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A silica deposit of possible Tertiary age in the Carboniferous Limestone near Birr, County Offaly, Ireland

Published online by Cambridge University Press:  01 May 2009

A. P. Beese ,
P. M. Brück ,
J. Feehan  and
T. Murphy
A. P. Beese
Affiliation:
Department of Geology, University of Geology, Cork, Ireland
P. M. Brück
Affiliation:
Department of Geology, University of Geology, Cork, Ireland
J. Feehan
Affiliation:
Department of Geology, Trinity College, Dublin 2, Ireland
T. Murphy
Affiliation:
School of Cosmic Physics, Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin 2, Ireland
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Abstract

Summary. Stony clays, comprising weathered bryzoan-rich chert and silica clay, are found adjacent to Carboniferous Limestone on the west and a weathered dolomitized zone on the east near Birr, County Offaly, Ireland. A gravity survey together with a stratigraphy obtained from boreholes and other test borings suggests a depth of about 40 m and a surface width or diameter of approximately 60 m for the deposit. Indirect evidence points to a possible Tertiary age. The interpreted origin of the stony clays is by silification of Carboniferous Limestone and preservation by solution subsidence along a possible fault zone.

Type
Articles
Information
Geological Magazine , Volume 120 , Issue 4 , July 1983 , pp. 331 - 340
Copyright
Copyright © Cambridge University Press 1983

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