. 1-3, p. 25-38. https://doi.org/10.1016/0040-1951(89)90338-7
  44. Silver, P.G., 1996, Seismic anisotropy beneath the continents: probing the depths of geology. Annual Review of Earth and Planetary Sciences, 24, 385. https://doi.org/10.1146/annurev.earth.24.1.385
  45. Skemer, P., Katayama, I., Jiang, Z. and Karato, S.-i., 2005, The misorientation index: Development of a new method for calculating the strength of lattice-preferred orientation. Tectonophysics, v. 411, no. 1-4, p. 157-167. https://doi.org/10.1016/j.tecto.2005.08.023
  46. Tatham, D., Lloyd, G., Butler, R. and Casey, M., 2008, Amphibole and lower crustal seismic properties. Earth and Planetary Science Letters, v. 267, no. 1, p. 118-128. https://doi.org/10.1016/j.epsl.2007.11.042
  47. Zhang, J., Green, H.W. and Bozhilov, K.N., 2006, Rheology of omphacite at high temperature and pressure and significance of its lattice preferred orientations. Earth and Planetary Science Letters, 246(3-4), 432-443. https://doi.org/10.1016/j.epsl.2006.04.006