Serpentinization of hyperbasites and the forming of chrysotile-asbestos deposits

摘要

Mineral composition of chrysotile-asbestos-bearingultramafic rocks and development of serpentinization process areanalyzed from the point of forming of the minable asbestos veins.Variations in composition of mineral associations related todifferent ore zones should be caused by evolution of ore-formingcolutions during their penetration from faults into blocks of partlyserpentinized alpinotype dunite-harzburgites. The process hadstarted by the #beta#-lizarditizatio which spread over zones offaults, thin fissures and veinlets and stopped steadily within the《large netting》zone. Increase of alkalinity in solutions at the frontwave of #beta#-lizarditization provided the chrysotilization ofrocks but it was limited usually by fringes of simple and nettedveins. In numerous asbestos deposits (Bazhenovskoye,Kiembaiskoye, Molodezhnoye, etc) the chrysotilization was suitedby antigoritization going far from fringes over barren weaklyserpentinized blocks. Generally, this process was followed by thedeposition of chrysotile-asbestos. But in some deposits(Dzhetygora, Ostaninskoye, Aktovrakskoye) the antigoritizationhad the smallest development.