From hot to cold: Assessing the mineralogical diversity of hydrothermal vent plume particles on Earth with an eye towards hydrothermally active icy ocean worlds
Abstract
The Cassini spacecraft's discoveries of molecular hydrogen generation and silica nanoparticles emitted from Saturn's moon Enceladus suggest hydrothermal processes may be ongoing beneath the ice-covered oceans of several moons in our solar system, (e.g. Enceladus and Europa), fueling theories that chemosynthetic life might occur on these other ocean worlds. On Earth, hydrothermal vents are hosts to diverse chemolithotrophic ecosystems and generate plumes wherein nanoparticulate minerals, carbonaceous compounds, and biomolecules are mixed and aggregated into larger (micron-scale) composite plume particles. These particles form microsites that record geochemical conditions at their point of formation. Their high transport potential and function as a ( bio) geochemical tracer make plume particles an enticing astrobiological target, offering a mechanism for delivering biosignatures (if life is present) to a detectable location within the upper ocean water column and/or the outer ice shell. Before we can turn our eyes towards other ocean worlds, we must better understand what determines the mineralogical characteristics of plume particles here on Earth. Despite the explosion of research on hydrothermal vents since their discovery in 1977, there are only a handful of studies characterizing the mineralogy of particles entrained within rising and neutrally buoyant hydrothermal vent plumes. We present new results from Earth's deepest hydrothermal vent field (Beebe vent at 4957 m) using an analytical technique (synchrotron-based Laue X-ray diffraction, SL-XRD) that has never before been applied towards mineralogical study of plume particles. We nest our findings from Beebe vent in a comprehensive review that frames what is currently known about plume particles, focusing on identifying the unique mineralogical character arising across gradients in depth, fluid temperature and lithology. We also highlight the strengths and weaknesses of previous analytical approaches, and identify knowledge gaps in the field. This review improves our understanding of plume particle dynamics in the Earth system, and sheds light on the potential strengths and limitations of utilizing particles as (bio)geochemical tracers of hydrothermal processes on other ocean worlds.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMP075...06W
- Keywords:
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- 0738 Ice;
- CRYOSPHERE;
- 4299 General or miscellaneous;
- OCEANOGRAPHY: GENERAL;
- 6207 Comparative planetology;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS;
- 6297 Instruments and techniques;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS