Radiometric Ages from the Mt. Desert Island Area, Maine

摘要

Evaluation of geochronologic dates published by Metzger and Bickford (1972), coupled with unpublished information, suggests that there is too much disagreement between the various data to allow a reliable "minimum date" to be placed on the Bar Harbor Series. Further, the stratigraphic relations between the Cranberry Island Series and Bar Harbor Series cannot be resolved in the light of available data, especially as the two series are not in contact. The published Somesville granite dates (which range from 389 m.y. to 429 ± 13 m.y.), coupled with absolute time scale uncertainties, do not allow one to state with certainty that the Bar Harbor Series are Middle Silurian. The Silurian fauna identified from Bar Harbor correlatives occur some 50 km from Mt. Desert Island and in a different sequence of rock types.