Diversity of biogenic minerals in low-temperature Si-rich deposits from a newly discovered hydrothermal field on the ultraslow spreading Southwest Indian Ridge

Abstract

[1] A newly discovered hydrothermal field on the ultraslow spreading Southwest Indian Ridge expands the known ranges of biogenic minerals, microbes, and hydrothermal deposits. The deposits from this vent site show typical characteristics of low-temperature hydrothermal deposits. Rare earth element fractionation might be partly influenced by bacterial activity. A physicochemical gradient is present across the layer of deposits, providing suitable microhabitats for various microbes. Molecular phylogenetic analysis demonstrates a diverse range of bacteria, some of which are involved in sulfur, iron, and nitrogen metabolism. A high diversity of biogenic Fe and Si minerals are present in the deposits. Biogenic silica, Fe-sulfides, and Fe-oxides with distinctive morphologies are closely related to microbes. Several novel Fe-oxide structures are found and attributed to new types of biogenic minerals. The precipitation of porous silica spherules and Fesulfides can be strongly promoted by extracellular polymer saccharides. Biomineralization features indicate that these deposits evolved through four stages. These results help us to better understand the formation of biogenic minerals and low-temperature deposits associated with microbes in the Earth's modern and ancient seafloor hydrothermal vent fields.Citation: Peng, X., S. Chen, H. Zhou, L. Zhang, Z. Wu, J. Li, J. Li, and H. Xu (2011), Diversity of biogenic minerals in lowtemperature Si-rich deposits from a newly discovered hydrothermal field on the ultraslow spreading Southwest Indian Ridge,

Microbial Sulfur Cycle in Two Hydrothermal Chimneys on the Southwest Indian Ridge

“…S1, consistent with the results of a previous study conducted in the same region (16). The concentrations of inorganic nitrogen compounds and dissolved organic carbon in the pore water of S32 were higher than those in S35 (Table 1).…”

Coexistence of Fe(II)- and Mn(II)-oxidizing bacteria govern the formation of deep sea umber deposits

“…The major elements were measured using a Shimadzu XRF-1800 X-ray fluorescence spectrometer operated at 40 kV and 95 mA after the fusion of 0.1 g of sample material with 3.6 g of dilithium tetraborate at 1050°C for 16 min. To determine trace elements and rare earth elements (REE), samples were dissolved using a solution of HNO 3 +HF diluted in 2% HNO 3 and then characterized using a Thermo VG-X7 inductively coupled plasma mass spectrometer (Peng et al, 2011).…”

“…Recently, much research has gone into an understanding of sedimentation on ocean ridges, especially metalliferous sediments generated by activity of submarine hydrothermal systems (Dekov et al, 2010;Edwards et al, 2011;Peng et al, 2011;Li et al, 2013). Hydrothermal umber deposits are fossiliferous, siliceous fine-grained, Fe-Mn-rich sediments.…”

Cutting through the smoke: the diversity of microorganisms in deep-sea hydrothermal plumes

“…This vent field is mostly constructed of chalcopyrite (CuFeS 2 ), kusachiite (CuBi 2 O 4 ), pyrite (FeS 2 ), manganese phosphate hydrate and remarkably high concentrations of sulfate have been documented in some areas [37,39]. …”