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Pillar size and stope span design at the Cadjebut Mine, Western Australia
Published in T. Szwedzicki, Geotechnical Instrumentation and Monitoring in Open Pit and Underground Mining, 2020
C. Gwatkin, D. Lawrence, C. Moormann, M. Lee, K. McNabb, L. Wardle, M. Wold
The host Lower Dolomite Unit consists of a sequence of relatively stiff, strong and competent (occasionally bedded, but unjointed) dolomites interbedded with softer and weaker siltstones. These siltstones contain smectite and are potentially prone to slaking and swelling/shrinking where their moisture contents change during mining.
Silurian and Lower Devonian
Published in W. A. Peck, J.L. Neilson, R.J. Olds, K.D. Seddon, Engineering Geology of Melbourne, 2018
In an interval of tunnel between the Melbourne -Gippsland railway line and the Heatherton Road Access Shaft, Dandenong, the sequence consists of 75 % to 90% siltstone with minor sandstone. The siltstone is predominantly dark grey, very fine grained and massively bedded. The siltstone is highly siliceous, and possibly is partially metamorphosed by the near-by Lysterfield Granodiorite to the east of the tunnel. It is of extremely high strength and the unconfined rock substance strength is up to approximately 250 MPa.
Correlation of the lithostratigraphic facies relationships and depositional environments of the uppermost Silurian through Lower Devonian strata across the central Darling Basin, western New South Wales, SE Australia
Published in Australian Journal of Earth Sciences, 2021
Sedimentary lithofacies 2, in the middle of the LFA-X1 (Figure 9) unit, is composed of alternating parallel-laminated medium-grained to very fine-grained sandstone, fine- to fine-grained silty sandstone and siltstone. The micaceous sandstone, siltstone and silty sandstone within these units show clear evidence of trough cross-bedding to planar cross-lamination. Shales show gradual change into shaley siltstone. Siltstones may show fine-grained ripple cross-laminations, and these are also preserved in sandy beds. Some siltstones are micaceous and carbonaceous and grade through silty claystone to brown-grey claystone with thin grey to dark grey shale layers. Individual bioturbated muddy planar-bedded sandy and silty layers are also present LF2 in the Supplementary paper (Figures A2 and A3). The sub-environments of this lithofacies are interpreted to belong to multi-storey channel sandstone associated with a smaller-scale floodplain (e.g. Clifton, 2006; Jackson, 1981; Khalifa & Mills, 2020; Labourdette, 2011; Miall, 2014; Noorbergen et al., 2018; Reading, 1986, 1996; Sixsmith et al., 2008; Zakir Hossain et al., 2002).
U–Pb geochronology reveals evidence of a Late Devonian hydrothermal event, and protracted hydrothermal–epithermal system, within the Mount Painter Inlier, northern Flinders Ranges, South Australia
Published in Australian Journal of Earth Sciences, 2020
S. B. Hore, S. M. Hill, A. Reid, B. Wade, N. F. Alley, D. R. Mason
The contact between the coarse feldspathic lithology and the fine-grained sands is sharp and well defined, although Steveson’s (1975) petrological description is that it is irregular in thin-section. The sandstone is fine-grained and homogenous, although there are a few crystals that can be seen with the naked eye. The siltstone consists of detrital grains of quartz, feldspar and muscovite that have been compressed together leaving little or no intergranular matrix material. The average grainsize of the rock is 0.05–0.1mm. The grains have well-defined irregular outlines, and there has clearly been sufficient compression of the rock to cause deformation and possibly some recrystallisation of the quartz and feldspars such that original rounded detrital shapes no longer exist, and the grains are closely packed. The sample contains small quantities of accessory heavy minerals, of which rutile is the most abundant. The sample is a siltstone that shows the effects of compression, and the rock has a compact and granular texture. Monazite grains (>50µm) suitable for geochronological analysis were not recovered from the separation process, with only zircon available for geochronological analysis.
Characterization of rock formation at Toshka fourth depression – Egypt
Published in HBRC Journal, 2022
Mohie Elmashad, Salwa Yassin, Mona Afifi
Siltstone is characterized by very low permeability, high to sever slaking potential and very low to medium durability. The uniaxial compressive strength of this stone is highly degraded after soaking. The saturated shearing strength parameter of this stone is 4.8 kg/cm2 for cohesion as a maximum value 20° as internal friction. Chemical tests indicated moderate aggressive effect on construction materials. In addition, uniaxial compressive strength of the natural samples ranged from 4.2 kg/cm2 to 824 kg/cm2. Meanwhile, all samples used for soaking tests were disintegrated upon soaking, and hence there was no sample to test.