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Złoto okruchowe i inne minerały ciężkie w osadach potoku Maruszka k. Burgrabic (Sudety Wschodnie)

Godlewski A., Wierchowiec J.

Przegląd Geologiczny

2004

Vol. 52, nr 3

216-222

Two main heavy mineral associations were found in the studied sediments: magnetite–ilmenite and garnet–zircon– pyroxene. The parental rocks for those minerals were rocks from a metamorphic complex: gneisses, amphibolites, quartzities and crystalline limestones. Furthermore, the detrital gold was found in the alluvial deposits of Maruszka stream. The shape of most gold grains is discoidal or elliptical and they show various mechanical deformations (scratches, furrows, impact, and sandwich structures). The most significant primary gold source are amphibolites, which occur in Devonian quartzities and quartz schists of Vrbno group. The morphology, surface textures, and chemical composition of the gold particles suggest that the majority of gold was transported presumably in a suspended form as flakes, scales, and small grains. Gold could have also been dissolved and transported as complex compounds, colloidal solutions or suspensions. Moreover, some of the gold could have been redeposited and entered the Maruszka stream directly as a result of erosion of the Neogene, Gozdnica Series -like sediments and of Quaternary clays.

Morphology and chemistry of placer gold grains - indicators of the origin of the placers : an example from the East Sudetic Foreland, Poland

Wierchowiec J.

Acta Geologica Polonica

2002

Vol. 52, nr 4

563-576

The gold in the vicinity of Głuchołazy - Prudnik (the East Sudetic Forelands) is associated with Pliocene piedmontfans and Pre-Pleistocene river systems, primarily with the paleobeds of the Prudnik river and its tributaries. The morphology (roundness, flatness index and particles folding), surface textures and chemical composition of the gold particles suggest that the placer gold occurrences in the East Sudetic Foreland are multicycled (recycled paleoplacers) and multisourced. The most significant primary gold source was the sedimentary and epimetamorphic cover of the Żulova granitoids, eroded and removed during the Neogene. The majority of the gold was transported (redeposited) in a suspended form as flakes, scales, small grains and gold dust. This entered the river directly as a result of erosion of auriferous sediments. The homogeneous, porous, gold particles were formed in the weathering zones of polymetallic veins and other types of mineralization. Coatings of both crystalline and amorphous gold on particle surfaces suggest chemical accretion of authigenic gold on to pre-existing grains. Some porous gold particles may have been formed post-depositionally as the result of precipitation from colloidal solutions.