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Volcanism on Gough Island: a revised stratigraphy

Published online by Cambridge University Press:  01 May 2009

J. G. Maund ,
D. C. Rex ,
A. P. Le Roex  and
D. L. Reid
J. G. Maund
Affiliation:
Department of Geology, University of Cape Town, Rondebosch 7700, South Africa
D. C. Rex
Affiliation:
Department of Earth Sciences, University of Leeds, Leeds, U.K.
A. P. Le Roex
Affiliation:
Department of Geology, University of Cape Town, Rondebosch 7700, South Africa
D. L. Reid
Affiliation:
Department of Geochemistry, University of Cape Town, Rondebosch 7700, South Africa
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Abstract

Recent field work on Gough Island combined with K–Ar dating of the lavas requires revision of the age and volcanic stratigraphy. Four main periods of volcanic activity on the island are recognized. These comprise the eruption of the Older Basalt Group which ranges in age from 2.5 to 0.52 Ma, the intrusion of aegerine-augite trachyte plugs (0.8−0.47 Ma), voluminous trachyte extrusion (0.30–0.12 Ma) and finally to eruption of the Edinburgh Basalt (0.20–0.13 Ma).

Within the Older Basalt Group three phases of activity can be recognized; the earliest involving the eruption of pillow basalts and hyaloclastites when the island emerged from below sea level. This was followed by subaerial as-type lava flows and also dyke intrusion (phase two) which probably contributed to forming a large shield-type volcanic island, which in turn supported the eruption and deposition of flat-lying flows on an angular unconformity (phase three). Intrusion of aegirine-augite trachyte plugs occurred concurrently with the latter stages of Older Basalt eruption. After a period of considerable erosion the voluminous trachyte lavas and pyroclastics were erupted. The Edinburgh Basalt, erupted in the vicinity of Edinburgh Peak, represents the youngest volcanic activity on the island.

Type
Articles
Information
Geological Magazine , Volume 125 , Issue 2 , March 1988 , pp. 175 - 181
Copyright
Copyright © Cambridge University Press 1988

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