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Magnetic minerals and magnetic properties of the Siwalik Group sediments of the Karnali river section in Nepal

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Abstract

Sandstones and siltstones collected from the Siwalik molasse sequence (~ 16 to 5 Ma) of the Karnali river section have been studied for their magnetic properties. Behavior of the specimens during demagnetization (of the NRM and IRM) and magnetic susceptibility vs. temperature data suggest that goethite, maghemite/magnetite, and hematite are the main magnetic minerals in the section. Goethite, carrying a recent component, is the dominant magnetic mineral in the fine-grained lithologies from the lower part. Maghemite and magnetite, which also carry a secondary remanence, occur in the sandstones from the upper part. Hematite, mainly of detrital origin, is present in the whole sequence. The magnetic fabric is defined by mainly oblate AMS ellipsoids and a low degree of anisotropy (P′ < 1.20). The magnetic lineations (declinations: 75°–130° or 245°–310°; peak orientation: 290°/2.8°) are subparallel to the fold axes/bedding strikes/thrust fronts (WNW-ESE). The initial sedimentary-compactional fabric has been overprinted by a secondary tectonic fabric, which was probably induced by mild deformation active in the compressive tectonic setting.

References

  1. Appel, E., W. RÖsler, and G. Corvinus, Magnetostratigraphy of the Miocene-Pleistocene Surai Khola Siwaliks in west Nepal, Geophys. J. Int., 105, 191–198, 1991.

  2. Aubourg, C., D. Frizon de Lamotte, A. Poisson, and E. Mercier, Magnetic fabrics and oblique ramp-related folding: a case study from the western Taurus (Turkey), J. Struct. Geol., 19, 1111–1120, 1997.

  3. Barndt, J., N. M. Johnson, G. D. Johnson, N. D. Opdyke, E. H. Lindsay, D. Pilbeam, and R. A. K. Tahirkheli, The magnetic polarity stratigraphy and age of the Siwalik Group near Dhok Pathan village, Potwar Plateau, Pakistan, Earth Planet. Sci. Lett., 41, 355–364, 1978.

  4. Burbank, D. W., R. A. Beck, and T. Mulder, The Himalayan foreland basin, in The Tectonic Evolution of Asia, edited by A. Yin and M. Harrison, pp. 149–188, Cambridge University Press, 1996.

  5. Cande, S. C. and D. V. Kent, Revised calibration of the geomagnetic polarity timescale for the Late Cretaceous and Cenozoic, J. Geophys. Res., 100, 6093–6095, 1995.

  6. Decelles, P. G., G. E. Gehrels, J. Quade, T. P. Ojha, P. A. Kapp, and B. N. Upreti, Neogene foreland basin deposits, erosional unroofing, and the kinematic history of the Himalayan fold-thrust belt, western Nepal, GSA Bulletin, 110, 2–21, 1998.

  7. Dhital, M. R., A. P. Gajurel, D. Pathak, L. P. Paudel, and K. Kizaki, Geology and structure of the Siwaliks and Lesser Himalaya in the Surai Khola-Bardanda area, mid Western Nepal, Bull. Dept. Geol., Tribhuvan Univ., 4, special issue, 1–70, 1995.

  8. Dunlop, D. J. and Ö. Özdemir, Rock Magnetism: Fundamentals and Frontiers, 573 pp., Cambridge University Press, 1997.

  9. Gansser, A., Geology of the Himalayas, 264 pp., Wiley Interscience, London, 1964.

  10. Gautam, P. and E. Appel, Magnetic-polarity stratigraphy of Siwalik Group sediments of Tinau Khola section in west central Nepal, revisited, Geophys. J. Int., 117, 223–234, 1994.

  11. Gautam, P. and S. R. Pant, Magnetic fabric of Siwalik Group sediments of Tinau Khola section, west central Nepal, Bull. Dept. Geol., Tribhuvan Univ., 5, 21–36, 1996.

  12. Gautam, P. and W. Rosler, Depositional chronology and fabric of Siwalik Group sediments in central Nepal from magnetostratigraphy and magnetic anisotropy, in Geology of the Nepal Himalaya: Recent Advances, edited by P. LeFort and B. N. Upreti, J. Asian Earth Sciences, 17, 659–682, 1999.

  13. Gautam, P. and Y. Fujiwara, Magnetic polarity stratigraphy of Siwalik Group sediments from the Karnali river Section in western Nepal, in Terra Nostra 2 (Abstracts of the 14th Himalaya-Karakoram-Tibet Workshop), pp. 53–55, Kloster Ettal, Germany, 1999.

  14. Harrison, T. M., P. Copeland, S. A. Hall, J. Quade, S. Burner, T. P. Ojha, and W. S. F. Kidd, Isotopic preservation of Himalayan/Tibetan uplift, denudation, and climatic histories in two molasse deposits, J. Geology, 101, 157–175, 1993.

  15. Hrouda, F., Magnetic anisotropy of rocks and its application in geology and geophysics, Geophys. Surv, 5, 37–82, 1982.

  16. Hrouda, F., A technique for the measurement of thermal changes of magnetic susceptibility of weakly magnetic rocks by the CS-2 apparatus and KLY-2 Kappabridge, Geophys. J. Int., 118, 604–612, 1994.

  17. Hrouda, F. and M. Potfaj, Deformation of sediments in the post-orogenic Intra-Carpathian Paleogene Basin as indicated by magnetic anisotropy, Tectonophys., 224, 425–434, 1993.

  18. Jelinek, V., Characterization of magnetic fabric of rocks, Tectonophys., 79, T63–T67, 1981.

  19. Johnson, N. M., N. D. Opdyke, G. D. Johnson, E. H. Lindsay, and R. A. K. Tahirkheli, Magnetic polarity stratigraphy and ages of Siwalik Group rocks of the Potwar Plateau, Pakistan, Paleogeogr. Paleoclimatol. Paleoecol, 37, 17–42, 1982.

  20. Johnson, G. D., N. D. Opdyke, S. K. Tandon, and A. C. Nanda, The magnetic polarity stratigraphy of the Siwalik Group at Haritalyangar (India) and a new last appearance datum for Ramapithecus and Sivapithecus in Asia, Palaeogeogr. Palaeoclimatol. Palaeoecol, 44, 223–249, 1983.

  21. Kissel, C., C. Laj, and A. Mazaud, First paleomagnetic results from Neogene formations in Evia, Skyros and the Volos region and the deformation of central Aegea, Geophys. Res. Lett., 13, 1446–1449, 1986.

  22. Lee, T. Q., C. Kissel, C. Laj, C. S. Horng, and Y. T. Lue, Magnetic fabric analysis of the Plio-Pleistocene sedimentary formations of the Coastal Range of Taiwan, Earth Planet. Sci. Lett., 98, 23–32, 1990.

  23. Mugnier, J. L., B. Delcaillau, P. Huyghe, and P. Leturmy, The break-back thrust splay of the Main Dun Thrust (Himalayas of western Nepal): evidence of an intermediate displacement scale between earthquake slip and finite geometry of thrust systems, J. Struct. Geol., 20, 857–864, 1998.

  24. Opdyke, N. D., Magnetic stratigraphy of Cenozoic terrestrial sediments and mammalian dispersal, J. Geology, 98, 621–637, 1990.

  25. Opdyke, N. D., E. Lindsay, G. D. Johnson, N. M. Johnson, R. A. K. Tahirkheli, and M. A. Mirza, Magnetic polarity stratigraphy and vertebrate paleontology of the Upper Siwalik subgroups of Northern Pakistan, Paleogeogr. Paleoclimatol. Paleoecol, 27, 1–34, 1979.

  26. Ranga Rao, A., R. P. Agarwal, U. N. Sharma, M. S. Bhalla, and A. C. Nanda, Magnetic polarity stratigraphy and vertebrate paleontology of the upper Siwalik subgroup of Jammu Hills, India, Geol. Soc India Journal, 31, 361–385, 1988.

  27. Robin, P.-Y. F. and E. C. Jowett, Computerized density contouring and statistical evaluation of orientation data using counting circles and continuous weighting functions, Tectonophys., 121, 207–223, 1986.

  28. Rosler, W. and E. Appel, Fidelity and time resolution of the magnetostrati-graphic record in Siwalik sediments: high-resolution study of a complete polarity transition and evidence for cryptochrons in Miocene fluviatile section, Geophys. J. Int., 135, 861–875, 1998.

  29. Rosler, W., W. Metzler, and E. Appel, Neogene magnetic polarity stratigraphy of some fluviatile Siwalik sections, Nepal, Geophys. J. Int., 130, 89–111, 1997.

  30. Sagnotti, L., F. Speranza, A. Winkler, M. Mattei, and R. Funiciello, Magnetic fabric of clay sediments from the external northern Apennines (Italy), Phys. Earth Planet. Int., 105, 73–93, 1998.

  31. Schwertmann, U., Occurrence and formation of iron oxides in various pe-doenvironments, in Iron in Soils andClayMinerals, edited by J. W. Stucki et al, pp. 267–308, D. Reidel, Norwell, MA, 1988.

  32. Tauxe, L. and D. V. Kent, Properties of a detrital remanence carried by haematite from study of modern river deposits and laboratory redeposition experiments, Geophys. J. R. Astron. Soc., 76, 543–561, 1984.

  33. Tauxe, L. and N. D. Opdyke, A time framework based on magnetostratigraphy for the Siwalik sediments of the Khaur area, northern Pakistan, Palaeogeogr., Palaeoclimatol., Palaeoecol., 37, 43–61, 1982.

  34. Tauxe, L., C. Constable, L. Stokking, and C. Badgley, Use of anisotropy to determine the origin of characteristic remanence in the Siwalik red beds of Northern Pakistan, J. Geophys. Res., 95, 4391–4404, 1990.

  35. Taylor, R. M. and U. Schwertmann, Maghemite in soils and its origin, I. Properties and observations on soil maghemites, Clay Mineral., 10, 299–310, 1974.

  36. Tokuoka, T., K. Takayasu, M. Yoshida, and K. Hisatomi, The Churia (Siwalik) Group of the Arung Khola area, west central Nepal, Mem. Fac. Sci., Shimane Univ., 20, 135–210, 1986.

  37. Ulak, P. D. and K. Nakayama, Lithostratigraphy and evolution of fluvial style of the Siwalik Group in the Hetauda—Bakiya Khola area, central Nepal, Bull. Dept. Geol., Tribhuvan Univ., 6, 1–14, 1998.

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Correspondence to Pitambar Gautam.

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Gautam, P., Hosoi, A., Regmi, K.R. et al. Magnetic minerals and magnetic properties of the Siwalik Group sediments of the Karnali river section in Nepal. Earth Planet Sp 52, 337–345 (2000) doi:10.1186/BF03351645

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Keywords

  • Goethite
  • Magnetic Mineral
  • Natural Remanent Magnetization
  • Isothermal Remanent Magnetization
  • Isothermal Remanent Magnetization Saturation