[1] The oxygen and hydrogen isotope compositions of vein minerals and dO values of 64 whole rocks from the deeper kilometer of the 1.5 km lower crustal section of ODP Hole 735B in the SW Indian Ocean were analyzed in order to investigate seawater penetration into and reaction with the lower oceanic crust. Vein amphiboles have dD values of 35 to 65%, indicating formation from seawater fluids and...

Introduction: Hydrocarbons with an apparent abiotic origin are found in hydrothermal fluids from vents on unsedimented mid-ocean ridges. In particular, fluids from ultramafic-hosted hydrothermal systems contain significant quantities of many organic species other than methane [1-3]. Generation of significant amounts of long chain hydrocarbons was not reported in previous experimental studies [4...

Low-temperature fluid flow has been identified as an important component of the heat, mass and chemical flux at sites of active venting. One way to study the movement of water through hydrothermal deposits is to analyse the pore-fluids extracted from sulfidic sediments. The composition of diffuse flow fluids in one sediment core from the south of the active TAG mound reflects the dilution of hi...

Hydrothermal vent fluids are highly enriched in iron (Fe) compared to ambient seawater, and organic ligands may play a role in facilitating the transport of some hydrothermal Fe into the open ocean. This is important since Fe is a limiting micronutrient for primary production in large parts of the world’s surface ocean. We have investigated the concentration and speciation of Fe in several vent...

BACKGROUND The most widespread bacteria in oxic zones of carbonate chimneys at the serpentinite-hosted Lost City hydrothermal field, Mid-Atlantic Ridge, belong to the Thiomicrospira group of sulfur-oxidizing chemolithoautotrophs. It is unclear why Thiomicrospira-like organisms thrive in these chimneys considering that Lost City hydrothermal fluids are notably lacking in hydrogen sulfide and car...

tourmalinization characterizes the most pervasive alteration type in the nezam abad ore deposit, west-central iran. it delineates high-temperature centers of mineralization and together with quartz and cassiterite form inner parts of the alteration halo. the composition of tourmalines plots mostly along and between the proton and alkali-deficient end members. tourmaline in quartzdioritic host i...

The speciation of carbon in subseafloor hydrothermal systems has direct implications for the maintenance of life in present-day vent ecosystems and possibly the origin of life on early Earth. Carbon monoxide is of particular interest because it represents a key reactant during the abiotic synthesis of reduced carbon compounds via Fischer–Tropsch-type processes. Laboratory experiments were condu...

hydrothermal alteration processes are extensively took place on volcanic and pyroclstics of takestan area. existence of abundant, deep fracturing and subvolcanic intrusions are enhanced extend hydrothermal alteration zones. the following alteration zones are determined: propylitic, argillic, advanced argillic and sillicic. there are outcropped and widespread in different size and limit. formati...

Despite their potential importance as analogs of primitive microbial metabolisms, the knowledge of the structure and functioning of the deep ecosystems associated with serpentinizing environments is hampered by the lack of accessibility to relevant systems. These hyperalkaline environments are depleted in dissolved inorganic carbon (DIC), making the carbon sources and assimilation pathways in t...