Comparison of thermal stability between internal and external surfaces of zircon

✍ Scribed by Satoshi Koshimizu

• Publisher: Elsevier Science
• Year: 1993
• Weight: 258 KB
• Volume: 22
• Category: Article
• ISSN: 0969-8078
• DOI: 10.1016/0969-8078(93)90178-7

✦ Synopsis

F-T ages were ussured for both internel and external surfaces of zircon crystals in quartz-diorite ssaplss obtained free central Japan (I~J~shinizu, 1990). These data suggested that ages tightly cluster around 3.8 ~ for inten~al surfaces and around 7.4 Ma for external surfaces. This age discrepancy can be experimntally elucidated by therml stability difference in internal and external surfaces of zircon. To establish a ccaparis~n of therul stability bet~ internal and external surfaces of zircon, 1 h annealing experi~te for spontaneous and induced fission tracks on both surfaces of zircon were Lu~rtaken in this study. At tssperaturss betwen 200" C and 800" C, the dnity of spontaneous and induced fission tracks is reducml on both internal and external surface. This reduction, however, takes place at lower t~peraturss on internal surfaces of zircon. This suggests that external surface is sore stable with respect to therml influsncss and that fission track closure tssperatures vary frca internal to external surfaces of zircon.