암석학회지 (The Journal of the Petrological Society of Korea)

한국암석학회 (The Petrological Society of Korea)
권호 표지
DOI QR코드

DOI QR Code

경상분지 남동부 일대의 백악기 및 제3기 암류에서 발달하는 단층분절의 분포특성

Distributional Characteristics of Fault Segments in Cretaceous and Tertiary Rocks from Southeastern Gyeongsang Basin

  • 박덕원 (한국지질자원연구원 전략기술연구본부)
  • Park, Deok-Won (Climate Change Mitigation and Sustainability Division, Korea Institute of Geoscience and Mineral Resources)
  • 투고 : 2018.04.23
  • 심사 : 2018.06.26
  • 발행 : 2018.09.30
PDF 다운로드
⟨ 이전 논문 다음 논문 ⟩

초록

경상분지 남동부 일대의 백악기 및 제3기 암류에서 발달하는 단층분절에 대한 분포특성을 도출하였다. 선형을 보이는 267조의 단층분절은 광역 지질도 상에서 표시된 곡선의 단층선에서 추출하였다. 첫째, 단층분절에 대한 방향각(${\theta}$)-길이(L)의 도면을 작성하였다. 관계도에서 단층분절의 전반적인 분포형태를 도출하였다. 도면의 분포곡선은 전체 형태에 따라서 4개의 구간으로 구분하였다. 상기 구간의 정점에 해당하는 북북동, 북북서 및 서북서의 방향은 양산, 울산 및 가음 단층계의 방향을 시사한다. 단층분절의 집단은 최대 정점에 해당하는 $N19^{\circ}E$의 방향에 대하여 거의 대칭 분포를 보여 준다. 둘째, 방향각-빈도수(N), 평균 길이(Lm), 총 길이(Lt) 및 밀도(${\rho}$)의 도면을 작성하였다. 관계도에서 상기한 도면의 전 영역을 분포곡선의 분포상에 의하여 19개의 영역으로 구분하였다. 상기한 영역의 정점에 해당하는 방향은 암체에 가해진 대표적인 응력의 방향을 시사한다. 셋째, 18개의 부집단에 대한 길이-누적 빈도수 그래프를 작성하였다. 관계도에서 지수(${\lambda}$)는 시계방향($N10{\sim}20^{\circ}E{\rightarrow}N50{\sim}60^{\circ}E$)과 반시계방향($N10{\sim}20^{\circ}W{\rightarrow}N50{\sim}60^{\circ}W$)으로 갈수록 증가한다. 반면 길이의 분포 폭 및 평균 길이는 감소한다. 서로 다른 진화 특성을 갖는 상기한 부집단에 대한 도면은 진화과정의 한 단면을 나타내고 있다. 넷째, 18개의 그래프에 대한 종합 분포도를 작성하였다. 관계도에서 상기한 그래프를 분포 구역에 따라 5개의 그룹(A~E)으로 분류하였다. 단층분절의 길이는 그룹 E ($N80{\sim}90^{\circ}E{\cdot}N70{\sim}80^{\circ}E{\cdot}N80{\sim}90^{\circ}W{\cdot}N50{\sim}60^{\circ}W{\cdot}N30{\sim}40^{\circ}W{\cdot}N40{\sim}50^{\circ}W$) < D ($N70{\sim}80^{\circ}W{\cdot}N60{\sim}70^{\circ}W{\cdot}N60{\sim}70^{\circ}E{\cdot}N50{\sim}60^{\circ}E{\cdot}N40{\sim}50^{\circ}E{\cdot}N0{\sim}10^{\circ}W$) < C ($N20{\sim}30^{\circ}W{\cdot}N10{\sim}20^{\circ}W$) < B ($N0{\sim}10^{\circ}E{\cdot}N30{\sim}40^{\circ}E$) < A ($N20{\sim}30^{\circ}E{\cdot}N10{\sim}20^{\circ}E$)의 순으로 증가한다. 특히 그래프의 형태는 균등 분포에서 지수 분포로 점차 변화한다. 마지막으로, 단층분절의 길이에 대한 여섯 개 변수의 값을 5개 그룹으로 구분하였다. 여섯 개 변수 중, 평균 길이 및 가장 긴 단층분절의 길이는 그룹 III ($N10^{\circ}W{\sim}N20^{\circ}E$) > IV ($N20{\sim}60^{\circ}E$) > II ($N10{\sim}60^{\circ}W$) > I ($N60{\sim}90^{\circ}W$) > V ($N60{\sim}90^{\circ}E$)의 순으로 감소한다. 그룹 V에 속하는 단층분절의 빈도수, 최장 길이, 총 길이, 평균 길이 및 밀도가 가장 낮은 값을 보여 준다. 5개 그룹 사이의 상기 배열순은 단층분절의 상대적인 생성시기와의 상관성을 시사한다.

The distributional characteristics of fault segments in Cretaceous and Tertiary rocks from southeastern Gyeongsang Basin were derived. The 267 sets of fault segments showing linear type were extracted from the curved fault lines delineated on the regional geological map. First, the directional angle(${\theta}$)-length(L) chart for the whole fault segments was made. From the related chart, the general d istribution pattern of fault segments was derived. The distribution curve in the chart was divided into four sections according to its overall shape. NNE, NNW and WNW directions, corresponding to the peaks of the above sections, indicate those of the Yangsan, Ulsan and Gaeum fault systems. The fault segment population show near symmetrical distribution with respect to $N19^{\circ}E$ direction corresponding to the maximum peak. Second, the directional angle-frequency(N), mean length(Lm), total length(Lt) and density(${\rho}$) chart was made. From the related chart, whole domain of the above chart was divided into 19 domains in terms of the phases of the distribution curve. The directions corresponding to the peaks of the above domains suggest the directions of representative stresses acted on rock body. Third, the length-cumulative frequency graphs for the 18 sub-populations were made. From the related chart, the value of exponent(${\lambda}$) increase in the clockwise direction($N10{\sim}20^{\circ}E{\rightarrow}N50{\sim}60^{\circ}E$) and counterclockwise direction ($N10{\sim}20^{\circ}W{\rightarrow}N50{\sim}60^{\circ}W$). On the other hand, the width of distribution of lengths and mean length decrease. The chart for the above sub-populations having mutually different evolution characteristics, reveals a cross section of evolutionary process. Fourth, the general distribution chart for the 18 graphs was made. From the related chart, the above graphs were classified into five groups(A~E) according to the distribution area. The lengths of fault segments increase in order of group E ($N80{\sim}90^{\circ}E{\cdot}N70{\sim}80^{\circ}E{\cdot}N80{\sim}90^{\circ}W{\cdot}N50{\sim}60^{\circ}W{\cdot}N30{\sim}40^{\circ}W{\cdot}N40{\sim}50^{\circ}W$) < D ($N70{\sim}80^{\circ}W{\cdot}N60{\sim}70^{\circ}W{\cdot}N60{\sim}70^{\circ}E{\cdot}N50{\sim}60^{\circ}E{\cdot}N40{\sim}50^{\circ}E{\cdot}N0{\sim}10^{\circ}W$) < C ($N20{\sim}30^{\circ}W{\cdot}N10{\sim}20^{\circ}W$) < B ($N0{\sim}10^{\circ}E{\cdot}N30{\sim}40^{\circ}E$) < A ($N20{\sim}30^{\circ}E{\cdot}N10{\sim}20^{\circ}E$). Especially the forms of graph gradually transition from a uniform distribution to an exponential one. Lastly, the values of the six parameters for fault-segment length were divided into five groups. Among the six parameters, mean length and length of the longest fault segment decrease in the order of group III ($N10^{\circ}W{\sim}N20^{\circ}E$) > IV ($N20{\sim}60^{\circ}E$) > II ($N10{\sim}60^{\circ}W$) > I ($N60{\sim}90^{\circ}W$) > V ($N60{\sim}90^{\circ}E$). Frequency, longest length, total length, mean length and density of fault segments, belonging to group V, show the lowest values. The above order of arrangement among five groups suggests the interrelationship with the relative formation ages of fault segments.

키워드

참고문헌

  1. Chang, C.J. and Chang, T.W., 1998, Movement history of the Yangsan fault based on paleostress analysis. The Journal of Engineering Geology of Korea, 8, 35-49.
  2. Chang, K.H., 1975. Cretaceous stratigraphy of southeast Korea. Journal of Geological Society of Korea. 11, 1-23.
  3. Chang, K.H., Woo, B.G., Lee, J.H., Park, S.O. and Yao, A., 1990, Cretaceous and early Cenozoic stratigraphy and history of eastern Kyongsang Basin, S. Korea. Journal of the Geological Society of Korea, 26, 471-487.
  4. Choi, J.H., Kim, Y.S. and Klinger. Y., 2017, Recent progress in studies on the characteristics of surface rupture associated with large earthquakes. Journal of the Petrological Society of Korea, 53, 127-157.
  5. Cladouhos, T.T. and Marret, R., 1996, Are fault growth and linkage models consistent with power-law distributions of fault lengths?. Journal of Structural Geology, 18, 281-293. https://doi.org/10.1016/S0191-8141(96)80050-2
  6. Flodin, E.A. and Aydin, A., 2004, Evolution of a strike-slip fault network, Valley of Fire State Park, southern Nevada. Geological Society of America Bulletin, 116, 42-59. https://doi.org/10.1130/B25282.1
  7. Fossen, H. and Rornes, A., 1996, Properties of fault populations in the Gullfaks Field, northern North Sea. Journal of Structural Geology, 18, 179-190. https://doi.org/10.1016/S0191-8141(96)80043-5
  8. Gall, B.L., Tshoso, G., Dyment, J., Kampunzu, A.B., Jourdan, F., Feraud, G., Bertrant, H., Aubourg, C. and Vetel, W., 2005, The Okavango giant mafic dyke swarm(NE Botswana): its structural significance within the Karoo Large Igneous Province. Journal of Structural Geology, 27, 2234-2255. https://doi.org/10.1016/j.jsg.2005.07.004
  9. Hwang, B.H., Lee. J.D. and Yang. K.H., 2004, Petrological study of the granitic rocks around the Yangsan Fault: lateral displacement of the Yangsan fault. Journal of the Geological Society of Korea, 40, 161-178.
  10. KIGAM, 1995, Geological map of Korea (1:1,000,000). Korea Institute of Geology, Mining, and Materials.
  11. Kim, D.H., Hwang, J. H., Park, K.H. and Song, K.Y., 1998, Geological report of the Pusan sheet (1:250,000). Korea Institute of Energy and Resources, 62p.
  12. Kim, H.J. and Chang, T.W., 2009, Fracture characteristics and segmentation of Yangsan Fault around Mt. Namsan, Gyeongju city, Korea. The Journal of Engineering Geology of Korea, 19, 51-61.
  13. Knuepfer, P.L.K., 1989, Implications of the characteristics of end-points of historical surface fault ruptures for the nature of fault segmentation. U.S. Geolological Survey. Open File Report, USGS-OFR 89-315, 193-228.
  14. Koike, K. and Ichikawa, Y. 2006, Spartial correlation structures of fracture systems for deriving a scaling law and modeling fracture distributions. Computer & Geosciences, 32, 1079-1-1095. https://doi.org/10.1016/j.cageo.2006.02.013
  15. Lee, B.J. and Son-woo, C., 2003, Engineering geological geotechnical characteristics of newly constructed road between the Yangsan fault and the Donrae fault. The Journal of Engineering Geology of Korea, 13, 193-205.
  16. Lee, K.J., Kim, K.Y., Kim, U.H. and Im, C.B., 2000, Seismic studies on velocity anisotropy in the Ulsan fault zone. Journal of the Korean Geophysical Society, 3, 49-56.
  17. McCalpin, J.P., 1996, Application of paleoseismic data to seismic hazard assessment and neotectonic research. International Geophysics, 62, 439-493.
  18. Mansfield, C. and Cartwright, J., 2001, Fault growth by linkage: observation and implications from analogue models. Journal of Structural Geology, 23, 745-763. https://doi.org/10.1016/S0191-8141(00)00134-6
  19. Marrett, R and Allmendinger, R,W., 1992, Amount of extension on small faults: An example from the Viking graben. Geology, 20, 47-50. https://doi.org/10.1130/0091-7613(1992)020<0047:AOEOSF>2.3.CO;2
  20. Odling, N., 1997, Scaling and connectivity of joint system in sandstones from Western Norway. Jounal of Structual Geology, 19, 1257-1271. https://doi.org/10.1016/S0191-8141(97)00041-2
  21. Park, D.W., 2009, Microcrack orientations in Tertiary crystalline tuff from northeastern Gyeongsang Basin. Journal of the Petrological Society of Korea, 18, 115-135.
  22. Park, D.W., 2011, Statistical analysis on microcrack length distribution in Tertiary crystalline tuff. Journal of the Petrological Society of Korea, 20, 23-37. https://doi.org/10.7854/JPSK.2011.20.1.023
  23. Ryu, I.C., Choi, S.G. and Wee, S.M., 2006, An Inquiry into the formation and deformation of the Cretaceous Gyeongsang (Kyongsang) Basin, Southeastern Korea. Economic and Environmental Geology, 39. 129-149.
  24. Solvia, R. and Schultz, R.A., 2008, Distributed and localized faulting in extensional settings: Insight from the North Ethiopian Rift-Afar transition area. Tectonics, 27, TC2003, 10.1029/2007TC002148.
  25. Swanson, M.T., 2006, Late Paleozoic strike-slip faults and related vein array of Cape Elizabeth, Maine. Journal of Structural Geology, 28, 456-473. https://doi.org/10.1016/j.jsg.2005.12.009
  26. Watterrson, J., Walsh, J.J., Gillespie, P.A. and Easten, S., 1996, Scaling systematics of fault sizes on a large-scale fault map. Journal of Structural Geology, 18, 199-214. https://doi.org/10.1016/S0191-8141(96)80045-9
  27. Wojtal, S., 1994, Fault scaling laws and the temporal evolution of fault systems. Journal of Structural Geology, 16, 603-612. https://doi.org/10.1016/0191-8141(94)90100-7