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Negative Gravity Anomalies over Acid “Intrusions” and their Relation to the Structure of the Earth's Crust

Published online by Cambridge University Press:  01 May 2009

M. H. P. Bott
M. H. P. Bott
Affiliation:
The Sedgwick Museum, Cambridge.
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Abstract

The results of gravity surveys over various exposed and buried acid intrusions are summarized. Some sample density determinations are discussed. It is found that the acid intrusions considered are almost invariably associated with negative Bouguer anomalies, which are certainly often caused by direct density contrast between the less dense acid intrusive, and the denser country rock. This has two immediate implications. (1) Large negative Bouguer anomalies over “granites” may suggest magmatic origin. (2) These gravity anomalies, supported by seismological and seismic evidence, and the petrological distribution of igneous rocks, lead to the postulation of a denser “metasedimentary” layer overlying the “granitic” layer. The bearing of this on the mechanism of intrusion is briefly discussed.

Type
Articles
Information
Geological Magazine , Volume 90 , Issue 4 , August 1953 , pp. 257 - 267
Copyright
Copyright © Cambridge University Press 1953

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References

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