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The deep structure of a sea-floor hydrothermal deposit

R.A. Zierenberg·Y. Fouquet·D. J. Miller·J.M. Bahr·P.A. Baker·T. Bjerkgard·C.A. Brunner·R.C. Duckworth·R. Gable·J. Gieskes·W.D. Goodfellow·H. M. Groschel-Becker·G. Guerin·J. Ishibashi·G. Iturrino·R.H. James·K.S. Lackschewitz·L.L. Marquez·P. Nehlig·J.M. Peter·C.A. Rigsby·P. Schultheiss·Wayne C. Shanks·Bernd R. T. Simoneit·M. Summit·D.A.H. Teagle·M. Urbat·G.G. Zuffa
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Abstract

Hydrothermal circulation at the crests of mid-ocean ridges plays an important role in transferring heat from the interior of the Earth. A consequence of this hydrothermal circulation is the formation of metallic ore bodies known as volcanic-associated massive sulphide deposits. Such deposits, preserved on land, were important sources of copper for ancient civilizations and continue to provide a significant source of base metals (for example, copper and zinc). Here we present results from Ocean Drilling Program Leg 169, which drilled through a massive sulphide deposit on the northern Juan de Fuca spreading centre and penetrated the hydrothermal feeder zone through which the metal-rich fluids reached the sea floor. We found that the style of feeder-zone mineralization changes with depth in response to changes in the pore pressure of the hydrothermal fluids and discovered a stratified zone of high-grade copper-rich replacement mineralization below the massive sulphide deposit. This copper-rich zone represents a type of mineralization not previously observed below sea-floor deposits, and may provide new targets for land-based mineral exploration.

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R.A. Zierenberg, Y. Fouquet, D. J. Miller, J.M. Bahr, P.A. Baker, T. Bjerkgard, C.A. Brunner, R.C. Duckworth, R. Gable, J. Gieskes, W.D. Goodfellow, H. M. Groschel-Becker, G. Guerin, J. Ishibashi, G. Iturrino, R.H. James, K.S. Lackschewitz, L.L. Marquez, P. Nehlig, J.M. Peter, C.A. Rigsby, P. Schultheiss, Wayne C. Shanks, Bernd R. T. Simoneit, M. Summit, D.A.H. Teagle, M. Urbat, G.G. Zuffa. 1998. The deep structure of a sea-floor hydrothermal deposit. https://doi.org/10.1038/33126

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