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Evidence for a major Late Precambrian tectonic event (rifting?) in the Eastern Midcontinent Region, United States
Author(s) -
Keller G. R.,
Bland A. E.,
Greenberg J. K.
Publication year - 1982
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/tc001i002p00213
Subject(s) - geology , rift , seismology , precambrian , tectonics , magnetic anomaly , gravity anomaly , basement , paleontology , civil engineering , oil field , engineering
Recently acquired gravity and aeromagnetic data delineate a large linear gravity anomaly which extends through eastern Kentucky and Tennessee and coincides with a zone of complex, high‐amplitude magnetic anomalies. Basement lithologies in the area can be interpreted as a bimodal volcanic suite which is locally peralkaline in nature. These volcanics appear to be metamorphosed where they lie east of the Grenville front, suggesting they predate the Grenville metamorphic event. The available gravity, aeromagnetic, seismic refraction, and petrologic data, along with regional correlations, suggest that the best tectonic interpretation of these data is that a Keweenawan rift zone extended through the area. This rift can be roughly outlined by the gravity high, which is locally offset, suggesting the presence of transform faults. The boundaries of this rift have been locally reactivated and, in fact, a recent earthquake was located along its western boundary in northern Kentucky.