Mantle helium in pore fluids of deep-sea sediments around the Azores archipelago
- Journal Article
Rights / licenseCreative Commons Attribution 4.0 International
We present noble gas concentrations and helium isotope ratios measured in the pore fluids of two deep-sea sediment cores taken at the Azores Plateau. Nesingle bondXe concentrations were used to estimate the atmospheric noble gas component within the pore fluids and to then determine the terrigenic helium component. The concentrations of terrigenic 3He indicate the presence of hydrothermal fluids and a mantle He component within the sediment pore space. At both sampling locations, the concentration of terrigenic helium increases with sediment depth. The observed concentration gradients suggest a diffusive transport of He through the sediments. The helium isotope ratio of the source of the terrigenic helium is characterized by a typical mid-ocean ridge basalt (MORB). These results support previous studies suggesting that the pelagic sediments surrounding the Azores host active hydrothermal systems. Our data indicate that the transport of terrigenic helium takes place diffusively over larger areas of the ocean floor, and that the concentration of terrigenic helium in the pelagic sediments increases towards the Mid-Atlantic Ridge and Terceira Rift. The data further suggests that in the Azores region the terrigenic noble gas component is only detectable in the sediment pore fluids and cannot be observed in the overlying bottom water. This highlights the potential of measuring noble gas concentrations and isotope ratios in the sediment column to identify hydrothermal activity in the ocean. Show more
Journal / seriesChemical Geology
Pages / Article No.
SubjectNoble gases; Hydrothermal fluids; Sediment pore fluids; Azores; Mantle helium
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