Controls on Heat Flow, Fluid Migration, and Massive Sulfide Formation of an Off-axis Hydrothermal System - the Lau Basin Perspective
Schardt, C and Large, RR and Yang, J (2006) Controls on Heat Flow, Fluid Migration, and Massive Sulfide Formation of an Off-axis Hydrothermal System - the Lau Basin Perspective. American Journal of Science, 306 (2). pp. 103-134.
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Official URL: http://www.ajsonline.org/cgi/content/abstract/306/2/103
A numerical model has been developed to investigate heat and fluid migration in a modem off-axis seafloor hydrothermal system, that is, hydrothermal activity and fluid discharge distal to an axial magma chamber emphasizing model geometry, rock/fault properties and fault distribution. The model is based on geophysical data and seafloor observations of the Lau back-arc basin and results suggest a different hydrothermal convection scheme than axial hydrothermal systems. Major hydrothermal activity is predicted to occur at topographic highs due to significant fluid migration along inferred basement topography off-axis with associated permeability differences. Major hydrothermal fluid discharge occurs at off-axis topographic elevated positions with temperatures (150°C - 450°C) and exit fluid velocities (similar to 4 m/s), in good agreement with seafloor observation and theoretical calculations. Heuristic mass calculations pertaining to the formation of massive sulfide deposits imply that a significant base metal sulfide deposit (5 Mt at 10% Cu + Zn) may form in less than 6,000 years, assuming a fluid containing a maximum of 10 ppm base metals and a deposition efficiency of 10 percent. The size and distribution patterns of massive sulfide deposits are determined primarily by fault distribution, provided that adequate fluid flow pathways and heat supply exist.
|Keywords:||VHMS, VMS, seafloor convection, seafloor massive sulfide, black smokers, Lau basin, back-arc, ore genesis|
|Deposited By:||utas eprints|
|Deposited On:||23 Aug 2006|
|Last Modified:||18 Jul 2008 19:42|
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