Roundness and surface features of quartz grains in Middle Devonian deposits of the East Baltic and their palaeogeographical implications

Abstract

The roundness and surface texture of quartz grains were studied in Devonian sediments of 32 drill cores. Roundness was estimated in more than 800 samples and surface textures were examined under scanning electron microscope on 70 grains. The grains were mostly subrounded to subangular. The concentration of rounded grains in some beds of the Pärnu Formation (Fm.), the basal beds of the Leivu Fm., and the upper part of the investigated sequence indicates zones of sediment recycling and reworking. Based on the distribution of roundness degrees of quartz grains, some possible ancient coastlines in Pärnu time were defined.Variations in quartz surface textures were detected at different stratigraphical levels, whereas the texture created by mechanical processes was predominating. Abundant abrasion features like V-shaped pits, and linear and curved grooves usually give evidence of transport in a fluvial medium. On levels with intensive reworking and redeposition (Burtnieki and Gauja formations and on some levels of the Pärnu Fm.) preliminary relief of grains was smoothed and obliterated. The diagenetic dissolution features were more frequent in the Pärnu Fm., Kernave Fm., and lower part of the Aruküla Fm., where intercalation of dolomitic and siliciclastic rocks is common. Possible chemical etching in Devonian soil profiles was observed in the upper part of the section. Data on the roundness of particles and surface textures of quartz grains, and their horizontal and vertical variability help to clarify the history of basin evolution and to distinguish stratigraphical discontinuites.

Quartz grain features in modern glacial and proglacial environments: A microscopic study from the Russell Glacier, southwest Greenland

“…6, Table 2), which tend to be produced under energetic fluvial conditions (Nanson et al 1995;Kleesment 2009;Vos et al 2014 ). More fluvial-induced grains can be found, for example, in the sandur sediments.…”

“…Quartz grains are highly resistant to weathering and thus remain in the sedimentary environment (Krinsley and Doornkamp 1973;Mahaney 2002) and may record sedimentary processes (Newsome and Ladd 1999;Moral Cardona et al 2005;Konopinski et al 2012;Vos et al 2014), identify mode of transport (Kleesment 2009) or estimate duration of processes modeling the grains (Krinsley and Doornkamp 1973;Refaat and Hamdan 2015).…”

Upper Pleistocene palaeoenvironmental changes at the Zwierzyniec site, central Poland

“…The quartz grain mor phol ogy re lates to the mode of transpor ta tion, dis tance from source, and tim ing, but it is equally a func tion of the orig i nal grain shape in the par ent rock (Mahaney et al, 2001;Kleesment, 2009;Costa et al, 2013;Kaliñska and Nartišs, 2014;Vos et al, 2014). In this study, a pre lim i nary analy sis of the round ness of quartz sand grains and the char ac ter of their sur face com bined with min er al og i cal com po si tion open up great op por tu ni ties for fu ture work at higher res o lu tion.…”

Grain surface features of alluvial sediments of upper Pravara Basin and their environmental implications

“…In fluvially transported grains, the surface textures are to a considerable extent determined by the flow magnitude and turbidity. Therefore, the SEM studies of riverine sediments could be helpful in the better interpretation of the associated hydrological conditions and the palaeoenvironmental history as well as post-depositional changes (Bull, 1981;Tiwari et al 2001;Jimin et al 2005;Matthias and Kari, 2005;Culver et al 2006;Madhavaraju et al, 2006;Babu et al 2007;Kleesment, 2009). The basic purpose of this study is to determine the surface textures and their frequencies of alluvial sediments that occur in the semi-arid part of the Deccan volcanic provinces.…”