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Measurement of53Mn in deep-sea iron and stony spherules
Authors:Kunihiko Nishiizumi
Institution:Department of Chemistry, B-017, University of California at San Diego, La Jolla, CA 92093 U.S.A.
Abstract:Cosmic-ray-produced53Mn (t1/2 = 3.7 × 106years) was measured in individual and groups of deep-sea iron and stony spherules by highly sensitive neutron activation analysis. The activities found were less than 20 dpm53Mn/kg Fe (10?5?10?6 dpm53Mn/sample) in iron spherules except one iron spherule whose activity was 241 ± 73 dpm53Mn/kg Fe. These low activities may indicate evaporative loss of53Mn due to heating in the earth's atmosphere. On the other hand, all stony spherules contained 200–260 dpm53Mn/kg Fe which is similar to chondritic values. These spherules may be ablation debris from large objects.
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