Abstract
The Andaman arc is associated with a major Free-air anomaly pair of mean amplitude 180 mgal. Two-dimensional gravity interpretation suggests significant mass anomalies below the arc that presumably have resulted due to subduction of the Indian plate below the Burma plate. It is inferred that the Andaman trench is of asymmetric V-shape containing about 7 km sediments. An outer bathymetric rise seaward of the trench possibly corresponds to a lithospheric flexure by 500 m. The Cretaceous-Tertiary sediments constituting the Andaman sedimentary arc attain their maximum thickness of about 13 km under the Nicobar. Deep at the subduction zone. At this location a mafic mass is emplaced within the sedimentary section. The underlying oceanic crust apparently experiences phase transition at about 27 km depth in a Benioff zone environment. The Andaman volcanic arc underlies a low density zone that is at least 60 km wide. Along the east margin of the Andaman Sea, cuustal transition presumably occurs below the Mergui Terrace at the Malayan coast.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Burns, R. E., 1964, Sea Bottom Heat-Flow Measurements in the Andaman Sea, J. Geophys. Res. 69, 4918–4919
Chatterjee, P. K., 1967, Geology of the Main Islands of the Andaman Area, Proc. Symp. Upper Mantle Project, Hyderabad, India, Jan. 1967, 348–362.
Christensen, N. I. and Salisbury, M. H., 1975, Structure and Constitution of the Lower Oceanic Crust, Rev. Geophys. Space Phys. 13, 57–86.
Coleman, R. G., 1971, Plate Tectonic Emplacement of Upper Mantle Periodotites Along Continental Edges, J. Geophys. Res. 76, 1212–1222.
Curray, J. R. and Moore, D. G., 1971, Growth of the Bengal Deep-Sea Fan and Denudation in the Himalayas, Geol. Soc. Am. Bull. 82, 563–572.
Curray, J. R. and Moore, D. G., 1974, Sedimentary and Tectonic Processes in the Bengal Deep-Sea Fan and Geosyncline, in Burk, C. A. and Drake, C. L. (eds.), The Geology of Continental Margins, Springer-Verlag, New York, pp. 617–627.
Curray, J. R., Moore, D. G., Lawver, L. A., Emmel, F. J., Raitt, R. W., Henry, M., and Kieckhefer, R., 1979, Tectonics of the Andaman Sea and Burma, Am. Assoc. Petrol. Geol. Memoir 29, 189–198.
Curray, J. R., Emmel, F. J., Moore, D. G., and Raitt, R. W., 1982, Structure, Tectonics and Geological History of the Northeastern Indian Ocean, in Nairn, A.E.M. and Stehli, F.G. (eds.), The Ocean Basins and Margins, Plenum Publ. Corp. 6, pp. 399–450.
Dehlinger, P., 1978, Marine Gravity, Elsevier, Amsterdam, pp. 322.
Dewey, J. F. and Bird, J. M., 1971, Orgin and Emplacement of the Ophiolite Suite: Appalachian Ophiolites in Newfoundland, J. Geophys. Res. 76, 3179–3206.
Ermenko, N. A. and Sastri, V. V., 1977, On the Petroleum Geology of Andaman Islands, Bull. Oil & Natural Gas Commn. India 14, 1–13.
Evans, P. and Crompton, W., 1946, Geological Factors in Gravity Interpretation by Evidence from India and Burma, Q. J. Geol. Soc. London 102, 211–249.
Fitch, T. J., 1970, Earthquake Mechanisms in the Himalayan, Burmese, and Andaman Regions and Continental Tectonics in Central Asia, J. Geophys. Res. 75, 2699–2709.
Grow, J. A., 1973, Crustal and Upper Mantle Structure of the Central Aleutian Arc, Geol. Soc. Am. Bull. 84, 2169–2192.
Grow, J. A. and Bowin, C. O., 1975, Evidence for High-Density Crust and Mantle Beneath the Chile Trench Due to the Descending Lithosphere, J. Geophys. Res. 80, 1449–1458.
Hager, B. H., O'Connell, R. J., and Raefsky, A., 1983, Subduction, Back-Arc Spreading and Global Mantle Flow, Tectonophys., 99, 165–189.
Hamilton, E. L., Bachman, R. T., Curray, J. R., and Moore, D. G., 1977, Sediment Velocities from Sonobouys: Bengal Fan, Sunda Trench, Andaman Basin, and Nicobar Fan, J. Geophys. Res. 82, 3003–3012.
Kahle, H.-G. and Talwani, M., 1973, Gravimetric Indian Ocean Geoid, Z. Geophys. 39, 167–187.
Karunakaran, C., Ray, K. K., and Saha, S. S., 1968, Tertiary Sedimentation in the Andaman-Nicobar Geosyncline, J. Geol. Soc. India 9, 32–39.
Luyendyk, B. P. and Rennick, W., 1977, Tectonic History of Aseismic Ridges in the Eastern Indian Ocean, Geol. Soc. Am. Bull. 88, 1347–1356.
Minear, J. H. and Toksoz, M. N., 1970, Thermal Regime of a Downgoing Slab and New Global Tectonics, J. Geophys. Res. 75, 1397–1419.
Moore, G. F. and Curray, J. R., 1980, Structure of the Sunda Trench Lower Slope off Sumatra from Multichannel Seismic Reflection Data, Marine Geophys. Res. 4, 319–340.
Mukhopadhyay, M., 1984, Seismotectonics of Subduction and Back-Acr Rifting under the Andaman Sea, Tectonophys. 108, 229–239.
Naini, B. and Leyden, R., 1973, Ganges Cone: A Wide Angle Seismic Reflection and Refraction Study, J. Geophys. Res. 78, 8711–8720.
Peter, G., Weeks, L. A., and Burns, R. E., 1966, A Reconnaissance Geophysical Survey in the Andaman Sea and Across the Andaman-Nicobar Island Arc, J. Geophys. Res. 71, 495–509.
Rodolfo, K. S., 1969a, Bathymetry and Marine Geology of the Andaman Basin and Tectonic Implications for Southeast Asia, Am. Assoc. Petrol. Geol. Bull. 52, 2422–2437.
Rodolfo, K. S., 1969b, Sediments of the Andaman Basin, Northeastern Indian Ocean, Marine Geol. 7, 371–402.
Roy, T. K., 1983, Geology and Hydrocarbon Prospects of Andaman-Nicobar Basin, Petrol. Asia J. Nov. 1983, 37–50.
Sacks, I. S., Linde, A. T., Rodriguez, A. B., and Snoke, J. A., 1978, Shallow Seismicity in Subduction Zones, Geophys. Res. Lett. 5, 901–903.
Silver, E. A., Joyodiwiryo, Y., and McCaffrey, R., 1978, Gravity Results and Emplacement Geometry of the Sulawesi Ultramafic Belt, Indonesia, Geology 6, 527–531.
Talwani, M., Worzel, J. L., and Landisman, M., 1959, Rapid Gravity Computations for Two Dimensional Bodies with Application to the Mendocino Fracture Zone, J. Geophys. Res. 64, 49–59.
Uyeda, S. and Kanamori, H., 1979, Back-Arc Opening and the Mode of Subduction, J. Geophys. Res. 84, 1049–1061.
Watts, A. B. and Talwani, M., 1974, Gravity Anomalies Seaward of Deep-Sea Trenches and Their Tectonic Implications, Geophys. Royal Astron. Soc. J. 36, 57–90.
Watts, A. B. and Daly, S. F., 1981, Long Wavelength Gravity and Topography Anomalies, Ann. Rev. Earth Planet. Sci. 9, 415–448.
Weeks, L. A., Harbison, R. A., and Peter, G., 1967, Island Arc System in Andaman Sea, Am. Assoc. Petrol. Geol. Bull. 51, 1803–1815.
Welland, M. J. P. and Mitchell, A. H. G., 1977, Emplacement of Oman Ophiolite: A Mechanism Related to Subduction and Collision, Geol. Soc. Am. Bull. 88, 1081–1088.
Yamashina, K., Shimazaki, K., and Kato, T., 1978, Aseismic Belt along the Frontal Arc and Plate Subduction in Japan, J. Phys. Earth 26, Suppl. S447-S458.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Mukhopadhyay, M. Gravity anomalies and deep structure of the Andaman arc. Mar Geophys Res 9, 197–210 (1988). https://doi.org/10.1007/BF00309973
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00309973