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Provenance of quartz debris in the Central Western Carpathians at the end of the Triassic, as indicated by cathodoluminescence colours

Vďačný Marek, Michalík Josef

Acta Geologica Polonica

2023

Vol. 73, no. 1

103--114

Lithic fragments including quartz grains occur infrequently in the shallow-marine limestone sequence of the Fatra Formation deposited in the tensional intra-shelf depression of the Central Western Carpathians during the Rhaetian. Nevertheless, their study can bring data answering questions of sources, palaeogeodynamic arrangement, and processes at the end of the Triassic. In this study, we examined optically the cathodoluminescence (CL) colours of single quartz grains from the Kardolína section (Tatra Mts, Slovakia). These colours reveal a dominance of grains derived from regionally metamorphosed and plutonic rocks. Grains of hydrothermal and pegmatite origin are less frequent. Some of the quartz grains show recycled cement rims suggesting at least a second cycle origin. This sedimentary basin was situated near to the passive margin formed by the Variscan consolidated terrains of the Vindelician Highlands. Our study of the CL colours of quartz grains contributes to the elucidation of the nature of the rocks of the vanished Vindelician mountain belt.

Mikromorfologia powierzchni ziaren eolicznego pyłu kwarcowego z pokryw stokowych Ślęży (Przedgórze Sudeckie)

Woronko B., Żurawek R.

Przegląd Geologiczny

2004

Vol. 52, nr 4

321-324

Three samples of aeolian silty deposits from slopes of Mt. OElęża (Sudetic Foreland, SW Poland) have been observed in scanning electron microscope in order to define their characteristic micromorphologic features. Four categories of quartz grains have been distinguished, i.e.: fresh, coated, etched, and broken. The majority (up to 70 %) of particles was fresh, with well visible conchoidal or linear fractures, possibly with initial coating, the percentage of coated and etched particles varied depending on sample investigated and there were very few broken particles (less than 8 %). This characteristic shows that the silty deposits have been little affected by epigenetic processes . Fluvial sediments, fluvioglacial deposits or older aeolian covers have been assumed as possible source of the loessic silt.