Skip to main content


We’d like to understand how you use our websites in order to improve them. Register your interest.

Rock magnetism and microscopy of the Jacupiranga alkaline-carbonatitic complex, southern Brazil


This study of the Cajati deposit provides evidence that the ore was neither purely hydrothermal, nor volcanic in origin, as previous workers have proposed. The ores were formed from magnetite-rich magmas, hydrothermally altered and intruded at an indicated crustal depth in excess of 500 m. The mineralogical and textural association between magnetite and magnesioferrite in the carbonatite, and between the titanomagnetite and magnesioferrite-Ti mineralization in the pyroxenite of hedenbergite, seems to be analog mineralizations strongly related to the ionic substitution of Fe2+ by Mg. Relatively high Q ratios (≥5) for Jacupirangite-pyroxenite may indicate a thermo remanent magnetization (TRM) by the ore during post-metamorphic cooling, however it can also be developed from chemical remanent magnetization (CRM). Vector plots for the pyroxenite samples show reasonably linear and stable magnetic components. The intensity decay curves show that only two components of magnetizations are likely present. Continuous susceptibility measurements with increasing temperature show that the main magnetic phase seems to be magnetite. Maghemite is probably produced during the cooling process. Susceptibility recorded from low temperature (liquid nitrogen (-196°C)) to room temperature produces typical curves, indicating Verwey transition of magnetite. Hysteresis parameters point out that nearly all values fall in a novel region of the Day plot, parallel to but below magnetite SD + MD mixing curves.


  1. Alva-Valdivia, L. and J. Urrutia-Fucugauchi, Rock magnetic surveys in the iron ore deposit of El Encino, Mexico, J. South Am. Earth Sci., 8, 209–220, 1995.

  2. Alva-Valdivia, L. and J. Urrutia-Fucugauchi, Rock magnetic properties and ore microscopy of the iron ore deposit of Las Truchas, Michoacan, Mexico, J. Appl. Geophys., 38, 277–299, 1998.

  3. Alva-Valdivia, L., J. Urrutia-Fucugauchi, H. Bohnel, and D. Moran-Zenteno, Aeromagnetic anomalies and paleomagnetism in Jalisco and Michoacan, southern Mexico continental margin, and their implications for iron-ore deposits exploration, Tectonophysics, 192, 169–190, 1991.

  4. Alva-Valdivia, L. M., J. Urrutia-Fucugauchi, A. Goguichaichvili, and D. Dunlop, Magnetic mineralogy and properties of the Pena Colorada iron ore deposit, Guerrero Terrane: implications for magnetometric modeling, J. South Am. Earth Sci., 13, 415–428, 2000.

  5. Alva-Valdivia, L. M., J. Urrutia-Fucugauchi, A. Goguitchaichvili, and W. Vivallo, Rock-magnetism and ore microscopy of magnetite-apatite ore deposit from Cerro de Mercado, Mexico, Earth Planets Space, 53, 181–192, 2001.

  6. Alva-Valdivia, L. M., M. L. Rivas-Sánchez, A. Gonzalez, A. Goguitchaichvili, J. Urrutia-Fucugauchi, J. Morales, and W. Vivallo, Integratted magnetic studies of the El Romeral Iron-ore Deposit, Chile: implications for the ore genesis and modeling magnetic anomalies, J. Appl. Geophys., 53, 137–151, 2003a.

  7. Alva-Valdivia, L. M., M. L. Rivas, A. Goguitchaichvili, J. Urrutia-Fucugauchi, J. A. Gonzalez, J. Morales, S. Gómez, F. Henríquez, J. O. Nystrom, and R. H. Naslund, Rock Magnetic and Oxide Microscopy Studies of the El Laco, Iron-Ore Deposits, Chilean High Andes and Implications for Magnetic Anomaly Modeling, Int. Geol. Rev., 45, 533–547, 2003b.

  8. Alves, P. R. and R. D. Hagni, Bunge’s Cajati apatite mine, SE Brazil: mineralogy and petrography of the carbonatite intrusions and the relationship to mineral processing, in Appl. Mineral., edited by Pecchio et al., 653–656, ICAM-BR, Sao Paulo, ISBN 85-98656-02-X, 2004.

  9. Bonás, T. B., Consolidç~ao de critérios de descryç~ao litológica para o minério apatítico do complexo alcalino de Jacupiranga, 48 pp., Monografia de trabalho de formatura, IG-USP, 2001.

  10. Brand~ao, A. G. and L. M. Sant’Agostino, Technological characterization of carbonatitic raw material manufacture from Cajati (SP), in Appl. Mineral., edited by Pecchio et al., 977–980, ICAM-BR, S~ao Paulo, ISBN 85-98656-02-X, 2004.

  11. Day, R., M. Fuller, and V. A. Schmidt, Hysteresis properties of titanomag-netites: grain size and compositional dependence, Phys. Earth Planet. Inter., 13, 260–267, 1977.

  12. Direen, N. G., K. M. Pfeiffer, P. W. Schmidt, and M. Sexton, Strong remanent magnetization in Pyrrothite: a structurally-controlled example from the Paleoproterozoic Tnami Orogenic gold province, northern Australia, Precam. Res., 165, 96–106, 2008.

  13. Dunlop, D. J., Theory and application of the Day plot ((Mrs/Ms versus Hcr/Hc) 2. Application to data for rocks, sediments, and soils, J. Geophys. Res., 107(B3), doi:10.1029/2001JB000487, 2002a.

  14. Dunlop, D. J., Theory and application of the Day plot ((Mrs/Ms versus Hcr/Hc) 1. Theoretical curves and tests using titanomagnetite data, J. Geophys. Res., 107(B3), doi:10.1029/2001JB000486, 2002b.

  15. Dunlop, D. and O. Özdemir, Rock-Magnetism, fundamentals and frontiers, 573 pp., Cambrige University Press, 1997.

  16. Haggerty, S. E., Oxidation of opaque mineral oxides in basalts, in Oxide Minerals (Short Course Notes), Miner. Soc. Am., edited by D. Rumble, 3, 1–100, 1976.

  17. Henkel, H., Standard diagrams of magnetic properties and density—a tool for understanding magnetic petrology, J. Appl. Geophys., 32, 43–53, 1994.

  18. Kirschvink, J. L., The least-square line and plane and analysis of palaeomagnetic data, Geophys. J. R. Astron. Soc, 62, 699–718, 1980.

  19. Melcher, G. C, Nota sobre os distrito Alcalino de Jacpiranga, Sao Paulo Div. Geol. Min., 84, 1954.

  20. Prévot, M., E. A. Mainkinen, S. Grommé, and A. Lecaille, High paleoin-tensity of the geomagnetic field from thermomagnetic studies on rift valley pillow basalts from the middle Atlantic ridge, J. Geophys. Res., 88, 2316–2326, 1983.

  21. Ruberti, E., C. B. Gomes, and G. C. Melchor, The Jacupiranga Carbonatite Complex: geological and petrological aspects of the Jacupiranga alkaline-carbonatite association, southern Brazil, Post-Congress Field Trip Aft 08 Guidebook, International Geological Congress, Part I: 1–21, Rio de Janeiro, Brazil, 2000.

  22. Schmidt, P. W., S. A. McEnroe, D. A. Clark, and P. Robinson, Magneic properties and potential field modeling of the Peculiar Knob metamorphosed iron formation, South Australia: An analog for the source of the intense Martian magnetic anomalies?, J. Geophys. Res., 112, B03102, doi:10.1029/2006JB004495, 2007.

  23. Skilbrei, J. R., T. Skyseth, and O. Olesen, Petrophysical data and opaque mineralogy of high-grade and retrogressed lithologies: implications for the interpretation of aeromagnetic anomalies in Northern Vestranden, Central Norway, Tectonophysics, 192, 21–31, 1991.

  24. Tauxe, L. and H. N. Bertram, Physical interpretation of hysteresis loops: micromagnetic modelling of fine particle magnetite, Geochem. Geophys. Geosyst., doi:10.1029/2001GC000280, 2002.

  25. Tornos, D., Procesos de alteracion y relleno hidrotermal sobre rocas sili-coaluminícas, Atlas de asociaciones minerales en lamina delgada, Universidad de Barcelona, 249–271, 1997.

  26. Vahle, C., A. Kontny, H. P. Gunnlaugsson, and L. Kristjansson, The Stardalur magnetic anomaly revisited—New insights into a complex cooling and alteration history, Phys. Earth Planet. Inter, 164, 119–141, 2007.

  27. Williams, W. and D. J. Dunlop, Simulation of magnetic Hysteresis in pseudo-single domain grains of magnetite, J. Geophys. Res., 100, 3859–3871, 1995.

Download references

Author information



Corresponding author

Correspondence to Luis M. Alva-Valdivia.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Alva-Valdivia, L.M., Perrin, M., Rivas-Sánchez, M.L. et al. Rock magnetism and microscopy of the Jacupiranga alkaline-carbonatitic complex, southern Brazil. Earth Planet Sp 61, 161–171 (2009).

Download citation

Key words

  • Rock-magnetism
  • microscopy
  • Jacupiranga complex
  • Brazil