Nódulos opalinos en facies marginales del salar Olaroz (Puna Argentina)

M. A. Bustillo; R. Alonso

doi:10.3989/egeol.89451-2480

Nódulos opalinos en facies marginales del salar Olaroz (Puna Argentina)

Authors

M. A. Bustillo Departamento de Geología. MNCN
R. Alonso Departamento de Geología. Facultad de Ciencias Naturales. UNSAT

DOI:

https://doi.org/10.3989/egeol.89451-2480

Keywords:

Nodules of C-T opa, high-silica thermal water, alluvial fans, salt-lakes

Abstract

This article reports the results of a petrological and geochemical study of silica nodules from Quaternary alluvial fallS of the Olaroz Salar. The nodules are mainly constituted by C-T opal, d. (101) spacing to 4,11 A, implying a high-disorder; this is commonly observed in opa! rocks formed in near surface environments, without burial and heating. The chemical composition of the nodules is anomalous when compared with other typical silica-rocks formed in arid continental closed basin, without any eruptive environments (for instance the Cuenca del Tajo in Spain). The siliceous nodules do not have the characteristics of the silcretes and are not associated to the evaporitic facies of the salar. Their genesis is probably related to contamination of groundwater of the alluvial fan with high-silica thermal water. The C-T opal would thus precipitate by either displacing tbe terrigenous host-rock or replacing previous ulexite nodules.

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Published

1989-04-30

How to Cite

Bustillo, M. A., & Alonso, R. (1989). Nódulos opalinos en facies marginales del salar Olaroz (Puna Argentina). Estudios Geológicos, 45(1-2), 55–59. https://doi.org/10.3989/egeol.89451-2480

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Issue

Vol. 45 No. 1-2 (1989)

Section

Articles

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