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Rare Earth Element mobility in a weathering profile - a case study from the Karkonosze Massif (SW Poland)

Galbarczyk-Gąsiorowska L.

Acta Geologica Polonica

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2010

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Vol. 60, no. 4

599-616

EN

The rare earth element (REE) contents of soils were determined to study the behaviour of REE in the weathering profile. The bedrock for the soils was the Karkonosze granite. A five-step extraction scheme was conducted on six soil profiles in order to determine the ability of REE to be released to the environment. Sequential extraction indicated that the REE are mostly concentrated in the organic and Fe-Mn oxyhydroxide soil fraction. Heavy REE appear to be more leachable than light REE. The change in concentration has been determined using the Nesbitt and Markovics formula. The soils from the soil profiles are enriched in REE in comparison to the parent rock.

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Mantled alkali-feldspar megacrysts from the marginal part of the Karkonosze granitoid massif (SW Poland)

Słaby E., Galbarczyk-Gąsiorowska L., Baszkiewicz A.

Acta Geologica Polonica

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2002

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Vol. 52, nr 4

501-519

EN

Mantled alkali feldspar megacrysts from the porphyritic granite variety of the Karkonosze Variscan pluton (SW Poland) have been studied. The feldspars contain numerous inclusions of minerals (mainly plagioclases), which form inner rims, marking successive zones of megacryst growth, and they are surroundet by a plagioclase mantle (rapakivi texture). Although, due to maturation and coarsening, the feldspars display a heterogeneous exsolutions pattern, in the core part some homogeneous sectors (without visible decomposition) are also preserved. Chemical composition of alkali feldspar megacrysts (including barium concentration) and of plagioclases (inner inclusions and mantle) has been determined and used for evaluation of thermal conditions of melt crystallization. The highest calculated temperature for single equilibrium and close-to-equilibrium pairs of un-decomposed domains in alkali feldspar + plagioclase inclusion ranges 809-750 stopni C. The differences in crystallization temperature calculated for the pairs alkali feldspar domains (megacryst) and plagioclase inclusions from successive inner rims or for the pairs alkali feldspar domains (megacryst) - plagioclase mantle varied within 100 stopni C. Common lack of equilibrium for neighbouring pairs of plagioclase inclusion - alkali feldspar is noticeable. Growth morphologies of plagioclases (inclusions and mantle) and alkali feldspar have been proved by means of CL. Mostly the feldspars display sings of resorption and re-growth at many stages of their formation. The barium concentration in the feldspars also points to discontinuous growth. The crystallization path of the megacrysts and the formation of rapakivi texture were influenced by magma mixing, not by decompression processes.

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Mechanizm rozpadu piaskowców wywołany krystalizacją soli

Słaby E., Galbarczyk-Gąsiorowska L., Trzciński J., Górka H., Łukaszewski P., Dobrowolska A.

Przegląd Geologiczny

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2001

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Vol. 49, nr 2

124-133

PL

Geneza krzemieni i czertów należy do największych zagadek współczesnej geologii. Od 1999 r. zespół polsko-amerykański, reprezentowany przez autorów niniejszego artykułu, prowadzi badania nad wyjaśnieniem warunków tworzenia się krzemieni górnojurajskich w rejonie Ożarowa (NE obrzeżenie Gór Świętokrzyskich). Stwierdzono istnienie antykorelacji pomiędzy *D i *18O. Obecne badania koncentrują się nad dwoma najbardziej prawdopodobnymi modelami genetycznymi krzemieni: (1) zmian temperatur na skutek działalności podmorskich źródeł hydrotermalnych, (2) samoorganizującej się katalitycznej krystalizacji. Uzyskane wyniki będą stanowić istotny wkład do badań nad genezą krzemieni i czertów z różnowiekowych formacji skalnych.

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Experimental investigation of the reaction : An-rich plagioclase + quartz + fluid = analcime-wairakite[ss]

Galbarczyk-Gąsiorowska L., Słaby E.

Acta Geologica Polonica

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2001

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Vol. 51, nr 2

155-162

EN

The reaction An-rich plagioclase + quartz + fluid = analcime (NaAlSi4O12 * 2H2O) - wairakite (CaAl2Si4O12 * 2H2O)[ss] (solid solution series) has been studied experimentally in the temperature range 350-200 stopni C. Distilled water or 0.1 M NaHCO3 solution was used as fluid. All experiments have been performed under low silica activity. Due to the short duration of the experiments the reaction had not approached equilibrium and partly metastable phases were formed. Wairakite nucleated in the laumontite stability field in the system plagioclase-quartz-H2O. Higher sodium activites led to the formation of mixed analcime-wairakite crystals or analcime crystals. The mechanisms of zeolite formation seems to comprise topotaxial growth on the plagioclase surface caused by a dissolution-precipitation process. Some variations in the nucleation and growth kinetics were noticed which appear to be due to different physico-chemical conditions of zeolite formation