A little rain falls but faulting is essential: Extensional tectonics and the origin of Zn-Pb deposits in Western Europe

摘要

During the last two decades, the genesis of Mississippi Valley-type (MVT) zinc-lead deposits has mainly been attributed to a gravity-driven groundwater movement. This general genetic model has also been applied to MVT and related Zn-Pb deposits in Western Europe. However, structural, geochronological, and fluid geochemical data demonstrate that these deposits formed in response to extensional tectonics during the Palaeozoic and Mesozoic, some tens to more than one hundred Ma before or after any orogen which could have provided topographic relief for the initiation of gravity-driven fluid systems. In the light of these data such gravity-driven fluid flow models appear to be inappropriate to explain the formation of MVT and related Zn-Pb deposits in Western Europe.