Abstract

Mississippi valley-type ore field on the south side of Great Slave Lake. Pine Point has produced 58.2 million tons of 3.0 percent Pb and 6.7 percent Zn with present reserves of 25.7 million tons of 2.7 percent Pb and 6.3 percent Zn. Most Pine Point orebodies were deposited in interconnected paleokarst networks that developed at the lower limits of coarse dolomite alteration of upper barrier limestones. Karstic structures, which exhibit the largest cavity development and consequently the greatest amounts of infilling internal sediments, host the best grades of mineralization. The following conclusions are suggested: the barrier developed due to subtle epeirogenic crustal movements and/or eustatic sea-level changes affecting normal sedimentary processes; deformation of the barrier is possibly due to differential sediment compaction or warping of underlying evaporites; coarse dolomitization and paleokarstification; metals introduced by chloride-rich brines; brines (expelled by overburden pressures) migrated eastward along the barrier and precipitated metals in paleokarst structures upon encountering reduced sulfur species.--Modified journal abstract.

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