China
Africa
Explore chapters and articles related to this topic
Mainland Europe, Turkey and Cyprus
Published in Ian Sims, Alan Poole, Alkali-Aggregate Reaction in Concrete: A World Review, 2017
Isabel Fernandes, Özge Andiç-Çakir, Colin Giebson, Katrin Seyfarth
Nearly all cases of ASR damage involve river derived aggregates. Marine aggregates, which have been used in the Netherlands for about a quarter of a century, have not been involved (Nijland & Siemes, 2002). Polarization and fluorescence studies of the concrete of ASR-affected structures show that the reactive aggregate grains are chalcedony, impure sandstones, greywacke, sericitic limestone, etc., in addition to porous chert. Microcrystalline quartz in quartzite and schist/slate has been identified to participate in the reaction. In one case, quartz porphyry was used as aggregate.
Stratigraphic and igneous relationships west of Yass, eastern Lachlan Orogen, southeastern Australia: subsurface structure related to caldera collapse?
Published in Australian Journal of Earth Sciences, 2019
C. L. Fergusson, B. E. Chenhall, S. Guy, B. G. Jones, M. Solomons, G. P. Colquhoun
Most of the lower succession consists of interbedded greenish-grey/dark grey/black mudstone layers, 2–20 cm thick, and recessive limestone beds, ∼5–20 cm thick (Figure 8d). Many limestone beds are nodular and massive limestone also forms mappable lenses up to 250 m thick. In the absence of associated breccias and indicators of discordance, these are interpreted as probably allodapic limestone and shelf bioherms, respectively. Much of the limestone and mudstone is weakly to locally strongly contact metamorphosed; limestone has recrystallised to form fine- to medium-grained granoblastic marble. Cramsie et al. (1978) referred to the non-carbonate layers interbedded with the limestones as ‘tuffs’ but we have found no evidence that they are of volcanic origin. Limestones are locally fossiliferous containing crinoids, tabulate corals, pentamerid brachiopods, stromatoporoids and bryozoans (Pickett, 1982; Sherwin, 1968). The fossil faunas are poorly preserved in the unit and only a general Silurian age (probably Wenlock to Ludlow) has been determined (Colquhoun et al., 2012). Quartzose sandstone occurs on the western side of the quartz porphyry intrusion east of upper Limestone Creek (Smsm, Figure 4). Skarns occur locally near intrusions (Figure 4) and include zoned skarn with an outer layer of wollastonite and an inner layer of wollastonite and vesuvianite. Massive skarns contain grossular-rich garnet, epidote, wollastonite, and vesuvianite and minor altered plagioclase.
VHMS mineralisation at Erayinia in the Eastern Goldfields Superterrane: Geology and geochemistry of the metamorphosed King Zn deposit
Published in Australian Journal of Earth Sciences, 2019
S. P. Hollis, D. Podmore, M. James, J. F. Menuge, A. L. Doran, C. J. Yeats, S. Wyche
Hanging-wall banded schists range in composition from mafic to felsic according to their Zr/TiO2 ratios and Co concentrations (Figure 10c, d), consistent with their variations in mineralogy (quartz–biotite dominated to amphibole ± garnet) (Figure 7f). Quartz-porphyry sills, which intrude and are interpreted as coeval with the King stratigraphy (Figure 6c; labelled 1), are intermediate to dacitic in composition (Figure 10c, d), with high calc-alkaline Zr/Y (16.7–18.5) and Th/Yb ratios, and low HFSE concentrations (Figure 10e, f). Chondrite-normalised REE profiles are steep, with respect to both the LREE and HREE (Figure 11a). The younger quartz-porphyry sills (Figure 6c, labelled 2) and late basaltic dykes were not analysed.
Analytical and numerical assessment of a preliminary support design – a case study
Published in Cogent Engineering, 2021
Sylvanus Sebbeh-Newton, Shaib Abdulazeez Shehu, Prosper Ayawah, Azupuri A. Kaba, Hareyani Zabidi
The tunnel cuts through two major formations. The Karak Formation of Silurian-Devonian age extends from the inlet portal to chainage 3.82 km consist of metasediments such as hornfels, shale, metaschist, and phyllite. The Main Range granite is composed of coarse to very coarse-grained, porphyritic biotite granite cut by minor porphyritic differentiates and fine-grained variety of granite which represent a later phase of granite intrusion. Micro-granite, granodiorite, diorite, monzonite, granite porphyry, quartz porphyry, felsite, vein quartz, megacrysts biotite granite, megacrystic muscovite-biotite granite and equigranular tourmaline-muscovite granite are the other foundation rocks within the Main Range Granite.