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Origin of ash deposits in the Santiago area, Central Chile

Published online by Cambridge University Press:  01 May 2009

J. E. Guest  and
G. P. Jones
J. E. Guest
Affiliation:
University of London Observatory, Mill Hill ParkLondon N.W.7
G. P. Jones
Affiliation:
Department of Geology, University College, Gower Street, London W.C.1.
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Summary

Non-stratified, poorly-sorted rhyolitic ash deposits previously described as morainic and mudflow deposits are reinterpreted as ignimbrites emplaced in the topographically lower parts of the Santiago basin by pyroclastic flows. These flows probably originated from sources high in the Andes, and swept down the deep Maipo valley to spread out over the sediments filling the basin. An ignimbrite with a zone of dense welding but otherwise of similar character to the non-welded ashes of the basin occurs in one of the Andean valleys; and peculiar ‘pipe’ structures in the ashes of the basin support a pyroclastic flow origin.

Further study of the nature and origin of these rocks may lead to a better understanding of the structural evolution of the area.

Type
Articles
Information
Geological Magazine , Volume 107 , Issue 4 , July 1970 , pp. 369 - 381
Copyright
Copyright © Cambridge University Press 1970

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References

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