Use of mica in fission track dating

Abstract

Fission track ages determined by some geochronologists on micas differ from those obtained on the same samples by other methods. The assumption advocated for these anomalous ages, is the presence of abnormal levels of uranium contents in the crystal fractures and defects as compared to normal low level uranium present in the remaining crystal. Factor responsible for the presence of abnormal uranium content in certain parts of the mica crystal is the rupture of closed crystal system which leads to the lateral entry or removal of uranium in the crystal system. In this connection, some studies have been carried out to reveal the factors responsible for showing anomalous ages by different sheets of mica isolated from a small mica book.