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0001

Fluid evolution and mineralogy of Mn-Fe-barite-fluorite

mineralizations at the contact of the Thuringian Basin,

Thüringer Wald and Thüringer Schiefergebirge in Germany

JURAJ MAJZLAN

, MARIA BREY-FUNKE

, ALEXANDER MALZ

, STEFAN DONNDORF

and RASTISLAV MILOVSKÝ

Institute of Geosciences, Friedrich Schiller University, Carl-Zeiss Promenade 10, D-07745 Jena, Germany; Juraj.Majzlan@uni-jena.de

Earth Science Institute of the Slovak Academy of Sciences, Ďumbierska 1, SK-974 01 Banská Bystrica, Slovakia

(Manuscript received July 4, 2015; accepted in revised form October 1, 2015)

Abstract: Numerous small deposits and occurrences of Mn-Fe-fluorite-barite mineralization have developed at the
contact of the Thuringian Basin, Thüringer Wald and Thüringer Schiefergebirge in central Germany. The studied
mineralizations comprise the assemblages siderite+ankerite-calcite-fluorite-barite and hematite-Mn oxides-calcite-barite,
with the precipitation sequence in that order within each assemblage. A structural geological analysis places the origin
of the barite veins between the Middle Jurassic and

Early

Cretaceous. Primary fluid inclusions contain water vapour

and an aqueous phase with NaCl and CaCl

as the main solutes, with salinities mostly between 24—27 mass. % CaCl

eq. T

measurements range between 85 °C and 160 °C in barite, between 139 °C and 163 °C in siderite, and between

80 °C and 130 °C in fluorite and calcite. Stable isotopes (S, O) point to the evaporitic source of sulphur in the observed
mineralizations. The S,C,O isotopic compositions suggest that barite and calcite could not have precipitated from the
same fluid. The isotopic composition of the fluid that precipitated barite is close to the sea water in the entire Permo—
Mesozoic time span whereas calcite is isotopically distinctly heavier, as if the fluids were affected by evaporation. The
fluid evolution in the siliciclastic/volcanic Rotliegend sediments (as determined by a number of earlier petrological and
geochemical studies) can be correlated with the deposition sequence of the ore minerals. In particular, the bleaching of
the sediments by reduced Rotliegend fluids (basinal brines) could be the event that mobilized Fe and Mn. These ele-
ments were deposited as siderite+ankerite within the Zechstein carbonate rocks and as hematite+Mn oxides within
the oxidizing environment of the Permian volcanic and volcanoclastic rocks. A Middle-Jurassic illitization event
delivered Ca, Na, Ba, and Pb from the feldspars into the basinal brines. Of these elements, Ba was deposited as massive
barite veins.

Key words: hydrothermal mineralization, fluid inclusion, stable isotopes, Thuringian basin.

Introduction

The Thuringian Basin is an 80×160 km wide syncline,
slightly elongated along a NW—SE axis, formed by Permian
to Triassic strata with a total thickness of up to 2.5 km.
The basin is situated in the central part of the state of Thurin-

gia  (central  Germany)  and  is  bordered  by  the  Harz  Moun-
tains  to  the  north  and  the  Thüringer  Schiefergebirge  and
Thüringer Wald to the south (Thomson & Zeh 2000; Fig. 1).
These  large  basement-cored  anticlines  and  uplifted  blocks
were  deformed  during  the  Late  Cretaceous  compressional
event,  which  affected  large  areas  of  western  and  central

Fig. 1. A simplified geological map of Thüringen, displaying the location of the sampled deposits.

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Europe  (Schröder  1987;  Ziegler  1987;  Kley & Voigt  2008).
The  contractional  deformation  is  often  suspected  to  initiate
the  migration  of  fluids  from  the  basement  upward  (Meinel
1993) and the large-scale fluid circulation is thought to have
led  to  the  formation  of  numerous  hydrothermal  deposits
along the margins of the Thuringian Basin (Rüger & Decker
1992).  These  deposits  were  economically  exploitable,  parti-
cularly  in  the  southern  area  of  the  basin,  and  have  been
mined since the Middle Ages (Zimmermann 1914).

Some of the more important ore deposits are situated in the

Saalfeld-Kamsdorf  region  where  a  total  of  1.4 million  tons
of iron ore were mined from 1715 to 1867 (Beyschlag 1988);
the  Ilmenau  region  where  2.9 million  tons  of  fluorite  and
barite were excavated from the Floßberg vein alone between
1950  and  1991;  and  the  Hühn  region  (Trusetal)  where  iron
ore, fluorite, and barite were excavated from the 16

century

to 1968. Persistent economic interest in these deposits stimu-
lated a number of scientific studies over the last 40 years in
order to understand their mineralogy, structural geology, re-
serves, and, to a lesser extent, their origin and fluid chemistry.

Equally historically important were the oxidic and silicate

manganese ores, mined in the wider vicinity of the township
of Ilmenau. The first written documents about the ore exploi-
tation here date back to 1668 and 1732 and the mining
ceased in 1949. About 44,700 tonnes of the Mn ores were
extracted in the Arlesberg district and the remaining reserves
are considered to be negligible.

The mineralizations on the southern edge of the Thuringian

Basin bear a number of similar features to numerous deposits
and  occurrences  throughout  post-Variscan  Europe,  such  as
deposits  in  France  (Charef  &  Sheppard  1988;  Munoz  et  al.
1994,  2005;  McGaig  et  al.  2000),  Spain  (Halliday  and
Mitchell  1984;  Wickham  &  Taylor  1990;  Canals  and
Cardellach 1993; Galindo et al. 1994; Subías and Fernández-
Nieto 1995; Johnson et al. 1996; Crespo et al. 2002; Piqué et
al.  2008),  Sardinia  (Muchez  et  al.  2005;  Boni  et  al.  2009),
Germany (Behr & Gerler 1987; Mertz et al. 1989; Boness et
al. 1990; Lüders & Möller 1992; Meinel 1993; Hähnel et al.
1995;  Krahn  &  Baumann  1996;  Meyer  et  al.  2000;  Zeh  &
Thomson  2000;  Wagner  &  Lorenz  2002;  Schwinn  et  al.
2006; Baatartsogt et al. 2007; Staude et al. 2007, 2011; Wag-
ner  et  al.  2010),  Poland  (Leach  et  al.  1996;  Heijlen  et  al.
2003; Schmidt-Mumm & Wolfgramm 2004), Slovakia (Hu-
rai et al. 2002, 2008), Belgium (Slobodnik et al. 1994), Hun-
gary  (Benkó  et  al.  2014),  Czech  Republic  (Kučera  et  al.
2010), England (Gleeson et al. 2000) and Ireland (O’Reily et
al.  1997).  All  these  deposits  show  similarity  in  some  com-
mon  parameters,  such  as  their  age,  fluid  chemistry,  stable
isotopes,  mineralization  styles  and  their  mineralogical  and
geological background.

Modern, active systems and analogues of these deposits

can  be  also  found,  for  example  in  the  geothermal  field  of
Soultz-Sous-Forêts (France) and the Rhein graben (Scheiber
et  al.  2012).  A  large-scale  circulation  of  the  hydrothermal
fluids  significantly  affects  the  geothermal  gradient  in  the
area (Genter et al. 2010, their fig. 8) and causes alteration of
the host rocks. The fluids at this site are currently precipita-
ting  barite-celestite  solid  solution,  galena,  and  other  sul-
phides (Nitschke et al. 2014).

Here we present an analysis of fluid inclusions of the stu-

died  mineralizations.  The  fluid  inclusion  data  are  given  to-
gether with further mineralogical and geochemical data from
the ores in order to develop a sequence of events compatible
with the regional tectonic evolution of the Thuringian Basin.
We link the mineralizations to the evolution of the Permian
siliciclastic  rocks.  This  link  may  account  for  the  observa-
tions  made  in  this  and  other  studies  and  explains  well  the
timing, geochemistry, and mineralogy of the studied ore de-
posits.

In this study, we have analysed several hydrothermal de-

posits located in a belt along the southern edge of the
Thuringian basin. Most of these deposits were mined be-
tween the 16

and mid-20

century and are no longer acces-

sible today. Hence, much historical information has been
drawn from the literature, written by those who saw these
veins in the spectacular underground outcrops.

According to Hähnel et al. (1995) and Baumann & Leeder

(1969),  the  earliest  mineralization  of  the  studied  hydrother-
mal vein deposits are sparse veinlets of quartz, hematite, and
locally  small  amounts  of  carbonates  coloured  red  by  finely
dispersed  hematite.  According  to  the  observations  in  the
Sächsisches  Erzgebirge,  Schröder  (1970)  assigned  late
Variscan—Permian  age  to  this  quartz-hematite-ankerite  mi-
neralization.

The precipitation of quartz, hematite, and the carbonates

was  followed  by  the  deposition  of  ankerite.  According  to
Kling (1995), ankerite replaced the Zechstein limestones and
is limited to the largest faults and their vicinity. Afterwards,
the  siderite+ankerite  assemblage  studied  here  formed.  It  is
represented  by  large  metasomatic  bodies  of  siderite  and
ankerite in the Zechstein carbonates or in the earlier ankerite.
Siderite  occurs  also  as  veins  and  is  spatially  bound  to  the
Zechstein strata and found in the marginal areas of both the
Thüringer  Schiefergebirge  and  Thüringer  Wald.  Deposits
developed  in  the  Paleozoic  basement,  for  example  Gehren,
do not contain siderite. In these deposits, calcite is the major
carbonate  mineral.  Meinel  (1993)  and  Franzke  and  Schie-
menz (1980) attribute the absence of siderite and ankerite to
the  highly  oxidizing  environment  within  the  abundant  Per-
mian volcanics and sediments in this area.

The siderite mineralization is thought to be connected

with the mid-Mesozoic extension stage whose main activi-
ty  is  traceable  in  the  Upper  Jurassic—Lower  Cretaceous
(Hähnel et al. 1995; Thomson & Zeh 2000). After the em-
placement  of  the  siderite  mineralization,  the  tectonic  re-
gime  changed  in  the  late  Cretaceous—Tertiary  to
contractional  strain.  White  calcite  replaced  siderite  and
formed  as  lenses  up  to  15 m  thick.  In  the  Gehren  region,
calcite is later accompanied by fluorite. The main phases of
fluorite and barite deposition postdate calcite precipitation.
In the wide geographic region of the Thuringian Basin and
the adjacent geological units, barite and fluorite are thought
to  be  related  to  the  upper  Cretaceous  uplift,  either  in  the
Harz  Mountains  (Lüders  &  Möller  1992),  the  Thüringer
Wald (Zeh & Thomson 2000), or in the Thüringer Schiefer-
gebirge (Meinel 1993).

The deposition of fluorite, however, is limited to the mar-

ginal areas between the Thuringian Basin and the Harz

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Mountains (Lüders & Möller 1992) and the Thuringian Ba-
sin and the Thüringer Wald. Fluorite is missing at the inter-
face  of  the  basin  and  the  Thüringer  Schiefergebirge,  except
for  the  circumference  of  the  two  intrusive  granitoid  com-
plexes  (Sparnberger  Granit,  Henneberggranit).  An  explana-
tion  for  the  absence  of  fluorite  is  the  low  total F content of
the rocks of the Thüringer Schiefergebirge (Meinel 1993).

The barite-fluorite veins, steep vertical or shallow horizon-

tal  lenses  reach  a  thickness  of  up  to  10m.  Distinct  replace-
ment  patterns  can  be  observed  throughout  the  deposits
–  fluorite  replaces  calcite  (Hähnel  et  al.  1995;  Kießling
2007) and barite replaces fluorite. In addition, there are hints
of  multiple  deposition  of  barite  in  specific  tectonic  pulses
– “seismic pumping” (Meinel 1993; Hähnel et al. 1995).

The latest mineralogical overprint is represented by the

anhydrite-quartz  veins  with  a  thickness  of  up  to  10 m,  espe-
cially in the Hühn area. Anhydrite replaces calcite and side-
rite.  There  is  no  anhydrite  mineralization  except  for  a  few
relics  in  the  Kamsdorf  region.  The  youngest  hydrothermal
event  is  pervasive  silicification.  Quartz  replaces  preferably
anhydrite (if existing) but also siderite and ankerite.

Materials and methods

Samples of hydrothermal sulphides, Mn oxides and

silicates,  calcite,  fluorite,  ankerite,  siderite,  and  barite  from
the southern edge of the Thuringian basin were investigated
(Fig. 1). Most of the samples were collected in the field and
complemented with selected samples from the Mineralogical
Collection  of  the  University  of  Jena  and  of  the  Thüringer
Landesamt für Umwelt und Geologie, Weimar. The collected
samples  were  prepared  for  petrographic  observations  as
standard  thin  and  polished  sections.  They  were  studied  in
transmitted  and  reflected  polarized  light  prior  to  further
analyses.

Microthermometry

Fluid inclusions were observed and analysed in 23 doubly

polished sections (200—300 µm thick) of barite, calcite (from
Gehren region), fluorite, and siderite (from Hühn region).
Phase transitions (melting temperature of ice, T

m,ice

; melting

temperature of hydrohalite, T

m,hydrohalite

; eutectic tempera-

ture, T

; temperature of total homogenization, T

) in fluid in-

clusions  were  measured  using  a  Linkam  THM  600
programmable  freezing-heating  stage  mounted  on  a  ZEISS
AXIOPLAN  microscope.  A  digital  JVC  camera,  long-
working-distance  Nikon  objectives  with  magnifications  of
20

×, 32× and 50×, and an image analysing system were used

to  visualize  the  inclusions  on  a  computer  screen.  The  stage
was  calibrated  against  the  phase  transitions  of  three  pure
chemical  compounds  with  known  transition  temperatures:
the triple point of CO

(—56.6 °C) in natural fluid inclusions

(previously checked by Raman spectroscopy to contain only
CO

in the gas phase), the melting temperature of H

(0.0 °C), and the melting temperature of sulphur (119.2 °C).
The reproducibility of measurements was within ±0.1 °C for
the cryogenic temperatures and ±1—2 °C for the T

measure-

ments. Temperatures of phase transitions were always mea-
sured upon heating using a heating rate of 0.1° C/min.

The salinities were calculated from the measured final ice

melting  temperature  of  aqueous  two-phase  inclusions  with
the  Aqso2e  program  of  Bakker  (2009)  based  on  the  equa-
tions of Naden (1996). The salinity of the fluids is given here
in  CaCl

eq. wt% to express all data in one single salt sys-

tem. For the NaCl-CaCl

-H

O-system, salinities were calcu-

lated as NaCl (eq. mass%) and CaCl

(eq. mass%)

equivalents, for which the final melting temperatures of ice
(T

m,ice

) and hydrohalite (T

m,hydrohalite

) were needed (after

Steele-MacInnis et al. 2011).

Stable isotope analysis

The stable isotope compositions of barite and anhydrite

samples  were  analysed  at  the  isotope  laboratory  of  the  TU
Bergakademie  Freiberg.  Mineral  separates  of  the  sulphates
were  hand-picked  under  a  binocular  microscope,  followed
by  cleaning  in  doubly  distilled  water  to  remove  any  water-
soluble impurities. The sulphates were measured using pro-
cedures  given  in  Giesemann  et  al.  (1994).  The  sulphur
isotope compositions of the mineral separates were analysed
using  an  elemental  analyser  (Fisions  CarloErba)  coupled  to
the  mass  spectrometer  (CF-IRMS-Delta  plus  ThermoQuest-
Finnigan). The

O values of BaSO

and CaSO

were ana-

lysed using a high-temperature pyrolysis system from
HEKAtech (Kornexl et al. 1999) coupled to continuous flow
isotope ratio mass spectrometry (CF-IRMS-Delta plus Ther-
moQuinn-Finnigan). Isotope ratios are reported as

O and

S values in per mil (‰) relative to the V-SMOW and

V-CDT  standards,  respectively.  Standards  used  for  the  sys-
tem  calibration  were  IAEA-SO-5  and  IAEA-SO-6  for  oxy-
gen  isotopes  and  IAEA-S-2,  IAEA-S-3  and  NBS  127  for
sulphur  isotopes  (Kornexl  et  al.  1999;  Ding  et  al.  2001).
Every sample was measured at least three times. The repro-
ducibility  of  oxygen  isotopes  from  sulphate  is  better  than
0.5 ‰ and the reproducibility of the

S measurements was

better than 0.3 ‰, although the internal error of three succes-
sive measurements was often smaller.

Carbon and oxygen isotopes of carbonates were measured

with  an  automated  carbonate  preparation  system  Gasbench
coupled to isotope ratio mass spectrometer MAT253 (Ther-
mo).  Powdered  samples  of  ca.  600—800 mg  were  flushed
with  helium  in  septum-sealed  glass  vials,  then  reacted  with
anhydrous H

for 24 hours at 25 °C. The CO

yield was

chromatographically  separated  and  introduced  into  a  mass
spectrometer  in  continuous  flow  mode  (helium  as  carrier
gas), whereby three injections of reference gas are followed
by four injections of sample aliquots. A set of working stan-
dards,  traceable  to  international  standards  were  regularly
scattered between samples to check for accuracy. The usual
precision  of  the  method  is  0.2 ‰  for

O and 0.1 ‰ for

Powder X-ray diffraction (pXRD)

All samples from the Mn oxide-silicate mineralization and

selected samples from the barite-fluorite mineralization were

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ground to powder and front-loaded in plastic sample holders.
pXRD data were collected with a Bruker (D8 AXS Advance
DaVinci) diffractometer, equipped with a Cu X-ray source
and operating at 40 kV and 40 mA. The pXRD patterns were
compared to the database entries in the PDF 2.0 database,
using the Bruker software EVA.

X-ray fluorescence (XRF) analysis

The bulk chemical composition of selected samples (espe-

cially the samples from the Mn-Fe mineralization) was mea-
sured with an XRF spectrometer Philips (PW 2404) in the
wavelength-dispersive mode. The samples were ground to
analytical fineness, thoroughly mixed with wax (sample:wax
ratio of 4:1), pressed into pellets in a hydraulic press under
the load of 294.2 kN, and dried for 24 hours at 45 °C.

Results

Structural geological settings

Saalfeld-Kamsdorf

The Kamsdorf ore field is situated at the contact of the

Thuringian Basin to the Thüringer Schiefergebirge (Figs. 1,
2) and hosts barite and sulphide ore mineralizations within
repeatedly deformed rocks. The rocks are of Upper Permian
(Zechstein) age and are mildly tilted (~3°) to the north. In the
Kamsdorf ore field, we recognized two main events of brittle
deformation (Fig. 3), each with a different direction and ki-
nematics, and one main event of mineralization (Fig. 4). The

first event is associated with the formation of normal faults
and conjugated shear fractures, suggesting vertical orienta-
tion of the maximal stress (

). Hence, the settings, which

formed these structures, can be interpreted in terms of an ex-
tensional regime. According to the mean trending direction
of the normal faults striking NW—SE (Fig. 4), the tensional
stress (

) was very likely oriented NE—SW, coinciding with

the results of earlier studies on the stress evolution in
Thuringia (Rauche & Franzke, 1990).

The second deformation event is characterized by the for-

mation of thrust faults and the reverse reactivation of normal
faults. In the Kamsdorf region, the contractional structures

Fig. 2. Geological map of the vicinity of the village of Kamsdorf, with the barite-siderite veins (simplified after Wucher et al. 2001).
The metasomatic siderite bodies are lying flat and do not appear on the geological map.

Fig. 3. Barite vein from Kamsdorf, offset by the compressional tec-
tonic events related to the basin inversion.

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strike to the northeast (ENE 080) and show north-dipping
and south-dipping thrust and reverse faults. Dip-slip stria-
tions perpendicular to the strike direction suggest an event of
N—S compression.

In this study, we also analysed the direction of the mine-

ralized fractures and veins. The main strike direction of the
veins  is  to  the  northwest  (Fig. 4  main  direction  of  barite
veins), which coincides with the direction of the extensional
structures.  In  outcrops  where  veins  and  contractional  struc-
tures  intersect,  a  contractional  overprint  of  the  mineraliza-
tions is observable (Fig. 3).

Hence, a relative timing of the tectonic events and the

mineralizations  can  be  reconstructed  in  the  available  out-
crops.  The  first  event  of  NE—SW  extension  caused  the  for-
mation  of  normal  faults  and  extensional  fractures.
Afterwards, the hydrothermal fluids from the basement were
injected into these fractures and deposited the observed mi-
neralization. During the second deformation event, the vein
mineralizations  were  deformed  by  small  reverse  faults  and
compressional fractures without mineralizations developed.

Gehren

The Ilmenau region (including the studied site Gehren) is

located at the contact between the Thuringian Basin in the

north, the Thüringer Schiefergebirge in the southeast and the
Thüringer Wald in the southwest (Fig. 1). The exposed
rocks, mostly of Neoproterozoic and Paleozoic age, were de-
formed and metamorphosed during the Variscan orogeny. Later
deformation was mostly of brittle style and comprises seve-
ral events of extension and contraction during the Mesozoic
(Förster & Romer 2010). A detailed temporal reconstruction
of the deformation and mineralization events was not possi-
ble within the framework of this work, due to the lack of
well-exposed rocks in the studied area.

The only suitable exposures can be found in the under-

ground of the adit Flußspatgrube in Gehren. There, the main
fluorite-barite  mineralization  is  spatially  associated  with
a fault dipping towards the southwest (Franzke & Schiemenz
1980; Franzke et al. 1982; Franzke 1992). This normal fault
shows  an  extensional  character  with  tens  of  metres  of  dis-
placement  and  is  called  the  Floßberg  fault.  The  Floßberg
fault shows signs of polyphase activity during the Mesozoic,
which is proved by K/Ar-dating of fault gouges and cataclas-
tic  rocks  (Franzke  et  al.  1996).  The  development  of  the
Floßberg  fault  began  during  the  Middle  Keuper  (Karn;
228—225 Ma) and was possibly associated with a first episode
of  fluid  migration  into  the  fault  zone.  Afterwards,  the  fault
zone was reactivated with normal senses of slip during Upper
Jurassic (154—134 Ma) until Lower Cretaceous (123—102 Ma)

Fig. 4. Stereographic projections and rose diagrams of the structural measurements in Kamsdorf, Gehren, and Trusetal. If possible,
the measurements are divided into different phases of formation.

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times.  Franzke  et  al.  (1996)  recognized  several  mineraliza-
tion processes during these main deformation phases. A con-
tractional  reactivation  of  the  Floßberg  fault  during  the  Late
Cretaceous  is  not  well  documented  in  the  outcrops  but
probably  led  to  a  compressional  overprint  of  the
mineralizations.

Trusetal/Hühn region

Trusetal is located at the border of the Thüringer Wald to

its southern foreland (Fig. 1). The exposed rocks in this area
are Variscan gneisses and granites of the Mid-German-Crys-
talline rise as well as Zechstein evaporites and Triassic rocks
of the sedimentary cover. The deposit Hühn itself is located
in the Variscan high-grade complex. Our strike and dip mea-
surements of fissures can be divided into two main and one
minor  directions  of  brittle  fractures.  The  main  strike  direc-
tions are oriented principally E—W and WNW—ESE (Fig. 4)
and  coincide  with  the  direction  of  post-Variscan  brittle  de-
formation in the Kamsdorf and Ilmenau regions. The minor
strike direction is NE—SW trending and agrees with the mean
strike direction of the Variscan consolidated basement, thus
probably indicating late syn-Variscan deformation. For illus-
tration,  fissures  with  and  without  barite  veins  were  plotted
separately  (Fig. 4).  An  obvious  conclusion  drawn  from
Fig. 4  is  that  the  barite  veins  mostly  show  the  WNW—ESE
direction. In contrast, barren fractures show the E—W direc-
tion.  With  the  assumption  that  fluids  only  enter  open  fis-
sures,  the  construction  of  WNW—ESE  fractures  must  be
described as the first deformation event. Afterwards, the in-
flux of fluids predating the creation of E—W fractures led to
the mineralization of pre-existing fissures of the first defor-
mation event. Subsequent contraction resulted in the forma-
tion  of  E—W  fractures  without  mineralizations  and  in  the
deformation  of  the  rocks  and  veins.  In  the  Hühn  region,  no
absolute timing constraints can be found. Nevertheless, in re-
lation to the wider area, the earliest time of deformation can
be assumed to post-date Late Permian times due to NW—SE-
striking  barite  veins  within  Zechstein  sediments  in  the  out-
crops  of  the  Hohe  Klinge  and  the  Grube  Mommel.
Accordingly,  a  polyphase  deformation  history  can  be  as-
sumed for the area around Trusetal. The dominant deforma-
tion characteristics are extensional. A compressional regime
has prevailed in this area since the Late Cretaceous until the
present time (Rauche & Franzke 1990).

Mineralogy and geochemistry

Siderite-barite-fluorite deposits

The mineralogy of these deposits is in most cases simple

(Fig. 5). The major minerals are carbonates (calcite, ankerite,
siderite), barite, and fluorite but they need not occur together
in  one  deposit.  Some  deposits  are  missing  fluorite,  other
ones  siderite.  Sulphides  are  found  essentially  only  at  the
Kamsdorf deposit as lenses and disseminated mineralization
in the siderite bodies or in the barite veins. In Kamsdorf, the
Zechstein  carbonate  rocks  which  host  the  siderite  bodies
contain  two  thin  (10—130 cm)  horizons  of  grey  shale  en-

riched  in  pyrite.  This  shale  occupies  the  same  stratigraphic
position as the Kupferschiefer shale and is considered to be
an  analogue  of  Kupferschiefer.  A  clear  spatial  relationship
between  the  shales  in  Kamsdorf  and  the  sparse  sulphidic
mineralization could not be proven, but also not refuted. The
sulphides found in Kamsdorf are pyrite, chalcopyrite, marca-
site,  tennantite,  tetrahedrite,  and  galena.  The  deepest  acces-
sible portions of the deposit also contain Co-Ni-As sulphides
and Ag-rich tetrahedrite. The other studied barite-fluorite de-
posits  contain  very  little  or  essentially  no  sulphides  (for
example Hühn, Pratzka 1956; Hähnel et al. 1995).

Mn-Fe deposits

The minerals reported in this section were identified by re-

flected-light  polarized  microscopy,  powder  X-ray  diffrac-
tion,  and  electron  microprobe.  The  analytical  results  of  the
electron  microprobe  studies  are  tabulated  in  Brey-Funke
(2014).  The  bulk  chemical  composition  of  the  Mn-Fe  sam-
ples  (determined  by  XRF,  see  Brey-Funke  2014),  when
placed  in  the  discrimination  diagram  of  Toth  (1980),  indi-
cates hydrothermal origin of the studied ores. The mineralogy
of  the  two  districts  with  Mn-Fe  mineralizations  (Arlesberg
and  Oehrenstock,  both  in  the  vicinity  of  Ilmenau,  Fig. 1)  is
different. At Arlesberg, the veins and nests hosted by rhyo-
lites  (Figs. 6, 7a)  contain  hematite,  braunite,  pyrolusite,  ba-
rite,  and  traces  of  manganite.  Only  small  and  insignificant
veins were emplaced in the conglomerates of the Rotliegend
(Fig. 6,  Brosin  &  Veitenhansl  2005).  At  Oehrenstock,  the
mineralized structures located in the acidic pyroclastic rocks
contain  hausmannite,  manganite,  braunite,  barite,  and  seve-
ral varieties of calcite.

In the samples from Arlesberg which contain both hema-

tite and Mn minerals, coarse-grained, crystalline hematite is
the  earlier  mineral.  In  addition,  hematite  and  the  Mn  mine-
rals  are  usually  spatially  separated,  hematite  occupying
deeper  portions  of  the  deposit  (Beyschlag  1914).  Historical
accounts  report  that  manganite  was  common  at  Arlesberg
but Schiemenz (2001) notes that manganite cannot be found
there  today.  We  have  not  found  manganite  at  Arlesberg
either  and  the  historical  accounts  should  be  perhaps  taken
with  a  grain  of  scepticism.  Braunite,  on  the  other  hand,  is
abundant at Arlesberg. It replaces the rock-forming minerals

Fig. 5. Sequence of the vein mineralisations of the barite-fluorite-
siderite mineralization at the southern edge of the Thuringian Basin
(based on our observations and the reported temporal relationships
from Pratzka, 1956; Werner, 1958; Kuschka & Franzke, 1974;
Meinel, 1993; Hähnel, et al. 1995; Kling, 1995; Kießling, 2007).

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of the rhyolite, first the feldspars in the fine-grained matrix
of  the  volcanic  rock,  then  the  K-feldspars,  and  eventually
also  quartz  in  the  matrix.  Occasionally,  the  rims  of  the
braunite  grains  are  replaced  by  pyrolusite.  Pyrolusite  also
forms pseudomorphs after manganite; the earlier manganite
was  observed  very  rarely  (Fig. 7f).  The  abundance  of  the
pseudomorphs could be also the explanation for the early de-
scriptions of manganite from Arlesberg.

In the samples from Oehrenstock, the mineralization com-

mences  with  hausmannite,  mostly  as  massive  aggregates,
rarely as  subhedral crystals with mosaic texture. Manganite is
found as prismatic or acicular crystals and, according to our
observations  in  polarized  light,  is  slightly  younger  than
hausmannite.  Hausmannite  is  replaced  to  a  great  extent  by
euhedral  to  subhedral  crystals  of  braunite.  The  crystals  are
porous and the cores of the crystals are replaced by calcite,
less commonly by barite (Figs. 7d,e). Calcite, as mentioned,
occurs  here  in  several  varieties  or  perhaps  generations.  The
earliest  variety  is  black  calcite,  macroscopically  similar  to
the Mn oxides (Fig. 7b). In an optical microscope and back-
scattered  electron  images,  one  can  see  innumerable  micro-
scopic  inclusions  of  Mn  oxides  in  the  calcite  (Fig. 7c),
responsible  for  its  black  colour.  The  analysed  inclusions

appear  to  have  already  weathered  to  hollandite  and  crypto-
melane. Black calcite replaces manganite, according to Schie-
menz  (2001)  also  hausmannite  and  braunite.  Younger,
brown  calcite  replaces  braunite  and  black  calcite.  The
youngest  variety  is  coarse-crystalline,  sometimes  euhedral
white calcite.

Barite is a relatively young mineral within the precipita-

tion sequence. Locally, however, crystals of manganese
crystals clearly grow on the aggregates of barite. These fea-
tures may be a result of multiple remobilization of manga-
nese or multiple generations of barite.

Late stage evolution of the deposit are marked by crypto-

crystalline hematite, braunite, and calcite. Weathering mine-
rals include hollandite, cryptomelane, coronadite, todorokite,
chalcophanite, and romanèchite.

Comparison of the size of the two types of deposits

For the later discussion of geological and geochemical

similarities of the studied mineralizations, it is of interest to
compare  their  size  and  ore  resources.  The  extracted  44,700
tonnes  of  manganese  ores  in  the  Arlesberg  (F. Veitenhansl,
pers.  comm.)  district  are  dwarfed  by  the  1.4  million  tonnes

Fig. 6. Geological map of the vicinity of the township of Ilmenau, with the Mn-Fe ores veins. Note the close spatial association of these
veins and the Permian volcanic rocks (geological map simplified after Andreas et al. 1996).

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Fluid inclusion petrography and microthermometry

Fluid inclusions were analysed in siderite, calcite, fluorite,

and  barite.  No  fluid  inclusions  were  found  in  the  bluish,
massive anhydrite. Emphasis was placed on studying prima-
ry  fluid  inclusions,  even  though  secondary  inclusions  were
commonly  observed.  We  characterized  an  inclusion  as  pri-
mary according to the criteria listed in Roedder (1984) after
a careful petrographic study of the sections.

Siderite, calcite, fluorite

Fluid inclusions in siderite, calcite and fluorite (Fig. 8)

contain  either  a  two  (aqueous  liquid  and  water  vapour)  or
a single (aqueous) phase. Most of the inclusions are irregular
but  negative  crystal  shapes  were  also  observed,  particularly
in  fluorite,  less  commonly  in  the  carbonates.  The
liquid:vapour  ratio  in  the  two-phase  inclusions  was  consis-
tently  approximately  90:10.  The  size  of  the  primary  inclu-
sions varies between 5 and 100

µm. The secondary inclusions

are smaller, with sizes from <5 to 20

µm, arranged in trails,

and often consisting of a single aqueous phase.

The primary fluid inclusions from siderite, calcite, and fluo-

rite show a range of T

values from —65.6 to —49.7 °C

(Table1), indicating predominantly the H

O-NaCl-CaCl

system in the aqueous phase (Davis et al. 1990; Spencer et
al. 1990). Final melting temperatures of ice (T

m,ice

) range

from —36.6 to —25.2 °C. The salinities of the included fluids
vary in a narrow range and are graphically shown in Fig. 9.
To facilitate comparison among all measured inclusions, all
data are presented in eq. mass % CaCl

. Melting of hydro-

halite  was  observed  only  in  four  fluorite  samples  from
Gehren,  Ilmenau,  and  Hühn  (Table 1).  In  those  fluid  inclu-
sions,  where  melting  temperatures  of  both  ice  and  hydro-
halite  were  measured,  the  fluid  compositions  were  derived
using the approach of Steele-MacInnis et al. (2011). The re-
sulting  calculated  CaCl

/(CaCl

+NaCl) ratios are in the

range of 0.4 to 0.6 (Fig. 10).

The fluid inclusions in siderite, calcite, and fluorite always

homogenize to the liquid phase, with T

values between 134

to 163 °C for siderite and 103 and 134 °C for calcite (Fig. 9,
Table 1). The inclusions in fluorite have homogenization
temperatures of 73—127 °C for samples from Gehren; 81—
135 °C for Ilmenau (Volle Rose); 65—129 °C for the Hühn re-
gion and 69—141 °C for Eisenach-East.

Barite

Barite samples from all the studied deposits are similar in

terms of the observed fluid inclusions and their composition.
Based on the number of phases present at room temperature,
the fluid inclusions in barite can be divided into four groups:
1. two-phase liquid-rich, 2. two-phase vapour-rich, 3. one-

phase with only a liquid phase and  4. one-phase with only a
vapour phase. All types can be found together in close vici-
nity  with  each  other.  Group 1  inclusions  generally  show
a  liquid  to  vapour  ratio  of  85:15.  We  suppose  that  fluid  in-
clusions with the predominant gas phase or only with the gas
phase are a result of leakage coincidental with the post-mine-
ralization tectonic events.

Fig. 8. Microphotographs of fluid inclusions in the studied
mineralizations. a – two-phase primary fluid inclusion in siderite;
b and c – primary and secondary fluid inclusions in fluorite and
barite, respectively.

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The primary inclusions occur as isolated and three dimen-

sional clusters (Fig. 8c), with their size ranging from 10 µm
to  350 µm.  Most  of  them  are  irregularly  shaped;  some  are
rounded or elongated. Primary fluid inclusions with a nega-
tive crystal shape are rare and were found only in a few cases.
Primary  inclusions  are  liquid-rich  with  a  gas  bubble.  The
secondary inclusions occur along trails and are of very small
size  <5 µm  to  10 µm.  Most  of  the  secondary  trails  contain
rounded and irregular fluid inclusions, with single gas phase.

For fluid inclusions study in barite, a further selection was

carried out for the inclusions to be measured. The inclusions
were carefully selected according to the criteria of Ullrich &
Bodnar  (1987):  they  were  small,  with  round  shape  and
smooth  walls.  According  to  Ullrich  &  Bodnar  (1987)  such
inclusions in barite are most likely to yield correct data and
withstand post-depositional damage, mostly owing to the ex-
cellent  cleavage  of  barite.  Even  data  for  inclusions  with  no
signs of leakage, necking down and so on were discarded if
they were larger or elongated. The measured T

values are re-

producible,  suggesting  that  the  measured  inclusions  are  not
prone  to  leakage  at  the  present  time.  Additionally,  we  have
tested the validity of the fluid inclusion data in a double-sided
polished  section  that  consisted  of  barite  with  millimetre-
thick  bands  of  fluorite.  The  results  are  shown  in  Fig. 9d,
documenting the accuracy of the information from the inclu-
sions  in  barite.  Further  support  for  the  validity  of  the  fluid
inclusion data for barite comes from the measurements in co-

existing  barite  and  calcite  from  the  Fe-Mn  mineralization
(Fig. 9c).  Here,  the  scatter  for  the  data  in  both  minerals  is
identical,  documenting  that  the  fluid  inclusions  in  barite
yield correct and useful data.

Primary fluid inclusions in barite from the Kamsdorf-Saal-

feld region record a broad range of T

m,ice

and T

temperatures

(Fig. 9b). The measured T

in all these barite samples varies

from —53.9 to —24.3 °C (Table 1), with most values in the
range around —50 °C, typical for systems with an appreciable
concentration of CaCl

(Hurai et al. 2015). Values of T

m,ice

range between —23.8 to —9.4 °C with corresponding salinities
of 22.3 to 13.6 eq. mass % CaCl

. The homogenization tem-

peratures in these samples range between 116 and 160 °C.
Individual barite samples from all studied locations, that is,
Friedrichsroda, Gehren, Hühn and Eisenach-East show
a similar scatter of results (Table 1, Fig. 9b).

The fluid inclusions from Oehrenstock and Arlesberg (the

Fe-Mn mineralization) also point at the system H

O-NaCl-

CaCl

with their T

temperatures of —67.0 to —48.2 °C. The

ice melting temperatures of —41.9 to —21.6 °C, correspond to
salinities of 28.5 to 21.3 wt % CaCl

eq. The T

values

ranged between 78 and 156 °C.

Stable isotope data

The results of the

S and

O stable isotope analyses

from a suite of barite and one anhydrite sample are given in

Table 1: Microthermometric data for primary fluid inclusions in barite, fluorite, calcite, and siderite. All temperatures in °C.

Region Sample

Mineral

(n)

m,ice

(n)

m,hydrohalite

(n)

KAM 1

barite

–53.0 to –42.8 (4)

–23.8 to –17.6 (4)

156 (1)

Saalfeld -

KAM 2

barite

–36.9 to –25.3 (2)

–25.4 to –14.4 (2)

Kamsdorf

KAM 7b

barite

–46.2 to –30.1 (3)

–21.0 to –12.0 (6)

116 to 160 (4)

KAM 9

barite

–50.1 to –25.0 (2)

–24.0 to –12.6 (3)

158 (1)

KAM 11

barite

–53.9 to –51.3 (2)

–25.3 to –9.4 (3)

–21.5

KAM 14

barite

–50.9 to –50.1 (3)

–20.2 to –17.1 (3)

156 (1)

KAM 15

barite

–51.1 to –24.3 (3)

–15.1 to –11.4 (3)

107 (1)

HG 25330

barite

–52.6 to –49.4 (5)

–26.8 to –18.4 (9)

87 to 120 (5)

Friedrichsroda

HG 25312

barite

–52.3 to –48.3 (4)

–26.3 to –17.7 (6)

91 to 161 (4)

GEH 2

calcite

–61.3 to –54.3 (5)

–33.0 to –27.4 (12)

103 to 134 (12)

Gehren

GEH 2

fluorite

–55.7 to –53.3 (2)

–32.0 to –31.2 (3)

94 to 127 (4)

GEH 3

barite

–52.6 to –48.9 (4)

–24.0 to –17.9 (8)

104 to 107 (5)

GEH 3

fluorite

–61.3 to –52.9 (9)

–38.0 to –27.0 (20)

75 to 127 (20)

GEH 5

fluorite

–61.3 to –53.8 (7)

–36.2 to –29.3 (15)

73 to 123 (15)

GEH 7

fluorite

–60.9 to –52.3 (6)

–35.2 to –27.6 (15)

–10.8 (1)

99 to 121 (7)

Volle Rose

VR 1

fluorite

–69.3 to –49.7 (6)

–35.8 to –25.2 (17)

–9.7 to –8.8 (3)

81 to 135 (15)

(Ilmenau)

BHÜB 1

barite

–51.3 to –49.0 (3)

–25.6 to –18 (4)

128 to 161 (2)

Hühn - Trusetal

HÜB 4

fluorite

–61.4 to –58.0 (6)

–38.8 to –27.9 (18)

–15.9 to –5.3 (3) 65 to 129 (18)

HÜB 6

barite

–50.9 to –49.2 (4)

–22.7 to –21.0 (10)

67 to 124 (9)

HÜB 6

fluorite

–63.6 to –63.4 (5)

–35.3 to –25.2 (10)

–7.6 (1)

70 to 129 (21)

SID 1

siderite

–52.9 to –50.5 (6)

–36.6 to –27.4 (18)

134 to 163 (15)

Eisenach - East

EO-I-4997

fluorite

–65.6 to –61.4 (2)

–37.3 to –26.4 (17)

69 to 141 (16)

EO-102

barite

–51.4 to –48.8 (3)

–24.1 to –13.9 (10)

97 to 166 (6)

Oehrenstock

EGS 10a

calcite

–51.7 to –47.3 (10)

–26.2 to –23.4 (15)

89 to 140 (21)

EGS 10c

calcite

–55.0 to –48.0 (11)

–31.2 to –21.8 (16)

78 to 168 (20)

EGS 7i

barite

–67.0 to –48.2 (12)

–39.6 to –21.6 (15)

101 to 156 (17)

Arlesberg

EGS 17c

barite

–60.2 to –49.4 (9)

–41.9 to –23.1 (15)

78 to 149 (15)

— eutectic temperature

m,ice

— melting temperature of ice

m,hydrohalite

— melting temperature of hydrohalite

— total homogenisation temperature

n — number of measurements
NM — not measured

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Table 2  and  plotted  in  Fig. 11.  The
results from this study compare well
to  the  previously  reported  values  of
Lahiry  (1974).  Variations  between
barite-bearing  veins  hosted  by  diffe-
rent  lithological  units,  like  the  crys-
talline  basement,  Permian  rhyolite
and Zechstein dolomite are relatively
small  but  there  are  systematic  varia-
tions. It seems that the barite samples
hosted  by  the  volcanic  rocks  (rhyo-
lites, acid volcanoclastic rocks) have
lower

S values than the other sam-

ples, with one exception. Fig. 11 also
shows  a  comparison  with  sulphate
minerals  (barite  and  anhydrite)  from
the  North  German  basin.  Although
this  basin  is  now  separated  from  the
Thuringian  basin  by  the  crystalline
complex  of  the  Harz  Mountains,  the
two basins represented a single sedi-
mentation  space  in  the  Permian.

Fig.11.  Isotopic  composition  of  barite  from  the  barite-fluorite-
siderite  mineralization  (black  circles,  this  study),  barite  from
the  Mn-Fe  mineralization  (black  diamonds,  this  study),  anhydrite
from  the  anhydrite  veins  (black  square,  this  study),  barite  from
the  mineralizations  in  the  Thuringian  basin  (black  stars,  Lahiry
1974),  anhydrite  in  the  Zechstein  rocks  in  western  Poland  (open
circles,  Peryt  et  al.  2010),  anhydrite  in  the  Rotliegend  rocks  from
the  Northeast  German  basin  (open  squares,  Wolfgramm  2002),
anhydrite and barite from Permian volcanic rocks from the North-
east  German  basin  (open  triangles,  Wolfgramm  2002),  hydrother-
mal sulphates in the Middle Harz Mountains (grey circles, Zheng &
Hoefs 1993), and hydrothermal sulphates in the Upper Harz Moun-
tains  (grey  diamonds,  Zheng  &  Hoefs  1993).  The  fields  of  Devo-
nian-Triassic,  atmospheric,  and  terrestrial  sulphates  after  Clark  &
Fritz  (1997)  are  also  shown.  Note  that  these  fields  are  cut  off
according  to  the  spread  of  the  data  points  and  actually  extend
beyond the limits of this diagram.

Table 2: Sulphur and oxygen isotopic data of hydrothermal barite and anhydrite hosted in
crystalline basement, Rotliegend sediments and Zechstein sedimentary rocks.

Therefore, the results from the North German basin can be
used for the comparison with our data.

Isotopic analyses of carbonates from the studied veins

(

C and

O values) are summarized in Table 3 and plotted

in Fig. 12, together with isotopic composition of carbonates
from  hydrothermal  veins  in  Schwarzwald  (Schwinn  et  al.
2006)  and  cement,  fissure  filling  and  druses  of  carbonates
from the North German basin (Wolfgramm 2002). The mate-
rials  analysed  from  the  North  German  basin  came  mostly
from  Permian  rocks  (siliclastic  and  volcanic  rocks),  with
a  few  samples  from  Upper  Carboniferous  and  Mesozoic
rocks. Similar rocks also occur in the Thuringian basin.

Discussion

Fluid evolution

Fluid inclusion studies in siderite, calcite, and fluorite

show a narrow range in salinity (22.9 to 27.7 eq. mass %
CaCl

) and homogenization temperatures between 134 and

163 °C for siderite and between 65 and 135 °C for calcite and
fluorite  (Fig. 9).  These  results  are  in  good  agreement  with
previous fluid inclusion studies of fluorite veins in Ilmenau
&  Trusetal  (Hühn)  area  (Lahiry  1974;  Thomas,  1979;  Loos
et al. 1981; Klemm, 1986; Hähnel et al. 1995). Fluid inclu-
sion studies of barite samples from the Thüringer Wald and
the  Kamsdorf  area  show  a  greater  scatter  of  salinities  be-
tween 13.6 and 26.8 eq. mass % CaCl

, also documented by

Meinel (1993) and Thomas (1979). In line with our results,
studies have reported homogenization temperatures of about
50 °C  in  barite  samples  from  the  Thüringer  Wald  (Thomas
1979;  Hähnel  et  al.  1995)  and  80 °C  for  barite  from  Kams-
dorf  region  (Kling  1995).  In  our  work,  we  have  measured
a  wide  spread  of  homogenization  temperatures  between  65
to  166 °C  in  all  barite  samples  (Fig. 9).  Hence,  we  observe
a  monotonous  decrease  of  the  fluid  temperatures  from

Sample Locality Host

rock

V-CDT

V-SMOW

(‰) (‰)

barite in the siderite-barite-fluorite mineralization

KAM

Kamsdorf

Zechstein sedimentary rocks

13.6

14.8

KAM

Kamsdorf

Zechstein sedimentary rocks

14.0

14.7

KAM

Kamsdorf

Zechstein sedimentary rocks

12.8

13.9

Geh

Gehren

Rotliegend volcanics and sediments

9.3

12.2

25312 Friedrichsroda Rotliegend volcanics and sediments

15.4

13.1

Hüb 6

Trusetal

crystalline basement

12.2

12.4

Bhüb

Trusetal

crystalline

basement

13.2

12.7

barite in the Mn-Fe mineralization

EgS8b

Öhrenstock

Permian volcanoclastic rocks

9.9

14.6

EgS9c

Öhrenstock

Permian volcanoclastic rocks

9.5

9.1

EgS17c

Arlesberg

Permian rhyolites

8.7

12.2

EgS17g

Arlesberg

Permian rhyolites

7.9

13.1

anhydrite

Hühn

Trusetal

crystalline

basement

10.4

12.1

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134—163 °C to about 70 °C with constant salinity, only locally
modified by mixing with low-salinity fluids during precipi-
tation of the latest mineral, namely barite. The fluids respon-
sible for the precipitation of siderite, calcite, fluorite, and
barite were CaCl

-NaCl brines (Table 1). In terms of compo-

sition  and  temperature,  we  know  little  about  the  fluids  that
deposited  the  Mn  mineralization.  The  data  presented  here
were  measured  in  calcite  and  barite  which  accompany  the
Mn  minerals  but  not  in  the  Mn  minerals  themselves.  Our
attempts to observe fluid inclusions in the Mn minerals with
infrared microscopy failed.

The

S values of our barite samples vary between 9.3

and 15.4 ‰, a range typical of Upper Permian (Zechstein)
and Triassic evaporitic rocks (Fig. 11), which fall between

9.7  and  12.6 ‰  in  the  Zechstein  evaporites  and  12.2  to
20.8 ‰ in the Triassic evaporites (Kramm & Wedepohl 1991;
Kampschulte  et  al.  1998).  Hence,  most  of  the  dissolved  sul-
phate in the hydrothermal fluids was derived from groundwa-
ter  and/or  seawater  that  had  interacted  with  the  evapo-rites
(Wagner  et  al.  2010).  Barite  with  more  positive

S values

than the average Zechstein sulphates could be explained by a
contribution of sulphates from Triassic evaporites.

The isotopic composition of the fluids (for

O relative to

V-SMOW), calculated (after Zheng 1999) from the isotopic
composition of the minerals and the homogenization tempe-
ratures  of  fluid  inclusions,  is  4.3  to  13.5 ‰  for  calcite  and
10.8  to  5.6 ‰  for  barite.  These  values  suggest  that  barite
and  calcite  could  not  have  precipitated  from  the  same  fluid.
The isotopic composition of the fluid that precipitated barite
is close to the sea water in the entire Permo-Mesozoic time
span  whereas  calcite  is  isotopically  distinctly  heavier,  as  if
the  fluids  were  affected  by  evaporation.  Further  work
is  needed  in  order  to  interpret  the  isotopic  data  with  more
confidence.

Relative timing of the observed mineralizations

Within the mineralizations studied in this work, the rela-

tive timing is relatively easy to establish. We observed two
distinct assemblages with sequences:

1. siderite+ankerite-calcite-fluorite-barite
2. hematite-hausmannite-manganite-braunite-pyrolusite-
calcite-barite.

Here we neglect the minor sulphides and products of

weathering. There are several observations which will be criti-
cal for the following discussion. First, the geochemistry of the
earlier  stages  of  both  assemblages  (siderite+ankerite)  versus
(hematite-hausmannite-manganite-braunite-pyrolusite)  is  very
similar  and  we  consider  these  earlier  stages  of  the  two  as-
semblages  to  be  coeval.  These  stages  are  both  Mn-Fe  rich.
Siderite  and  ankerite  are  restricted  mostly  to  metasomatic
bodies in the Upper Permian Zechstein rocks, the oxide and
silicate Mn-Fe minerals to the Permian volcanic or volcano-
clastic rocks (Fig. 6). In the case of the Mn-Fe oxide-silicate
assemblage, we see spatial separation of the Fe-rich portions
(dominated  by  hematite)  and  Mn-rich  portions  (dominated
by  Mn  oxides  and  braunite).  This  observation  suggests  that
both metals (Fe and Mn) were originally reduced in the fluid
and then separated by redox gradients.

The second interesting observation is that barite is rela-

tively young in both mineralizations. In hand specimens,
barite and Mn minerals are intergrown and barite seems to be
both older and younger than some Mn minerals. This observa-
tion indicates either remobilization of Mn minerals during
deposition of barite or multiple barite generations. Fluid in-
clusion and isotopic data suggest that the fluids responsible
for barite in both assemblages were very similar.

Post-Variscan evolution of fluids in the Thuringian Basin

The post-Variscan fluids and the associated mineralizations

in the Thuringian Basin can be correlated with the processes
which operated in the thick Permian siliciclastic sequence

Fig. 12.  Isotopic  composition  of  the  carbonates  from  the  studied
mineralizations  (large  open  circles),  compared  to  Triassic  lime-
stones  (Muschelkalk,  inverted  open  triangles,  Lippmann  et  al.
2005), Zechstein calcite (west Poland, small open circles, Peryt et
al. 2010), Zechstein dolomite (west Poland, open diamonds, Peryt
et  al.  2010),  and  hydrothermal  mineralizations  from  Schwarzwald
(small black diamonds, Schwinn et al. 2006). Furthermore showing
the  data  from  the  Northeast  German  basin  (all  data  from  Wolf-
gramm  2002):  Mesozoic  rocks  (grey  circles),  Rotliegend  (grey
squares),  Permian  volcanic  rocks  (grey  triangles),  Zechstein  (grey
crosses), Carboniferous rocks (grey stars)

Table 3: Carbon and oxygen isotopic data of hydrothermal carbo-
nates from Öhrenstock. These veins are hosted by Permian volcanic
rocks.

sample description

(cc=calcite) δ

V-PDB

V-SMOW

(‰)

EGS 7h

black cc

–7.2

21.8

EGS 7o

black and white cc

–4.6

22.6

EGS 8a

black cc

–7.9

21.9

EGS 8d

white cc

–3.8

27.8

EGS 8g

white cc

–3.8

26.9

EGS 10b

white cc

–5.1

25.6

EGS 10b

black cc

–3.8

26.3

EGS 10c

white cc

–2.5

27.1

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called  Rotliegend  (Fig. 13a).  The  properties  of  the  fluids
which  co-existed  with  these  sediments  throughout  post-
Variscan  Europe  in  the  geological  past  were  determined  by
the  investigation  of  the  mineralogical  and  geochemical
changes  in  these  sediments  (Gaupp  &  Okkerman  2011)
(Fig. 13a).  The  information  about  these  fluids,  reported  be-
low,  draws  on  their  publication.  A  temperature  profile
through  the  geological  time  of  a  selected  Permian  stratum
(Kupferschiefer) in the area studied is presented in Fig. 13d.
We  must  stress  that  our  work  investigated  neither  the  Rot-
liegend  sediments  nor  their  evolution  in  space,  time,  and
chemical composition (including that of the fluids). We cor-
relate  the  data  from  these  sediments,  acquired  over  a  long
time by R. Gaupp and his co-workers, with our results from
the vein mineralizations in the area studied. Hence, the phy-
sico-chemical properties of the fluids and the mineralogy of
the  siliciclastic  sediments,  described  in  the  following  para-
graphs, refer to the fluids in the Rotliegend (Gaupp & Okker-
man 2011), unless stated otherwise.

Stage 1. Early diagenetic post-Variscan fluids were playa-

sediment fluids which circulated in the freshly deposited si-
liciclastic sediments of Rotliegend. These fluids were
alkaline and saturated with respect to sodium sulphate, car-
bonate, and chloride. The anion abundance also decreased in
the same order. The evidence for this character of the fluid
comes from the absence of feldspar alteration during the ear-
ly diagenesis. We assume that the alkaline nature of the fluids
enabled them to mobilize quartz in amounts that were larger
than in the later fluids. Evidence for mobilization of SiO

also traceable on the microscale as quartz overgrowths on
the detritic quartz grains in the sediments. Hence, these fluids
were at least initially oxidizing and precipitated quartz,
calcite+hematite instead of siderite.

Stage 2. The pH of the fluids in this stage has shifted to

mildly acidic. The acidification of the fluids was caused by
the  release  of  carboxylic  acids  from  the  organic  matter
(cf.  Spirakis  &  Heyl  1988)  released  from  the  Westphalian
carbonaceous sediments. The redox state shifted to reducing,
as  clearly  indicated  by  pervasive  chloritization  and  deposi-
tion of the Fe

-bearing carbonates within the pore spaces of

the siliciclastic rocks. The mildly acidic and reducing condi-
tions  are  ideal  for  the  mobilization  of  iron  and  manganese,
possibly  other  metals  and  metalloids,  from  the  Rotliegend.
This mobilization is documented by bleaching of the sedi-
ments (Fig. 13a) upon which they lost their typical red co-
lour  and  turned  beige  or  almost  white.  In  this  process,
hematite,  other  metal  oxides  and  the  elements  associated
with these mine-rals were dissolved in the pore fluids. We
further  subdivide  this  stage  into  two  parts  but  we  want  to
emphasize  that  these  two  substages  (2A  and  2B)  are  not
separated  in  time.  Instead,  they  are  separated  by  different
physico-chemical conditions of mineral precipitation.

Substage 2A. Where these fluids invaded the Zechstein

carbonates, they deposited the assemblage siderite+ankerite
in the form of metasomatic bodies and veins. Deposition of
the Fe

-bearing carbonates in the pores of the siliciclastic

sediments means that the fluids were saturated or supersatu-
rated with respect to these minerals already at the beginning
of stage 2. Hence, their injection into carbonate rocks with

associated pH buffering and increased CO

(aq) activity easily

led to the precipitation of siderite and ankerite. The interaction
with the carbonate Zechstein rocks appears to be of great im-
portance here. We recall the geological observation that
missing Zechstein sediments mean the absence of the side-
rite-ankerite bodies.

Substage 2B. Where the same fluids invaded Permian vol-

canic or volcanoclastic rocks, they became oxidized and pre-
cipitated  an  assemblage  of  hematite+Mn  oxides  and
braunite. Oxidation was an effective mechanism for the spa-
tial separation of Fe and Mn observed in the field. According
to  the  known  phase  equilibria,  Fe  oxidizes  first  and  hence
precipitates  first  as  hematite.  The  progressive  oxidation  is
further documented by the temporal relationships of the Mn
minerals. The precipitation starts with hausmannite (Mn

2+/3+

)

and manganite (Mn

), continues with braunite (silicate of

2+/3+

) and ends with massive precipitation and replace-

ment of pre-existing minerals by pyrolusite (Mn

We must note that rhyolites (or their volcanoclastic

equivalents)  must  have  played  a  special  role  in  the  deposi-
tion  of  the  oxidized  Mn  mineralization.  They  host  the  Mn
minerals  in  the  Thüringer  Wald  (cf.  Fig. 6)  but  also  in  the
Harz Mts. (Liessmann 2010) or in the Spessart Mts. (Wagner
et al. 2010; Fusswinkel et al. 2013, 2014). Hence, this close
spatial relationship cannot be overlooked and must be taken
into  account  when  one  looks  for  an  explanation  for  the  ob-
served  mineralizations.  The  source  of  manganese  for  the
studied  deposits  in  the  Thüringer  Wald  was  sought  in  the
acidic volcanic rocks (Freyberg 1923; Meinel 1993) or in the
Zechstein Permian sediments (Zimmermann 1924). The Per-
mian  volcanic  rocks,  however,  are  by  no  means  more  en-
riched  in  manganese  than  the  siliciclastic  sediments  and,
therefore,  their  role  in  the  formation  of  the  Mn  mineraliza-
tion must be sought elsewhere. We feel that the ideas presented
here do excellently in this respect.

Stage 3. After bleaching of the sandstones, a major illitiza-

tion event took place (Fig. 13a), dated to middle Jurassic (ac-
cording to K/Ar dating, Fig. 13b). Illite formed mainly at the
expense of feldspars which released a substantial amount of
Na, Ca, and Ba into the solution. The released potassium was
bound in illite. These fluids formed convection cells within
the Rotliegend sequence capped by the Zechstein sediments
(cf.  Jowett  1986).  In these convection cells, calcite and later
barite  were  precipitating.  In  the  vicinity  of  the  crystalline
basement  of  Thüringer  Wald  or  Thüringer  Schiefergebirge,
the  fluids  were  also  enriched  in  fluorine  and  precipitated
fluorite. Fluorine was transported in the low-temperature, sa-
line  hydrothermal  fluid  in  the  form  of  Ca-F,  Na-F  or  Mg-F
complexes (Richardson & Holland 1979) or complexes with
organic ligands (Bouabdellah et al. 2013). The  presence of
organic matter can be assumed with a great certainty because
the  siliciclastic  sediments  were  in  the  oil  window  and  are
known  to  be  a  fertile  source  of  hydrocarbons.  There  was
a  limited  and  local  communication  with  low-salinity  waters,
documented by a large scatter of fluid inclusion data in some
barite  samples  (especially  in  Kamsdorf).  Calcite-barite±fluo-
rite  mineralization  accompanies  both  siderite+ankerite  and
Mn oxide-braunite assemblages and appears to be of regional
importance. This type of mineralization is developed similarly

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in the Zechstein sediments and the Permian volcanic/volcano-
clastic rocks. This is logical because in this mineralization
(i.e., calcite, barite, fluorite), there is little to oxidize or reduce.

Barite is connected without doubt to the extensional period

that is manifested in the tectonic record not only in the Thu-
ringian  basin  but  also  everywhere  in  the  central  European
sedimentary basin. The assignment of   barite to the exten-
sional  phase  is  based  on  our  structural  data  (Figs. 3, 4),
which  show  that  the  barite  veins  occupy  the  extensional
structures and are cut and offset by the later contractional de-
formation.  According  to  the  observations  from  the  North
German Basin, the main period of NE—SW extension lasted
from  Late  Jurassic  to  Early  Cretaceous  times  (Betz  et  al.
1987; Ziegler 1987; Kockel 2002) and, therefore, the barite
mineralization  must  be  placed  in  the  time  interval  between
the Middle Jurassic and Early Cretaceous.

It is intriguing that the large-scale illitization coincides in

time  with  a  major  crustal  thermal  and  hydrothermal  event,
rifting  with  enhanced  heat  flow,  assumed  to  occur  at  ~195—
175 Ma  (Fig. 13c,  Zielinski  et  al.  2012).  This  event  initiated
convective heat transfer within the siliciclastic rocks. The con-
vection cells were capped by the Zechstein evaporitic sequences.

Conclusions

Considering the mineralogy of the localities studied, the

precipitation sequence, and the temperatures determined by

fluid  inclusions  studied,  a  link  may  be  found  between  the
fluid  evolution  in  the  siliciclastic/volcanic  Rotliegend  sedi-
ments  (as  determined  by  earlier    petrological  studies  by
Gaupp & Okkerman 2011; Peisker et al. 2014; etc.) and the
ore mineralizations. There is no doubt that further work must
be done to test the ideas presented in this work. The correla-
tion  between  the  two  independent  data  sets,  however,  pro-
vides a striking parallel in terms of the fluid evolution in the
siliciclastic  sediments  and  hydrothermal  veins  in  the  area
studied.  Iron  and  manganese  could  have  been  mobilized
during the bleaching of the sediments by reduced Rotliegend
fluids.  Iron  and  manganese  were  deposited  as  siderite+
ankerite  within  the  Zechstein  carbonate  rocks  and  as
hematite+Mn oxides within the oxidizing environment of the
Permian volcanic and volcanoclastic rocks. A Middle-Jurassic
illitization event released Ca, Na, Ba, and Pb from the feld-
spars  and  Cu,  Zn  from  the  mafic  minerals  into  the  basinal
brines.  Calcium  and  barium  precipitated  as  massive  carbo-
nate-barite veins.

Acknowledgements: We thank an anonymous reviewer and
J. Zachariáš for their comments and suggestions that signifi-
cantly clarified, improved and shortened an earlier version of
this manuscript. We are grateful to R. Gaupp for fruitful and
inspiring discussions about the Rotliegend  rocks,  B.  Kreher-
Hartmann  (Jena),  V.  Morgenroth  (Schmalkalden)  and
H. Huckriede (Weimar) for helping us to localize and collect
samples.  We  also  wish  to  thank  K.  Berger  (Kamsdorf),

Fig.13. a – Summary and timing of processes (precipitation and dissolution of minerals) which operated in the Permian Rotliegend rocks
(after Gaupp & Okkerman, their fig.2); b – A histogram of K-Ar model ages of illite formation from the German Rotliegend rocks (after
Gaupp & Okkerman, their fig.9a); c – the age of the widespread early to mid-Jurassic hydrothermal event that affected the Rotliegend
rocks (Zielinski et al. 2012); d – the temperature profile of the Kupferschiefer layer in the Thuringian basin (after Peisker et al. 2013).

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R.  Storch  (Trusetal),  and  F.  Veitenhansl  (Erfurt)  for  giving
us  access  to  the  old  mines,  unpublished  reports,  and  their
knowledge. We thank F. Haubrich (Freiberg) for stable iso-
tope analysis at the   laboratory at the TU Bergakademie in
Freiberg  and  his  unpublished  isotopic  data  from  sulphide
minerals from Kamsdorf. Additional thanks go to K. Siewert
(Jena)  and  M.  Sattler  (Jena)  for  their  help  with  microther-
mometry  measurement.  We  are  grateful  to  J.  Kley  (Jena)
for  assistance  with  the  structural  measurements  and  his
constructive  critical  comments.  This  work  is  a  part  of
INFLUINS,  a  research  project  (03IS2091A)  funded  by  the
program of “Spitzenforschung und Innovation in den Neuen
Ländern”  from  the  German  Federal  Ministry  of  Education
and Research (BMBF) whose financial assistance is gratefully
acknowledged.

References

Andreas D., Kästner H., Seidel G., Wiefel H. & Wunderlich J.

1996: Geologische Karte Thüringer Wald 1:100,000. Thüringer
Landesamt für Geologie, Weimar.

Baatartsogt B., Schwinn G., Wagner T., Taubald H., Beitter T. &

Markl G. 2007: Contrasting paleofluid systems in the conti-
nental basement: a fluid inclusion and stable isotope study of
hydrothermal vein mineralization, Schwarzwald district, Ger-
many. Geofluids 7, 123—147.

Bakker R.J. 2009: Package FLUIDS. Part 3: correlations between

equations of state, thermodynamics and fluid inclusions. Geo-
fluids 9, 63—74.

Baumann L. & Leeder O. 1969: Paragenetische Zusammenhänge

der mitteleuropäischen Fluorit-Baryt-Lagerstätten. Freiberger
Forschung Hefte C 266, 89—99.

Behr H.J. & Gerler J. 1987: Inclusions of sedimentary brines in

post-Variscan mineralizations in the Federal Republic of Ger-
many – a study by neutron activation analysis. Chem. Geol.
61, 65—77.

Benkó Z., Molnár F., Lespinasse M., Billström K., Pécskay Z. &

Németh  T.  2014:  Triassic  fluid  mobilization  and  epigenetic
lead-zinc  sulphide  mineralization  in  the  Transdanubian  Shear
Zone (Pannonian Basin, Hungary). Geol. Carpathica 65,   177—194.

Betz D., Führer F. & Plein E. 1987: Evolution of the lower Saxony

basin. Tectonophysics 137, 127—170.

Beyschlag F. 1988: Die Erzlagerstätten in der Umgebung von

Kamsdorf in Thüringen. Jb. Preußisch Geol. Landesanst. 9,
329—377.

Boness M., Haack U. & Feldmann K.H. 1990: Rb/Sr-Datierung der

hydrothermalen Pb-Zn-Vererzung von Bad Grund (Harz),
BRD. Chem. Erde-Geochem. 50, 1—25.

Boni M., Balassonem G., Fedele L. & Mondillo N. 2009: Post-

Variscan hydrothermal activity and ore deposits in southern
Sardinia (Italy): selected examples from Gerrei (Silius vein
system) and the Iglesiente district. Period. Mineral. 78, 19—35.

Bouabdellah M., Castorina F., Bodnar R.J., Banks D., Jébrak M.,

Prochaska W., Lowry D., Klügel A. & Hoernle K. 2013: Petro-
leum migration, fluid mixing, and halokinesis as the main ore-
forming processes at the Peridiapiric Jbel Tirremi
fluorite-barite hydrothermal deposit, northeastern Morocco.
Econ. Geol. 108, 1223—1256.

Brey-Funke M. 2014: Mineralisierte Fluide im Thüringer Becken.

PhD Dissertation, Friedrich-Schiller University of Jena, 1—189.

Brosin P. & Veitenhansl F. 2005: Ausgewählte montangeologische,

bergtechnische und bergrechtliche Aspekte in der Geschichte
des Arlesberger Manganerzbergbaues. Beiträge Zur Geologie

Von Thüringen 2005, 167—187.

Canals A. & Cardellach E. 1993: Strontium and sulfur isotope

geochemistry of low-temperature barite-fluorite veins of the
Catalonian Coastel Ranges (NE-Spain) – a fluid mixing
model and age constraints. Chem. Geol. 104, 269—280.

Charef A. & Sheppard S.M.F. 1988: The Malines Cambrian carbo-

nate-shale-hosted Pb-Zn deposit, France: Thermometric and
Isotopic (H, O) evidence for pulsating hydrothermal minera-
lization. Miner. Deposita 23, 86—95.

Clark I.D. & Fritz P. 1997: Environmental Isotopes in Hydrogeology.

CRC Press, 1—352.

Crespo T.M., Delgado A., Vindel Catena E., López García J.A. &

Fabre C. 2002: The latest post-Variscan fluids in the Spanish
Central System: evidence from fluid inclusion and stable iso-
tope data. Mar. Petrol. Geol. 19, 323—337.

Davis D.W., Lowenstein T.K. & Spencer R.J. 1990: Melting beha-

vior of fluid inclusions in laboratory grow halite crystals in the
system NaCl-H

O, NaCl-KCl-H

O, NaCl-MgCl

-H

O and

NaCl-CaCl

-H

O. Geochim. Cosmochim. Acta 54, 591—601.

Ding T., Valkiers S., Kipphardt H., DeBievre P., Taylor P.D.P.,

Gonfiantini R. & Krouse R. 2001: Calibrated sulfur isotope
abundance ratios of three IAEA sulfur isotope reference mate-
rials and V-CDT with reassessment of the atomic weight of
sulfur. Geochim. Cosmochim. Acta 65, 2433—2437.

Förster H.J. & Romer R.L. 2010: Carboniferous magmatism. In

Linnemann U. & Romer R.L. (Eds.): Pre-Mesozoic Geology of
Saxo-Thuringia-From the Cadomian Active Margin to the
Variscan Orogen. Schweizbart, Stuttgart, 287—308.

Fournier R.O. & Truesdell A.H. 1973: An empirical Na-K-Ca-

chemical geothermometer for natural waters. Geochim. Cosmo-
chim. Acta 37, 1255—1275.

Franzke H.J. 1992: Bruchprozesse an der Floßberg-Störung bei

Ilmenau im Thüringer Wald. Geol. Bl. NO-Bayern 42, 69—84.

Franzke H.J. & Schiemenz F. 1980: Die Bruchkinematik des

Floßberg-Stechberg-Gangsystems bei Ilmenau im Thüringer
Wald. Z. Angew. Geol. 26, 547—554.

Franzke H.J., Kapelle G. & Rölling G. 1982: Flächentrendanalyse

der Hauptstörungsebene des Floßberg-Stechberg-Mineralgang-
systems bei Ilmenau/Thüringer Wald. Z. Angew. Geol. 28,
73—76.

Franzke H.J., Ahrendt H., Kurz S. & Wemmer K. 1996: K-Ar

Datierungen von Illiten aus Kataklasiten der Floßbergstörung
im südöstlichen Thüringer Wald und ihre geologische Interpre-
tation. Z. Geol. Wiss. 24, 441—456.

Freyberg B. 1923: Erz- und Minerallagerstätten des Thüringer

Waldes. Verlag von Gebrüder Borntrager, 97—119.

Fusswinkel T., Wagner T., Wenzel T., Wälle M. & Lorenz J. 2013:

Evolution of unconformity-related Mn-Fe-As vein mineraliza-
tion, Sailauf (Germany): Insight from major and trace elements
in oxide and carbonate minerals. Ore Geol. Rev. 50, 28—51.

Fusswinkel T., Wagner T., Wenzel T., Wälle M. & Lorenz J. 2014:

Red bed and basement sourced fluids recorded in hydrothermal
Mn-Fe-As veins, Sailauf (Germany): A LA-ICPMS fluid in-
clusion study. Chem. Geol. 363, 22—39.

Galindo C., Tornos F., Darbyshire D.P.F. & Casquet C. 1994: The

age and origin of the barite-fluorite (Pb-Zn) veins of the Sierra
del Guadarrama (Spanish Central System, Spain): a radiogenic
(Nd, Sr) and stable isotope study. Chem. Geol. 112, 351—364.

Gaupp R. & Okkerman J.A. 2011: Diagenesis and reservoir quality

of Rotliegend sandstones in the northern Netherlands – a re-
view. In: Grötsch J. & Gaupp R. (Eds.): The Permian Rotlie-
gend of The Netherlands. SEPM Spec. Publ. 98, 193—226.

Genter A., Evans K., Cuenot N., Fritsch D. & Sanjuan B. 2010:

Contribution of the exploration of deep crystalline fractured
reservoir of Soultz to the knowledge of enhanced geothermal
systems (EGS). C. R. Geosci. 342, 502—516.

FLUIDS EVOLUTION AND MN-FE-BARITE-FLUORITE MINERALIZATIONS, GERMANY

GEOL

EOL

EOLOGICA CARPA

OGICA CARPA

OGICA CARPATHICA

THICA

THICA, 2016, 67, 1, 3—20

Giesemann A., Jäger H.J., Norman A.L., Krouse H.R. & Brand

W.A. 1994: On-line sulfur isotope determination using an ele-
mental analyzer coupled to a mass spectrometer. Anal. Chem.
66, 2816—2819.

Gleeson S.A., Wilkinson J.J., Shaw H.F. & Herrington R.J. 2000:

Post-magmatic hydrothermal circulation and the origin of base
metal mineralization, Cornwall, U.K. J. Geol. Soc. (London)
157, 580—600.

Hähnel R., Hähnel C., Mädler J., Meinel G. & Wunderlich J. 1995:

Strukturelle und stoffliche Entwicklung der anhydritführenden
Karbonat-Baryt-Fluorit-Assoziation in der Lagerstätte Hühn
(Nordwestlicher Thüringer Wald). Geol. Jb. Hessen 123, 5—24.

Halliday A.N. & Mitchell J.G. 1984: K-Ar ages of clay-size con-

centrates from the mineralisation of the Pedroches Batholitz,
Spain, and evidence for Mesozoic hydrothermal activity asso-
ciated with the breakup of Pangaea. Earth Planet. Sci. Lett. 68,
229—239.

Heijlen W., Muchez P.H., Banks D.A., Schneider J., Kucha H. &

Keppens E. 2003: Carbonate-hosted Zn-Pb deposits in Upper
Silesia, Poland: origin and evolution of mineralizing fluids and
constraints on genetic models. Econ. Geol. 98, 911—932.

Hurai V., Huraiová M., Slobodník M. & Thomas R. 2015: Geo-

fluids. Developments in Microthermometry, Spectroscopy,
Thermodynamics, and Stable Isotopes. Elsevier, 1—472.

Hurai V., Harčová E., Huraiová M., Ozdín D., Prochaska W. &

Wiegerová V. 2002: Origin of siderite veins in the Western
Carpathians I. P-T-X-

C-

O relations in ore-forming

brines of the Rudňany deposits. Ore Geol. Rev. 21, 67—101.

Hurai V., Prochaska W., Lexa O., Schulmann K., Thomas R. & Ivan

P. 2008: High density nitrogen inclusions in barite from a giant
siderite vein: implications for Alpine evolution of the Variscan
basement of Western Carpathians, Slovakia. J. Metamorph.
Geology 26, 487—498.

Johnson C.A., Cardellach E., Tritlla J. & Hanan B.B. 1996: Cierco

Pb-Zn-Ag vein deposits: isotopic and fluid inclusion evidence
for formation during the Mesozoic extension in the Pyrenees of
Spain. Econ. Geol. 91, 497—506.

Jowett E.C. 1986: Genesis of Kupferschiefer Cu-Ag deposits by

convective flow of Rotliegendes brines during Triassic rifting.
Econ. Geol. 81, 1823—1837.

Kampschulte A., Buhl D. & Strauss H. 1998: The sulfur and stron-

tium isotopic composition of Permian evaporites from the
Zechstein basin, northern Germany. Geol. Rdsch. 87, 192—199.

Kießling T. 2007: Die Flussspatgewinnung bei Ilmenau im

Thüringer Wald. Bergbau 3, 112—120.

Klemm W. 1986: Beiträge zur analytischen Geochemie von Gas-

Flüssigkeits-Einschlüssen hydrothermaler Minerale. Disserta-
tion B, TUBA Freiberg, 1—72.

Kley J. & Voigt T. 2008: Late Cretaceous intraplate thrusting in

central Europe: Effect of Africa-Iberia-Europe convergence,
not Alpine collision. Geology 36, 839—842.

Kling M. 1995: The ankerite-siderite-sulphide-barite deposit of

Kamsdorf  (Thuringia,  Germany).  In:  Pašava  J.,  Kříbek  B.  &
Žák K. (Eds.): Mineral Deposits: From their origin to their en-
vironmental  impacts.  Proceedings  of  the  Third  Biennal  SGA
Meeting,  Prague/Czech  Republic,  Balkema,  Rotterdam,
275—276.

Kockel F. 2002: Rifting processes in NW-Germany and the German

North Sea Sector. Geologie en Mijnbouw 81, 149—158.

Kornexl B.E., Gehre M., Höfling R. & Werner R.A. 1999: On-line

O measurement of organic and inorganic substances. Rapid

Commun. Mass Spectrom. 13, 1685—1693.

Krahn L. & Baumann A. 1996: Lead isotope systematics of epige-

netic lead-zinc mineralization in the western part of the Rheini-
sches Schiefergebirge, Germany. Miner. Deposita 31,
225—237.

Kramm U. & Wedepohl K.H. 1991: The isotopic composition of

strontium and sulfur in seawater of late Permian (Zechstein)
age. Chem. Geol. 90, 253—262.

Kučera J., Muchez P., Slobodník M. & Prochaska W. 2010:

Geochemistry of highly saline fluids in siliciclastic sequences:
genetic implications for post-Variscan fluid flow in the Mora-
vosilesian Palaozoic of the Czech Republic. Int. J. Earth Sci.
99, 269—284.

Kuschka E. & Franzke H.J. 1974: Zur Kenntnis der Hydrother-

malite des Harzes. Z. Geol. Wiss. 2, 1417—1436.

Lahiry A.K. 1974: Untersuchungen an Flüssigkeitseinschlüssen zur

Klärung der paragenetischen Verhältnisse am Beispiel saxoni-
scher Lagerstätten. Freiberger Forschung Hefte C 302, 1—95.

Leach D.L., Viets J.G., Kozlowski A. & Kibitlewski S. 1996: Geology,

geochemistry and genesis of the Silesia-Cracow zinc-lead dis-
trict, southern Poland. Econ. Geol. Spec. Pap. 4, 70—144.

Liessmann W. 2010: Historischer Bergbau im Harz. Springer,

1—470.

Lippmann R., Voigt T., Lützner H., Baunack C. & Föhlisch K.

2005: Geochemische Zyklen im Unteren Muschelkalk (Typus-
profil der Jena Formation, Steinbruch Steudnitz). Z. Geol.
Wiss. 331, 27—50.

Loos G., Saupe M., Mädler U. & Meinel G. 1981: Beitrag zur

Klärung der epithermalen Fluoritgenese mit Hilfe der
Spurenelementanalyse. Z. Geol. Wiss. 27, 567—573.

Lüders V. & Möller P. 1992: Fluid evolution and ore deposition in

the Harz Mountains (Germany). Eur. J. Mineral. 4, 1053—1068.

McGaig A.M., Tritlla J. & Banks D.A. 2000: Fluid mixing and re-

cycling during Pyrenean thrusting: Evidence from fluid inclu-
sion halogen ratios. Geochim. Cosmochim. Acta 19,
3395—3412.

Meinel G. 1993: Die Bildung der Gangmineralisationen Thürin-

gens. Geowiss. Mitt. Thüringen Beih. 1, 1—111.

Mertz D.F., Lippolt H.J. & Schnorrer-Köhler G. 1989: Early Creta-

ceous mineralizing activity in the St. Andreasberg ore district
(Southwest Harz, Federal Republic of Germany). Miner. Depo-
sita 24, 9—13.

Meyer M., Brockamp O., Clauer N., Renk A. & Zuther M. 2000:

Further  evidence  for  a  Jurassic  mineralizing  event  in  central
Europe:  K-Ar  dating  of  hydrothermal  alteration  and  fluid  in-
clusion  systematics  in  wall  rocks  of  the  Käfersteige  fluorite
vein  deposit  in  the  northern  Black  Forest,  Germany.  Miner.
Deposita 35, 754—761.

Muchez P., Heijlen W., Banks D., Blundell D., Boni M. & Grandia

F. 2005: Extensional tectonics and the timing and formation of
basin-hosted deposits in Europe. Ore Geol. Rev. 27, 241—267.

Munoz M. & Premo W.R. 2005: Sm-Nd dating of fluorite from the

worldclass Montroc fluorite deposit, southern Massif Central,
France. Miner. Deposita 39, 970—975.

Munoz M., Boyce A.J., Courjault-Rade P., Fallick A.E. & Tollon F.

1994: Multi-stage fluid incursion in the Palaeozoic basement-
hosted Saint-Salvy ore deposit (NW Montagne Noire, southern
France). Appl. Geochem. 9, 609—626.

Naden J. 1996: Calcic Brine; a Microsoft Excel 5.0 add-in for cal-

culating salinities from microthermometric data in the system
NaCl-CaCl

-H

O. In: Brown P.E. & Hagemann S.G. (Eds.):

PACROFI VI. University of Wisconsin, Madison, WI, 87—89.

Nitschke F., Scheiber J., Kramar U. & Neumann T. 2014: Forma-

tion of alternating layered Ba-Sr-sulfate and Pb-sulfide scaling
in the geothermal plant of Soultz-sous-Forêts. Neu. Jb. Mineral.
Abh. 191, 2, 145—156.

O’Reily C.O., Jenkin G.R.T., Feely M., Alderton D.H.M. & Fallick

A.E. 1997: A fluid inclusion and stable isotope study of 200
Ma of fluid evolution in the Galway Granite, Connemara,
Ireland. Contr. Mineral. Petrology 129, 120—142.

Peisker J., Voigt T., Aehnelt M. & Köster J. 2013: Rekonstruktion

MAJZLAN, BREY-FUNKE, MALZ, DONNDORF and MILOVSKÝ

GEOL

EOL

EOLOGICA CARPA

OGICA CARPA

OGICA CARPATHICA

THICA

THICA, 2016, 67, 1, 3—20

Subías I. & Fernández-Nieto C. 1995: Hydrothermal events in the

Valle de Tena (Spanish Western Pyrenees) as evidenced by
fluid inclusions and trace-element distribution from fluorite
deposits. Chem. Geol. 124, 267—282.

Symons D.T.A., Kawasaki K., Walther S. & Borg G. 2011: Paleo-

magnetism of the Cu-Zn-Pb-bearing Kupferschiefer black
shale (Upper Permian) at Sangerhausen, Germany. Miner.
Deposita 46, 137—152.

Thomas R. 1979: Untersuchungen von Einschlüssen zur thermody-

namischen und physikochemischen Charkteristik lagerstätten-
bildender Lösungen und Prozesse im magmatischen und
postmagmatischen Bereich. Dissertation A, TUBA Freiberg,
1—245.

Toth J.R. 1980: Deposition of submarine crusts rich in manganese

and iron. Bull. Geol. Soc. Am. 91, 44—54.

Ullrich M.R. & Bodnar R.J. 1987: Systematics of stretching of fluid

inclusions II: Barite at 1 atm confining pressure. Econ. Geol.
83, 1037—1046.

Verma S.P. & Santoyo E. 1997: New improved equations for Na/K,

Na/Li and SiO

geothermometers by outlier detection and

rejection. J. Volcanol. Geotherm. Res. 79, 9—23.

Wagner T. & Lorenz J. 2002: Mineralogy of complex Co-Ni-Bi

vein mineralization, Bieber deposit, Spessart, Germany. Mine-
ral. Mag. 66, 385—407.

Wagner T., Okrusch M., Weyer S., Lorenz J., Lahaye Y., Taubald

H. & Schmitt R.T. 2010: The role of the Kupferschiefer in the
formation of hydrothermal base metal mineralization in the
Spessart ore district, Germany: insight from detailed sulfur
isotope studies. Miner. Deposita 45, 217—239.

Werner C.D. 1958: Geochemie und Paragenese der saxonischen

Schwerspat-Flußspat-Gänge im Schmalkaldener Revier.
Freiberger Forschung Hefte C 47, 7—110.

Wickham S.M. & Taylor H.P. 1990: Hydrothermal systems associa-

ted with regional metamorphism and crustal anatexis: Example
from the Pyrenees, France. In: Geophysics Study Committee:
The role of fluids in crustal processes. National Academy
Press, 96—112.

Wucher K., Steinmüller A. & Puff P. 2001: Geologische Karte von

Thüringen 1:25,000; 5334 Saalfeld (Saale). 3

edition, TLUG,

Jena.

Zeh A. & Thomson S.N. 2000: Fission-track thermochronology of

the Ruhla Crystalline Complex: new contraints on the post-
Variscan thermal evolution of the NW Saxo-Bohemian Massif.
Tectonophysics 324, 17—35.

Zheng Y.-F. 1999: Oxygen isotope fractionation in carbonate and

sulfate minerals. Geochemical J. 33, 109—126.

Zheng Y.-F. & Hoefs J. 1993: Stable isotope geochemistry of hy-

drothermal mineralizations in the Harz Mountains. II. Sulfur
and oxygen isotopes of sulfides and sulfate and constraints on
metallogenetic models. In: Möller P. & Lüders V. (Eds.): For-
mation of hydrothermal vein deposits. Monogr. Ser. Min.
Deps. 30, 211—230.

Ziegler P.A. 1987: Late Cretaceous and Cenozoic intra-plate com-

pressional deformations in the Alpine Foreland – a geody-
namic model. Tectonophysics 137, 389—420.

Zieliński G.W., Poprawa P., Szewczyk J., Grotek I., Kiersnowski

H. & Zieliński R.L.B. 2012: Thermal effects of Zechstein salt
and the Early to Middle Jurassic hydrothermal event in the
central Polish Basin. AAPG Bulletin 96, 1981—1996.

Zimmermann E. 1914: Erläuterungen zur Geologischen Karte von

Preussen und benachbarten Bundesstaaten 1:25,000; Blatt
Saalfeld a. Saale. Königlich Preußischen Geol. Landesanst.,
Berlin.

der Versenkungsgeschichte des zentralen Thüringer Beckens
mit Inkolhungswerten aus dem Kupferschiefer. Beitr. Geol.
Thüringen 20, 121—137.

Piqué A., Canals A., Grandia F. & Banks D.A. 2008: Mesozoic

fluorite veins in NE Spain record regional base metal-rich
brine circulation through basin and basement during extensio-
nal events. Chem. Geol. 257, 139—152.

Pratzka G. 1956: Lagerstättengeologische Bearbeitung der Schwer-

spat- Flußspatlagerstätten in der Umgebung von Trusetal/Thür.
Diploma Thesis, Bergakademie Freiberg, 1—88.

Rauche H. & Franzke H.J. 1990: Stress field evolution at the northern

part of the South German Block on the territory of the GDR.
Gerlands Beitr. Geophysik 99, 441—461.

Richardson C.K. & Holland H.D. 1979: The solubility of fluorite in

hydrothermal solutions, an experimental study. Geochim. Cosmo-
chim. Acta 43, 1313—1325.

Roedder E. 1984: Fluid inclusions. Rev. Mineralogy 12, 1—604.
Rüger F. & Decker H. 1992: Bergbaugeschichte, Geologie und

Mineralien des Saalfeld-Kamsdorfer Bergreviers. Veröff.
Museum Gera, Naturw. Reihe 19, 1—70.

Scheiber J., Nitschke F., Seibt A. & Genter A. 2012: Geochemical

and mineralogical monitoring of the geothermal power plant in
Soultz-sous-Forêts (France). In: Proceedings of the Thirty-
Seventh Workshop on Geothermal Reservoir Engineering.
Stanford University, SGP-TR-194.

Schmidt-Mumm A. & Wolfgramm M. 2004: Fluid systems and

mineralizations in the north German and Polish Basin. Geofluids
4, 315—328.

Schröder B. 1987: Inversion tectonics along the western margin of

the Bohemian Massif. Tectonophysics 137, 93—100.

Schröder N. 1970: Die magmatogenen Mineralisationen des

Thüringer Waldes und ihre Stellung im variszischen und saxo-
nischen Mineralisationszyklus Mitteleuropas. Freiberger For-
schung Hefte C 261, 7—52.

Schwinn G., Wagner T., Baatartsogt B. & Markl G. 2006: Quantifi-

cation of mixing processes in ore-forming hydrothermal sys-
tems by combination of stable isotope and fluid inclusion
analyses. Geochim. Cosmochim. Acta 70, 965—982.

Slobodnik M., Muchez P.H. & Viaene W. 1994: Variscan and Post-

Variscan fluid flow in the Rhenohercynicum of the Ardennes
(southern Belgium) and in the eastern part of the Bohemian
Massif. J. Czech Geol. Soc. 39, 106—107.

Spencer R.J., Möller N. & Weare J.H. 1990: The prediction of mi-

neral solubilities in natural waters: a chemical equilibrium
model for the Na-K-Ca-Mg-Cl-SO

-H

O systems at the tempe-

ratures below 25 °C. Geochim. Cosmochim. Acta 54, 575—590.

Spirakis C.S. & Heyl A.V. 1988: Possible effects of thermal degra-

dation of organic matter on carbonate paragenesis and fluorite
precipitation in Mississippi Valley-type deposits. Geology 16,
1117—1120.

Staude S., Wagner T. & Markl G. 2007: Mineralogy, mineral com-

positions and fluid evolution at the Wenzel hydrothermal de-
posit, southern Germany: Implications for the formation of
Kongsberg-type silver deposit. Canad. Mineralogist 45,
1147—1176.

Staude S., Göb S., Pfaff K., Ströble F., Premo W.R. & Markl G.

2011: Deciphering fluid sources of hydrothermal systems:
A combined Sr- and S-isotope study on barite (Schwarzwald,
SW Germany). Chem. Geol. 286, 1—20.

Steele-MacInnies M., Bodnar R.J. & Naden J. 2011: Numerical

model to determine the composition of H

O-NaCl-CaCl

fluid

inclusions based on microthermometric and microanalytical
data. Geochim. Cosmochim. Acta 75, 21—40.