Growth history of hydrothermal black smoker chimneys

Abstract

Hollow mineral spires known as ‘black smoker’ chimneys precipitate around 350 °C jets of hydrothermal fluid spouting from the sea floor on the East Pacific Rise (EPR) at 21° N (refs 1, 2). I describe and discuss here the formation of mineral zoning across the walls of these structures throughout two major growth phases, a sulphate-dominated stage and a sulphide replacement stage. During the sulphide replacement stage, at least four distinct sulphide mineral zonation sequences develop across chimney walls from interior to exterior. The apparently successive formation of these sulphide zonation sequences is attributed to evolution of radial thermal and chemical gradients accompanying the gradual thickening and sealing of black smoker chimney walls.