Sedimentology of Sodium Sulphate Deposits and Special Clays from the Tertiary Madrid Basin (Spain)

  1. P. Anadón,
  2. Li. Cabrera and
  3. K. Kelts
  1. S. Ordóñez1,
  2. J. P. Calvo1,
  3. M. A. García del Cura2,
  4. A. M. Alonso-Zarza2 and
  5. M. Hoyos3

Published Online: 14 APR 2009

DOI: 10.1002/9781444303919.ch2

Lacustrine Facies Analysis

Lacustrine Facies Analysis

How to Cite

Ordóñez, S., Calvo, J. P., García del Cura, M. A., Alonso-Zarza, A. M. and Hoyos, M. (1991) Sedimentology of Sodium Sulphate Deposits and Special Clays from the Tertiary Madrid Basin (Spain), in Lacustrine Facies Analysis (eds P. Anadón, Li. Cabrera and K. Kelts), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303919.ch2

Author Information

  1. 1

    Departamento de Petrología y Geoquímica, Facultad de Ciencias Geológicas, Universidad Complutense, 28040-Madrid, Spain

  2. 2

    Instituto de Geología Económica, C.S.I.C. Facultad de C. Geológicas, Universidad Complutense, 28040-Madrid, Spain

  3. 3

    Museo Nacional de Ciencias Naturales, C.S.I.C. C/José Gutiérrez Abascal, 2-28006-Madrid, Spain

Publication History

  1. Published Online: 14 APR 2009
  2. Published Print: 6 SEP 1991

ISBN Information

Print ISBN: 9780632031498

Online ISBN: 9781444303919



  • Madrid Basin, large Tertiary intra-cratonic depression;
  • Polyhalite, occurring as diagenetic saline;
  • ‘El Castellar’;
  • Miocene Intermediate Unit, showing concentric sedimentary pattern;
  • Thenardite, occurring at uppermost part of Saline Unit;
  • sedimentology of sodium sulphate deposits, Tertiary Madrid Basin


The Madrid Basin is a large Tertiary intra-cratonic depression, which contains some of the largest fossil sodium sulphate and sepiolite deposits in the world. These minerals, together with several types of Mg smectites (‘bentonites’), occur in lacustrine sequences within the Neogene sedimentary record of the basin. Sodium sulphates (glauberite and thenardite) are restricted to the Lower Saline Unit, where they are associated with anhydrite, halite, magnesite, and minor clays. Glauberite and thenardite are thought to have been deposited in the most central part of a perennial saline lake. The accumulation of thenardite might have taken place during a stage of contraction of the lake system at the beginning of the middle Aragonian (middle Miocene). Polyhalite occurs as a diagenetic saline phase related both to calcium and sodium sulphates.

Both sepiolite and bentonite deposits occur widely distributed within distal fan and marginal lacustrine sequences in the so-called Intermediate Unit of the Miocene (middle to upper Aragonian). Thick beds of nearly pure sepiolite were deposited in ponds extended at the toes of arkosic alluviums. Sepiolite is also found within calcrete profiles in these environments. Minor amounts of sepiolite are commonly recognized along with palygorskite in open lacustrine areas. On the other hand, Mg bentonites characteristically occur associated with dolostones and fine micaceous sands in sequences that provide evidence of fluctuations in the lake level. The mineralogy of the bentonite deposits closely reflects the environmental variations in the lake margins.