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Origin, Recognition, and Importance of Erosional Unconformities in Sedimentary Basins

  • G. Shanmugam
Part of the Frontiers in Sedimentary Geology book series (SEDIMENTARY)

Abstract

Erosional unconformities of different scales (local to global) are an ubiquitous element of all sedimentary basins. Erosional unconformities of subaerial origin are believed to have been caused by tectonic uplifts and by eustatic sea-level fall. Erosional unconformities of submarine origin may be related to transgression, mass movements, turbidity currents, thermohaline currents, carbonate dissolution, storms, and clastic influx on carbonate shelves. Important criteria for recognizing subaerial unconformities include discordance of dip, karst facies, basal conglomerate, and a major gap in the fossil record. Paleosol horizons, duricrust, and continental deposits, indicative of subaerial exposure, can also be used to define surfaces of potential subaerial unconformities. Submarine unconformities may be recognized by mass-movement deposits, glauconitic minerals, and manganese nodules.

Recognition of unconformities is useful for subdividing stratigraphic units, determining the timing of tectonic activity, interpreting lateral facies relationships, constructing burial and uplift curves, correlating certain stratigraphic boundaries, interpreting sea-level changes, and for reconstructing paleogeography. Erosional unconformities may be important to exploration because they can be used to predict deep-sea turbidite reservoir facies; they can mark upper boundaries of zones of increased porosity (e.g., Statfjord Field, North Sea); they can provide an ideal juxtaposition of reservoir and source rocks (e.g., Prudhoe Bay Field, Alaska); they can act as avenues of hydrocarbon migration (e.g., Maracaibo Basin, Venezuela); they can generate hydrocarbon traps (e.g., Messla Field, Libya); and they can be favorable sites for mineralization (e.g., uranium, aluminum, phosphates, and gold).

Keywords

Meteoric Water Tectonic Uplift Subaerial Exposure Manganese Nodule Condensed Section 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. AL-GAILANI, M.B. (1981) Authigenic mineralizations at unconformities: Implication for reservoir characteristics. Sedimentary Geology 29:89–115.CrossRefGoogle Scholar
  2. ALHILALI, K.A. and DAMUTH, J.E. (1987) Slide block (?) of Jurassic sandstone and submarine channels in the basal Upper Cretaceous of the Viking Graben: Norwegian North Sea. Marine Petroleum Geology 4:35–48.CrossRefGoogle Scholar
  3. AL-SHAIEB, Z., WARD, W.C., and SHELTON, J.W. (1981) Diagenesis and secondary porosity evolution of Sarir sandstone, southeastern Sirte basin, Libya (Abstract). American Association Petroleum Geologists Bulletin 65:889–890.Google Scholar
  4. BARRELL, J. (1917) Rhythms and measurement of geologic time. Geological Society America Bulletin 28: 745–904.Google Scholar
  5. BATEMAN, A.M. (1942) Economic Mineral Deposits. New York: John Wiley & Sons, Inc., 808 p.Google Scholar
  6. BATES, R.L. and JACKSON, J.A. (eds) (1980) Glossary of Geology. Falls Church, Virginia: American Geological Institute, 749 p.Google Scholar
  7. BERNER, R. A. (1978) Rate control of mineral dissolution under earth surface conditions. American Journal Science 278:1235–1252.CrossRefGoogle Scholar
  8. BJøRLYKKE, K. (1983) Diagenetic reactions in sandstones. In: Parker, A. and Sellwood, B.W. (eds) Sediment Diagenesis. Dordrecht: D. Reidel Publishing Company, pp. 169–213.Google Scholar
  9. BJøRLYKKE, K. and BRENDSDAL, A. (1986) Diagenesis of the Brent Sandstone in the Statfjord field, North Sea. In: Gautier, D.L. (ed) Roles of Organic Matter in Sediment Diagenesis. Society Economic Paleontologists Mineralogists Special Publication 38, pp. 157–167.Google Scholar
  10. BODARD, J.M., WALL, V.J., and CAS, R.A.F. (1984) Diagenesis and the evolution of Gippsland basin reservoirs. Australian Petroleum Exploration Association Journal 24, pt. 1:314–335.Google Scholar
  11. BOWIE, S.H.U. (1979) The mode of occurrence and distribution of uranium deposits. Philosophical Transactions Royal Society London A291:289–300.Google Scholar
  12. BUSHNELL, H. (1981) Unconformities-key to N. Slope oil. Oil Gas Journal 79(2): 114–118.Google Scholar
  13. CHENWORTH, P.A. (1967) Unconformity analysis. American Association Petroleum Geologists Bulletin 51:4–27.Google Scholar
  14. CHENWORTH, P.A. (1972) Unconformity traps. In: King, R.E. (ed) Stratigraphic Oil and Gas Fields-Classification, Exploration Methods, and Case Histories. American Association Petroleum Geologists Memoir 16, pp. 42–46.Google Scholar
  15. CLIFFORD, H.J., Grund, R., and Musrati, H. (1980) Geology of a stratigraphic giant: Messla oil field, Libya. In: Halbouty, M.T. (ed) Giant Oil and Gas Fields of the Decade 1968–1978. American Association Petroleum Geologists Memoir 30, pp. 507–524.Google Scholar
  16. CLOETINGH, S. (1986) Intraplate stresses: A new tectonic mechanism for fluctuations of relative sea level. Geology 14:617–620.CrossRefGoogle Scholar
  17. CREASE, J. (1965) The flow of Norwegian sea water through the Faroe bank channel. Deep-Sea Research 12:143–150.Google Scholar
  18. CRONAN, D.S. (1977) Deep-sea nodules: Distribution and geochemistry. In: Glasby, G.P. (ed) Marine Manganese Deposits. Amsterdam: Elsevier Scientific Publishing Company, pp. 11–44.CrossRefGoogle Scholar
  19. DAMUTH, J.E., JACOBI, R.D, and HAYES, D.E. (1983) Sedimentation processes in the Northwest Pacific Basin revealed by echo-character mapping studies. Geological Society America Bulletin 94:381–395.CrossRefGoogle Scholar
  20. DARWIN, C. (1859) On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: Murray, 502 p.Google Scholar
  21. DAVID, M. (1946) Devonian (?) producing zone, TXL pool, Ector county, Texas. American Association Petroleum Geologists Bulletin 30:118–119.Google Scholar
  22. DICKEY, P.A. and HUNT, J.M. (1972) Geochemical and hydrogeologic methods of prospecting for stratigraphie traps. In: King, R.E. (ed) Stratigraphie Oil and Gas Fields-Classification, Exploration Methods, and Case Histories. American Association Petroleum Geologists Memoir 16, pp. 136–167.Google Scholar
  23. DOTT, R.H. JR. and BATTEN, R.L. (1971) Evolution of the Earth. New York: McGraw-Hill Book Company, 649 p.Google Scholar
  24. DUNBAR, C.O. and RODGERS, J. (1957) Principles of Stratigraphy. New York: Wiley, 356 p.Google Scholar
  25. ESTEBAN, M. and KLAPPA, C.F. (1983) Subaerial exposure environment. In: Scholle, P.A., Bebout, D.G., and Moore, C.H. (eds) Carbonate Depositional Environments. American Association Petroleum Geologists Memoir 33, pp. 1–54.Google Scholar
  26. FAERSETH, R.B., OPPEBOEN, K.A., and SAEBOE, A. (1986) Trapping styles and associated hydrocarbon potential in the Norwegian North Sea. In: Halbouty, M.T. (ed) Future Petroleum Provinces of the World. American Association Petroleum Geologists Memoir 40, pp. 585–597.Google Scholar
  27. FREEZE, R.A. and CHERRY, J.A. (1979) Groundwater. Englewood Cliffs, NJ: Prentice-Hall, Inc., 604 p.Google Scholar
  28. GALLOWAY, W.E. and HOBDAY, D.K. (1983) Terrigenous Clastic Depositional Systems. New York: Springer-Verlag, 423 p.Google Scholar
  29. GDULA, J.E. (1983) Reservoir geology, structural framework, and petrophysical aspects of the DeWijk gas field. Geologie Mijnbouw 62:191–202.Google Scholar
  30. GILES, M.R. and MARSHALL, J.D. (1986) Constraints on the development of secondary porosity in the subsurface: Re-evaluation of processes. Marine Petroleum Geology 3:243–255.CrossRefGoogle Scholar
  31. GILREATH, J.A. and MARICELLI, J.J. (1964) Detailed stratigraphic control through dip computations. American Association Petroleum Geologists Bulletin 48: 1902–1910.Google Scholar
  32. GOUDIE, A. (1973) Duricrust in Tropical and Subtropical Landscapes. Oxford: Clarendon Press, 174 p.Google Scholar
  33. GRANT, W.D., WILLIAMS, A.J. III, and GROSS, T.F. (1985) A description of the bottom boundary layer at the Hebble site: Low-frequency forcing, bottom stress and temperature structure. In: Nowell, A.R.M. and Hollister, C.D. (eds) Deep Ocean Sediment Transport. Amsterdam: Elsevier, pp. 219–241.Google Scholar
  34. GUANGMING, Z. and QUANHENG, Z. (1982) Buried-hill oil and gas pools in the North China basin. In: Halbouty, M.T. (ed) The Deliberate Search for the Subtle Trap. American Association Petroleum Geologists Memoir 32, pp. 317–335.Google Scholar
  35. HALBOUTY, M.T. (ed) (1982) The Deliberate Search for the Subtle Trap. American Association Petroleum Geologists Memoir 32, 351 p.Google Scholar
  36. HANCOCK, N.J. and TAYLOR, A.M. (1978) Clay mineral diagenesis and oil migration in the Middle Jurassic Brent Sand Formation. Journal Geological Society London 135:69–72.CrossRefGoogle Scholar
  37. HANSON, B.M. (1985) Truncated Devonian and Fussel-man fields and their relationship to the Permian basin reserve. Transactions Southwest Section American Association Petroleum Geologists 1985 Convention, Fort Worth, Texas, p. 132.Google Scholar
  38. HEA, J.P. (1971) Petrography of the Paleozoic-Mesozoic sandstones of the southern Sirte basin, Libya. In: Gray, C. (ed) Symposium on the Geology of Libya. University of Libya, pp. 100–125.Google Scholar
  39. HOEFS, J. (1980) Stable Isotope Geochemistry. Berlin: Springer-Verlag, 208 p.Google Scholar
  40. HOLLISTER, CD. and HEEZEN, B.C. (1972) Geologic effects of ocean bottom currents: Western North Atlantic. In: Gordon, A.L. (ed) Studies in Physical Oceanography, Volume 2. New York: Gordon and Breach Science Publishers, pp. 37–66.Google Scholar
  41. HUANG, W.H. and KELLER, W.D. (1970) Dissolution of rock-forming silicate minerals in organic acids: Simulated first-stage weathering of fresh mineral surfaces. American Mineralogist 55:2076–2094.Google Scholar
  42. HUTTON, J. (1788) Theory of the Earth, or an investigation of the laws observable in the composition, dissolution and restoration of land upon the globe. Royal Society Edinburgh Transactions 1:109–304.Google Scholar
  43. JACOBI, R.D. (1981) Peripheral bulge-a causal mechanism for the Lower/Middle Ordovician unconformity along the western margin of the northern Appalachians. Earth Planetary Science Letters 56:245–251.CrossRefGoogle Scholar
  44. JENSEN, M.L. and BATEMAN, A.M. (1981) Economic Mineral Deposits, 3rd edition. New York: John Wiley & Sons, 593 p.Google Scholar
  45. JONES, H.P. and SPEERS, R.G. (1976) Permo-Triassic reservoirs of Prudhoe Bay field, North Slope, Alaska. In: Braunstein, J. (ed) North American Oil and Gas Fields. American Association Petroleum Geologists Memoir 24, pp. 23–50.Google Scholar
  46. KELLER, G., HERBERT, T., DORSEY, R., D’HONDT, S., JOHNSSON, M., and CHI, WR. (1987) Global distribution of late Paleogene hiatuses. Geology 18:199–203.CrossRefGoogle Scholar
  47. KING, R.E. (ed) (1972) Stratigraphic Oil and Gas Fields—Classification, Exploration Methods, and Case Histories. American Association Petroleum Geologists Memoir 16, 687 p.Google Scholar
  48. KIRK, R.H. (1980) Statfjord field: A North Sea giant. In: Halbouty, M.T. (ed) Giant Oil and Gas Fields of the Decade 1968-1978. American Association Petroleum Geologists Memoir 30, pp. 95–116.Google Scholar
  49. KRUMBEIN, W.C. (1942) Criteria for subsurface recognition of unconformities. American Association Petroleum Geologists Bulletin 26:36–62.Google Scholar
  50. KRUMBEIN, W.C. and SLOSS, L.L. (1963) Stratigraphy and Sedimentation. San Francisco: W.H. Freeman and Company, 660 p.Google Scholar
  51. KYLE, J.R. (1983) Economic aspects of subaerial carbonates. In: Scholle, P.A., Bebout, D.G., and Moore, C.H. (eds) Carbonate Depositional Environments. American Association Petroleum Geologists Memoir 33, pp. 73–92.Google Scholar
  52. LEVORSEN, A.I. (1934) Relation of oil and gas pools to unconformities in the mid-continent region. In: Wrather, W.E. and Lahee, F.H. (eds) Problems of Petroleum Geology. American Association Petroleum Geologists Sidney Powers Memorial Volume, pp. 761–784.Google Scholar
  53. LEVORSEN, A.I. (1936) Stratigraphic versus structural accumulation. American Association Petroleum Geologists Bulletin 20:521–530.Google Scholar
  54. LEVORSEN, A.I. (1954) Geology of Petroleum. San Francisco: W.H. Freeman and Company, 703 p.Google Scholar
  55. LEWIS, K.B. (1971) Slumping on a continental slope inclined at l°–4°. Sedimentology 16:97–110.CrossRefGoogle Scholar
  56. LONGSTAFFE, F.J. (1984) The role of meteoric water in diagenesis of shallow sandstones: Stable isotope studies of the Milk River aquifer and gas pool, southern Alberta. In: McDonald, D.A. and Surdam, R.C. (eds) Clastic Diagenesis. American Association Petroleum Geologists Memoir 37, pp. 81–98.Google Scholar
  57. MCPHERSON, J.G. (1979) Calcrete (caliche) paleosols in fluvial redbeds of the Aztec Siltstone (Upper Devonian), Southern Victoria Land, Antarctica. Sedimentary Geology 22:267–285.CrossRefGoogle Scholar
  58. MIALL, A.D. (1984) Principles of Sedimentary Basin Analysis. New York: Springer-Verlag, 490 p.Google Scholar
  59. MIALL, A.D. (1986) Eustatic sea level changes interpreted from seismic stratigraphy: A critique of the methodology with particular reference to the North Sea Jurassic record. American Association Petroleum Geologists Bulletin 70:131–137.Google Scholar
  60. MIDDLETON, G.V. (1973) Johannes Walther’s law of correlation of facies. Geological Society America Bulletin 84:979–988.CrossRefGoogle Scholar
  61. MILLER, E.G. (1972) Parkman field, Williston basin, Saskatchewan. In: King, R.E. (ed) Stratigraphic Oil and Gas Fields—Classification, Exploration Methods, and Case Histories. American Association Petroleum Geologists Memoir 16, pp. 502–510.Google Scholar
  62. MORGRIDGE, D.L. and SMITH, W.B. (1972) Geology and discovery of Prudhoe Bay field, eastern Arctic Slope. In: King, R.E. (ed) Stratigraphie Oil and Gas Fields—Classification, Exploration Methods, and Case Histories. American Association Petroleum Geologists Memoir 16, pp. 489–501.Google Scholar
  63. ODIN, G.S. (1985) Significance of green particles (glaucony, berthierine, chlorite) in arenites. In: Zuffa, G.G. (ed) Provenance of Arenites. Dordrecht: D. Reidel Publishing Company, pp. 279–307.Google Scholar
  64. PETTIJOHN, F.J. (1926) Intraformational phosphate pebbles of the Twin-City Ordovician. Journal Geology 34:361–375.CrossRefGoogle Scholar
  65. PITMAN, W.C. (1978) Relationship between eustacy and stratigraphic sequences of passive margins. Geological Society America Bulletin 89:1389–1403.CrossRefGoogle Scholar
  66. READ, J.F. and GROVER, JR. G. (1977) Scalloped and planar erosion surfaces, Middle Ordovician limestones, Virginia: Analogues of Holocene exposed karst or tidal rock platforms. Journal Sedimentary Petrology 47:956–972.Google Scholar
  67. REEVES, C.C. (1976) Caliche. Lubbock, TX: Estacado Books, 233 p.Google Scholar
  68. ROSE, A.W, HAWKES, H.E., and WEBB, J.S. (1979) Geochemistry in mineral exploration. London: Academic Press, 657 p.Google Scholar
  69. SANFORD, R.M. (1970) Sarir oil field-Libya desert surprise. American Association Petroleum Geologists Memoir 14, pp. 449–476.Google Scholar
  70. SCHLAGER, W and CAMBER, O. (1986) Submarine slope angles, drowning unconformities, and self-erosion of limestone escarpments. Geology 14:762–765.CrossRefGoogle Scholar
  71. SCHLEE, J.S. (ed) (1984) Interregional Unconformities and Hydrocarbon Accumulation. American Association Petroleum Geologists Memoir 36, 184 p.Google Scholar
  72. SCHWAN, W. (1980) Geodynamic peaks in Alpinotype orogenies and changes in ocean-floor spreading during Late Jurassic-Late Tertiary time. American Association Petroleum Geologists Bulletin 64:359–373.Google Scholar
  73. SELLEY, R.C. (1984) Porosity evolution of truncation traps: Diagenetic models and log responses. Stavanger, Norway: Norwegian Petroleum Society Offshore North Seas Conference Paper No. G3, 18 p.Google Scholar
  74. SELLEY, R.C. (1985) Elements of Petroleum Geology. New York: W.H. Freeman and Company, 449 p.Google Scholar
  75. SHANMUGAM, G. (1978) The Stratigraphy, Sedimentology, and Tectonics of the Middle Ordovician Sevier Shale Basin in East Tennessee. Unpublished Ph.D. Dissertation. Knoxville: The University of Tennessee, 222 p.Google Scholar
  76. SHANMUGAM, G. (1985a) Significance of secondary porosity in interpreting sandstone composition. American Association Petroleum Geologists Bulletin 69:378–384.Google Scholar
  77. SHANMUGAM, G. (1985b) Types of porosity in sandstones and their significance in interpreting provenance. In: Zuffa, G.G. (ed) Provenance of Arenites. Dordrecht: D. Reidel Publishing Company, pp. 115–137.Google Scholar
  78. SHANMUGAM, G. (1985c) Significance of coniferous rain forests and related organic matter in generating commercial quantities of oil, Gippsland basin, Australia. American Association Petroleum Geologists Bulletin 69:1241–1254.Google Scholar
  79. SHANMUGAM, G. and HIGGINS, I.B. (1987) Porosity development from chert dissolution beneath the Neoco-mian Unconformity: Ivishak Formation, North Slope, Alaska: SEPM Mid-Year Meeting Abstracts (Austin, Texas) 4:76.Google Scholar
  80. SHANMUGAM, G. and LASH, G.G. (1982) Analogous tectonic evolution of the Orodovician foredeeps, southern and central Appalachians. Geology 10:562–566.CrossRefGoogle Scholar
  81. SHANMUGAM, G. and MOIOLA, R.J. (1982a) Eustatic control of turbidites and winnowed turbidites. Geology 10:231–235.CrossRefGoogle Scholar
  82. SHANMUGAM, G. and MOIOLA, R.J. (1982b) Prediction of deep-sea reservoir facies. Transactions-Gulf Coast Association Geological Societies 32:275–281.Google Scholar
  83. SHANMUGAM, G., DAMUTH, I.E., and MOIOLA, R.J. (1985a) Is the turbidite facies association scheme valid for interpreting ancient submarine fan environments? Geology 13:234–237.CrossRefGoogle Scholar
  84. SHANMUGAM, G., MOIOLA, R.J., and DAMUTH, J.E. (1985b) Eustatic control of submarine fan development. In: Bouma, A.H., Normark, W.R., and Barnes, N.E. (eds) Submarine Fans and Related Turbidite Systems. New York: Springer-Verlag, pp. 23–28.CrossRefGoogle Scholar
  85. SHELTON, J.W. (1967) Stratigraphic models and general criteria for recognition of alluvial, barrier bar and turbidity current sand deposits. American Association Petroleum Geologists Bulletin 51:2441–2460.Google Scholar
  86. SHINN, E.A. (1983) Tidal flat environment. In: Scholle, P.A., Bebout, D.G., and Moore, C.H. (eds) Carbonate Depositional Environments. American Association Petroleum Geologists Memoir 33, pp. 171–210.Google Scholar
  87. SIEVER, R. (1951) The Mississippian-Pennsylvanian unconformity in southern Illinois. American Association Petroleum Geologists Bulletin 35:542–581.Google Scholar
  88. SLOSS, L.L. (1984) Comparative anatomy of cratonic unconformities. In: Schlee, IS. (ed) Interregional Unconformities and Hydrocarbon Accumulation. American Association Petroleum Geologists Memoir 36, pp. 1–6.Google Scholar
  89. SOMMER, F. (1978) Diagenesis of Jurassic sandstones in the Viking Graben. Journal Geological Society London 135:63–67.CrossRefGoogle Scholar
  90. STOW, D.A.V. and LOVELL, J.P.B. (1979) Contourites: Their recognition in modern and ancient sediments. Earth-Science Reviews 14:251–291.CrossRefGoogle Scholar
  91. THIRY, M. and MILLOT, G. (1987) Mineralogical forms of silica and their sequence of formation in silcretes. Journal Sedimentary Petrology 57:343–352.Google Scholar
  92. TUCHOLKE, B.E. and EMBLEY, R.W. (1984) Cenozoic regional erosion of the abyssal sea floor off South Africa. In: Schlee, I.S. (ed) Interregional Unconformities and Hydrocarbon Accumulation. American Association Petroleum Geologists Memoir 36, pp. 145–164.Google Scholar
  93. VAIL, P.R., MITCHUM, R.M., TODD, R.G., WID-MIER, I.M., THOMPSON, S., SANGREE, I.B., BUBB, I.N., and HATLELID, W.G. (1977) Seismic stratigraphy and global changes of sea level. In: Payton, C.E. (ed) Seismic Stratigraphy—Application to Hydrocarbon Exploration. American Association Petroleum Geologists Memoir 26, pp. 49–212.Google Scholar
  94. VAIL, PR. and TODD, R.G. (1981) Northern North Sea Jurassic unconformities, chronostratigraphy and sea-level changes from seismic stratigraphy. In: Illing, L.V and Hodson, G.D. (eds) Petroleum Geology of the Continental Shelf of Northwest Europe. London: Heyden and Son, Ltd., pp. 216–235.Google Scholar
  95. VAIL, PR., HARDENBOL, I, and TODD, R.G. (1984) Jurassic unconformities, chronostratigraphy, and sea-level changes from seismic stratigraphy and biostra-tigraphy. In: Schlee, I.S. (ed) Interregional Unconformities and Hydrocarbon Accumulation. American Association Petroleum Geologists Memoir 36, pp. 129–144.Google Scholar
  96. VISSER, M.J. (1980) Neap-spring cycles reflected in Holocene subtidal large-scale bedform deposits: A preliminary note. Geology 8:543–546.CrossRefGoogle Scholar
  97. WALKER, K.R., SHANMUGAM, G., and RUPPEL, S.C. (1983) A model for carbonate to terrigenous clastic sequences. Geological Society America Bulletin 94: 700–712.CrossRefGoogle Scholar
  98. WATKINS, N.D. and KENNETT, I.P. (1972) Regional sedimentary disconformities and upper Cenozoic changes in bottom water velocities between Australasia and Antarctica. Antarctic Research Series 19:273–293.CrossRefGoogle Scholar
  99. WRIGHT, V.P. (ed) (1986) Paleosols: Their Recognition and Interpretation. Princeton, NJ: Princeton University Press, 315 p.Google Scholar
  100. YOUNG, R.W. (1987) Sandstone landforms of the tropical east Kimberley region, northwestern Australia. Journal Geology 95:205–218.CrossRefGoogle Scholar
  101. ZIEGLER, W.H. (1975) Outline of the geological history of the North Sea. In: Woodland, A.W. (ed) Petroleum and the Continental Shelf of Northwest Europe. London: Institute Petroleum, pp. 165–190.Google Scholar

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  • G. Shanmugam

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