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Route Selection and Preliminary Investigations
Published in S. Ponnuswamy, D. Johnson Victor, Transportation Tunnels, 2017
S. Ponnuswamy, D. Johnson Victor
The 'Preliminary Studies' will cover study of the geological history of the region, structure and age of the crust and various component soils and rocks. The rock (and soil configuration) as originally formed; do not take a permanent set all at once; cooling of the earth's solid crust and accompanying contraction keep the deposited rock layers in continual motion. Various layers of rock are subject to compressive forces which cause deformation, creasing, ruffling and distortion, resulting in folding. Atmospheric action causes weathering of the rock, erosion, sedimentation etc. Typical structures of a rock formation are indicated in Figure 2.2. The main fold formation will generally be as indicated in Figure 2.32 .
Rocks, minerals and mineral inventory evaluation
Published in Ratan Raj Tatiya, Surface and Underground Excavations, 2013
Fold, anticline and syncline: the layered rocks, when subjected to stress, it commonly bends or wraps them, forming folds [figs 2.5(a), (b)]. A fold convex upward is anticline; and the one convex downward is syncline (fig. 2.3(viii)). The extent of folding and its ultimate shape depends on the intensity and duration of internal forces, as well as the properties of the rock material. In any type of rock folds may develop, however, in sedimentary and igneous rocks these structures are common. Classification of folds is given in figure 2.4.
Geochronology and geochemistry of the Devonian Gumbardo Formation (Adavale Basin): evidence for cratonisation of the Central Thomson Orogen by the Early Devonian
Published in Australian Journal of Earth Sciences, 2018
P. Asmussen, S. E. Bryan, C. M. Allen, D. J. Purdy
Sedimentary rocks in the basin are generally flat-lying and undeformed as evidenced from drill-hole intersections, but seismic profiles reveal some thrust faults and post-depositional long-wavelength folding (tens of kilometres; Draper et al., 2004), with fold axes oriented in an east–west direction. Much of the contractional deformation is interpreted to be Carboniferous in age because the structures do not persist into overlying Galilee Basin strata, and thus is thought to be regionally related to the 350–330 Ma Kanimblan Orogeny (Finlayson, 1993). This event has locally been referred to as the Quilpie Orogeny for the Adavale Basin System (Finlayson, Leven, Wake-Dyster & Johnstone, 1990), which appears to be coeval with the last phase of the Alice Springs Orogeny in central Australia during the middle Carboniferous (Haines, Hand & Sandiford, 2001).