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Geological History
Published in F.G.H. Blyth, M. H. de Freitas, A Geology for Engineers, 2017
F.G.H. Blyth, M. H. de Freitas
This transgression is believed to represent downwarping of a continental margin, caused by subduction of an oceanic plate beneath it. With reference to Fig. 2.4, the left continent can be visualized as Laurasia and the right as Gondwana, which was moving north. Sediments accumulated in a series of trenches that extended from the Baltic to the Appalachians. To their north existed a shallow shelf sea (as in Fig. 2.3) in which thick deposits of limestone were formed (e.g. the Carboniferous Limestone of the British Isles). Further north large deltas were flooding across the shelf bringing coarse sand and grit from the denudation of the Caledonian mountains inland (the Millstone Grit is such a deposit). On these deltas developed and flourished the swamps which supported dense growths of vegetation that later were compressed under the weight of overlying sediment to become coal, so forming the Coal Measures. These basic divisions are shown in Table 2.3.
Pit slopes design in French surface coal mines
Published in Raj K. Singhal, Geotechnical Stability in Surface Mining, 2022
French coal open pits have two main features: They have small horizontal extensions (because of geological or environmental factors) and great depths (7 pits will be more than 100 meters deep). Hence the values of the slope angles are particularly important.The geotechnical structure of the coal measures is generally complex, either because of their tectonic history, or existence of underground workings. Hence determination of slope angles is difficult.
Analysis of seepage behavior of the grout into roadway floor
Published in Heping Xie, Yuehan Wang, Yaodong Jiang, Computer Applications in the Mineral Industries, 2020
T. Sasaoka, M. Koga, H. Shimada, S. Kubota, K. Matsui
In underground coal mines, mine tunnels or roadways are driven in coal measures strata. The coal measures rocks in Japan are sandstone, shale, sandyshale, mudstone, tuff, congromerate, etc. Ground control problems in roadway drivage and maintenance are always closely connected with weak rock and soft rocks such as shale and mud-stone. Shale and mudstone are prone to slaking in the presence of water because they contain clay minerals such as kaolinaite and montmollironite that have great water absorption properties. Deterioration of these rocks strength due to water cause a significant decrease in the stability of the excavation and rock, and the fall of a roof and/or a rib and the floor heave may occur.
Origins of clay-rich strata in Cenozoic paleochannel deposits: an example from Suttor Formation, Queensland
Published in Australian Journal of Earth Sciences, 2023
T. Yu, J. Cooling, J. Esterle, T. Chadwick, A. Babaahmadi
Above the unconformity is the basal Unit 4. Although the strata were extremely weathered and soft, upon slabbing and drying of the core, it could be distinguished as a matrix supported breccia (Figure 5i) that transitions upwards to a conglomerate and then into silty and sandy claystone. The clasts in both the breccia and conglomerate are of the dark grey laminated and carbonaceous siltstone from the coal measures. Clasts are poorly sorted, rotated in random orientations and separated by a finer-grained matrix of either sand or clay, featuring soft sediment deformation. As the clasts fine upwards into the conglomerate, they become slightly better sorted. Based on the TIR spectral interpretation (Figure 4b, c) the hyperspectral data indicate that the laminated siltstone clasts contain a mix of kaolinite, quartz and minor feldspar and white mica, which confirm the observation of muscovite in the hand specimen, reflecting their origin from the Permian laminated siltstones. The SWIR range shows that the proportion of white mica gradually declines towards the conglomeratic top and is significantly reduced in the overlying unit. This was also observed in hand samples.
Detrital zircons in Triassic–Cretaceous sandstones, Clarence-Moreton Basin, eastern Australia: speculations upon Australia and Zealandia provenances
Published in Australian Journal of Earth Sciences, 2022
C. J. Adams, H. J. Campbell, R. J. Korsch, W. L. Griffin
In the eastern sector, within the Permian–Triassic Gympie Province (Terrane) at Keefton, sandstone GYM36X (17) is from marine, Lower Triassic Keefton Formation. To the south, within a southern continuation of the Permian–Triassic Esk Basin at Nymboida, NSW, sandstone NYM1 (18) is from a thin granule conglomerate and quartzose sandstone of the Lower–Middle Triassic Nymboida Coal Measures. This unit is very close to the southwest margin of the Clarence-Moreton Basin. The small, isolated Lorne Basin, about 150 km to the south, contains a correlative succession, and a quartz-rich sandstone LOR1 (19) comes from thin granule conglomerate and sandstone within the Upper Triassic Milligans Road Formation (Pratt, 2010). The southernmost locality is in the northern Sydney Basin at Terrigal, where sandstone TERR1 (20) is from marine–deltaic Middle Triassic Terrigal Formation (Narrabeen Group). Finally, at Lamberts Beach, Mackay, a quartz-rich sandstone YARRX3A (16) occurs in a local epiclastic sandstone association (Bryan et al.,2004). This locality was mapped originally as Devonian–Carboniferous Campwyn Volcanics (Yarrol Belt) but later remapped as Lower Cretaceous volcanic rocks by Bryan et al. (2003) and is now considered a siliciclastic unit within the Lower Cretaceous Whitsunday Volcanics. However, our new data (see below) only constrain a post-Permian age.
Refining the depositional model of the lower Permian Carynginia Formation in the northern Perth Basin: anatomy of an ancient mouth bar
Published in Australian Journal of Earth Sciences, 2022
A. Dillinger, R. Vaucher, D. W. Haig
On the Irwin Terrace, the Carynginia Formation conformably overlies the lower Artinskian Irwin River Coal Measures and is overlain by the Guadalupian Wagina Sandstone across a low-angle unconformity (Figure 2). The formation is assigned to the upper Microbaculispora trisina spore-pollen zone (Haig et al., 2014; Mory & Backhouse, 1997) and Praecolpatites sinuosus zone (Backhouse, 1993), and is thus late Artinskian–Kungurian in age (Backhouse & Mory, 2020; Mory et al., 2015) (Figure 2). The Carynginia Formation is largely regarded as the depositional record of a low-energy, restricted, marginal-marine environment under proglacial conditions that progressively evolved into a more open-marine, warmer setting. Le Blanc Smith and Mory (1995) inferred that deposition took place under wave, storm, and tidal influences that partially reworked ice-rafted material (also see N. Eyles et al., 2006), whereas Haig et al. (2017) suggested sediment influx from laden freshwater onto a low-gradient seafloor. The formation reaches over 300m in thickness in the onshore and offshore subsurface of the northern Perth Basin (Mory & Iasky, 1996), and has been evaluated as a potential gas-prone unconventional play (Cooper et al., 2015).