Mississippi Valley Type Pb-Zn

Across the many MVT Pb-Zn deposits associated with evaporites, there are two fabric/structure styles: 1) Halokinetic edges, with the metalliferous brine interactions typically tied to fluid interfaces within the sulphate fringe (caprock or carapace), which defines the dissolutional periphery of a diapir crest or stem, a salt allochthon periphery, or below a salt-lubricated décollement plane, and; 2) Bedded sulphate interactions typically located where fault-controlled metalliferous fluids intersected with, and interacted with, one or more platform sulphate beds (salina or saltern) (Warren 2016; Chapter 15). For SedEx deposits there is a third evaporite type, a suprasalt allochthon structuration that creates fault-fed, metal-prone, seafloor brine lakes. Thus we can target exploration in a predictive fashion for those MVT Pb-Zn deposits with an evaporite association: the targeting is based on identifying favourable intersections where fault structures (extensional faults or thrust planes) intersect units of dissolving bedded or halokinetic evaporites now marked by residues and other “salt that was” textures.


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