"Surface microtextures on detrital accessory garnets in the fluvial environment: Case study from an active stream (Malá Fatra Mts., Western Carpathians)"

Surface analysis of detritus from a modern fluvial environment can be a useful tool in understanding various weathering and transport processes; the results of which are applicable in the provenance and environmental interpretations of ancient sedimentary rocks.In this study, we provide a report on the microtextural and geochemical relationships within detrital garnets hosted in modern fluvial sediments.Garnets from seventeen heavy-mineral concentrates taken from the Strnsky potok brook were analysed by optical microscopy, scanning electron microscopy, Raman spectroscopy, and electron microprobe to obtain information on their provenance and surface microtextural development.The results show that detrital almandines (1) Alm 57-72 Sps 12-23 Prp 10-15 Grs 1-5 And 0-1 and (2) Alm 66-77 Prp 15-24 Sps 3-9 Grs 1-4 And 0-1 were primarily sourced in local Variscan crystalline basement rocks, such as metagranite (diatexite) with gneiss xenoliths.A large part of recycled almandine was likely derived from the Permian Strany Formation (Fm.) and/or Triassic Lna Fm. siliciclastic rocks.Almandine recorded various transport traces, such as conchoidal fractures, arcuate and straight steps, V-shaped cracks and crescentic percussion marks formed in the (a) contemporary Variscan basement and (b) older fluvial environments.Chemically-induced features, such as facets developed on first-cycle almandines are a remnant after corrosion caused by acid solutions -resorption in the garnet rims interacted with other minerals during metamorphic events in the Mal Fatra Mountains, and the solution crevasses developed considerably on recycled grain surfaces formed by intrastratal dissolution.The investigation of detrital garnet in the recent stream of the Mal Fatra Mts.revealed (paleo)environmental and depositional conditions of sedimentation.