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In the present study,the analytical method for 129iodine(129I) in ferromanganese crusts is developed and129iodine/127iodine(129I/127I) ratio in ferromanganese crusts is measured by the accelerator mass spectrometry(AMS).The developed method is applied to analyze 129I/127 I ratio in two ferromanganese crusts MP5D44 and CXD08-1 collected from the Mid-Pacific Ocean.The results show that 129I/127 I ratio in MP5D44 and CXD08-1crusts varies from 7×10–14 to 1.27×10–12,with the lowest value falling on the detection limit level of AMS reported by previous literatures.For the depth distribution of 129I/127 I,it is found that both MP5D44 and CXD08-1 crusts have two growth generations,and the 129I/127 I profiles in two generations all displayed an approximate exponential decay.According to the 129I/127 I ratio,the generate age of bottom layer of MP5D44 and CXD08-1 was estimated to be 54.77 and 69.69 Ma,respectively.
In the present study, the analytical method for 129 iodine (129I) in ferromanganese crusts is developed and 129 iodine / 127 iodine (129I / 127I) ratio in ferromanganese crusts is measured by the accelerator mass spectrometry (AMS) 127 I ratio in two ferromanganese crusts MP5D44 and CXD08-1 collected from the Mid-Pacific Ocean. The results show that 129I / 127 I ratio in MP5D44 and CXD08-1crusts varies from 7 × 10-14 to 1.27 × 10-12, with the lowest value falling on the detection limit level of AMS reported by previous literatures. For the depth distribution of 129I / 127 I, it is found that both both MP5D44 and CXD08-1 crusts have two growth generations, and the 129I / 127 I profiles in two generations all displayed an approximate exponential decay. According to 129I / 127 I ratio, the generation age of bottom layer of MP5D44 and CXD08-1 was estimated to be 54.77 and 69.69 Ma, respectively.