中部地方領家変成岩のRbとSr

概要

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Rb-Sr method has been tested to the whole rock samples of metasediments which belong to the greenschist facies and epidote-amphibolite facies, from Tatsuno-Shiojiri district, Central Japan. For the Sr isotope analyses, we used mass spectrometer. Concentration measurements of Rb and Sr were carried out by X-ray fluorescense. The points for the greenschist facies rocks, the recrystallization of which are incomplete, seems to lie on a reference isochron for 200 my, the stratigraphically known time of sedimentation. The metasediments from the metamorphic facies of the higher degrees are recrystallized completely. The points for the rocks of upper greenschist facies and epidoteamphibolite facies do not lie on a single line in the isochron diagram. Three rocks from the amphibolite facies seem to make an isochron of 70 my. Initial (^<87>Sr/^<86>Sr)_O of the metasediments are 0.717 and significantly higher than the values of basaltic rocks and Sanbagawa metamorphic rocks.
地学団体研究会の論文
1976-09-20