THE IDENTIFICATION OF THE FOSSIL BLACK SMOKER CHIMNEY AND ITS IMPLICATION FOR SCIENTIFIC RESEARCH

Abstract

The present day black smoker chimneys and mounds have been widely found in the settings of mid-oceanic ridge, backarc basin, shallow sea and continental rift, which result in the formation of massive sulfide deposits at the vent sites. Moreover, these deep vents support chemosynthetic metabolizing bacteria. The modern sulfide chimneys commonly show evident columnar to conical geometry, characterized with the concentric mineralogical zonation around a central conduit. The black smoker chimney is formed when the mineral laden hydrothermal fluid is mixed with the surrounding ocean water. It begins to grow by the instant precipitation around outer wall, followed by the crystallization of polymetal sulphide on inner wall of conduits. The deeply seated magma as heat source, hydrothermal fluid concentrated within fissures and continuous eruption are favorable to the creation of a giant black smoker chimney. The drilling in sulphide mounds at the ocean bottom and their comparison with VMS (volcanogenic massive sulfide) indicate that they have similar internal structures and mineral zonation. The sulphide mounds of economic value are built with the accumulation of collapsed chimney and breccias, reworked by replacement and recrystalization. Finally, the identification of chimney structures within VMS is very important for the understanding of the process of minerallization and the origin of life.