Earthquakes and plutons in the midcontinent - evidence from the Bloomfield Pluton, New Madrid rift complex ( Missouri, USA).

D. N. Ravat, L. W. Braile, W. J. Hinze

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18 Scopus citations

Abstract

Based on the location of hypocenters and earthquake focal mechanisms, there is no evidence that stress concentration associated with the mass excess of the pluton is the cause of earthquakes near the pluton. The seismicity may be along zones of weakness independent of the pluton. Among other explanations investigated to explain the constant distance of earthquakes from the pluton, we favor the possibility of a zone of rigidity contrast caused by the thermal metamorphism of the country rock associated with the pluton intrusion. We have estimated increased temperatures of the country rock using an instantaneous intrusion model. Maximum anomalous country rock temperatures of greater than 100oC dominated the region within 10 km of the pluton edge. This 'thermally metamorphosed' aureole may provide sufficient homogeneity in the upper crust to localize anomalous stresses away from the margin and along the most favorable zones of weakness, thus influencing the locations of earthquakes. -from Authors

Original languageEnglish
Pages (from-to)41-52
Number of pages12
JournalSeismological Research Letters
Volume58
Issue number2
DOIs
StatePublished - 1987

ASJC Scopus subject areas

  • Geophysics

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