Studia Geophysica et Geodaetica

, Volume 47, Issue 2, pp 237–254 | Cite as

Stable Eocene Magnetization Carried by Magnetite and Iron Sulphides in Marine Marls (Pamplona-Arguis Formation, Southern Pyrenees, Northern Spain)



In order to establish the magnetic carriers and assess the reliability of previous paleomagnetic results obtained for Eocene marine marls from the south Pyrenean basin, we carried out a combined paleo- and rock-magnetic study of the Pamplona-Arguis Formation, which crops out in the western sector of the southern Pyrenees (N Spain). The unblocking temperatures suggest that the characteristic remanent magnetization (ChRM) is carried by magnetite and iron sulphides. The ChRM has both normal and reversed polarities regardless of whether it resides in magnetite or iron sulphides, and represents a primary Eocene magnetization acquired before folding. Rock magnetic results confirm the presence of magnetite and smaller amounts of magnetic iron sulphides, most likely pyrrhotite, in all the studied samples. Framboidal pyrite is ubiquitous in the marls and suggests that iron sulphides formed during early diagenesis under sulphate-reducing conditions. ChRM directions carried by magnetic iron sulphides are consistent with those recorded by magnetite. These observations suggest that magnetic iron sulphides carry a chemical remanent magnetization that coexists with a remanence residing in detrital magnetite. We suggest that the south Pyrenean Eocene marls are suitable for magnetostratigraphic and tectonic purposes but not for studies of polarity transitions, secular variations and geomagnetic excursions, because it is difficult to test for short time differences in remanence lock-in time for the two minerals. The presence of iron sulphide minerals contributing to the primary magnetization in Eocene marine marls reinforces the idea that these minerals can persist over long periods of time in the geological record.

paleomagnetism rock magnetism marine sediments early diagenesis magnetic iron sulphides Pyrenees 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Bentham P.A., 1992. The Tectono-Stratigraphic Development of the Western Oblique Ramp of the South-Central Pyrenean Thrust System, Northern Spain. Ph.D. Thesis, University of Southern California, Los Angeles.Google Scholar
  2. Berner R.A., 1971. Principles of Chemical Sedimentology. Mc-Graw-Hill, New York.Google Scholar
  3. Berner R.A., 1984. Sedimentary pyrite formation: an update. Geochim. Cosmochim. Acta, 48, 605-615.Google Scholar
  4. Burbank D.W., Vergés J., Muñoz J.A. and Bentham P., 1992a. Coeval hindward-and forward-imbricating thrusting in the south-central Pyrenees, Spain: timing and rates of shortening and deposition. Geol. Soc. Am. Bull., 104, 3-17.Google Scholar
  5. Burbank D.W., Puigdefàbregas C. and Muñoz J.A., 1992b. The chronology of the Eocene tectonic and stratigraphic development of the eastern Pyrenean foreland basin, northeast Spain. Geol. Soc. Am. Bull., 104, 1101-1120.Google Scholar
  6. Canfield D.E., 1994. Factors influencing organic carbon preservation in marine sediments. Chem. Geol., 114, 315-329.Google Scholar
  7. Canfield D.E. and Berner R.A., 1987. Dissolution and pyritization of magnetite in anoxic marine sediment. Geochim. Cosmochim. Acta, 51, 645-659.Google Scholar
  8. Canudo J.I., Molina E., Riveline J., Serra-Kiel J. and Sucunza M., 1988. Les événements biostratigraphyques de la zone prépyrénée d´Aragón (Espagne), de l´Eocene moyen á l´Oligocéne inférieur. Rev. Micropal., 31, 15-29 (in French).Google Scholar
  9. Dankers P.H., 1978. Magnetic Properties of Dispersed Natural Iron Oxides of Known Grain Size. Ph.D. Thesis, University of Utrecht.Google Scholar
  10. Dekkers M.J., 1990. Magnetic monitoring of pyrrhotite alteration during thermal demagnetization. Geophys. Res. Lett., 17, 779-782.Google Scholar
  11. Dekkers M.J., Mattéi J.L., Fillion G. and Rochette P., 1988. Grain-size dependence of the magnetic behavior of pyrrhotite during its low-temperature transition at 34 K. Geophys. Res. Lett., 16, 855-858.Google Scholar
  12. Dinarès-Turell J., McClelland E. and Santanach P., 1992. Contrasting rotations within thrust sheets and kinematics of thrust tectonics as derived from palaeomagnetic data: an example from the Southern Pyrenees. In: K.R. McClay (Ed.), Thrust Tectonics, Chapman and Hall, London, 265-276.Google Scholar
  13. Dinarès-Turell J. and Dekkers M.J., 1999. Diagenesis and remanence acquisition in the Lower Pliocene Trubi marls at Punta di Maiata (southern Sicily): palaeomagnetic and rock magnetic observations. In: D.H. Tarling and P. Turner (Eds.), Palaeomagnetism and Diagenesis in Sediments, Geol. Soc. London, Special Publication, 151, 53-69.Google Scholar
  14. Florindo F. and Sagnotti L., 1995. Palaeomagnetism and rock-magnetism in the upper Pliocene Valle Ricca (Rome, Italy) section. Geophys. J. Int., 123, 340-354.Google Scholar
  15. Hogan P.J., 1993. Geochronologic, Tectonic and Stratigraphic Evolution of the Southwest Pyrenean Foreland Basin, Northern Spain. Ph.D. Thesis, University of Southern California, Los Angeles.Google Scholar
  16. Hogan P.J. and Burbank D.W., 1996. Evolution of the Jaca piggyback basin and emergence of the External Sierra, southern Pyrenees. In: P.F. Friend and C.J. Dabrio (Eds.), Tertiary Basins of Spain, Cambridge Univ. Press, Cambridge, 153-160.Google Scholar
  17. Holl J.E. and Anastasio D.J., 1993. Paleomagnetically derived folding rates in the southern Pyrenees, Spain. Geology, 21, 271-274.Google Scholar
  18. Housen B.A. and Musgrave R.J., 1996. Rock-magnetic signature of gas hydrates in accretionary prism sediments. Earth Planet. Sci. Lett., 139, 509-519.Google Scholar
  19. Horng C.-S. Torii M., Shea K.-S. and Kao S.-J., 1998. Inconsistent magnetic polarities between greigite-and pyrrhotite/magnetite-bearing marine sediments from the Tsailiao-chi section, southwestern Taiwan. Earth Planet. Sci. Lett., 164, 467-482.Google Scholar
  20. Jiang W.-T., Horng C.-S., Roberts A.P. and Peacor D.R., 2001. Contradictory magnetic polarities in sediments and variable timing of neoformation of authigenic greigite. Earth Planet. Sci. Lett., 193, 1-12.Google Scholar
  21. Karlin R., 1990. Magnetite diagenesis in marine sediments from the Oregon continental margin. J. Geophys. Res., 95, 4405-4419.Google Scholar
  22. Katz B., Elmore R.D. and Engel M.H., 1998. Authigenesis of magnetite in organic-rich sediments next to a dike: implications for thermoviscous and chemical remagnetizations. Earth Planet. Sci. Lett., 163, 221-234.Google Scholar
  23. Krs M., Krsová M., Pruner P., Zeman A., Novák F. and Jansa J., 1990. A petromagnetic study of Miocene rocks bearing micro-organic material and the magnetic mineral greigite (Sokolov and Cheb basins, Czechoslovakia). Phys. Earth Planet. Inter., 63, 98-112.Google Scholar
  24. Krs M., Novák F., Pruner P., Kouklíková L. and Jansa J., 1992. Magnetic properties of greigitesmythite mineralization in brown-coal basins of the Krušné hory Piedmont, Bohemia. Phys. Earth Planet. Inter., 70, 273-287.Google Scholar
  25. Larrasoaña J.C., Parés J.M., Millán H., DelValle, J. and Pueyo E.L., 2003. Paleomagnetic, structural and stratigraphic constraints on tranverse fault development during basin inversion: The Pamplona Fault (Pyrenees, N Spain). Tectonics, in pressGoogle Scholar
  26. Leslie B.W., Lund S.P. and Hammond D.E., 1990. Rock magnetic evidence of dissolution and authigenic growth of magnetic minerals within anoxic marine sediments of the California continental borderland. J. Geophys. Res., 95, 4437-4452.Google Scholar
  27. Linssen J.H., 1988. Preliminary results of a study of four successive sedimentary reversal records from the Mediterranean. Phys. Earth Planet. Inter., 52, 207-231.Google Scholar
  28. Lowrie W., 1990. Identification of ferromagnetic minerals in a rock by coercivity and unblocking temperature properties. Geophys. Res. Lett., 17, 159-162.Google Scholar
  29. Mary C., Iaccarino S., Courtillot V., Besse J. and Aisaoui D.M., 1993. Magnetostratigraphy of Pliocene sediments from the Stirone river (Po Valley). Geophys. J. Int., 112, 359–380.Google Scholar
  30. Millán H., Aurell M. and Meléndez A., 1994. Synchronous detachment folds and coeval sedimentation in the Prepyrenean External Sierras (Spain): a case study for a tectonic origin of sequences and system tracks. Sedimentology, 41, 1001-1024.Google Scholar
  31. Moskowitz B.M., Frankel R.B. and Bazylinski D.A., 1993. Rock-magnetic criteria for the detection of biogenic magnetite. Earth Planet. Sci. Lett., 120, 283-300.Google Scholar
  32. Oldfield F., 1994. Toward the discrimination of fine-grained ferrimagnets by magnetic measurements in lake and near shore marine sediments. J. Geophys. Res., 99, 9045-9050.Google Scholar
  33. Passier H.F., de Lange G.J. and Dekkers M.J., 2001. Magnetic properties and geochemistry of the active oxidation front at the youngest sapropel in the eastern Mediterranean Sea. Geophys. J. Int., 145, 604-614.Google Scholar
  34. Pueyo E.L., Millán H., Pocoví J. and Parés J.M., 1997. Cinemática rotacional del cabalgamiento basal surpirenaico en las Sierras Exteriores Aragonesas: datos magnetotectónicos. Acta Geol. Hisp., 32, 237-256 (in Spanish).Google Scholar
  35. Pueyo E.L., Millán H. and Pocoví A., 2002. Rotation velocity of a thrust: a paleomagnetic study in the External Sierras (Southern Pyrenees). Sedim. Geol., 146, 191-208.Google Scholar
  36. Pueyo E.L, Pocoví A., Parés J.M., Millán H. and Larrasoaña J.C., 2003. Thrust ramp geometries and spurious rotations of paleomagnetic vectors. Stud. Geophys. Geod., 47, 331–357.Google Scholar
  37. Puigdefàbregas C., 1975. La sedimentación molásica de la cuenca de Jaca. Pirineos, 104, 1–188 (in Spanish).Google Scholar
  38. Reynolds R.L., Fishman N.S. and Hudson M.R., 1991. Sources of aeromagnetic anomalies over Cement Oil Field (Oklahoma), Simpson Oil Field (Alaska), and the Wyoming-Idaho-Utah Thrust Belt. Geophysics, 56, 606–617.Google Scholar
  39. Reynolds R.L., Tuttle M.N., Rice C.A., Fishman N.S., Karachewsky J.A. and Sherman D.M., 1994. Magnetization and geochemistry of greigite-bearing Cretaceous strata, North Slope Basin, Alaska. Am. J. Sci., 294, 485-528.Google Scholar
  40. Roberts A.P., 1995. Magnetic properties of sedimentary greigite (Fe3S4). Earth Planet. Sci. Lett., 134, 227-236.Google Scholar
  41. Roberts A.P. and Turner G.M., 1993. Diagenetic formation of ferrimagnetic iron sulphide minerals in rapidly deposited marine sediments, South Island, New Zealand. Earth Planet. Sci. Lett., 115, 257-273.Google Scholar
  42. Rochette P., Fillion G., Mattéi J.L. and Dekkers M.J., 1990. Magnetic transition at 30-34 Kelvin in pyrrhotite: insight into a widespread occurrence of this mineral in rocks. Earth Planet. Sci. Lett., 98, 319-328.Google Scholar
  43. Rochette P., Ménard G. and Dunn R., 1992. Thermochronometry and cooling rates deduced from single sample records of successive magnetic polarities during uplift of metamorphic rocks in the Alps (France). Geophys. J. Int., 108, 491-501.Google Scholar
  44. Sweeney R.E. and Kaplan I.R., 1973. Pyrite framboid formation. Laboratory synthesis and marine sediments. Econ. Geol., 68, 618-634.Google Scholar
  45. Taberner C., Dinarés-Turell J., Giménez J. and Docherty C., 1999. Basin infill architecture and evolution from magnetostratigraphic cross-basin correlations in the southeastern Pyrenean foreland basin. Geol. Soc. Am. Bull., 111, 2-21.Google Scholar
  46. Teixell A., 1996. The Ansó transect of the southern Pyrenees: basement and cover thrust geometries. J. Geol. Soc. London, 153, 301-310.Google Scholar
  47. Torii M., Fukuma K., Horng C.-S. and Lee T.-Q., 1996. Magnetic discrimination of pyrrhotite-and greigite-bearing sediment samples. Geophys. Res. Lett., 23, 1813-1816.Google Scholar
  48. Tric E., Laj C., Jéhanno C., Valet J.-P., Kissel C., Mazaud A. and Iaccarino S., 1991. High resolution record of the upper Olduvai transition from Po Valley (Italy) sediments: support for dipolar transition geometry? Phys. Earth Planet. Inter., 65, 319-336.Google Scholar
  49. van Hoof A.A.M. and Langereis C.G., 1991. Reversal records in marine marls and delayed acquisition of remanent magnetization. Nature, 351, 223-224.Google Scholar
  50. Verosub K.L. and Roberts A.P., 1995. Environmental magnetism: past, present and future. J. Geophys. Res., 100, 2175-2192.Google Scholar
  51. Weaver R., Roberts A.P. and Baker A.J., 2002. A late diagenetic (synfolding) magnetization carried by pyrrhotite: implications for paleomagnetic studies from magnetic iron sulphide-bearing sediments. Earth Planet. Sci. Lett., 200, 365-380.Google Scholar

Copyright information

© StudiaGeo s.r.o. 2003

Authors and Affiliations

  1. 1.Paleomagnetic Laboratory, Institute of Earth Sciences “Jaume Almera”CSICBarcelonaSpain
  2. 2.Department of Earth SciencesUniversity of ZaragozaZaragozaSpain
  3. 3.Department of Geological SciencesUniversity of Michigan, 1006 C. C. Little BuildingAnn ArborUSA

Personalised recommendations