Skip to main content


Anisotropy of magnetic susceptibility analysis of the Cantera Ignimbrite, San Luis Potosi, México: flow source recognition


Anisotropy of magnetic susceptibility (AMS) was selected as the key technique to find the source of the widespread Cantera Ignimbrite and to seek its possible relationship with the San Luis Potosí Caldera. Eighteen sites (372 specimens from 155 cores) from the Oligocene Cantera Ignimbrite were sampled. AMS was measured on a KLY2 Kappabridge. AMS data were processed with Anisoft 3 software using Jelinek statistics as well as ‘SpheriStat’ principal components and density distribution. Mean susceptibilities range from 290 to 5026 × 10-6 SI (average = 2526 × 10-6 SI). The anisotropy degree (Pj) ranges from 1.005 to 1.055, with only one site displaying a value of 1.134 (Pj average = 1.031). AMS ellipsoid shapes are mostly oblate, with the T-factor ranging from 0.843 to 0.144 (T average = 0.529), although one site is mainly prolate (T = -0.005), and three additional sites have an important proportion of prolate specimens. Magnetic fabrics of most sites shows k3 axes around nearly circular distributions and k1-k2 axes around elongated-girdle distributions defining sub-horizontal foliation planes; exceptions to this are related to sites with a significant percentage of prolate specimens. Flow directions inferred from AMS analysis indicate several ignimbrite sources located along selected NW-SE linear features (faults and fractures such as El Potosino Fault) as well as along the rim of the caldera structure. The geometry of volcanic outcrops, the NW-SE faulting-fracture system, as well as the AMS results suggest that this is a caldera structure resembling the trapdoor-type (Lipman, 1997).


  1. Aguirre-Díaz, G. J. and G. Labarthe-Hernández, Fissure ignimbrites: Fissure-source origin for voluminous ignimbrites of the Sierra Madre Occidental and its relationship with Basin and Range faulting, Geology, 31, 773–776, 2003.

  2. Alva-Valdivia, L. M., J. Rosas-E., T. Bravo-M., J. Urrutia-F, B. Henry, C. Caballero, M. L. Rivas-S, A. Goguitchaichvili, and H. López, Pa-leomagnetic and magnetic fabric studies of the San Gaspar ignimbrite, western Mexico—constraints on emplacement mode and source vents, J. Volcanol. Geotherm. Res., 147, 68–80, 2005.

  3. Cagnoli, B. and D. H. Tarling, The reliability of anisotropy of magnetic susceptibility (AMS) data as flow direction indicators in friable base surge and ignimbrite deposits: Italian examples, J. Volcanol. Geotherm. Res., 75, 309–320, 1996.

  4. Ekren, E. B. and F. M. Byers, Ash-flow fissure vent in west-central Nevada, Geology, 4, 247–251, 1976.

  5. Ekren, E. B., D. H. McIntyre, and E. H. Bennett, High-temperature, large-volume, lava-like ash flow tuffs without calderas in southwestern Idaho, Geol. Surv. Prof. Paper, 1272, 76 pp., 1983.

  6. Ellwood, B. B., Estimates of flow direction for calc-alkaline welded tuffs and palaeomagnetic data reliability from anisotropy of magnetic susceptibility measurements: central San Juan Mountains, south-west Colorado, Earth Planet. Sci. Lett., 59, 303–314, 1982.

  7. Elston, W. E. and E. I. Smith, Determination of flow direction of rhyolite ash flow tuffs from fluidal textures, Geol. Soc. Am. Bull., 81, 3393–3406, 1970.

  8. Hillhouse, J. W. and R. E. Wells, Magnetic fabric, flow directions, and source area of the lower Miocene Peach Springs Tuff in Arizona, California, and Nevada, J. Geophys. Res., 96(B7), 12443–12460, 1991.

  9. Incoronato, A., F. T. Addison, D. H. Tarling, G. Nardi, and T. Pescatore, Magnetic fabric investigations of pyroclastic deposits from Phlegrean Fields, southern Italy, Nature, 306, 461–463, 1983.

  10. Jelinek, V., Statistical processing of anisotropy of magnetic susceptibility measured on groups of specimens, Studia Geoph. Geod., 22, 50–62, 1978.

  11. Jelinek, V., Characterization of the magnetic fabrics of rocks, Tectono-physics, 79, 63–67, 1981.

  12. Knight, M. D., G. P. L. Walker, B. B. Ellwood, and J. F. Diehl, Stratigraphy, paleomagnetism, and magnetic fabric of the Toba Tufts: constraints on the sources and eruptive styles, J. Geophys. Res., 91, 10355–10382, 1986.

  13. Labarthe-Hernández, G. and M. Tristán-González, Cartografía geológica de la Hoja San Luis Potosí, Universidad Autonoma de San Luis Potosí, Instituto de Geología y Metalurgia: Folleto Tecnico, 59, 41 pp., 1 map, 1978.

  14. Labarthe-Hernández, G. and L. S. Jiménez-López, Características físicas de lavas e ignimbritas riolíticas en la Sierra de San Miguelito, S.L.P, Universidad Autonoma de San Luis Potosí, Instituto de Geología: Folleto Tecnico, 114, 31 pp., 1 map, 1992.

  15. Labarthe-Hernández, G. and L. S. Jiménez-López, Geología del Domo Cerro Grande, Sierra de San Miguelito, S.L.P, Universidad Autonoma de San Luis Potosí: Instituto de Geología y Metalurgia: Folleto Tecnico, 117, 22 pp., 1 map, 1993.

  16. Labarthe-Hernández, G. and L. S. Jiménez-López, Geología de la porción sureste de la Sierra de San Miguelito, S.L.P, Universidad Autonoma de San Luis Potosí, Instituto de Geología: Folleto Tecnico, 120, 34 pp., 1 map, 1994.

  17. Labarthe-Hernández, G., M. Tristán-González, and J. J. Aranda-Gomez, Revisión estratigráfica del Cenozoico de la parte central del Estado de San Luis Potosí, Universidad Autonoma de San Luis Potosí, Instituto de Geología y Metalurgia: Folleto Tecnico, 85, 208 pp., 1982.

  18. Labarthe-Hernández, G, L. S. Jiménez-López, and J. J. Aranda-Gomez, Reinterpretación de la geología del Centro Volcánico de Ahualulco, SLP, Universidad Autonoma de San Luis Potosí, Instituto de Geología: Folleto Tecnico, 121, 30 pp., 1995.

  19. Lipman, P. W., Subsidence of ash-flow calderas: relation to caldera size and magma chamber geometry, Bull. Volcanol., 59, 198–212, 1997.

  20. MacDonald, W D. and H. C. Palmer, Flow directions in ash flow tuffs: a comparison of geological and magnetic susceptibility measurements, Tshirege member (upper Bandelier Tuff), Valles caldera New Mexico, USA, Bull. Volcanol., 53, 45–59, 1990.

  21. Ort, M., M. Rosi, and C. D. Anderson, Correlation of deposits and vent locations of the proximal Campanian Ignimbrite deposits, Campi Fle-grei, Italy, based on natural remanent magnetization and anisotropy of magnetic susceptibility characteristics, J. Volcanol. Geotherm. Res., 91, 167–178, 1999.

  22. Ort, M. H., G. Orsi, L. Pappalardo, and R. V. Fisher, Anisotropy of magnetic susceptibility studies of depositional processes in the Campanian Ignimbrite, Italy, Bull. Volcanol., 65, 55–72, 2003.

  23. Palmer, H. C. and W. D. MacDonald, Anisotropy of magnetic susceptibility in relation to source vents of ignimbrites: empirical observations, Tectonophysics, 307, 207–218, 1999.

  24. Rhodes, R. C. and E. I. Smith, Distribution and directional fabric of ash-flow sheets in the north-western Mogollon Plateau, New Mexico, Geol. Soc. Am. Bull., 83, 1863–1869, 1972.

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

  26. Suzuki, K. and T. Ui, Grain orientation and depositional ramps as flow direction indicators of a large-scale pyroclastic flow deposit in Japan, Geology, 10, 429–433, 1982.

  27. Torres-Hernández, R., Las fuentes de las Ignimbritas Cantera y Panalillo en el Campo Volcánico de San Luis Potosí-, S.L.P, Universidad Autónoma de San Luis Potosí, PhD Thesis, 2008 (unpublished).

  28. Torres-Hernández, R., G. Labarthe-Hernández, A. Aguillón-Robles, Gómez-Martín Anguiano, and J. L. Mata-Segura, The pyroclastic dikes of the Tertiary San Luis Potosí volcanic field: Implications on the emplacement of Panalillo ignimbrite, Geofísica Internacional, 45(4), 243–253, 2006.

  29. Wright, J. V. and G. P. L. Walker, The ignimbrite source problem: the significance of a co-ignimbrite lag-fall deposit, Geology, 5, 729–732, 1977.

Download references

Author information

Correspondence to C. I. Caballero-Miranda.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Caballero-Miranda, C.I., Torres-Hernández, J.R. & Alva-Valdivia, L.M. Anisotropy of magnetic susceptibility analysis of the Cantera Ignimbrite, San Luis Potosi, México: flow source recognition. Earth Planet Sp 61, 173–182 (2009).

Download citation

Key words

  • Anisotropy of magnetic susceptibility (AMS)
  • magnetic fabric
  • inference of flow source
  • Cantera Ignimbrite
  • San Luis Potosi Volcanic Field (SLPVF)
  • Tertiary
  • Mexico