WISTAMERZ Prognose wirtschaftsstrategischer
Hochtechnologiemetalle am Beispiel
des Erzgebirges
FKZ: 033R133A

1. Project Objectives

The objective of the project WISTAMERZ is the development and test of new approaches for prospectivity evaluation of large territories. The project focuses on rare and technology metals as Ga, Ge, In, Li, Sb, Se, Sn, Ta, Te, W and the area of the famous Erzgebirge. Based on a combination of new data, their integration with existing data, the development of new metallogenic models and the implementation of new data processing technologies (i.e. artificial neural networks and other data and knowledge driven approaches) the project is aiming a new level of data integration and prediction accuracy. Existing metallogenic models are reviewed regarding their general viability, metallic components and extension in space and time. Finally, the new knowledge is summarized in a new metallogenic map incl. the delineation of exploration targets. 

The project was funded by the Federal Ministry of Education and Science in the frame of the program „r4 – Innovative Technologien für Ressourceneffizienz – Forschung zur Bereitstellung wirtschaftsstrategischer Rohstoffe“ (FKZ: 033R133A).

2. Relation to research and development targets

The project WISTAMERZ is a part of the research projects “Strategic Minerals for the high-tech location Germany“, which was published in October 2012 in frame program “Research for sustainable development (FONA)”(https://www.fona.de/) focusing on non-energetic minerals as rare and high-tech metals, required for future technologies. In detail, WISTAMERZ contributes to the topic 2.1.b „Exploitation of primary minerals” published on 17th July, 2013.

The following concrete project requirements were set:

  • Development of concepts for the exploration of primary minerals,
  • Development of new approaches for prospecting the national mineral potential (e.g. remote sensing, geophysics, geochemistry and mineralogy),
  • Re-evaluation of known mineral deposits,
  • Development of 4D metallogenic models,
  • Reinterpretation of existing datasets and creation of new mineralogical, geochemical, and geochronological data,
  • Interpretation of mineral deposit genesis and development of new exploration concepts for unknown mineral occurrences

3. Situation in 2013

Because of the strong development of new technologies and the related rising demand for rare and high-tech metals in the 2000 years, Europe and Germany were facing dramatically changing frame conditions regarding the supply chain with the respective metals. These new frame conditions led to several political decisions, as:

  • Coalition contract CDU/CSU, SPD for the legislation period 2013-2017,
  • European Commission (2008): “The raw materials initiative – meeting our critical needs for growth and jobs in Europe”,
  • European Commission (2011): “Tackling the challenges in commodity markets and on raw materials”,
  • European Commission (2010): “Critical raw materials for the EU”.

 

The situation of the last years is marked by an extreme volatility of prices and mineral availability, as well as the utilization of national monopoly postions for securing strategic and political advantages. This situation led to the shortage of metals, political interferences into supply chains, and many more negative effects.

In this environment, the increased usage of national minerals became an important option to provide the national economies with minerals. Unfortunately, the respective knowledge, especially with regard to rare and high-tech metals is very low, as these metals did not have much importance in the past. The understanding of their geochemistry and metallogeny is rather insufficient, and consequently, a profound prospectivity evaluation is impossible.

The generation of new empiric knowledge about the rare and high-tech metals is necessary for the development of new metallogenic concepts and related mineral potential evaluations and exploration strategies. 

The Erzgebirge, known for a high density of occurrences of the metals Ag, Cu, Fe, Li, Pb, Sn, U, W, Zn, fluorite and barite, has obviously a high potential for the occurrence of rare and technology metals.

Location of Sn, W, fluorite occurrences in the Erzgebirge

There is a big amount of exploration data about the traditional metals Sn, W, Pb, Zn from the period 1945 – 1990. This data consists of reports, maps, drilling logs and a big amount of various primary data. It is mostly not published. The biggest archive is located at the Saxon Geological Survey in Freiberg (LfULG). Another big host of archive data is the Wismut GmbH (the former east German Uranium producer).

4. The Geochemical Atlas

The newly created geochemical stream sediment datasets considerable contribute to the extension of our empirical knowledge about the Erzgebirge. Together with the new geological 3D data they allow a profound evaluation regarding new mineralisation types and concealed mineral occurrences.

The new stream sediment maps (www.rohstoffe-erzgebirge.de) have been compiled using the following technology:

  • identification of small surface water catchment areas of 1 – 2 km2 size throughout the investigation area,
  • sampling of the recent sediments of dry or water bearing streams at the exit point of each catchment,
  • on-site screening of a sample < 2 mm,
  • investigation of the fraction < 0,18 mm at ALS laboratories using the method MEMS-41 (Ultra trace Aqua Regia ICP-MS: all elements), and ME-XRF 05 (trace level XRF analysis auf Sn, W), and Au ICP22 (50 g FA ICP-AES finish auf Au), (see https://www.alsglobal.com/).
Stream sediment sampling: screening of the fraction < 2mm

The stream sediment data have been processed as follows:

  • relation of the sample points to catchment areas,
  • Positioning of the sample point at the center of the catchment area,
  • logarithm the values to the base 10,
  • inverse distance interpolation of 25 m grids,
  • further smoothing using Moving Average by Focal Statistics
Processing of stream sediment data
  • Creation of mono-element maps together with important geological and mineral information
Geochemical map of the element Indium

5. The Information System

The project information system is a customized advangeo® Software Solution. It is based on commercial software:

  • Microsoft SQL-Server database for the data server,
  • advangeo® Field Cap (MySQL) for mobile field data capture,
  • Esri ArcGIS 10.7.

Data base structure and interfaces have been adapted to the project using Beak´s advangeo® Software Products.

Database user interface
  • The mineral occurrence database is populated with the various data, including mineral occurrence name, coordinates, size, genetic type, shape, age, etc. Data is completed by information about mining activities (mined minerals, grades, operational periods, mining methods, ….  )Field data was captured using advangeo® field cap software in combination with a Panasonic tablet computer.
advangeo® Field Cap user interface
  • In order to avoid loss of data field work data was consequently uploaded to server.Further, the analytical results have been linked with the field data, and the GIS was created. 
GIS-component of the information system

A simplified version of the data is published on this web site. The data of the interactive map is continuously completed with data from other projects.

Interactive map of the information system WISTAMERZ

6. The Metallogenic Map of the Erzgebirge/ Vogtland area

The Metallogenic Map of the Erzgebirge/ Vogtland area summarizes the pre-existing knowledge together with new data and knowledge gained in the projects Wistamerz, NEXT, and GEM and will be completed and upgraded further. It is accompanied by the Geochemical Atlas.

The Metallogenic Map was compiled in the following steps:

  • Creation of the data technological concept
  • The map is produced as a hard copy of the current information system
  • The map can easily be upgraded if the data in the information system changes
  • The map represents the knowledge at the time of its production
  • Creation of the geoscientific concept
  • Synopsis of the spatial and temporal geological evolution
  • Creation of the respective links with the mineral forming processes
The metallogenic section – a general presentation of the spatial relationships between mineralisations and their geological environment
    • Presentation of important facts: geology, geochemistry, tectonics, minerals
    • Presentation of the temporal succession of the various mineralisations
    • Presentation of important metallotects
    • Presentation of prospective areas
    • Creation of the cartographic concept:
    • Clarity of the map,
    • Easy to read and understand,
    • Illustration by impressive schemes,
    • Presentation of both data and their interpretation.
Metallogenic Map of the Erzgebirge and Vogtland

7. Selected metallogenic aspects 

The identification and description of a wide spread meta-sediment hosted stratiform mineralisation type belongs to the main results of the project WISTAMERZ. This mineralisation type is characterized by a wide lateral extension with strongly varying metal composition: +/-Sn, +/- W, +/-Bi, +/-Cu, +/- Co, +/-Sb, +/- Au.

These obviously initially syn-sedimentary formations of various origin provided the initial metallogenic footprint to the entire area. They are the base for the wide variety of the metal composition and genetic types of mineralisations found in the Erzgebirge. Depending on the lithological / facial framework, the availability of metals, type of metamorphose, tectonics and nappe formation, the wide variety of mineralisations have been formed, ranking from massive sulfides, disseminated cassiterite and/or sulfides in phyllites, quartzites and biotite schists, and metal bearing calc-silicate rocks. The Sn mineralisations of Amtsberg (Phyllites) and Aue-Bockau were almost not known till now. They have been randomly mined in the past.

The mineral potential of the submarine metamorphosed and metamorphogenic mineralisations was seriously overprinted and increased by the intrusion of granites during the late orogeny. Contact-metamorphic overprinting and redistribution of metals formed the rich Sn and W skarns of the Westerzgebirge (z.B. Tellerhäuser, Pöhla-Globenstein). The schist and sear zone hosted metals have been assimilated by intruding granites and redistributed in their environment forming the well-known greisen and vein deposits. The related Sn-deposits like Altenberg, Sosa, Zinnwald, Ehrenfriedersdorf were mined for centuries. The intrusion of the latest porphyry like stocks led to the formation of large metal enrichments in breccias pipes (Gottesberg, Seiffen).

Cassiterite related to a quarz seggregation in chlorite schist, Amtsberg
Cassiterite in biotite schist (Bockau): left – polished section, right - µXRF image (Tornado-scan, recorded by BGR)

The zone with stratiform metal enrichments stretches over a distance of more than 140 km from WSW till ENE throughout the Erzgebirge. It is interrupted by several strongly specialised granite intrusions with a high metallogenic potential (plutons of the Western Erzgebirge, Central Erzgebirge and Northern Erzgebirge).

Metallogenic Map of the Erzgebirge / Vogtland: Metallotect of the Lower Paleozoic metalliferous metasediments (green outline)

8. The Metallogenic History

8.1 Overview

The current metallogenic situation is a result of long lasting of a time period of at least 450 M years. The today known mineral occurrences have been formed in polygenetic processes starting with initial syn-sedimentary metal enrichments and their later re-location, re-formation by various processes. Probably, already in the cadomian basement there are stratiform metalliferous formation which are hard to identify. The key metallogenic event was the formation of submarine metal bearing sludges and sulfidic enrichments of different genesis in the lower Paleozoic sediments. During the later metamorphism and tectonic overprinting (nappe formation) the metals were re-distributed, relocated and formed different minerals. This complex situation was further modified and overprinted by granitic intrusions with their strong heat and fluid sources, assimilating the metalliferous schists and forming the known greisens and veins, followed by a gradually decreasing tectonic and thermal activity. After a long period of tectonic silence, the last re-activitation in Upper Mesozoic/ Lower Cenozoic again reactivated the existing environment and formed the latest stages of metalliferous hydrothermal veins in lithological and geochemical traps.

8.2 the Cadomian Basement: 580 – 510 M years

Metallogenic stage of development - Cadomian basement

During the late Proterozoic and the Cambrian, turbiditic sediments with intercalations of carbonates, contemporarily intruded by granodioritic batholiths, form an active continental margin of Northern Gondwana. Carbon bearing layers in metasediments act as geochemical traps in later stages. Possibly accumulation of Fe, As, Sb, Ag, ±Au in sedimentary strata.

8.3 Der passive Kontinentalrand: 470 – 360 Mio Jahre

Metallogenic stage of development - passive continental margin

From the Ordovician to the Devonian, extensive plate-reorganization due to back-arc rifting form passive continental margins with sequences of turbiditic sediments with intercalations of carbonates, quartz sandstones and conglomerates. Bimodal volcanism and hydrothermal activity with metal bearing mounds and mud were interbedded with the sediments. Main metals are Fe, Zn, Cu, Sn, W, Co, Bi, Sb, Ag, and Au.

8.4 Variscan Orogeny: 340 – 330 M years

The Gondwana-Laurussia collision results in the Variscan orogeny. Peak metamorphic conditions (UHP) occurred around 340 Ma. At about 330 Ma, the orogenic collapse and exhumation of the subduction-accretionary complex led to the recently observed configuration of the nappe pile. Metal bearing mounds and muds form various stratiform mineralisations including sulfide seams, metamorphic skarns and similar metal-enriched formations. The redistribution of Hg, Sb, Au, As and Ag in different parts of the nappe pile depends on the specific metamorphic P-T conditions.

8.5 Late Orogenic Stage: 325 – 290 (?) M years

Metallogenic stage of development - late orogen

The main intrusion phase of the Variscan Granites lasts from 325 to 315 Ma, Minor extensive magmatic events occurred until 290 Ma. Rising fluid rich granitic melts assimilate metal bearing metasediments and redistribute the metal content. Sn, Li and W are enriched in suitable structures of apical parts of intrusions, volcanic pipes, breccias and fault zones, partly with a rich polymetallic component (Cu, Sb, Bi, Co, Au, In). Hydrothermal-metasomatic processes overprint preexisting stratiform deposits producing further enrichments in suitable lithologies. Hydrothermal-metasomatic processes overprint preexisting stratiform deposits producing further enrichments in suitable lithologies.

8.6 Transition and Platform Stage: 290 – 70 Mio Jahre

During the Permian to Cretaceous, fault zones with dominant NW-SE strike dissect the Erzgebirge/Vogtland into several tectonic blocks. Concurrent with the tectonic activities, heat domes produce several generations of metalliferous hydrothermal systems (e.g. fluorite, U, As, Sn, Cu, Pb, Zn, Au, Ag, relocating metals and minerals from former deposits into vein structures and seams using suitable lithologies as geochemical traps. Decreasing tectonic and thermal activities lead towards a slow cessation of endogenic activities in the upper Permian (257 Ma). In the Cenomanian to Turonian the area is partially covered by fluvial and shallow marine deposits hosting modest tin and gold placers.

8.7 Riftogenic Stage: 70 – 0 M years

Metallogenetic development stage - rift stage

The formation of the Eger rift above a mantle plume began with the intrusion of ultramafic alkaline dikes, followed by extensive volcanism (30 Ma). Small volumes of mafic and alkaline volcanics are emplaced throughout the Erzgebirge/ Vogtland area in dykes, pipes and maars. Faults were reactivated; heat domes led to continued mineralisation processes in mostly pre-existing tectonic structures (e.g. barite and fluorite veins, U, Co, Ni, Ag, As, Bi veins).

9. Delineation of mineral target areas

During the project WISTAMERZ the high mineral potential of the Lower Paleozoic sediments was recognized (Sn, W, Cu, Co, Bi, Sb, Au). Related prospective areas can be delineated for different genetic types and metals even under cover North of the Erzgebirge if the related metallogenic indications are known and present. The results of the stream sediment survey provide a strong contribution.

Rare and high-tech metals are often related to occurrences of other metals. They do not occur in separate occurrences. The respective prospecting strategy can be described as follows:

  • identification of sites with anomalies of Fe, Zn, Sn, W, Cu, Pb, Ag,
  • in combination with Bi, Sb, Se, Li, In.

As we can assume that all outcrops of usable mineralisation types have been identified in the past, the following situations are of interest:  

  • small outcropping mineralisations of the historically known types with unknown depth of mineralisation. (e.g. Greisen in the Eibenstock Granite, Sn-Sulfid-veins in the Osterzgebirge),
  • mineralisation types, which have not been considered in the past (tin- and sulfide layers in metasediments and mineralised shear zones),
  • mineralisation types, which have been considered as non-promissing in the past because of obsolet metallogenic models (e.g. Greisen bodies in large granite intrusives),
  • Mineralisation types, which are quickly weathering and therefore do not form prominent morphological forms (e.g. Sn and sulfide layers in metasediments and shear zones),
  • areas on top of deeply concealed intrusives within the limits of the currently known metalllotects (e.g. Northern Rim of the Erzgebirge).

 

The delineation of the prospective area was executed by using artificial neural networks implemented in advangeo® Prediction Software. The respective workflow is presented in the following image:

Workflow of the KNN-based raw material forecast calculations

Mineral predictive mapping focuses on the identification of areas prone to the occurrence/ presence of certain mineralisation types already known in the area or in a similar geological environment. In this sense, the known mineralisation points represent the depending variable, which presence is controlled by various metallogenic factors, as well as geochemical and geophysical indications. These factors and indications (the controlling parameters) can be used to identify still unknown mineral prospective areas. An artificial neural network (ANN) is used to analyse and recognise the relationships between the depending variable and the many controlling parameters. Once trained, the ANN can apply its knowledge to a larger survey area producing predictive maps, forecasting the presence of the mineralisation type under question.

Raw material potential map for lithologically controlled Sn and the corresponding accompanying components

Lithologically controlled Sn mineralisations contain mainly the following accompanying elements:  Fe, Zn, In, Ag, W. They are widely known in the Erzgebirge and stretch over the hidden intrusive of the Northern Erzgebirge rim from the Western Erzgebirge till the area North of Freiberg. Possibly, the so called Felsit – Formation is somehow bound to theses formations.

Lithologically controlled Sn mineralisations contain mainly the following genetic types:  Greisen (e.g. in Aplite- and Porphyre dykes, colcanic and breccia pipes, veins). They are bound mainly to the roofs of large and small intrusives. Their mineral potential can be very significant (e.g. Gottesberg) and they may contain a wide variety of metals, incl. Cu, Bi, Pb, Zn, Ag, Sb, In).

The location of fluorite deposits is controlled exclusively by tectonic structures. The respective mineralisations are bound almost exclusively to NW-SE striking fault zones.

10. The rare and strategic metal potential of the Erzgebirge

The statistical properties of the chemical elements indicate significant differences between the arithmetic mean and the median values.

Comparison of median / arithmetic mean of the sediment geochemistry (4800 samples)

Chemical elements with a ratio arithmetic mean/ median > 1.5 like W, Bi, Sn, Au, Ag, In, U, As, Rb, Cs, Cd, Sb, Mo, Ba, Hg obviously possess the highest mineral occurrence forming potential, while elements having a ratio of close to 1 do not possess a mineral deposit forming potential at all, as G, Ge, REE.

The consideration of the identified high absolute values of Bi, In, Li, Sb and their strong relations to elements as Fe, Zn, Sn, W underline their high mineral deposit forming potential. The respective mineral deposits can be found in very different genetic types: from greisens, quartz veins, till polymetallic veins, in stratiform metamorphogene, metamorphosed contact-metasomatic and shear zone related formations.

The geochemical properties of Ta show its metallogenic relevance in selected Sn-Li deposits of the Eastern Erzgebirge.

There is no potential for the occurrence of economic mineralisations of the metals Ga, Ge and REE.

Large deposits of the metals Sn, W, In, Cu, Co, Bi, Sb, Au are expected in stratiform bodies and large stockworks. 

The resource potential of the comparable small and easy to process hydrothermal vein deposits is obviously low. These mineralisations have been mined intensively in the past. They are mined out in their upper parts.

11. Publications

Based on the project WISTAMERZ many publications have been generated. This are for instance the metallogenic map, the geochemical atlas,  various thesis studies, scientific articles, presentations and posters. All publications are available at www.wistamerz.de. Here, the interactive GIS presents spatial data as well.

12. Prospects

Beak Consultants GmbH develops further new exploration technologies in the frame of other commercial and research projects. The aim is the development of technologies for clear identification of concealed mineralisations as drilling targets.

These projects are developed currently within the H2020 project NEXT (New Exploration Technologies), the EIT Raw Materials Project MAP (Mineral Assessment Platform), and the ERA-MIN Project LIGHTS (Lightweight Integrated Ground and Airborne Hyperspectral Topological Solution).

13. Co-operation

Beak Consultants GmbH offers a strong and fruitful co-operation to all interested parties from science, technology and industry. With great pleasure we support our partners in their prospecting/ exploration programs

14.Use of data and project results

The presented data are available as pdf or in the interactive GIS for free use.

With great pleasure we print for you a 1:1 copy of the Metallogenic Map (1,4m x 1,10 m) on high quality Photopaper. The cost will be 100 EUR + VAT.

 

The ISBN – Numbers of the main WISTAMERZ products are:

978-3-982091-60-0

 

Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) Metallogenic Map of the Erzgebirge/ Vogtland Area
978-3-948423-00-1 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Indium in stream sediments –
978-3-948423-01-8 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Silver in stream sediments –
978-3-948423-02-5 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Arsenic in stream sediments –
978-3-948423-03-2 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Gold in stream sediments –
978-3-948423-04-9 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Tin in stream sediments –
978-3-948423-05-6 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Barium in stream sediments –
978-3-948423-06-3 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Beryllium in stream sediments –
978-3-948423-07-0 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Bismuth in stream sediments –
978-3-948423-08-7 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Cadmium in stream sediments –
978-3-948423-09-4 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Cobalt in stream sediments –
978-3-948423-10-0 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Caesium in stream sediments –
978-3-948423-11-7 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Copper in stream sediments –
978-3-948423-12-4 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Gallium in stream sediments –
978-3-948423-13-1 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Germanium in stream sediments –
978-3-948423-14-8 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Mercury in stream sediments –
978-3-948423-15-5 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Lanthanum in stream sediments –
978-3-948423-16-2 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Lithium in stream sediments –
978-3-948423-17-9 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Tungsten in stream sediments –
978-3-948423-18-6 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Molybdenum in stream sediments –
978-3-948423-19-3 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Niobium in stream sediments –
978-3-948423-20-9 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Nickel in stream sediments –
978-3-948423-21-6 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Lead in stream sediments –
978-3-948423-22-3 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Rubidium in stream sediments –
978-3-948423-23-0 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Antimony in stream sediments –
978-3-948423-24-7 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Selenium in stream sediments –
978-3-948423-25-4 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Tellurium in stream sediments –
978-3-948423-26-1 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Thorium in stream sediments –
978-3-948423-27-8 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Titanium in stream sediments –
978-3-948423-28-5 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Thallium in stream sediments –
978-3-948423-29-2 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Uranium in stream sediments –
978-3-948423-30-8 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Zinc in stream sediments –
978-3-948423-31-5 Project: Prediction of Strategic High Technology Metals in the Erzgebirge (WISTAMERZ) – Zirconium in stream sediments –
Menu