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ARCHIWUM MINERALOGICZNE A JOURNAL OF GEOCHEMISTRY, MINERALOGY AND PETROLOGY ESTABLISHED IN 1925 BY STANISLAW THUGUTT |
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1993
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Note: below are given only the abstracts of the publications in vol. 49 no. 2, 1993. Any of the abstracts of the Symposium ECROFI XII and Session "Zinc and lead ore deposits - genetic problems" published in vol. 49 no.1, 1993 of "Archiwum Mineralogiczne" (total 117 items) is available by request as electronic or xerox copy from akozl@geo.uw.edu.pl. See Contents vol. 49 no. 1.
BAKUN-CZUBAROW, NONNA*; GAŁĄZKA-FRIEDMAN,
JOLANTA**; SUWALSKI, JAN***; SZPILA, KAZIMIERZ****
*Institute of Geological Sciences, Polish Academy of Sciences,
al. Żwirki i Wigury
93, 02-089 Warszawa, Poland; ** Institute of Physics, Warsaw University of
Technology, Koszykowa 75, 00-662 Warszawa, Poland; ***Institute of Atomic
Energy, Świerk, 05-400 Otwock,
Poland; ****Institute of Geochemistry, Mineralogy and
Petrography, Warsaw University, al.
Żwirki i Wigury 93, 02-089 Warszawa, Poland
WEATHERING OF THE LOWER SILESIAN BASALTOIDS STUDIED BY MÖSSBAUER
SPECTROSCOPY
Archiwum Mineralogiczne v. 49 no. 2 p. 3-21
The Fe3+/Fe2+ ratio seems to be the
important index of the hypergenic alterations of the iron-rich igneous rocks,
where various iron-bearing minerals are characterised by different iron
oxidation states. Ten samples of the rocks from the Zaręba
Górna quarry near Lubań, altered to
different degrees, were selected to study the weathering processes of the Lower
Silesian basaltoids. The Mössbauer spectra of the unaltered basaltoids consist
of subspectra of olivine, pyroxenes and of Fe-Ti oxides. The Mössbauer spectrum
of olivine containing Fe2+ forms the doublet characterized by isomer
shift IS = 1.2 mm/s and quadrupole splitting QS = 3 mm/s. In the spectra of
pyroxenes the ferric and ferrous doublets can be recognised. In the spectra of
the most altered basaltoids the intensive doublet of smectite (IS = 0.35 mm/s
and QS = 0.67 mm/s) as well as subspectra of the iron oxides can be seen. In the
investigated weathering sequence of the basaltoids the Fe3+/Fe2+
ratios, as calculated from Mössbauer spectra, range from 0.52 to 2.34, while in
the last three samples divalent iron has not been detected. Mössbauer
spectrometry has proved to be a useful tool in studies of transformations of
iron-bearing minerals as well as in investigations of iron migration in
environments under variable physical and chemical conditions. In the studied
rocks iron from the primary silicates and oxides migrated gradually into the
secondary silicates and oxides. Iron shows also a tendency to migrate from
silicate to oxide phases with increasing weathering. The Mössbauer technique
can also be applied to identify iron-bearing minerals.
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Basaltoids from the Łysanka
and Trupień hills (Lower Silesia) have been
studied as well as ultramafic and mafic enclaves present in them and pyroxene
and olivine megacrysts. The enclaves in the mentioned basaltoids represent
peridotites, pyroxenites and gabbroid rocks. The minerals of those rocks have
undergone the following processes: recrystallisation, blastesis and melting in
which intergranular solutions and metasomatic fluids have been significant. Due
to the influence of these media there occurred a migration of many chemical
elements, most important of them being calcium, chromium, aluminium and
titanium. The enclaves of peridotites and green clinopyroxenites presumabły
represent fragments of the matter from the upper mantle, while black
clinopyroxenites from the enclaves are mainly cumulates. As it is supposed the
early cumulates have undergone the process of gabbro formation which occurred in
joint magma chambers. Megacrysts of pyroxenes and some olivine megacrysts have
crystallised from the magmatic melt in the differentiated physico-chemical
conditions. The peridotite enclaves in which the olivines have undergone a
strong blastesis were a source for a majority of olivine megacrysts.
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This paper presents results of investigations of pegmatites
from Polish part of the Western Tatra Mts. It was stated that the rocks under
considerations were pure-line pegmatites. Their zonal structures were the
results of a mineralogical succession and variability of the distribution and
ratios of chemical components. There were distinguished two main mineral
parageneses, caused probably with two generations of pegmatites with different
relationships to the main deformational event and different crystallisation
temperatures.
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GÓRECKA, EWA
Polish Geological Institute, Rakowiecka 4, 00-975 Warszawa,
Poland
GENETIC MODEL OF Zn-Pb DEPOSIT IN THE OLKUSZ ORE DISTRICT (S POLAND)
Archiwum Mineralogiczne v. 49 no. 2 p. 23-80
General regularities of the formation of a Zn-Pb deposit in the Upper Devonian to Upper Jurassic carbonate sequence in the Olkusz ore district as well as the mineralogical and geochemical features are presented. Dynamics of the compressional, tensional and strike-slip structures influenced the flow of the mineralised fluids. Main ore bodies occur in tectonically downwarped areas formed by block faults of ledge character. Distinct cycles of the ZnS, PbS and FeS2 crystallisation were connected with pulsating inflow of the parent solutions. A genetic connection between the Zn-Pb ores hosted both by the Paleozoic and Mesozoic beds has been stated. The ore mineralisation probably developed during a relatively short time in the post-Jurassic age.
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Blockdiagram
presenting the distribution of the Zn-Pb ores in Mesozoic and Paleozoic
beds l -- Upper Devonian, 2 -- Lower Permian, 3 -- Lower Triassic, 4 -- Middle Triassic, 5 -- Upper Triassic, 6 -- Upper Jurassic, 7 -- Quaternary, 8 -- dislocation zone, 9 -- ore body, 10 -- ore zone, 11 -- presumed ore mineralization extent in Devonian beds. |
Alkali feldspars from the xenoliths occurring in basanite are
partły albitised microclines, annealed in
the basanite melt. The annealing of the feldspars has caused their partial
melting. The melting process has included mainly albite compounds of the
previous microcline. Characteristic shape of the crystal-melt border and the
diffusive alkali profiles on this border suggest that the microcline melting has
been controlled by diffusion. Calculated time of the crystals melting indicates
that the chemical equilibrium between crystal and melt has not been achieved.
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Pisolitic kaolins from Central Wadi Kalabsha (southern Egypt)
were studied to determine their mineralogy, internal structure of pisoids and
the genetic process that led to their formation. Pisolites are present in
varicoloured kaolins which are mainly composed of well crystalline kaolinite,
additionally hematite, anatase and minor amounts oi Al-oxides (gibbsite,
diaspore). On the basis of petrological and mineralogical studies different
types of pisoids were determined. The oxygen/hydrogen isotopic ratio indicates
that pisolitic kaolins were formed by lateritic weathering.
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The systematic position of the Sudetic volcanic rocks has
been based on the chemical classification of the volcanic rocks TAS (Total
Alkali-Silica) from 1989. According to that classification the Sudetic volcanic
rocks are represented by basanites, tephrites, foidites (melanephelinites),
picrobasalts, alkali basalts, medium- and high-potassium subalkaline basalts,
hawaiites, mugearites, benmoreites, latites, high-potassium dacites,
trachydacites, trachytes and high- and low-potassium rhyolites. The Cainozoic
volcanic rocks (ultrabasic and basic) have been assigned to the group of the
alkali olivine basalts of the continental type which are genetically related to
the Central-European rift zone. Isotopic ratios of strontium and neodymium and
the ratio of lanthanum vs niobium point to a mantle origin of the Cainozoic
volcanic rocks. Magmas bearing some enclaves of the mantle peridotites, present
in the volcanites, can be concemed as primary. The Lower Permian volcanic rocks
have been assigned to a calcium-alkali sequence of the Andean type. Their origin
can be considered in relation to two different magmas: the basic magma of the
mantle origin and acid anatectic one.
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