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Regional-residual Separation of Microgravity Data

고정밀 중력탐사 자료의 광역-나머지 이상 분리

  • Rim, Hyoungrea (Department of Earth Science Education, Pusan National University) ;
  • Park, Gyesoon (Convergence Research Center for Development of Mineral Resources, KIGAM) ;
  • Kim, Chang-Ryol (Mineral Resources Research Division, KIGAM)
  • 임형래 (부산대학교 지구과학교육과) ;
  • 박계순 (한국지질자원연구원 DMR 융합연구단) ;
  • 김창렬 (한국지질자원연구원 광물자원연구본부)
  • Received : 2019.05.03
  • Accepted : 2019.05.24
  • Published : 2019.05.31

Abstract

In this paper, we propose a method to apply the polynomial fitting for regional-residual separation of microgravity data based on the characteristics of gravity anomaly without a prior information. Since the microgravity survey is usually carried out in small regions, it is common to approximate regional anomaly by the first-order polynomial plane. However, if the regional anomaly patterns are difficult to be approximated to a first-order plane, the complete gravity anomaly is divided into small zones enough to approximate first-order plane by means of Parasnis density estimation method. The regional-residual separation is then applied on the splitted zones individually. When the gravity anomalies can be splitted spatially, we showed that the residual anomalies can be more effectively extracted based on the regional geological structures by regional anomaly separation from each of the divided regions, rather than applying the entire data set at one time.

이 논문에서는 사전 정보가 없는 경우 고정밀 중력 탐사 자료를 광역-나머지 이상으로 분리할 때 중력 이상 자료의 특성을 바탕으로 다항식 접합법을 적용하는 방법을 제시하였다. 소규모 영역을 대상으로 하는 고정밀 중력 탐사는 1차 평면으로 광역 이상을 근사하는 것이 이상적인데 중력 이상의 패턴이 1차 평면으로 근사하기 어려운 경우, 먼저 완전 부게 이상을 Parasnis 밀도 추정 방법으로 분석한 후 중력 이상을 1차 평면으로 근사 가능하도록 분할하였다. 다항식 접합법으로 중력 이상을 광역-나머지 이상으로 분리할 때 중력 이상 자료가 지질 구조 및 중력 이상 분포 특성을 바탕으로 공간적으로 분할이 가능한 경우에는 전체 측정 자료를 한꺼번에 분리하지 않고 구획된 각각의 영역에서 광역-나머지 이상을 별도로 분리하는 것이 더 효과적임을 보였다.

Keywords

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Fig. 1. Gravity observation stations on the topography.

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Fig. 3. Complete Bouguer anomaly.

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Fig. 4. Regional and residual anomaly maps from all data by polynomial fitting method: regional anomaly by (a) the first and (b) second orders, and residual anomaly by (c) the first and (d) second orders.

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Fig. 5. Density estimation by Parasnis method using (a) all the data, (b) the data within the northern part, and (c) those within the southern part of the study area.

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Fig. 6. Regional and residual anomaly maps from splitting data as northern and southern areas by polynomial fitting method: regional anomalies by (a) the first and (b) second orders, and residual anomalies by (c) the first and (d) second orders.

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Fig. 7. Comparing ranges of residual anomalies according to polynomial orders and applied areas.

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Fig. 2. (a) Free-air anomaly and (b) simple Bouguer anomaly.

References

  1. Agocs, W. B., 1951, Least-squares residual anomaly determination, Geophysics, 16(4), 686-696. https://doi.org/10.1190/1.1437720
  2. Arzi, A. A., 1975, Microgravimetry for engineering applications, Geophys. Prospect., 23(3), 408-425. https://doi.org/10.1111/j.1365-2478.1975.tb01539.x
  3. Beltrao, J. F., Silva, J. B. C., and Costa, J. C., 1991, Robust polynomial fitting method for regional gravity estimation, Geophysics, 56(1), 80-89. https://doi.org/10.1190/1.1442960
  4. Butler, D. K., 1984, Microgravimetric and gravity gradient techniques for detection of subsurface cavities, Geophysics, 49(7), 1084-1096. https://doi.org/10.1190/1.1441723
  5. Colley, G. C., 1963, The detection of caves by gravity measurements, Geophys. Prospect., 11(1), 1-9. https://doi.org/10.1111/j.1365-2478.1963.tb02019.x
  6. Gupta, V. K., and Ramani, N., 1980, Some aspects of regional residual separation of gravity anomalies in a Precambrian terrain, Geophysics, 45(9), 1412-1426. https://doi.org/10.1190/1.1441130
  7. Hammer, S., 1963, Deep gravity interpretation by stripping, Geophysics, 28(3), 369-378. https://doi.org/10.1190/1.1439186
  8. Jacobsen, B. H., 1987, A case for upward continuation as a separation filter for potential-field maps, Geophysics, 52(8), 1138-1148. https://doi.org/10.1190/1.1442378
  9. KIGAM, 1967, 1:50,000 Mungyeoung geological Map (sheet 6824-3).
  10. Lee, H., and Rim, H., 2010, Precise gravity terrain correction of gravity exploration for small anomalous bodies, Journal of Korean Earth Science Society, 31(1), 1-7 (in Korean with English abstract). https://doi.org/10.5467/JKESS.2010.31.1.001
  11. Li, Y., and Oldenburg, D. W., 1998, Separation of regional and residual magnetic field data, Geophysics, 63(2), 431-439. https://doi.org/10.1190/1.1444343
  12. Mickus, K. L., Aiken, C. L. V., and Kennedy, W. D., 1991, Regional-residual gravity anomaly separation using the minimum-curvature technique, Geophysics, 56(2), 279-283. https://doi.org/10.1190/1.1443041
  13. Neumann, R., 1967, High accuracy gravimetry application to the detection of cavities, Geophys. Prospect., 15(1), 116-134. https://doi.org/10.1111/j.1365-2478.1967.tb01776.x
  14. Parasnis, D. S., 1979, Principles of Applied Geophysics, Chapman and Hall, 284p.
  15. Park, Y.-S., Rim, H., and Lim, M., 2012, Separation-sounding filter for potential data, Geophys. and Geophys. Explor., 15(2), 51-56 (in Korean with English abstract). https://doi.org/10.7582/GGE.2012.15.2.051
  16. Park, Y.-S., Rim, H., Lim, M., and Chung, H., 2017, An inversion package for interpretation of microgravity data, Geophys. and Geophys. Explor., 20(4), 226-231 (in Korean with English abstract). https://doi.org/10.7582/GGE.2017.20.4.226
  17. Pawlowski, R. S., and Hansen, R. O., 1990, Gravity anomaly separation by Wiener filtering, Geophysics, 55(5), 539-548. https://doi.org/10.1190/1.1442865
  18. Telford, W. M., Geldart, L. P., and Sheriff, R. E., 1990, Applied Geophysics, Cambridge University Press, 770p.
  19. Yule, D. E., Sharp, M. K., and Butler, D. K., 1998, Microgravity investigations of foundation conditions, Geophysics, 63(1), 95-103. https://doi.org/10.1190/1.1444331