China
Africa
Explore chapters and articles related to this topic
Sediments and Sedimentary Rocks
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
The term siliciclastic refers to sediments composed mostly of silicate minerals. The most common sedimentary rocks—including shale, sandstone, and conglomerate— form from siliciclastic sediments. Other, less common kinds of rocks consist of carbonates, iron oxides, and hydroxides, such as hematite, goethite, or other minerals.
Utilising geochemical data for the identification and characterisation of mineral exploration sample media within cover sequence materials
Published in Australian Journal of Earth Sciences, 2019
C. J. Tiddy, S. M. Hill, D. Giles, B. G. van der Hoek, V. J. Normington, R. R. Anand, E. Baudet, K. Custance, R. Hill, A. Johnson, S. McLennan, C. Mitchell, D. Zivak, W. Salama, K. Stoate, K. Wolff
Samples with SiO2 >50 wt% tend to be siliciclastic lithologies including clays, sandstones, siltstones, conglomerate, diamictite, silcrete and stream sediments (quartz sands). A majority of these samples plot on a linear trend with the end members being clay-dominated lithologies at high Al2O3/low SiO2 and quartz sand-dominated and silcrete lithologies at low Al2O3/high SiO2. The intermediate composition lithologies (e.g. sandy clay, clayey sand and also including conglomerate and diamictite) are difficult to discriminate but can be confidently considered siliciclastic sediments at the very least given their siliciclastic content. Samples that plot below the main Al2O3–SiO2 linear trend and have SiO2 >50 wt% (Figure 3d) are likely indicative of sediments that have undergone some degree of carbonate or ferruginous dilution. Sandstone samples that plot below the main trend may be indicative of immature (impure) sandstones, as they also plot away from the average composition of quartz-arenite, which represents a very mature sandstone. These samples trend towards the CNK and FM axes in the A–CNK–FM diagram (Figure 5a).
Diverse provenance of the Lower Cretaceous sediments of the Eromanga Basin, South Australia: constraints on basin evolution
Published in Australian Journal of Earth Sciences, 2021
E. Baudet, C. Tiddy, D. Giles, S. Hill, G. Gordon
Source rock, depositional environment, climatic conditions during transport and deposition of the sediments, and post-depositional processes are all factors that control the chemical and mineralogical characteristics of siliciclastic sediments (Fralick & Kronberg, 1997; Pang et al., 2018). The distance travelled by the sediments between the source and the catchment, and the various environments and climates that the sediments went through before being deposited will also impact the sediments’ composition (e.g. González-Álvarez & Kerrich, 2012; Pang et al., 2018; van der Vegt et al., 2016; Yuan et al., 2019). The mineralogy and chemistry of sediments can therefore be used to recreate and define the conditions in which the sediments were deposited and their provenance. The concentration of immobile elements such as Th, Sc, Zr, Co, Cr, Ti and Hf, and rare earth elements (REE) in sediments have previously been used to identify sediment sources (e.g. Amedjoe et al., 2018; Bauluz et al., 2000; Condie 1991, 1993; Floyd & Leveridge, 1987; Fralick, 2003; Hayashi et al., 1997; McLennan et al., 1990, 1993, 2003; Rudnick & Gao, 2003; Taylor & McLennan, 1985, 1995; Wang et al., 2018). Different concentrations of these elements can be attributed to either felsic, intermediate or mafic igneous rock inputs into the sediments. Zirconium and Hf are particularly useful for evaluating the recycled sedimentary component of sediments (Floyd & Leveridge, 1987; McLennan et al., 1993). Mineral assemblages can also be attributed to different groups of rocks. For example, a dominance of Ca-plagioclase would suggest a mafic component while detrital K-feldspar and muscovite would indicate a felsic component (e.g. Brown & Parsons, 1994; Rakovan, 2009; Roberts et al., 2000). Clay minerals can be indicative of paleoclimate conditions as the formation of different clay species (e.g. kaolinite, illite and smectite) have been attributed to different climates (Beckmann et al., 2005; Gibson et al., 2000; Macphail, 2007; Roy & Roser, 2013; Viscarra Rossel, 2011).