Tadeusz Galkiewicz, 1967. "Genesis of Silesian-Cracovian Zinc-Lead Deposits", Genesis of Stratiform Lead-Zinc-Barite-Fluorite Deposits (Mississippi Valley Type Deposits), J.S. Brown
Download citation file:
The following evidence is presented in support of the hydrothermal origin of the Silesian-Cracovian zinc-lead deposits: the ore mineralization interval in the Devonian-Jurassic strata, the relation between mineralization and the WNW dislocations, the great variability in form and content of the ore bodies, characteristic ore textures, vertical zonality of mineralization, large aureoles or haloes of poor mineralization surrounding the ore bodies, distinct differences in the physico-chemical conditions of the origin of the ore mineralization and of wall rocks, the temperature of sphalerite formation up to 120° C, and the isotopic composition of lead. It follows from the metallogenic analysis that there most probably is a relation between these deposits, the basic-alkaline magmatism of the stabile zone of the Alpine cycle, and the great lineaments. It seems less probable that these deposits originated from parahydrothermal solutions or that there is a genetic relationship between them and the magmatism of the mobile zone. The Silesian-Cracovian and Rhineland ore deposits are situated on the opposite ends of a latitudinally elongated belt of basic-alkaline magmatic rocks and on the intersection with other large perpendicular dislocations. It is possible to distinguish two groups of zinc-lead deposits in carbonate rocks: one connected with the stabile, the other with the mobile zone.
Figures & Tables
Genesis of Stratiform Lead-Zinc-Barite-Fluorite Deposits (Mississippi Valley Type Deposits)
Proponents of syngenetic theory base their interpretation largely on widespread uniform mineralization within a restricted stratigraphic interval and a consistent relationship of mineralization to sedimentary features. Proponents of epigenetic theory base their interpretation on mineralization of post-depositional structures, changes in extent and grade of ore, open space filling, district-wide lack of close control by sedimentary features, and relation of ore to tectonic structures. These and other criteria are evaluated in an attempt to define diagnostic criteria.
On the basis of the criteria defined the major lead-zinc deposits of Mid-continent United States must be considered as epigenetic.
Features of the Southeast Missouri lead district are listed. The deposits are epigenetic. The metals are believed to have been derived from nearby sedimentary basins and carried out of basins onto shelf areas in a concentrated brine. Movement of solutions was controlled by basement topography and deposition of metals occurred when solutions entered the Bonneterre formation on the flanks of and over buried knobs.
Objective.—The problem of origin of stratiform ore bodies cannot be resolved until we define, and agree upon, what constitutes diagnostic evidence for each type of deposit. This paper is an attempt to review the nature of geologic evidence; to define those features that must be regarded as unique and necessary criteria in classifying any deposit or district; and to apply the criteria to a major district, the Southeast Missouri lead deposits.
Theories of Origin.—The major elements of theories on origin of stratiform ore bodies are summarized in Table 1. A deposit is Syngcnetic if formed by processes similar to and simultaneously with the enclosing rock; epigenetic if introduced into a pre-existing rock (3). A diagenetic origin implies deposition of metals with the host sediments but with recrystallization, rearrangement, and limited migration.
The search for an acceptable theory of origin must be separated into its two component parts: (1) definition of whether the deposit has syngenetic, diagenetic, or epigenetic features and. (2) history of mineralization to explain source, transport, and deposition of metals. A statement of preferred hypothesis is meaningless until the first is answered and accounts for all geologic facts. The answer must be based solely on observed megascopic and microscopic features and on geochemical and isotopic data; it should not be biased by lack of knowledge to answer all phases of the second. In evaluating the evidence to determine type of deposit one cannot be concerned