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In situ growth of monazite in anchizonal to epizonal mudrocks: first record from the Variscan accretionary prism of the Kaczawa Mountains, West Sudetes, SW Poland

Kryza R., Zalasiewicz J. A., Charnley N., Milodowski A. E., Kostylew J., Tyszka R.

Geologia Sudetica

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2004

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Vol. 36

39-51

EN

We report the first occurrence of diagenetic or low grade metamorphic monazite from the Palaeozoic mudrock successions of the Kaczawa Complex of the West Sudetes, Poland. Where observed in relation to the enclosing mudrock, this monazite comprises tiny irregular grains, less than 20 microns in diameter, intergrown with the surrounding matrix minerals. This monazite resembles previously described examples of diagenetic monazite from elsewhere in the world in mostly possessing low contents of Th and U but differs in forming much smaller grains, which show only slight zonation of rare earth elements (REEs). Some of the monazite grains studied also appear to have formed synchronously with the cleavage, perhaps a function of early deformation and fluid release in an accretionary prism environment. Relatively Th-rich cores, and an association with altered detrital biotite in some instances, suggests that at least some of the in situ monazite growth might have taken place as overgrowths on primary detrital monazite particles.

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Zróżnicowanie śladowych zawartości złota w skałach należących do kompleksu kaczawskiego

Kaliszuk R.

Przegląd Geologiczny

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2000

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Vol. 48, nr 2

166-170

PL

Oznaczenie zawartości Au w skałach kompleksu kaczawskiego metodą absorpcji atomowej (AAS) wykazuje, że najwyższe koncentracje tego pierwiastka charakteryzują skały krzemionkowe — lidyty (59 ppb) i łupki kwarcowe (16 ppb), a także keratofiry (13 ppb) i łupki grafitowe (16 ppb i 11 ppb). Natomiast zieleńce charakteryzuje niska zawartość złota ( poniżej 5 ppb). Daje się zauważyć zmienność koncentracji analizowanego pierwiastka w tego samego typu skałach (łupkach kwarcowych i łupkach grafitowych) pochodzących z różnych rejonów kompleksu kaczawskiego. Wzrost koncentracji Au jest konsekwentny od Kaczorowa przez Wojcieszów i Świerzawę do Złotoryi — miejsca występowania złota rodzimego.

EN

Analysis of gold concentration in rocks of the Kaczawa complex using the AAS method shows that the highest content of this element occurrs in silicic rocks - lidites (59 ppb) and quartz slates (16 ppb) as well as kerathofires (13 ppb) and graphite slates (16 ppb i 11 ppb). On the other hand greenstones are characterised by low content of gold (5 ppb). Gold content is variable in similar rocks (quartz slates and graphite slates) from different parts of the Kaczawa complex. It increases consequently from Kaczorów, through Wojcieszów and Świerzawa, to Złotoryja, place of native gold occurrence.

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Litologia i geneza zmetamorfizowanych skał osadowych i wulkanicznych jednostki Chełmca (Góry Kaczawskie)

Baronowski Z., Haydukiewicz A., Kryza R., Lorens S., Muszyński A., Urbanek Z.

Geologia Sudetica

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1998

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Vol. 31, nr 1

33-59

EN

Based on detailed drill core studies from fourteen boreholes (up to 1500 m deep) and on field observations, the Chełmiec tectonic unit in the northern part of the Kaczawa Mts appears to contain two types of tectonostratigraphic elements. The first is fragments of a stratigraphic sequence, composed mainly of dark muddy slates (metamudstones) and variegated laminated silty-clayey slates (both considered as Ordovician), and of volcaniclastic rocks, greenstones and dia-bases. The second element is represented by mélange bodies which consist of dark muddy slates (matrix) enclosing fragments of various lithologies: dark siliceous and graphitic slates, light siliceous slates, quartzites, greywackes, variegated silty-clayey slates etc. (probably Upper Devonian or Lower Carboniferous). Due to the lack of biostratigraphic evidence, the stratigraphic subdivision is based on lithological criteria. Using e.g. the rule of superposition and analysis of lithological contacts and sedimentary and volcanogenic structures, the stratigraphic succession was defined, and three informal lithostratigraphic units were distinguished: (a) an association of metamudstones and diabases, (b) an association of metavolcaniclastic rocks (both within the stratigraphic sequence), and (c) a mélange association. The dark metamudstones and variegated silty-clayey slates of the association of metamudstones and diabases are interpreted as turbidites. The volcaniclastic rocks, of clearly epiclastic character, were delivered episodically from marginal parts of the basin or volcanic heights by denser turbiditic currents and other types of gravity flows. Simultaneously, volcanic activity occurred within the basin itself producing basaltic lavas (now observed as subvolcanic diabases and effusive greenstones), which geochemically correspond to recent mildly alkaline within-plate basalts. The geotectonic setting of the basin is difficult to define precisely but the sequence was probably emplaced in an outer fan or in a basin at a continental margin. The mélange represents a later stage of the evolution of the Kaczawa Complex. Most probably, it was deposited from gravity flows and slumps in a trench or on a trench slope. Its origin is thought to have been connected within the formation of a Variscian accretionary prism in Late Devonian and Early Carboniferous times. The rock complex of the Chełmiec Unit experienced several stages of deformation during the Variscian orogeny. The first event resulted in a system of thrusts (and associated folds?) and it was related to (or partly preceeded by) the formation of mélange. It is likely that deformation at this stage (and in particular in its later phase) took place under blueschist facies conditions. The second deformation event, probably under greenschist facies conditions, was associated with folding which steepened the earlier foliation and produced new asymmetric folds. The third deformation event, partly under semi-brittle/brittle conditions, is responsible for new thrusts cutting the earlier structures and the formation of large open folds, such as the Bolków-Wojcieszów antiform. The deformation of the rocks of the Chełmiec Unit was associated with greenschist facies metamorphism. In general, primary sedimentary and volcanic structures are well preserved in the rocks of this unit which often seem to have suffered weaker deformation and metamorphism than that observed in other units of the Kaczawa Mts. No clear evidence of the early high-pressure episode which is widespread in other tectonic units of the Kaczawa Complex has been found in the Chełmiec Unit so far.