Influence of granitoid textural parameters on sediment composition: Implications for sediment generation

Abstract

The aim of this study is to determine and characterise the control exerted by parent rock texture on sand composition as a function of grain size. The sands investigated were generated from granitoid parent rocks by the Rhone, Damma and Sidelen glaciers, which drain the Aar Massif in the Central Alps (Switzerland), and were deposited in glacial and fluvio-glacial settings. Mechanical erosion, comminution (crystal breakdown and abrasion) and hydraulic sorting are the most important processes controlling the generation of sediments in this environment, whereas chemical and/or biochemical weathering plays a negligible role. By using a GIS-based Microscopic Information System (MIS), five samples from the glacier-drained portions of the Aar basement have been analysed to determine textural parameters such as modal composition, crystal size distribution and mineral interfaces (types and lengths). Petrographic data of analysed sands include traditional point counts (Gazzi-Dickinson method, minimum of 300 points) as well as textural counts to determine interface types, frequency, and polycrystallinity in phaneritic rock fragments. According to Pettijohn's classification, grain-size dependent compositions vary from feldspathic litharenite (0φ fraction) via lithic arkose (1φ and 2φ) to arkose (3φ and 4φ). Compositional differences among our data set were compared to modern plutoniclastic sands from the Iberian Massif (Spain) and the St. Gabriel Mts. (California, USA), which allowed us to assess the role exerted by glaciers in generating sediments. By combining data from the MIS with those from petrographic analysis, we outlined the evolution of mineral interfaces from the parent rocks to the sediments.

Petrography of Middle Jurassic to Early Cretaceous sandstones in the Kutch Basin, western India: Implications on provenance and basin evolution

“…Composition of major and accessory heavy minerals in sandstones provide crucial information regarding the provenance of sedimentary basins (Armstrong-Altrin et al 2012Arribas et al 2000;Caracciolo et al 2012;Critelli and Ingersoll 1994;Critelli and Le Pera 1994;Critelli et al 2003;Le Pera and Critelli 1997;Paikaray et al 2008;Saha et al 2010). Petrographic investigation of sandstone is widely used to infer tectonic setting, source rock composition, transportation and environment of deposition (Dickinson 1970(Dickinson , 1985Dickinson and Suczek 1979;Dickinson et al 1983;Ingersoll and Suczek 1979;Le Pera and Arribas 2004;Le Pera et al 2001;Zuffa 1985Zuffa , 1987.…”

Semi-automatic segmentation of petrographic thin section images using a “seeded-region growing algorithm” with an application to characterize wheathered subarkose sandstone

“…The resulting datasets allow for a straightforward assessment of grain fabric parameters such as modal composition and grain size distribution, which are prime objectives in the digital segmentation of thin section images (Francus, 1998;Barraud, 2006;Zhang et al, 2014). The strength of a GIS environment with respect to analysis of grain contacts in thin section images has been shown by Caracciolo et al (2012).…”

Weathering processes affecting granitoid profiles of Capo Vaticano (Calabria, southern Italy) based on petrographic, mineralogic and reaction path modelling approaches

“…These features generally produce a greater value of the sand generation index (SGI) proposed by Palomares and Arribas (1993) for granitoid rocks and explains the great productivity in sandy deposits of this lithology (cf. Caracciolo et al, 2012;Borrelli et al, 2014;Perri et al, 2014b).…”