DILL, H.G. (1994): Facies variation and mineralization in Central Europe from the late Paleozoic through the Cenozoic.- Economic Geology, 89: 42-61.
A b s t r a c t After the Variscan orogeny, from the Upper Carboniferous to the Quaternary syn(dia)genetic and epigenetic mineralization occurred in the Mid-European Basin. The U (e.g. Müllenbach, St. Hippolyte, Freital, Stockheim), base metal (e.g. Freihung, Nova Ruda, "Bleiglanzbank"), Sr-F-Ba (e.g. Süntel, Deister Hills), Fe-Mn (e.g. Salzgitter, Auerbach, Lindener Mark, "Minette" ore in Lorraine and Luxembourg) and Au-Sn placer deposits (e.g. Fichtelgebirge) are stratabound within clastic, volcaniclastic and calcareous rocks. Some vein-type and vein-like mineralization of post-Variscan age is found in the uplifted basement blocks, and is spatially related to the late Variscan and late Alpine unconformities (e.g. Sauerland).
Post-Variscan mineralization may be subdivided into 7 types with respect to the deposited environment of their host rocks: (1) saprolite/peneplain (Cu, Pb, Zn, F, Ba, Fe, Mn) (2) alluvial fan (Fe, Sn, Au, U, Pb, Zn, F, Ba), (3) braided streams/bed load fluvial systems (Pb, Zn, U, F, Ba), (4) meandering to anastomosing streams/mixed load fluvial systems (U, Pb, Cu), (5) high energy shore zone of lake margins or coastal regions (Fe, Pb, Cu, U), (6) low energy lake centres or near-shore marine deposits (lagoons) (Fe, Pb, Zn, Cu, U), (7) mixed terrigenous calcareous shelf deposits (F, Sr, Zn, Pb).
There were various sources of metals for the stratabound mineralization. During the Late Paleozoic and Lower Triassic the metals were supplied from volcanites and volcaniclastic rocks of calc-alkaline affiliation (volcanic arc (?)). The Cu-Pb-Zn mining districts in the "Kupferschiefer" are located above or close to a suture zone that delineates a former active plate margin with endogenous Cu-Mo porphyry deposits (e.g. Miedziana Gora, Zawierce). To follow down the stratigraphic column in the footwall of the "Kupferschiefer" the elements increase in the reverse order, as they were enriched in the "Kupferschiefer". From the Lower Triassic to the Upper Jurassic metamorphic and granitic rocks in the Variscan basement highs became exposed to chemical weathering and acted as metal source. The denudation of the Variscan basement is mirrored by the element spectrum of the Triassic stratabound deposits, commencing with Pb/Zn deposits, e.g., Upper Silesia (gneisses) and leading to U deposits, e.g., Burgsandstein (granites). From the Lower Cretaceous onwards some of the metals in the mineralization were derived from the basement. Most of the mineralization, however, originated from intrabasinal/intra-Mesozoic redeposition (e.g. ironstones).
Five "metallogenetic sequences" may be delineated, four of which start with mineralization in the fluvial environment and terminate with precipitation of Sr and F in a mixed clastic-carbonate shelf environment (sabkha). Metallogenetic sequences reflect marine transgression and regression, which may be correlated with different rifting and spreading stages in the Atlantic ocean.
Two major unconformities, one caused by the late Variscan uplift, the other by Subhercynian and Laramide movements may be traced across the basin. Supergene (e.g. U/ Rudolphstein, Mn-Fe/ Hunsrueck-type) and hypogene (e.g. Pb-Zn) mineralization (e.g. Maubach-Mechernich) are directly related to these first-order geohydraulic planes. Minor unconformities and erosional surfaces also influenced the development of host environments of stratabound ore deposits and the termination of "metallogenetic sequences". Low-relief erosional surfaces favoured restricted water circulation and resulted in the formation of transgressive black shales (e.g. Kupferschiefer). The development of a sabkha and its related mineral deposits also requires the presence of a low topography as well as an arid climate and resultant strong evapotranspiration. Karstification, essential to the Mid-European MVT deposits, commenced more or less contemporaneously with the evolution of tidal flats on these erosional surfaces in the supratidal zone and persisted until the hydrology was changed by a new transgression. Vein-type mineralization related to these unconformities was at least in part supplied by sulfur and strontium from sabkha-derived evaporites, as suggested by Sr and S-isotope analyses.
It is difficult to define the time of formation of the post-Variscan ore mineralization, except for syngenetic Fe-Mn, U ores (Tertiary) as well as Fe-(Cretaceous) and Sn-placers (Quaternary). The bulk of stratabound ore mineralization in the Mid-European Basin formed by diagenetic and epigenetic processes. The few age data and some evidence from basin subsidence suggest that there were two intervals of diagenetic and/or epigenetic ore mineralization. The period from Lower Triassic to Upper Dogger correlates with the early rifting in the central parts of the Atlantic ocean. Another set of data which derived from U-F deposits in the upper Cretaceous and MVT deposits attests to a thermal and fluid influx from deep-seated rifts (Rhine Graben, Ohre Rift) during Late Tertiary.