Experiments on hydrothermal degradation of Pyrococcus abyssi biomass were conducted at elevated pressure (40 MPa) over a 200-450 °C temperature range in sapphire reaction cells. Few organic compounds could be detected in the 200 °C experiment. This lack was attributed to an incomplete degradation of P. abyssi cells. On the contrary, a wide range of soluble organic molecules were generated at te...

The Von Damm Vent Field (VDVF) is located on the flanks of the Mid-Cayman Spreading Centre, 13 km west of the axial rift, within a gabbro and peridotite basement. Unlike any other active vent field, hydrothermal precipitates at the VDVF comprise 85-90% by volume of the magnesium silicate mineral, talc. Hydrothermal fluids vent from a 3-m high, 1-m diameter chimney and other orifices at up to 21...

Fluids from the ultramafic-hosted Lost City hydrothermal field were analyzed for total dissolved organic carbon and dissolved organic acids. Formate (36–158 lmol/kg) and acetate (1–35 lmol/kg) concentrations are higher than in other fluids from unsedimented hydrothermal vents, and are a higher ratio of the total dissolved organic carbon than has been found in most marine geothermal systems. Iso...

Seafloor massive sulphide deposits are potential resources for base and precious metals (Cu-Pb-Zn ± Ag ± Au), but difficulties in estimating precise reserves and assessing environmental impacts hinder exploration and commercial mining. Here, we report petrological and geochemical properties of sulphide chimneys less than 2 years old that formed where scientific boreholes vented hydrothermal flu...

The known dimensions of hydrothermal fluid circulation associated with emplacement of the 2.055-Ga Bushveld Igneous Complex (BIC) are extended with new isotopic ages for Paleoproterozoic mineral deposits in wallrocks (Transvaal Supergroup) surrounding the BIC. A fluorite-rich Mississippi Valley–type (MVT) deposit in the Zeerust district, dated at 2.05 Ga (Sm-Nd isochron age), has Nd isotopic co...

Hydrothermal processes on Mars: It has been suggested that hydrothermal process may have been active in the history of Mars[1]. This concept is supported by three lines of evidences: (1) widespread evidences of volcanic activity on Mars; (2) high levels of WEH (water-equivalent-hydrogen) found in two large equatorial regions on Mars (ODY_NS) [2]; (3) The ground ice excavated by meteorite impact...

Open spaces in epithermal veins of the Bohemia mining district, Oregon, USA, filled with sediments during hydrothermal activity. These sediments consist mainly of chalcedony, rock fragments, and vein quartz fragments. In addition, hematite is deposited during stage three of the vein development. Observed sedimentary features include draping laminae, erosion surfaces, slumping, and graded beddin...

Deep-sea hydrothermal vents play an important role in global biogeochemical cycles, providing biological oases at the seafloor that are supported by the thermal and chemical flux from the Earth's interior. As hot, acidic and reduced hydrothermal fluids mix with cold, alkaline and oxygenated seawater, minerals precipitate to form porous sulphide-sulphate deposits. These structures provide microh...

The recently discovered Lost City Hydrothermal Field (LCHF) represents a new type of submarine hydrothermal system driven primarily by exothermic serpentinization reactions in ultramafic oceanic crust. Highly reducing, alkaline hydrothermal environments at the LCHF produce considerable quantities of hydrogen, methane and organic molecules through chemo- and biosynthetic reactions. Here, we repo...