Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Bascuñan, S. Articles by Alfaro, G. Search for Related Content GeoRef GeoRef Citation

ZEOLITIZATION OF TUFFS AT QUINAMÁVIDA, CENTRAL SOUTHERN CHILE

Instituto de Geología Económica Aplicada, Universidad de Concepción, Casilla 160-C, Concepción, Chile

^* E-mail address of corresponding author: ukelm{at}udec.cl

Tuffs of the Tertiary Colbún Formation near Quinamávida in central southern Chile have been mapped and their mineralogy analyzed. The pyroclastic rocks present a maximum outcropping thickness of 120 m and are dominated by vitreous lapilli and minor lithic tuffs, the products of active volcanism nearby. About 10% of the tuffs consist of lenses of fine banded tuffs with a high leaf content that were deposited in shallow lakes during quiescent periods between periods of volcanic activity. This tuff sequence is pervasively transformed to clinoptilolite/heulandite and mordenite with variable amounts of plagioclase, minor quartz and smectite. Factors thought to have influenced this conversion to zeolites are a humid climate following deposition combined with a slightly elevated heat flow. Local hydrogeological conditions have modified the cation-hydrogen ion ratios across the study area favoring the formation of clinoptilolite/heulandite and mordenite with medium-minor smectite in the center and south, and a more abundant presence of smectite in the north of the study area.

Key Words: Chile • Heulandite • Clinoptilolite • Mordenite • Tuff • Zeolite