Stříbro and Planá-Michalovi hory ore district (Western Czechia)

One day field trip to Western Czechia was held on 18th May 2015. vozíky u štoly Prokop, Stříbro

Twelve students led by Mgr. Jan Bubal visited Open-Air museum in Stříbro with visiting of gallery Prokop and near ore heap (Pb-Zn mineralization).

Close to Stříbro, we also looked at the Vlčí hora Mnt. consist by tertiary basalts and pyroclastics with large phenocrysts of augite and amphibole. 

ore heap near Stříbro
In following area Planá-Michalovi hory ore district we saw some old open pits with Pb-Cu-Ni-Co mineralization.

For more photos click here.

 

 

Volcanic-hosted massive sulfide deposits from the Portuguese part of the Iberian Pyrite Belt

Our chapter organized its first field trip in 2015 (21.-27. April) to the Portuguese part of the world-class metallogenic province – the Iberian Pyrite Belt. This province is situated at the SW of the Iberian Peninsula extending from Seville in Spain to the south of Lisbon in Portugal. DSC_0668.This district has a long and rich mining history – from the pre-Roman times to present and is also known for an extraordinary density of the giant volcanic-hosted massive sulfide deposits (VHMS). DSC_0722This VHMS belt contains more than 85 massive sulfide deposits with total mass exceeding 1600 Mt of massive ore to which more than 2000 Mt of low-grade stockwork mineralization should be added. The mineralization is distributed between eight supergiant and a significant number of other smaller deposits. During the last hundred years approximately 80 mines have been operating. In total they produced ~ 300 million tons of polymetallic ores (Pb, Zn, Cu, Au, Ag, Sn), although sulfur and copper have been the main commodities processed in most cases.

No more for ore

no more for ore

The main attraction of this field-trip was the underground visit of the active mine Neves-Corvo (SOMINCOR company) – Cu-Sn-Zn ores. We have also visited the Lousal (S-Cu ores) closed mine with its wonderful science center, old open pit Sao Domingos (Au-Ag-Cu ores), which was mined for copper and gold since the roman times and several other localities in the field. Not mentioning the beautiful city Lisbon and its surroundings.

The 5 students participated in this 7-days field-trip, which was led by professor Jorge Relvas.

SGA News No 38 page 30

For more photos click here.

Vertical zoning of tin granite plutons in light of modern analytical methods

Czech Academy of Science, Institute of Geology, v.v.i., Praha Czech Science Foundation project No. P210/14/13600S
in collaboration with the SGA Prague Student Chapter

First announcement of international workshop

Vertical zoning of tin granite plutons in light of modern analytical methods

A 1596 m long fully-cored borehole CS-1 was realized in 1961-1963 in the Cínovec/Zinnwald granite cupola, Krušné Hory/Erzgebirge, Czech Republic. For more than 50 years this borehole represents one of the most inspiring sources of our knowledge about evolution of rare-metal granite plutons through the world.

Vertical zoning of the Cínovec cupola involving albite-lepidolite, albite-zinnwaldite, and albite-biotite granites combined with microgranites, feldspathites, greisens, and flat quartz veins gives an excellent opportunity for the study of magmatic/hydrothermal evolution of Sn- W-Nb-Ta-Li-bearing system and formulation of genetic models.

Rapid development of microanalytical methods in two last decades, electron microprobe and laser-ablation ICP-MS analyses, provides new, high precision chemical and mineralogical data. Back-scattered electron and cathodoluminescence imaging enable objective study of rock- and mineral textures. New data support formulation of more presumable genetic models.

Mining of tin and later also tungsten ores operating in Cínovec from the 16. century was interrupted in 1991. At present, some attempts for re-opening of the mine are going on. So the theoretical models may be immediately used in praxis.

Within the frame of Czech Science Foundation project No. P210/14/13600S we acquire principally new data about whole-rock and mineral changes along the borehole CS-1. In order to present these data, provoke discussion about the most plausible evolutionary model of this granite and deposit, and compare this object with other rare-metal granites worldwide, we organize two-day workshop connected with excursion to old tin mines in Krupka (Bohemia) and Zinnwald (Saxony).

Scope of the workshop: Vertical zoning of tin granite plutons in light of modern analytical methods

Place: Institute of Geology, Praha Time: 6.-7. October 2015 Tentative program:

  • Detail information about actual investigation of the Cínovec granite system
  • Contribution of other participants
  • Discussion about granite-related rare-metal deposits
  • Excursion to Krupka and Zinnwald

Contributions to all aspect of utilization of state-of-art methods in investigation of rare- metal granites are welcomed.

In case of your interest to attend this workshop, please contact us for further information.

Contact person: Karel Breiter, E-mail: breiter@gli.cas.cz

Diverse mineralization styles and ore-forming processes in the Krušné hory/ Erzgebirge Mts.

Our Chapter organized its last field trip in 2014 (7.-9. November) to investigate various mineralization styles and mining activities in the Krušné hory/Erzgebirge Mts., the mountain region spanning the border between the Czech Republic and Germany.
14-11-SGA_erz (66)
IMG_0472The main attractions of the field trip were underground visits to:            –the historical mines of Krupka (hydrothermal Mo-W vein mineralization)    –Markus-Röhling-Stolln in WiesaSchönfeld (Ag-Co mineralization)              –Dorothea-Stolln in Annaberg-Buchholz (Ag-CoNi-Cu mineralization)      –Markus-Semmler Stollen in Schneeberg (U stockwork)                                –with several stops including Zlatý kopec (polymetalic magnetite skarn).

IMG_0731
Fourteen students participated in this 3-days field-trip, which was led by David Dolejs.

SGA News No 37 page 17

Mineralization related to the Devonian crustal extension and volcanosedimentary processes in the Silesian domain, northeastern Bohemian Massif

The tra2ditional annual field trip (October 3-5, 2014) of our chapter has mainly focused on stratiform iron mineralization in the Neoproterozoic me1tasediments of the Děsná unit and iron mineralization of the Lahn-Dill type in the Devonian volcanosedimentary cover in the Jeseníky Mts., northeastern Bohemian Massif.

The main part of the excursion was designed as a transsect across the metamorphic and deformation gradient imposed on the same iron-bearing precursor of the Lahn-Dill type. We have thus investigated transition from jaspilites to metamorphosed magnetite ores as well as their banded magnetite-quartz counterparts. This provided many interesting examples, based on a number of small historically mined occurrences.

The 13 students participated in this 3-days excursion, which was led by David Dolejs.

SGA News no. 36 page 17

Professor David Groves – Geology of Gold Deposits: SGA Education Fund Short Course (September 14-16, 2013)

The SGA Education Fund, established in 2013, funded as its first educational activity the student-oriented short course on Gold Deposits: From Theory to Exploration Practice. The short course was presented by Professor David Groves, University of Western Australia and hosted by the SGA Student Chapter Prague on September 14-16, 2013. David Groves is an Emeritus Professor at the University of Western Australia, where he helped establish the Center for Exploration Targeting. He has co-authored more than 500 publications mainly in the fields of Archean evolution, komatiite-associated Ni-Cu deposits, orogenic gold deposits, the role of lithosphere in global metallogeny, and prospectivity mapping. During his career, he also supervised over 85 Ph.D., 55 M.Sc. and 120 B.Sc. Hons. thesis projects at the University of Western Australia and elsewhere. He was elected President of the SGA, SEG and the Geological Society of Australia, and for his career-long achievements he received both the SGANewmont Gold Medal and the SEG Penrose Gold Medal. His willingness to organize this short course symbolizes his personal gift to the SGA Education Fund. The course consisted of four lecture sessions devoted to exploration techniques and strategies (first day), with focus on geological settings, mineralization and alteration styles and global geodynamic context during the following days. The principal focus of the second-day presentations aimed at intrusion-related, iron-oxide copper gold and Carlin-type deposits, whereas the last day was devoted to orogenic gold mineralization styles. The big-picture and general – perspective approach was particularly welcome as were detailed genetic models and controls on each mineralization setting.

SGA News No 34 page 25

Iron ores of the Barrandian Paleozoic in central Europe (June 6, 2014)

4The SGA Student Chapter Prague organized one of its field trips to visit sedimentary iron mineralization in the Paleozoic volcanosedimentary sequences of the Prague Basin (Barrandian) in central Europe.

The Barrandian is a classical area of Neoproterozoic to Devonian volcanosedimentary strata, affected by the Variscan orogeny. In the Middle Cambrian through Ordovician, the deposition of predominantly shallow marine conglomerates, graywackes, mudrocks and shales was accompanied by intermittent volcanic activity of calc-alkaline basalts, andesites, rhyolites and their subaqueous pyroclast3ic products. Several of these volcanic centers were source of energy and chemical components for the formation of perivolcanic or hanging-wall iron-oxide mineralization. The formation of ironstones continued to stratigraphic hanging wall as well as more distal sedimentary settings, and gradually evolved into oolitic iron deposits, which occur as several horizons In the Ordovician siliciclastics. The deposition of these siderite-, chamosite- or hematite-bearing oolitic iron ores coincides with their worldwide formation on shallow marine continental shelves at this time interval. Ironstones in the Barrandian represent classical and previously economic accumulations, which were exploited from prehistoric times until 1960’s. The field stops offered a rich opportunity to compare volcanic and epiclastic products and several mineralization styles, which recorded different influences of volcanic activity, hydrothermal and subaquatic alteration and redox gradients during iron precipitation and diagenesis.

SGA News No 36 page 16

Western Carpathians deposits near Slovakia-Hungary border (October 2-6, 2013)

5The second field trip organised by the SGA Student Chapter Prague in 2013 was aimed at Slovakia and Hungary. Purpose of this excur6sion was to get in touch with different geological settings than the Bohemian massif. Major part of Slovakia and the northern part of Hungary (Tokaj Mountains) are situated in the mountain range of Western Carpathians. This system evolved during the Alpine orogeny as the northern branch of the Alpine-Himalayan fold and thrust system called the Alpine belt.

SGA News no. 35

Habachtal and Knappenwand – precious stones deposits in Hohe Tauern (3-6 September, 2013)

8The first field trip organised by the SGA Student Chapter Prague in 2013 lead to the famous Alpine deposits Habachtal and Knappenwand in Austria. Habachtal emerald deposit has been known since the Roman times. This locality provides the best emeralds in Europe and it is the 7only location where emeralds of gem quality occur. The mine has been active until these days, where the Steiner family has been irregularly mining the precious stones using just a simple technology. Access to the adit collar is rather difficult requiring good physical conditions. The emerald deposit is located at the tectonic contact of ortho-gneiss and basic to ultrabasic metamorphosed rocks: amphibolite,mica schist, serpentine and talc schist. The most important emerald bearing rocks are biotite-, talc- and actinolite schists occurring at the margins of serpentine bodies. The emeralds mostly appear in the form of automorphic hexagonal columns in a size up to 4–5 cm. The emeralds can be found in the Habach valley under the adit where they are transported by water.

SGA News no. 34 

Origin of ore deposits in the Erzgebirge (Krusne hory) Mts., Central Europe (November 4-5, 2012)

Main focus was on the origin of ore deposits in both the Czech and German parts of the Krusne hory/Erzgebirge Mts. The main attraction of the field trip was an underground visit in the historical mines of Ehrenfriedersdorf and Pöhla and at the Zlatý Kopec near Boží Dar (Gotesgab). The common feature of all localities is a widespread cassiterite mineralization related to the hydrothermal fluid flow from late Variscan biotite to topaz granites (327–312 Ma). The tin deposits are located in the paleoroof of the Krusne hory/Erzgebirge batholith formed by Neoproterozoic and Early Paleozoic supracrustal sequences: phyllites, micaschists, paragneisses, amphibolites, and marbles that were altered and host stratiform or disseminated mineralization. Altered rocks are also intersected by numerous ore-bearing veins. The highest abundances of economic minerals are concentrated in skarns that formed by replacement of dolomites or surrounding metasediments and metavolcanics. Therefore skarns were target of historical mining as well as post-war exploration and became the principal target of our field trip.

SGA News no. 33