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Underground soft rock mining
Published in A.J.S. (Sam) Spearing, Liqiang Ma, Cong-An Ma, Mine Design, Planning and Sustainable Exploitation in the Digital Age, 2023
A.J.S. (Sam) Spearing, Liqiang Ma, Cong-An Ma
A shaft that penetrates from the surface to the coal seam passes through a variety of overburden soil and rock strata. Consequently, the shaft support requirements vary considerably from shaft collar on the surface to the shaft bottom, some distance below the coal seam. The following can be used to develop a procedure for the design of shaft linings on the basis of the properties and conditions of the soil and rock through which the shaft passes. Designs for cohesive and cohesionless soil, and elastic-plastic and clastic rock need to be considered if applicable. Clastic rocks are composed of fragments, or clasts, of fragmented rock. Clastic rocks are generally sedimentary rocks.
Our Earth, its minerals and ore bodies
Published in Odwyn Jones, Mehrooz Aspandiar, Allison Dugdale, Neal Leggo, Ian Glacken, Bryan Smith, The Business of Mining, 2019
Odwyn Jones, Mehrooz Aspandiar, Allison Dugdale, Neal Leggo, Ian Glacken, Bryan Smith
Sedimentary rocks typically form in areas of low to negative topographic relief with respect to sea level, where minerals, derived from pre-existing rocks, are subjected to weathering, transportation and eventual deposition and lithification. The pre-existing rocks may be igneous, metamorphic or sedimentary in origin. Sedimentary rocks are classified as clastic, chemical or organic. Clastic rocks are formed from the weathering of terrestrial rocks. The minerals and rock fragments from this process are transported by water, wind or ice over variable distances and finally deposited and lithified. Chemical sediments by contrast are developed as a result of precipitation from a fluid e.g. evaporites. Organic sediments are dominated by organic material e.g. shells, carbon.
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
Many clastic rocks display another common texture—called graded bedding—characterized by a systematic change in grain size from coarse at the base of the bed to fine at the top. Figure 8.46 shows a good example. Clasts in the conglomerate in this figure vary (grade) from coarse at the bottom to fine at the top. Sometimes graded bedding involves very fine grains or is so subtle that we can only see it with a hand lens. Graded bedding generally forms because coarse, heavy grains are deposited from suspension before lighter grains are, so sediments pile up with coarse grains on the bottom and fine grains on the top. Grading forms, for example when river velocity slows and grains of different sizes, starting with large followed by small, settle to the river bed. This kind of texture may develop when submarine sediments slide down a continental slope and slowly settle in deeper water. The coarser material settles first and finer sediment is deposited on top. Repetitive marine deposits of this sort are termed turbidites. For example, the strata shown in Figure 8.42 are turbidite deposits and, if examined with a hand lens, exhibit graded bedding. (At the scale of the photos shown, however, the grading cannot be seen.) Some rare rocks exhibit inverse graded bedding, with coarse material on top of fine. This type of bedding is most commonly associated with debris flows related to kinds of mass wasting. Figure 8.15 shows one example of inverse grading created when submarine landslides deposited poorly sorted material in undersea canyons.
Risk assessment of geohazards along Cheng-Kun railway using fuzzy AHP incorporated into GIS
Published in Geomatics, Natural Hazards and Risk, 2021
Qian Zheng, Hai-Min Lyu, Annan Zhou, Shui-Long Shen
The stratigraphic lithology at the junction of Sichuan and Yunnan provinces is complex and diverse. According to the data from the Spatial Database of 1: 2,500,000 Digital Geologic Map of China (Ye et al. 2017), the study area contains mainly mudstone, sandstone, conglomerate, siltstone, shale, dolomite, limestone, clastic carbonate, granite, diabase, and gravel. These rock types can be divided into eight categories based on the global lithological map classifications (Hartmann and Moosdorf 2012). These are ice and glacier, water bodies, magmatic rock, loose sedimentary rock, metamorphic rock, carbonate clastic rock, pyroclastic rock, and clastic sedimentary rock. Figure 4 illustrates the distribution of the geologic formations in the study area, i.e., lithology (Figure 4(a)), faults (Figure 4(b)), and soil types (Figure 4(c)). Li (2001) divided the formation lithology into four categories according to the type of geological disasters, i.e., magmatic rock, metamorphic rock, pyroclastic rock and clastic sedimentary rock, and loose sedimentary and carbonate clastic rock (Li et al. 2001). Magmatic rock is relatively hard and corresponds to the area of the lowest incidence of geological hazards in this study. Metamorphic rock, pyroclastic rock, and clastic sedimentary rock correspond to the area with the highest incidence of geological hazards. Loose sedimentary and carbonate clastic rock correspond to the low- and high-risk areas, respectively.
Paleocurrent and paleowind direction reconstruction research progress and perspectives: a review
Published in Australian Journal of Earth Sciences, 2023
F. Y. Zhao, C. L. Hu, C. C. Han, Y. Q. Dong, Q. X. Yuan
Through the analysis of clastic rock composition, the nature of parent rocks, transportation distance and transportation time can be obtained to determine the paleocurrent and paleowind direction (Wei et al., 2003). For gravelly rocks, the grainsize and percentage content of gravels decrease along the direction of the paleocurrent and paleowind. For clastic sandstone, the composition and maturity of sandstone will also change regularly along the migration direction (Chen et al., 2008; Han et al., 2020; Hu et al., 2014). Mudstones are generally the product of a still water environment and thus have no distinct indication of the paleocurrent direction (Chen et al., 2008).
Cathaysian slivers in the Philippine island arc: geochronologic and geochemical evidence from sedimentary formations of the west Central Philippines
Published in Australian Journal of Earth Sciences, 2018
C. B. Dimalanta, D. V. Faustino-Eslava, J. T. Padrones, K. L. Queaño, R. A. B. Concepcion, S. Suzuki, G. P. Yumul
Various discrimination diagrams, binary and ternary plots have been proposed to discern the character of the source rocks that became incorporated in clastic rocks. Initially, the geochemical investigations of sedimentary rocks relied on the use of whole-rock major oxide compositions. Bhatia (1983) was one of the first to examine the geochemical compositions of sedimentary rocks to constrain the nature of their source rocks and the tectonic setting of the sedimentary basin. Subsequently various discriminants and ratios have been proposed for provenance and tectonic setting determination (e.g. Chen et al., 2014; Verma & Armstrong-Altrin, 2013).