Controls on Mineral Formation in High pH Fluids From the Lost City Hydrothermal Field
Creators
- 1. Department of Earth Sciences, ETH Zürich, Zürich, Switzerland
- 2. Department of Science and Technology—Philippine Nuclear Research Institute, Quezon City, Philippines
- 3. Space Exploration Institute, Neuchâtel, Switzerland
- 4. Department of Environmental Sciences, University of Basel, Basel, Switzerland
- 5. Department of Geosciences—Geology,University of Fribourg, Fribourg, Switzerland
- 6. Woods Hole Oceanographic Institution, Woods Hole, MA, USA
Description
Although the serpentinite‐hosted Lost City hydrothermal field (LCHF) was discovered more than 20 years ago, it remains unclear whether and how the presence of microbes affects the mineralogy and textures of the hydrothermal chimney structures. Most chimneys have flow textures comprised of mineral walls bounding paleo‐channels, which are preserved in inactive vent structures to a varying degree. Brucite lines the internal part of these channels, while aragonite dominates the exterior. Calcite is also present locally, mostly associated with brucite. Based on a combination of microscopic and geochemical analyses, we interpret brucite, calcite, and aragonite as primary minerals that precipitate abiotically from mixing seawater and hydrothermal fluids. We also observed local brucite precipitation on microbial filaments and, in some cases, microbial filaments may affect the growth direction of brucite crystals. Brucite is more fluorescent than carbonate minerals, possibly indicating the presence of organic compounds. Our results point to brucite as an important substrate for microbial life in alkaline hydrothermal systems.
Other (English)
Plain language summary
Water-serpentinite reactions at the Lost City hydrothermal field (LCHF) are considered similar to the interactions between seawater and volcanic rocks of the early Earth. The vent fluids that form as a result of this interaction are rich in organic compounds that serve as food and hydrogen that provides energy for microbial life. Systems such as Lost City are ideal sites for investigating processes relevant to early life on Earth. Dense microbial communities live in the mineral structures that form from mixing between vent fluids and seawater at the LCHF. The effect of these microbial inhabitants on the mineralogy and textures of the hydrothermal chimneys is still unknown. This study aims to better understand the mineralogy of the hydrothermal chimneys at Lost City and the relationships between microbes and minerals. Calcite and brucite form in the interior of the chimneys, while aragonite forms on the exterior. Brucite forms inorganic mineral membranes that bound cavities where microbes may live. Unlike calcite and aragonite, brucite is spatially closely associated with microbial activity.
Additional details
Identifiers
- DOI
- 10.1029/2023GC011010;
Publishing Information
- Journal Title
- Geochemistry, Geophysics, Geosystems
- Journal Volume
- 25
- Journal Issue
- 2
- Journal Page Range
- e2023GC011010
- ISSN
- 1525-2027
INIS
- Country of Publication
- United States
- Country of Input or Organization
- Philippines
- Subject category
- S58: GEOSCIENCES; S01: COAL, LIGNITE, AND PEAT;
- Descriptors DEI
- ARAGONITE; CALCITE; CARBONATES; CRYSTALS; FILAMENTS; FLUORESCENCE; GEOCHEMISTRY; GEOTHERMAL FIELDS; HYDROTHERMAL SYSTEMS; MINERALIZATION; MINERALOGY; PH VALUE; PRECIPITATION; SEAWATER; TEXTURE; URBAN AREAS
- Descriptors DEC
- CARBONATE MINERALS; CHEMISTRY; EMISSION; ENERGY SYSTEMS; GEOTHERMAL SYSTEMS; HYDROGEN COMPOUNDS; LUMINESCENCE; MINERALS; OXYGEN COMPOUNDS; PHOTON EMISSION; SEPARATION PROCESSES; WATER
- Proposed descriptors and Free-text terms
- Lost City hydrothermal field; hydrothermal chimneys; mineral-microbes; carbonate-brucite; alkaline hydrothermal vent
Optional Information
- Copyright
- © 2024 The Authors