Mineralogical and chemical changes during seafloor alteration in the Archaean

摘要: Hydrothermal circulation of seawater through the oceanic crust results in alteration and recrystallisation primary magmatic minerals redistribution chemical elements. Many elements removed from ocean during are added to therefore a systematic study consequences seafloor Archaean provides insight into composition seawater. In addition, affects compositions volcanic rocks complicates interpretation their histories. Finally, types distribution zones leaves record hydrothermal fluids thus information about scale vigour crust.We present here mineralogical geochemical basalts komatiites 2.7 Ga Abitibi belt Canada 3.5-3.2 Barberton greenstone South Africa. These belts have undergone multiple stages major focus is isolate changes that occurred those later metamorphism accompanied accretion, granite intrusion uplift. Previous studies compared whole rock analyses altered with unaltered rocks. This attempts specific mineral reactions for more detailed account alteration. Methodology used includes SEM, EMPA, microfluorescence spectroscopy. The first stage was devitrification glassy basaltic pillow margins which included growth chlorite clinozoisite, followed by replacement clinopyroxene tremolite, plagioclase sericite, phase carbonate veining. Preliminary show depleted Si, Fe, Mg, Ca, Na, Mn enriched Al, K, Ti. Comparison samples modern day analogues will allow us observe how this process has changed time.