© ICDP, the International Continental Scientific Drilling Program, 1996-2021

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Origin of vein-type ore deposits

Europe, Germany, Saxony, Erzgebirge, Schneeberg

new workshop-proposal: ICDP-2014/14
for the funding-period starting 2014-01-15
by Jens Gutzmer, Nigel C. Cook, Thomas Seifert, David Banks, Reiner Klemd
Abstract
We propose to organize an international ICDP Workshop to form an international science team to sharp the rationale and the expected scientific achievements of a project that aims at studying the sources and the origin of metalliferous vein-type ore deposits in the Erzgebirge (nominated as UNESCO World Heritage site), a metallogenic province of worldwide importance with a 850 years-long ancient to modern mining history (with Ag, Sn and U as economically most important metals). The proposal is directed at recovering additional drillcore material from several larger (decameter-sized) mineralized vein structures that are predicted (from state-of-the-art 3D and 2D seismic surveys) to get exposed between 2 and 4.5 kilometers depth during the drilling of a 5-km-deep geothermal borehole (Schneeberg 1) planned to be used for electricity production. The drilling will be performed in the western Erzgebirge of Germany within a deep reaching major fault zone (Gera-Jachymov Fault Zone); an area, which geologically is characterized by low-grade metamorphic rocks that are intruded by late-Variscan crustal granites, mantle-derived lamprophyre veins, and a great diversity of late-magmatic to post-magmatic ore veins of Sn-W-Mo-Pb-Zn-Ag-In-Cu-U-Fe-Se-F-Ba-Bi-Co-Ni -As. These veins formed episodically during four major episodes of lithosphere restructuring in the Carboniferous (collapse of the Variscan orogen), Permian (Gondwana breakup), Jurassic (Atlantic opening), and Cretaceous (collision between the Eurasian and African plates), respectively. The veins that constitute the focus of the project may be complexly mineralized (as evidenced by shallow subsurface exposures), i.e., bear ore associations related to two or more ore-forming events. Additionally to the presence of ore veins, the seismic soundings imply the occurrence of a yet unknown body to which the ore-bearing structures lead to (and which might represent one of the long searched types of source rocks for the generation of hydrothermal vein-type ore deposits in crystalline rocks), and the marginal portion of which will also get penetrated by the drilling. Beneficial to the proposed project are: several decades of modern research on the geology of ore veins and associated granitic-lamprophyric rocks, hundreds of years of well documented underground mining, and extensive superficial and shallow underground exposures. Together with samples from diverse collections and drill cuttings, which are monitored and sampled over the entire length of the drilling, the drillcore sections will provide a comprehensive insight into the origination of a complexly mineralized basement unit of both crustal and mantle input and, thus, will improve existing metallogenetic models. A better understanding of the processes of ore formation would help securing the supply of some of the critical metals the world is concerned about by promoting ore-exploration strategies.
Scientific Objectives
  • The Erzgebirge region is particularly suited for the study of ore-forming processes because of the great diversity of types of ore deposits that were formed in close proximity within a small area over a time span of more than 200 Ma. The major scientific objective in studying drill cores from the area is gaining an improved and comprehensive understanding of the complexity of processes that gave rise to the formation of diverse types of vein-type ore deposits (in particular W-Mo, Pb-Zn-Ag, U-Se, Bi-Co-Ni), which worldwide have a great economic importance as metal raw materials. The major open questions that need to be particularly addressed are: the role of crustal rocks (granites) and mantle rocks (lamprophyres) as element and heat source in the origin of spatially and temporally associated metal deposits, the importance of granites as source of ore metals multiply deposited in veins after magma solidification, the physicochemical conditions that have governed the precipitation of ore minerals, the nature and origin of fluids that have transported the elements during the various metallogenic episodes, the depth extent of mineralized zones (as essential factor in ore exploration), and the origin and compositional evolution of multiphase HHP granite plutons that served as source for world-class U deposits.
  • To achieve the scientific goals, several drill core sections from various depths encompassing the mineralized veins and their granitic country rock are mandatory.
Keywords
Crust-mantle processes, Drill core, Erzgebirge, Europe, Germany, ICDP-2014/14, Metals and fluids, Ore genesis, Saxony, Schneeberg
Location
Europe, Germany, Saxony, Erzgebirge, Schneeberg: 50.60000, 12.65000

© ICDP, the International Continental Scientific Drilling Program, 1996-2021

www.icdp-online.org