Spatiotemporal variability of hydrothermal Fe fluxes, authigenic minerals and microbial diversities recorded by sediment cores adjacent to the Tectonic-Controlled Tianxiu vent field, Carlsberg Ridge

This study explores the spatiotemporal evolution characteristics of mineralogy, geochemistry, and microbial diversity of sediment cores near the Tianxiu hydrothermal area on the Carlsberg Ridge in the northwestern Indian Ocean. Our research aims to elucidate the variability of hydrothermal activity across temporal scales ranging from tens of millennia to millennia, and how the spatial variation in hydrothermal iron fluxes were deposited. Additionally, we aim to investigate how microbial diversity and authigenic minerals responded to these variations.

Analysis of a distal-vent sediment core retrieved 2.2 km to the venting site of Tianxiu reveals its hydrothermal activity exhibits variability on a 10,000-year scale. Notably, significant enhancements in hydrothermal activity occurred during the deglacial periods and the Last Glacial Maximum (LGM) during the last 30,000 years, both driven by sea-level lowering but through different mechanisms: enhanced magma activity during the deglacial period due to increased partial mantle melting caused by LGM decompression and enhanced crustal permeability during the glacial period. The input of hydrothermal iron flux during the deglacial period was nearly double that of the LGM. 

Further analysis of a near-vent sediment push core TX219 obtained by submersible Jiaolong sheds light on the variability of hydrothermal depositional environments at the millennial scale. The surface 0-6 cm of the sediment core demonstrates signatures of the contribution of low-temperature diffuse flow, enriching the sediment with Fe, Cu and Zn derived from hydrothermal sources. The higher abundances of Fe, and S-oxidizers especially the presence of thermophilic microorganisms and biogenic barite and relatively light Ba isotope composition provide further evidence of the influence of low-temperature hydrothermal fluid.

Our findings contribute to a more comprehensive understanding of the dynamic interplay between hydrothermal activity, mineral precipitation, microbial communities, iron cycling, and the controlling mechanisms of a hydrothermal system.

 

References:

Li, M., Han, X., Qiu, Z., Fan, W., Wang, Y., Li, H., Chen, H., Hu, H., 2023. Sea‐Level Fall Driving Enhanced Hydrothermal and Tectonic Activities: Evidence From a Sediment Core Near the Tectonic‐Controlled Tianxiu Vent Field, Carlsberg Ridge. Geophys Res Lett 50(7). doi.org/10.1029/2022gl101599.

Qiu, Z., Fan, W., Han, X., Chen, X., Yin, X., 2023. Distribution, speciation and mobility of metals in sediments of the Tianxiu hydrothermal field, Carlsberg Ridge, Northwest Indian Ocean. J Marine Syst 237. doi.org/10.1016/j.jmarsys.2022.103826.

Han X., Guo H., Li H et al.,. Evolution of Hydrothermal Activity in Tianxiu Vent Field: Insights from Elemental Geochemistry, Ba Isotopes and Microbiology in Sedimentary Records. (in preparation)