Genetic models of many massive sulfide deposits postulate deposition of metalliferous sediment by venting of high-salinity hydrothermal fluids onto the sea floor. The Atlantis II deep, Red Sea, is a currently active modern example of such a process. Areal extent of the brine pool in the Atlantis II deep exerts primary control on the distribution of metalliferous sediment. The presence of a density-stratified brine pool allows dispersion of undiluted metal-rich brine to all parts of the deep. Currently, brine vents in the Southwest basin, advects vertically to the density interface between the brine pool and overlying sea water, and then flows laterally along the interface. The lower brine mass is isolated from oxygenated sea water, allowing base metal sulfides to precipit te in areas distal from the site of venting. The metalliferous sediments are extremely fine grained with interstitial water contents in the uppermost sediments of greater than 98% by weight. Sedimentation rates inside the brine pool are in excess of 100 cm/1,000 years. High salinity, high temperature, and high trace-metal content of the brine produce a toxic environment which ensures that the finely laminated sediments are not disturbed by bioturbation. However, metalliferous sediment deposited in the area of active brine venting is highly disturbed, with common features of soft sediment deformation. Heterolithic and homolithic breccias occur, some of which are metalliferous turbidites dislodged, by tectonic activity, from steep graben walls flanking the deep. Influx of new brine causes urther disruption and deposition of epigenetic minerals in veins which cut unlithified metalliferous sediment.

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