Journal of Earth System Science

, Volume 120, Issue 4, pp 605–615 | Cite as

Development of the negative gravity anomaly of the 85°E Ridge, northeastern Indian Ocean – A process oriented modelling approach

  • K M SREEJITHEmail author

The 85°E Ridge extends from the Mahanadi Basin, off northeastern margin of India to the Afanasy Nikitin Seamount in the Central Indian Basin. The ridge is associated with two contrasting gravity anomalies: negative anomaly over the north part (up to 5°N latitude), where the ridge structure is buried under thick Bengal Fan sediments and positive anomaly over the south part, where the structure is intermittently exposed above the seafloor. Ship-borne gravity and seismic reflection data are modelled using process oriented method and this suggest that the 85°E Ridge was emplaced on approximately 10–15 km thick elastic plate (Te) and in an off-ridge tectonic setting. We simulated gravity anomalies for different crust-sediment structural configurations of the ridge that were existing at three geological ages, such as Late Cretaceous, Early Miocene and Present. The study shows that the gravity anomaly of the ridge in the north has changed through time from its inception to present. During the Late Cretaceous the ridge was associated with a significant positive anomaly with a compensation generated by a broad flexure of the Moho boundary. By Early Miocene the ridge was approximately covered by the post-collision sediments and led to alteration of the initial gravity anomaly to a small positive anomaly. At present, the ridge is buried by approximately 3 km thick Bengal Fan sediments on its crestal region and about 8 km thick pre- and post-collision sediments on the flanks. This geological setting had changed physical properties of the sediments and led to alter the minor positive gravity anomaly of Early Miocene to the distinct negative gravity anomaly.


85°E Ridge elastic plate thickness lithospheric flexure process oriented modelling Bengal Fan northeastern Indian Ocean 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Allen A and Allen J R 1990 Basin Analysis, Principles and Applications (Oxford: Blackwell Scientific Publications).Google Scholar
  2. Anand S P, Rajaram M, Majumdar T J and Bhattacharyya R 2009 Structure and tectonics of 85°E Ridge from analysis of Geopotential data; Tectonophys., doi: 10.1016/j.tecto.2008.09.036.Google Scholar
  3. Bastia R, Radhakrishna M, Das S, Kale A S and Catuneanu O 2010 Delineation of the 85°E Ridge and its structure in the Mahanadi Offshore Basin, Eastern Continental Margin (ECMI), from seismic reflection imaging; Mar. Petrol. Geol. 27 1841–1848.CrossRefGoogle Scholar
  4. Borissova I, Coffin M F, Charvis P and Operto S 2003 Structure and development of a microcontinent: Elan Bank in the southern Indian Ocean; Geochem. Geophys. Geosyst. 4(9) 1071, doi: 10.1029/2003GC000535.CrossRefGoogle Scholar
  5. Curray J R 1991 Possible greenschist metamorphism at the base of a 22-km sedimentary section, Bay of Bengal; Geology 19 1097–1100.CrossRefGoogle Scholar
  6. Curray J R 1994 Sediment volume and mass beneath the Bay of Bengal; Earth Planet. Sci. Lett. 125 371–383.CrossRefGoogle Scholar
  7. Curray J R and Munasinghe T 1991 Origin of the Rajmahal Traps and the 85°E Ridge: Preliminary reconstructions of the trace of the Crozet hotspot; Geology 19 1237–1240.CrossRefGoogle Scholar
  8. Curray J R, Emmel F J, Moore D G and Russel W R 1982 Structure, tectonics, and geological history of the northeastern Indian Ocean; In: The Ocean Basins and Margins, The Indian Ocean (eds) Nairn A E and Stehli F G (New York: Plenum) 6 399–450.Google Scholar
  9. Curray J R, Emmel F J and Moore D G 2003 The Bengal Fan: Morphology, geometry, stratigraphy, history and processes; Mar. Petrol. Geol. 19 1191–1223.CrossRefGoogle Scholar
  10. Diament M and Goslin J 1986 Emplacement of the Marion Dufresne, Lena and Ob seamounts (South Indian Ocean) from a study of isostasy; Tectonophys. 121 253–262.CrossRefGoogle Scholar
  11. Gaina C, Müller R D, Brown B and Ishihara T 2003 Microcontinental formation around Australia; In: The evolution and dynamics of the Australian Plate (eds) Hillis R and Muller R D, Joint Geol. Soc. Aust. Am. Spec. Paper 22 399–410.Google Scholar
  12. Gaina C, Müller R D, Brown B and Ishihara T 2007 Breakup and early seafloor spreading between Indian and Antarctica; Geophys. J. Int. 170 151–169.CrossRefGoogle Scholar
  13. Gopala Rao D, Krishna K S and Sar D 1997 Crustal evolution and sedimentation history of the Bay of Bengal since the Cretaceous; J. Geophys. Res. 102 17,747–17,768.Google Scholar
  14. Krishna K S 2003 Structure and evolution of the Afanasy Nikitin Seamount, buried hills and 85°E Ridge in the northern Indian Ocean; Earth Planet. Sci. Lett. 209 379–394.CrossRefGoogle Scholar
  15. Krishna K S, Gopala Rao D and Sar D 2006 Nature of the crust in the Laxmi Basin (14°–20°N), western continental margin of India; Tectonics 25 TC1006, doi: 10.1029/2004TC001747.CrossRefGoogle Scholar
  16. Krishna K S, Michael L, Bhattacharyya R and Majumdar T J 2009 Geoid and gravity anomaly data of conjugate regions of Bay of Bengal and Enderby Basin: New constraints on breakup and early spreading history between India and Antarctica; J. Geophys. Res. 114 B03102, doi: 10.1029/2008JB005808.CrossRefGoogle Scholar
  17. Krishna K S, Scrutton R A, Bull J M, Jaisankar S and Banakar V K 2011 Growth of the Afanasy Nikitin Seamount, central Indian Ocean: The product of short-lived hotspots; Earth Planet. Sci. Letts. (submitted).Google Scholar
  18. Liu C S, Sandwell D T and Curray J R 1982 The negative gravity field over the 85°E Ridge; J. Geophys. Res. 87 7673–7686.CrossRefGoogle Scholar
  19. Mahoney J J, White W M, Upton B G J, Neal C R and Scrutton R A 1996 Beyond EM-1: Lavas from Afanasy–Nikitin Rise and the Crozet Archipelago, Indian Ocean; Geology 24 615–618.CrossRefGoogle Scholar
  20. Michael L and Krishna K S 2011 Dating of the 85°E Ridge (northeastern Indian Ocean) using marine magnetic anomalies; Curr. Sci. 100(9) 1314–1322.Google Scholar
  21. Moore D G, Curray J R, Raitt R W and Emmel F J 1974 Stratigraphic-seismic section correlations and implications to Bengal Fan history; Init. Rep. Deep Sea Drill. Proj. 22 403–412.Google Scholar
  22. Mukhopadhyay M and Krishna M R 1991 Gravity field and deep structure of the Bengal Fan and its surrounding continental margins, northeast Indian Ocean; Tectonophys. 186 365–386.CrossRefGoogle Scholar
  23. Müller R D, Royer J –Y and Lawver L A 1993 Revised plate motions relative to the hotspots from combined Atlantic and Indian Ocean hotspot tracks; Geology 21 275–278.CrossRefGoogle Scholar
  24. Müller R D, Gaina C, Tikku A A, Mihut D, Cande S C and Stock J M 2000 Mesozoic/Cenozoic tectonic events around Australia; In: The History and Dynamics of Global Plate Motions (eds) Richards M A, Gordon R and Vander Hilst R, AGU Geophysical Monograph 121 161–188.Google Scholar
  25. Naini B R and Leyden R 1973 Ganges Cone: A wide angle seismic reflection and refraction study; J. Geophys. Res. 78 8711–8720.CrossRefGoogle Scholar
  26. Naini B R and Talwani M 1983 Structural framework and the evolutionary history of the continental margin of western India, in studies; In: Continental Margin Geology (eds) Watkins J S and Drake C L, AAPG Memoir 34 167–191.Google Scholar
  27. Paul J, Singh R N, Subrahmanyam C and Drolia R K 1990 Emplacement of Afanasy–Nikitin Seamount based on transfer function analysis of gravity and bathymetry data; Earth Planet. Sci. Lett. 96 419–426.CrossRefGoogle Scholar
  28. Radhakrishna M, Subbrahmanyam C and Damodharan T 2010 Thin oceanic crust below Bay of Bengal inferred from 3-D gravity interpretation; Tectonophys. 493 93–105.CrossRefGoogle Scholar
  29. Ramana M V, Subrahmanyam V, Chaubey A K, Ramprasad T, Sarma K V L N S, Krishna K S, Maria Desa and Murty G P S 1997 Structure and origin of the 85°E Ridge; J. Geophys. Res. 102 17,995–18,012.Google Scholar
  30. Royer J.-Y and Coffin M F 1992 Jurassic to Recent plate tectonicreconstructions in the Kerguelen Plateau region; Proc. Ocean Drill. Program Sci. Results 120 917–928.Google Scholar
  31. Sandwell D T and Smith W H F 1997 Marine gravity from Geosat and ERS-1 satellite altimetry; J. Geophys. Res. 102 10,039–10,054.Google Scholar
  32. Sborshchikov I M, Murdmaa I O, Matveenkov V V, Kashintsev G L and Glomshtock A I, Al’mukhamedov A I 1995 Afanasy Nikitin Seamount within the intraplate deformation zone, Indian Ocean; Mar. Geol. 128 115–126.CrossRefGoogle Scholar
  33. Subrahmanyam C, Thakur N K, Gangadhara Rao T, Khanna R, Ramana M V and Subrahmanyam V 1999 Tectonics of the Bay of Bengal: New insights from satellite-gravity and ship-borne geophysical data; Earth Planet. Sci. Lett. 171 237–251.CrossRefGoogle Scholar
  34. Talwani M and Reif C 1998 Laxmi Ridge – A continental sliver in the Arabian Sea; Mar. Geophys. Res. 20 259–271.CrossRefGoogle Scholar
  35. Watts A B 1988 Gravity anomalies, crustal structure and flexure of the lithosphere at the Baltimore Canyon Trough; Earth Planet. Sci. Lett. 89 221–238.CrossRefGoogle Scholar
  36. Watts A B and Fairhead J D 1999 A process-oriented approach to modeling the gravity of continental margins; The Leading Edge 18 258–263.CrossRefGoogle Scholar
  37. Wessel P and Smith W H F 1995 New version of the Generic Mapping Tools released; EOS Trans. AGU 76 329.CrossRefGoogle Scholar

Copyright information

© Indian Academy of Sciences 2011

Authors and Affiliations

    • 1
    Email author
    • 2
    • 3
    • 4
  1. 1.Geosciences Division, Marine, Geo and Planetary Sciences Group, Space Applications CentreIndian Space Research OrganizationAhmedabadIndia
  2. 2.Department of Earth SciencesIndian Institute of Technology BombayMumbaiIndia
  3. 3.National Institute of OceanographyCouncil of Scientific and Industrial ResearchGoaIndia
  4. 4.Space Applications CentreIndian Space Research OrganizationAhmedabadIndia

Personalised recommendations