Abstract

Iodine scarcely finds on Earth’s crust. 99.6 % of Earth’s crust is composed of 32 main elements. Remaining 0.4 % is shared among 64 trace elements. Ranking 61 among these 64 elements concerning abundance, iodine is one of scarcest non-metal elements within the composition of Earth’s crust. Biological connection between iodine and carbon systems are well established. There is a strong relation between organic C and iodine concentrations in marine sediments. Iodine founds in low concentration in sedimentary rocks. Compliance of iodine with evaporite minerals is lower than that of bromine. Shales generally contain high iodine concentrations like 1-20 ppm. It is more related to preserved organic C. High amounts of iodine concentrations have measured in shales containing kerogen, the primary organic matter. As the iodine content increases in shales, the oil and organic carbon content also increase. Organic-rich sediments or their volatile derivatives (hydrocarbons) are the primary sources of iodine in many sedimentary basins. Iodine enrichment in waters increases with the proximity to the petroleum reservoirs and the depth of burial. Russians have asserted iodine as a hydrogeochemical indicator for petroleum. Iodine has been used in many studies as a sensitive tracer to discover oil or gas field. Iodine generally migrates together with organic matters due to its proximity to organic matters and is a good tracer for hydrocarbon migration and the movement history of the related waters. In this study, it has been shown that the 129I isotope system can provide useful information to decrease the costs of oil and gas exploration activities and to increase efficiency. Current studies showed that supporting the geological and geophysical survey with iodine hydrogeochemistry and soil geochemistry increases the efficiency of petroleum exploration. Use of iodine for the discovery of oil or gas fields has the advantage of both having reliable and consistent results and being simple and cost-effective.