Excess Ar in Some Metamorphic and Plutonic Rocks and Reduction of Thermal Neutron-induced ^<40>Ar by Cd Shielding

• Main Author: SAITO Kazuo
• Format: Report
• Language: English
• Published: Tohoku University 1994
• Subjects: ^<40>Ar-^<39>Ar dating; Excess Ar; Thermal Neutron-induced ^<40>Ar; shielding with Cd foil; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/10097/28521; https://tohoku.repo.nii.ac.jp/?action=repository_uri&item_id=47044; https://tohoku.repo.nii.ac.jp/?action=repository_action_common_download&item_id=47044&item_no=1&attribute_id=18&file_no=1

It is well known that, by the K-Ar dating, a reliable age cannot be obtained from a sample containing excess Ar. The ^<40>Ar-^<39>Ar method, on the other hand, has, potentially, ability to provive us geologically meaningful ages even for such samples with excess Ar. A Mowson charnockite from Antarctica shows a good example. In the ^<40>Ar-^<39>Ar dating, thermal neutron induced ^<40>Ar from 40K is one of the major source of errors in age calculation. Wrapping a sample with Cd foil is very effective in reducing this disturbing ^<40>Ar.