226Ra-210Pb and 228Ra-228Th Dating of Barite in Submarine Hydrothermal Sulfide Deposits Collected at the Okinawa Trough and the Southern Mariana Trough

Abstract

The 226 Ra-210 Pb and 228 Ra-228 Th ages were obtained for barite crystals in hydrothermal sulfide deposits taken at the Okinawa Trough and the Southern Mariana Trough. After calibrating the measurement systems with standard samples with pitchblende, it was confirmed that the U and Th concentrations obtained for GSJ samples are consistent with literature values. It was shown that radon does not escape from barite crystals extracted from hydrothermal sulfide deposits, which indicates that 226 Ra-210 Pb dating method works for these barite crystals. Most of the 226 Ra-210 Pb and 228 Ra-228 Th ages are younger than ESR and U-Th ages, where this inconsistency would be explained by the mixture of the barite crystals with younger and older ages, formed by several hydrothermal events.

210Pb and 210Po in Geological and Related Anthropogenic Materials: Implications for Their Mineralogical Distribution in Base Metal Ores

“…Alongside all U-bearing minerals, the potential hosts of 210 Pb and 210 Po may include Pb-bearing chalcogenides such as galena, as well as a range of sulphates, carbonates, and Fe-oxides. 210 Pb and 210 Po are also likely to occur as nanoparticles adsorbed onto the surface of other minerals, such as clays, Fe-(hydr)oxides and possibly also carbonates. In rocks, unsupported 210 Pb-and/or 210 Po-bearing nanoparticles may also be present within micro-fractures in minerals and at the interfaces of mineral grains.…”

“…210 Pb and 210 Po are intermediate isotopes within the 238 U decay-series ( Figure 1) and occur in minute amounts in nature [1]. Details of the uranium ( 238 U, 235 U) and thorium ( 232 Th) decay-series radionuclides are concisely provided in the review by Cowart and Burnett (1994) [2].…”

“…Details of the uranium ( 238 U, 235 U) and thorium ( 232 Th) decay-series radionuclides are concisely provided in the review by Cowart and Burnett (1994) [2]. 210 Pb has a half-life of 22.2 years and is generated via: (i) the decay of atmospheric 222 Rn gas ("unsupported" 210 Pb); and (ii) via the continuous production of 222 Rn from natural 226 Ra contained in crustal materials ("supported" 210 Pb). 210 Pb decays to 210 Bi by emission of a beta particle.…”

“…210 Pb has a half-life of 22.2 years and is generated via: (i) the decay of atmospheric 222 Rn gas ("unsupported" 210 Pb); and (ii) via the continuous production of 222 Rn from natural 226 Ra contained in crustal materials ("supported" 210 Pb). 210 Pb decays to 210 Bi by emission of a beta particle. 210 Pb is useful for determining the age of a recent sediment in that, provided that the atmospheric flux is constant, the decay profile relates directly to sedimentation rate.…”

“…Concentrations of natural 210 Pb and 210 Po in igneous and related hydrothermal environments are governed by release from crustal reservoirs. 210 Po may undergo volatilisation, inducing disequilibrium in magmatic systems. In sedimentary environments (marine, lacustrine, deltaic and fluvial), as in soils, concentrations of 210 Pb and 210 Po are commonly derived from a combination of natural and anthropogenic sources.…”