The Journal of the Petrological Society of Korea (암석학회지)

The Petrological Society of Korea (한국암석학회)
권호 표지

Geometrical Interpretation on the Development Sequence and the Movement Sense of Fractures in the Cheongsong Granite, Gilan-myeon Area, Uiseong Block of Gyeongsang Basin, Korea

경상분지 의성지괴 길안면지역에서 청송화강암의 단열 발달사 및 운동성에 대한 기하학적 해석

  • Kang, Ji-Hoon (Department of Earth and Environmental Sciences, Andong National University) ;
  • Ryoo, Chung-Ryul (Geology and Geoinformation Division, Korea Institute of Geoscience and Mineral Resources)
  • 강지훈 (안동대학교 지구환경과학과) ;
  • 류충렬 (한국지질자원연구원 지질기반정보연구부)
  • Published : 2006.12.30
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Abstract

The Gilan area in the central-northern part of Uiseong Block of Cretaceous Gyeongsang Basin is composed of Precambrian metamorphic rocks, Triassic Cheongsong granite, Early Cretaceous Hayans Group, and Late Cretaceous-Paleocene igneous rocks. In this area, the faults of various directions are developed: Oksan fault of $NS{\sim}NNW$ trend, Gilan fault of NW trend, Hwanghaksan fault of WNW trend, and Imbongsan fault of EW trend. Several fracture sets with various geometric indicators, which determine their relative timing (sequence and coexistence relationships) and shear sense, we well observed in the Cheongsong granite, the basement of Gyeongsang Basin. The aim of this study is to determine the development sequence of extension fractures and the movement sense of shear fractures in the Gitan area on the basis of detailed analysis of their geometric indicators (connection, termination, intersection patterns, and cross-cutting relations). This study suggests that the fracture system of the Gilan area was formed at least through seven different fracturing events, named as Pre-Dn to Dn +5 phases. The orientations of fracture sets show (W) NW, NNW, NNE, EW, NE in descending order of frequency. The orientation and frequency patterns are concordant with those of faults around and in the Gilan area on a geological map scale. The development sequence and movement sense of fracture sets are summarized as follows. (1) Pre-Dn phase: extension fracturing event of $NS{\sim}NNW$ and/or $WNW{\sim}ENE$ trend. The joint sets of $NS{\sim}NNW$ trend and of $WNW{\sim}ENE$ trend underwent the reactivation histories of sinistral ${\rightarrow}$dextral${\rightarrow}$sinistral shearing and of (dextral${\rightarrow}$) sinistral shearing with the change of stress field afterward, respectively. (2) Dn phase: that of NW trend. The joint set experienced the reactivations of sinistral${\rightarrow}$dextral shearing. (3) Dn + 1 phase: that of $NNE{\sim}NE$ trend. The joint set was reactivated as a sinistral shear fracture afterward. (4) Dn +2 phase: that of $ENE{\sim}EW$ trend. (5) Dn +3 phase: that of $WNW{\sim}NW$ trend. (6) Dn+4 phase: that of NNW trend. The joint set underwent a dextral shearing after this. (7) The last Dn +5 phase: that of NNE trend.

경상분지 의성지괴의 중앙 북부에 위치하는 안동시 길안면 지역은 선캠브리아기 변성암류, 트라이아스기 청송화강암, 백악기 초 하양층군, 백악기 말-고제3기 화성암류 등으로 구성되어 있다. 이 지역에는 다양한 방향의 단층(남북 내지 북북서 방향의 옥산단층, 북서 방향의 길안단층, 서북서 방향의 황학산단층, 그리고 동서 방향의 임봉산단층)들이 발달하고, 경상분지의 기반암류에 해당하는 청송화강암내에는 다수 단열조의 상대적 시간관계(선후관계 및 공존관계)와 전단단열의 운동감각을 결정하는데 이용되는 기하학적 지시자가 잘 관찰된다. 본 논문은 이들 단열조의 기하학적 특성(연결, 종료, 교차형상 및 절단관계)에 대한 정밀한 분석을 통하여 경상분지 의성지괴 길안면 지역에 발달하는 인장단열의 발달사와 전단단열의 운동성을 연구하였다. 그 결과, 길안면 지역에 발달하는 단열계는 적어도 7회의 변형단계(Dn 이전 단계에서 Dn+5 단계로 명기)를 걸쳐 형성되었고, 단열조의 우세 방향성은 길안면 주변지역에 발달하는 지질도 규모의 단층 우세 방향성과 거의 일치하는 (서)북서, 북북서, 북북동, 동서, 북동 순서로 나타난다. 단열조의 발달사와 운동성를 요약하면 다음과 같다. (1) Dn이전 단계: 남북 내지 북북서 또는 서북서 내지 동북동 방향의 인장단열 형성기. 이후 응력장 변화와 함께 남북 내지 북북서 방향의 절리조는 좌수향 ${\rightarrow}$우수향${\rightarrow}$좌수향 전단단열운동으로 그리고 서북서 내지 동북동 방향의 절리조는 (우수향${\rightarrow}$)좌수향 전단단열운동으로 각각 재활동하였다. (2) Dn 단계: 북서 방향의 인장단열 형성기. 이 단계의 절리조는 이후 좌수향${\rightarrow}$우수향 순서의 전단단열운동을 경험한다. (3) Dn+l 단계:북북동 내지 북동 방향의 인장단열 형성기. 이후, 좌수향 전단단열운동으로 활동하게 된다. (4) Dn+2 단계: 동북동 내지 동서 방향의 인장단열 형성기. (5) Dn+3 단계: 서북서 내지 북서 방향의 인장단열 형성기. (6) Dn+4 단계: 북북서 방향의 인장단열 형성기. 이후, 우수향 전단단열운동으로 활동하였다. (7) Dn+5 단계: 북북동 방향의 인장단열 형성기.

Keywords

References

  1. 김남장, 강필종, 이홍규, 1970,한국지질도(1:50,000), 증평동 지질도폭 및 설명서, 국립지질조사소, 19p
  2. 장기홍, 1977, 경상분지 상부중생계의 층서퇴적 및 지구조. 지질학회지, 13, 76-90
  3. 장기홍, 고인석, 박희인, 지정만, 김항묵, 1978, 한국지질도(1:50,000), 천지 지질도폭 및 설명서, 자원개발연구소, 20p
  4. 이병주, 황재하, 1997, 경상분지 북동부에서의 가음단층과 양산단층의 관계. 지질학회지, 33, 1-8
  5. 좌용주, 김종선, 김건기, 2005, 우리나라 트라이아스기 화강암의 스위트/슈퍼스위트 분류. 암석학회지, 14, 226-236
  6. 최위찬, 김규봉, 홍승호, 이병주, 황재하, 박기화, 황상기, 최범영, 송교영, 진명식, 1995, 한국지질도 1:000,000. 한국자원연구소, 성지문화사
  7. 황재하, 김동학, 조등룡, 송교영, 1996, 한국지질도(1:250,000), 안동 지질도폭 및 설명서, 과학기술처, 67p
  8. Chang, K.R., 1975, Cretaceous Stratigraphy of Southeast Korea. Journal of the Geological Society of Korea, 11, 123
  9. Cheong, C.-S., Kwon, S.-T. and Sagong, H., 2002, Geochemical and Sr-Nd-Pb isotopic investigation of Triassic granitoids and basement rocks in the northern Gyeongsang Basin, Korea: Implications for the young basement in the East Asian continental margin. The Island Arc, 11, 25-44 https://doi.org/10.1046/j.1440-1738.2002.00356.x
  10. Choi, P.Y., Lee, S.R., Choi, H.I., Hwang, J.H., Kwon, S.K., Ko, I.S. and An, G.O., 2002, Movement history of the Andong Fault System: Geometric and tectonic approaches. Geosciences Journal, 6, 91-102 https://doi.org/10.1007/BF03028280
  11. Cooke, M.L., 1997, Fracture localization along faults with spatially varying friction. Journal of Geophysical Research, 102, 22425-22434 https://doi.org/10.1029/97JB01829
  12. Cruikshank, K.M., Zhao, G. and Johnson, A.M., 1991, Analysis of minor fractures asociated with joints and faulted joints. Journal of Structural Geology, 13, 865-886 https://doi.org/10.1016/0191-8141(91)90083-U
  13. Dunne, W.M. and North, C.P., 1990, Orthogonal fracture system at the limits of thrusting: an example from southwestern Wales. Journal of Structural Geology, 12, 207-215 https://doi.org/10.1016/0191-8141(90)90005-J
  14. Dyer, R., 1988, Using joint interactions to estimate paleostress ratios. Journal of Structural Geology, 10, 685-699 https://doi.org/10.1016/0191-8141(88)90076-4
  15. Engelder, T. and Gross, M.R., 1993, Curving cross joints and the lithospheric stress field in eastern North America. Geology, 21, 817-820 https://doi.org/10.1130/0091-7613(1993)021<0817:CCJATL>2.3.CO;2
  16. Eyal, Y., Gross, M.R., Engelder, T. and Becker, A., 2001, Joint development during fluctuation of the regional stress field in southern Israel. Journal of Structural Geology, 23, 279-296 https://doi.org/10.1016/S0191-8141(00)00096-1
  17. Hancock, P.L., 1985, Brittle microtectonics: principles and practice. Journal of Structural Geology, 7, 437-457 https://doi.org/10.1016/0191-8141(85)90048-3
  18. Hancock, PL., Al Kadhi, A. and Sha'at, N.A., 1984, Regional joint sets in the Arabian Platform as indicators of intraplate processes. Tectonics, 3, 27-43 https://doi.org/10.1029/TC003i001p00027
  19. Martel, S.J., 1990, Formation of compound strike-slip fault zones, Mount Abbot Quadrangle, California. Journal of Structural Geology, 12, 869-882 https://doi.org/10.1016/0191-8141(90)90060-C
  20. Martel, S.J and Boger, W.A., 1998, Geometry and mechanics of secondary fracturing around small three-dimensional faults in granitic rock. Journal of Geophysical Research, 103, 21299-21314 https://doi.org/10.1029/98JB01393
  21. Martel, S.J., Pollard, D.D. and Segall, P., 1988, Development of simple strike-slip fault zones, Mount Abbot quadrangle, Sierra Nevada, California. Geological Society of America Bulletin, 100, 1451-1465 https://doi.org/10.1130/0016-7606(1988)100<1451:DOSSSF>2.3.CO;2
  22. Mollema, P.N. and Antonellini, M., 1999, Development of strike-slip faults in the dolomites of the sella Group, Northern Italy. Journal of Structural Geology, 21, 273-292 https://doi.org/10.1016/S0191-8141(98)00121-7
  23. Peacock, D.C.P., 2001, The temporal relationship between joint and faults. Journal of Structural Geology, 23, 329-341 https://doi.org/10.1016/S0191-8141(00)00099-7
  24. Petit, J.-P., 1988, Can natural fractures propagate under mode II condition? Tectonics, 7, 1243-1256 https://doi.org/10.1029/TC007i006p01243
  25. Pollard, D.D. and Aydin, A., 1988, Progress in understanding jointing over the past century. Geological Society of America Bulletin, 100, 1181-1204 https://doi.org/10.1130/0016-7606(1988)100<1181:PIUJOT>2.3.CO;2
  26. Ramsay, J.G. and Huber, M.I., 1987, The technique of modern structural geology. Volume 2: Folds and Fractures. A academic press INC. (London) LTD., 700p
  27. Rawnsley, K.D., Rives, T., Petit, J.P., Hencher, S.R. and Lumsden, A.C., 1992, Joint development in perturbed stress fields near faults. Journal of Structural Geology, 14, 939-951 https://doi.org/10.1016/0191-8141(92)90025-R
  28. Rawnsley, K.D., Peacock, D.C.P., Rives, T. and Petit, J.P., 1998, Jointing in the Mesozoic sediments around the Bristol Channel Basin. Journal of Structural Geology, 20, 1641-1661 https://doi.org/10.1016/S0191-8141(98)00070-4
  29. Reches, Z. and Lockner, D.A., 1994, Nucleation and growth of faults in brittle rocks. Journal of Geophysical Research, 99, 18159-18174 https://doi.org/10.1029/94JB00115
  30. Renshaw, C.E. and Pollard, D.D., 1995, An experimentally verified criterion for propagation across unbounded frictional interfaces in brittle, linear elastic materials. International Journal of Rock Mechanics and Mining Sciences and Geomechanics, Abstracts 32, 237-249
  31. Sagong, H., Kwon, S.- T. and Ree, J.-H, 2005, Mesozoic episodic magmatism in South Korea and its tectonic implication. Tectonics, 24, TC5002, doi:10.1029/2004TC001720
  32. Wilkins, S.J., Gross, M.R., Wacker, M., Eyal, Y. and Engelder, T., 2001, Faulted joints: kinematics, displacement-length scaling relations and criteria for their identification. Journal of Structural Geology, 23, 315-327 https://doi.org/10.1016/S0191-8141(00)00098-5
  33. Willemse, E.J.M. and Pollard, D.D., 1998, On the orientation and patterns of wing cracks and solution surfaces at the tips of a sliding flaw or fault. Journal of Geophysical Research, 103, 2427-2438 https://doi.org/10.1029/97JB01587