Rb Sr radiometric age of late Precambrian fossil-bearing and associated rocks from Sinai |
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| Authors: | Aryeh E Shimron Douglas G Brookins |
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| Institution: | Department of Geology, Hebrew University, Jerusalem, Israel;Department of Geology, The University of New Mexico, Albuquerque, N.M., U.S.A. |
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| Abstract: | Six samples of metamorphic rocks from three essentially coeval stratigraphic units, two of which contain Precambrian microfossils, have been analyzed by the Rb-Sr whole-rock radiometric method. Least-squares regression of the data yields an isochron date of 934 ± 80m.y. with initial 87Sr/86Sr= 0.7007 ± 0.0011. This date may reflect the approximate age of formation of these rocks or, alternately, a time of major metamorphism. Regardless, the date is significant in that it (a) is in agreement with the 900-m.y. date for rocks containing similar types of fossils from Bitter Springs, Australia, and (b) coupled with structural evidence, supports the time equivalence of these rocks with 1000-m.y. old rocks (“Kibaran cycle”) of Saudi Arabia. |
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