Remobilization of Iodine in Marine Sediments During Early Diagenesis

Based on the sedimentary geochemical studies of the Antarctic Ocean and the various geochemical parameters available,this paper deals with the process of emobilization of iodine in marine sediments during early diagenesis.The results showed that the process is not always controlled completely by organic matter as was expected previously.On average the adsorption and oxide phases of iodine account respectively for 23% and 32% of the total in continental-shelf and hemipelagic surficial sediments.Chemical analysis has revealed that the upward diffusion flux and redox conditions would play an important role in the concentration of iodine in the surface sediments.And the species of iodine in the surfial sediments characteristic of high I/Corg ratios would bepredominated by the oxide and adsorption phases.As experimentally evidenced,it is the early diagenetic remoibilization of iodine associated with the oxide and adsorption phases that led to the decrease of I/Corg with increasing depth.Calculations suggested that the diffusion flux of iodine from the deep parts of te sedimentary columum upwards is on the same order of magnitude as the deposition flux of it from sea water.This may be one of the important factors leading to the depletion of iodine in sedimentary rocks.On the basis of the above discussion and calculations the author has proposed a model for the remobilization of iodine in marine sediments during early diagenesis.

Remobilization of iodine in marine sediments during early diagenesis

Based on the sedimentary geochemical studies of the Antarctic Ocean and the various geochemical parameters available, this paper deals with the process of remobilization of iodine in marine sediments during early diagenesis. The results showed that the process is not always controlled completely by organic matter as was expected previously. On average the adsorption and oxide phases of iodine account respectively for 23% and 32% of the total in continental-shelf and hemipelagic surficial sediments. Chemical analysis has revealed that the upward diffusion flux and redox conditions would play an important role in the concentration of iodine in the surface sediments. And the species of iodine in the surfiial sediments characteristic of high I/C_org ratios would be predominated by the oxide and adsorption phases. As experimentally evidenced, it is the early diagenetic remobilization of iodine associated with the oxide and adsorption phases that led to the decrease of I/C_org with increasing depth. Calculations suggested that the diffusion flux of iodine from the deep parts of the sedimentary columum upwards is on the same order of magnitude as the deposition flux of it from sea water. This may be one of the important factors leading to the depletion of iodine in sedimentary rocks. On the basis of the above discussion and calculations the author has proposed a model for the remobilization of iodine in marine sediments during early diagenesis.