Petrological, geochemical and Nd-isotopic analyses have been carried out on rock samples from the Rainbow vent field to assess the evolution of the hydrothermal system. The Rainbow vent field is an ultramafic-hosted hydrothermal system located on the Mid-Atlantic Ridge, characterized by vigorous high-temperature venting (~365ºC) and unique chemical composition of fluids: high chlorinity, low pH...

ultramafic rocks are essentially constituted by silicates of magnesium: forsterite, and/or diopside-enstatite; who’s the most common hydrothermal alteration are the serpentinization. to bou azzer, the serpentinisation affected almost all of the ultrabasic rocks. among the phenomena bound to the serpentinisation observed on the ground, we distinguish the magnesium deposits (carbonated serpentini...

The hydration of mantle rocks occurs at mid-ocean ridges, in subduction zones and ophiolites where it strongly modifies the properties oceanic lithosphere. nanostructure reaction products is poorly constrained, but very important, as controls fluid transport during solid volume increase, influences phase reactivity further fluid/rock interaction low temperature. We image contacts between olivin...

Solid volume increases during the hydration of mantle rocks. The fluid pathways necessary to feed reaction front with water can be filled by low density products. As a result, dries out and stops at progress. This process porosity clogging is generally predicted dominate in reactive transport models, even when processes such as reaction-induced fracturing are considered. These predictions not c...

The Jayachamarajapura schist belt in western Dharwar craton, southern India, is predominantly an ultramafics dominant terrain. These rocks have been extensively metamorphosed and altered to serpentinite. komatiite nature of conspicuous. In most the areas these are massive nature. However, some ultramafic units show layered But, their outcrops encompassed within komatiitic bodies. Mg-rich also M...

Abiotic H2 produced in the Precambrian lithospheric crust is a key substrate at base of metabolic chain chemosynthetic and photosynthesis-independent microbial communities, significant to our understanding life on early Earth other planets. cycling processes are also relevant recent hydrogen exploration efforts engineered subsurface environments such as radioactive waste disposal sites. In crus...

A survey of surface, spring and borehole waters associated with the ophiolite rocks of Cyprus shows five broad water types (1) Mg-HCO3, (2) Na-SO4-Cl-HCO3, (3) Na-Ca-Cl-SO4-OH-CO3, (4) Na-Cl-SO4 and (5) Ca-SO4. The waters represent a progression in chemical reactivity from surface waters that evolve within a groundwater setting due to hydrolysis of the basic/ultrabasic rock as modified by CO2-w...