Reconstruction of ancient drainage in the contact karst of the Harmanecká dolina Valley, Western Carpathians, based on mineralogical data from the allochthonous sediments and isobase geomorphometry

Abstract

Caves are unique sedimentary archives that may record the evolution of the surrounding landscape. In this study, we applied combination of mineralogical data on allochthonous sediments with digital modelling of isobase surfaces to reconstruct the multi‐phased geomorphological development of the karst of the Harmanecká dolina Valley. The allochthonous cave sediments contain quartz and translucent heavy minerals (HMs) such as tourmaline, garnet, rutile, apatite, zircon, pyroxene, amphibole, staurolite, spinel, monazite, corundum, epidote, xenotime and florencite. Rounded shape and surface microtextures preserved on quartz and most HM grains point to predominantly a fluvial transport of detritus and its multiple recycling history. Pyroxene and amphibole are exceptions that denoted a very close source and the first‐cycle sedimentation from the adjacent volcanic Kremnické vrchy Mts. corresponding to obtained SHRIMP U–Pb detrital zircon ages of ~13.8–12.8 Ma. Heavy‐mineral geochemistry (e.g., zoned grossular‐rich garnet) and wide range of the Palaeozoic ages (Ordovician to Permian) confirms that the studied detritus sourced dominantly in the Western‐Carpathian crystalline basement rocks of the Veporic/Tatric tectonic units initially distributed by the palaeo‐Hron River and its tributaries from the east. Rare cummingtonite, remarkable tourmaline with omphacite inclusions and florencite point to the mixture of recycled sediments of Neogene Danube Basin formations containing also Austroalpine pre‐Neogene basement detritus, and confirm the original widespread distribution of the Neogene sediments currently eroded. Geomorphometric analyses of a LiDAR digital terrain model and derived isobase surface elevation models indicate the topographic development of wider area and support the findings about the transport direction of detritus. Presented multi‐method approach is suitable not only for the understanding of development of the surroundings of Harmanecká dolina Valley but also for the palaeogeographic and geomorphological reconstructions of similar karst and non‐karst areas.