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The Taxco fluorite deposit (Mexico): a new pseudo-chromatographic mechanism for rhythmite formation
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
J. Tritlla, A. Camprubí, R. Corona-Esquivel
The samples of the A-1 facies usually display a succession of silica-rich light bands and fluorite-rich dark bands Very often huge blocks of limestone are placement. A close look to the replacement front indicates that the fluorite fades away from the banded replacement body to the limestone and, in most of the cases, the limit is unprecise. Under the petrographic microscope, and from the fluorite mass to the fresh limestone this succession has repeatedly observed this way: Fluorite-silica rhythmite.Last band of purple fluorite in contact with limestone.Highly recrystallised limestone, where calcite crystals now display a blocky texture, with well developed triple junctions, indicating a passive recrystallisation. Close to the contact with the last fluorite band, small subhedral crystals of fluorite partially replace some calcite crystals just along the new-formed regular calcite grain borders. This band is devoid of silica.A silica-rich band in sharp contact with the recrystallised limestone, identical to the silica bands found within the rhythmite. Silica grains seldom contain limestone relicts.Non-recrystallized (fresh) fossiliferous limestone.
Parametric simulations on the stability conditions of the masonry wall of Chandakas, Heraklion City, Crete, Greece
Published in Renato Lancellotta, Carlo Viggiani, Alessandro Flora, Filomena de Silva, Lucia Mele, Geotechnical Engineering for the Preservation of Monuments and Historic Sites III, 2022
C. Loupasakis, N. Antoniadis, E. Grigorakou, I. Parcharidis, A.M. Tompolidi, M. Fragiadakis, V. Sithiakaki, E. Kanaki, P. Soupios, G. Kalousi V, P. Eleftheriou, P. Elias
Group 1: The cohesion and friction angle of the soil layers were altered between the MIN and the MAX values, while maintaining a constant value for the modulus of elasticity of the soil layers (Table 1). Regarding the masonry wall, at the Ottoman phase the mechanical parameters of the dolomitized limestone were assigned, while at the Venetian either those of the fossiliferous limestone or those of the calcareous sandstone. In each construction phase, the modulus of elasticity was considered constant. The values used were set equal to the calculated by the equation proposed by EC6.
UNESCO World Heritage Sites, International Union of Geological Sciences and Heritage Stone Subcommission
Published in Gurmeet Kaur, Sakoon Singh, Anuvinder Ahuja, Noor Dasmesh Singh, Natural Stone and World Heritage, 2020
Gurmeet Kaur, Sakoon Singh, Anuvinder Ahuja, Noor Dasmesh Singh
Lioz stone is microcrystalline limestone from Portugal. It is a fossiliferous limestone which imparts aesthetic appeal to the rock and has been in use since the 16th century. It has been recognized as the “Royal stone” for its use in a lot of stately buildings. It is still being quarried and also used in the restoration of old buildings (Silva, 2019).
Lower Cambrian volcanism in the Hawker Group and the Billy Creek Formation, Arrowie Basin, Flinders Ranges, South Australia
Published in Australian Journal of Earth Sciences, 2023
In the Bunyeroo Creek area, three to six tuff layers can be recognised within unit 1 along the mapped extent of the Mernmerna Formation (Figure 3). The tuff exposures can be traced readily by the trains of resistant green siliceous fragments. Some layers, including those only a few centimetres to decimetres thick have a thin platy outcrop habit akin to thinly bedded siliceous shale (Figure 6a). Tuffs up to 2.5 m thick have a more massive to laminated or blocky exposures as at the Big Green Tuff locality south of Bunyeroo Creek (see below). The thin green tuffs are faintly to distinctly finely laminated, and generally strongly stained by manganese oxides. A laminated fossiliferous limestone layer, 10–20 cm thick, underlying these tuffs, is generally dark brown, intensely silicified and strongly stained with manganese oxides. The basal contacts of the tuffs are sharp and planar to slightly wavy (Figure 6b). Upper contacts of the tuffs are sharp but have no silicified contact zone. The upper and lower contacts are always conformable to bedding in the enclosing limestones. None of the exposures show obvious volcanic textures or phenocrysts in hand specimen.
Tectonic setting and mineralisation potential of the Cowley Ophiolite Complex, north Queensland
Published in Australian Journal of Earth Sciences, 2022
A. Edgar, I. V. Sanislav, P. H. G. M. Dirks
The Silurian–Carboniferous Hodgkinson Province is the largest sub-unit in the Mossman Orogen. It extends north–south for >500 km, and east–west from the coast to the Palmerville Fault (Withnall & Cranfield, 2013). The Hodgkinson Province consists mainly of marine siliciclastic sediments, with mafic volcanic units and fossiliferous limestone more common in the western successions (Bultitude et al., 1990; Poblete et al., 2021). Folding and thrusting events have disturbed much of the stratigraphy within the Hodgkinson Province. The major lithological units in the province are exposed along north–south-trending, thrust-bound belts, which comprise, from east to west, the Hodgkinson Formation, Chillagoe Formation, Mountain Creek Conglomerate, Mulgrave Formation and the Quadroy Conglomerate (Bultitude et al., 1990). The tectonic setting of the Hodgkinson Province remains enigmatic. An investigation of basalt geochemistry by Vos et al. (2006) concluded that the Hodgkinson Province formed within an evolving backarc setting, with extension driven by the eastward retreat of an outboard subduction complex. Other authors have suggested formation within a forearc setting associated with oblique slip subduction (Henderson, 1980, 1987), or a continental margin rift setting (Garrad & Bultitude, 1999).
Late Ordovician subsurface carbonates and fossil assemblages from the area immediately west and northwest of Peak Hill in central New South Wales and their regional correlation
Published in Australian Journal of Earth Sciences, 2022
Y. Y. Zhen, T. J. Wells, C. J. Simpson, J. Parslow
The lowermost carbonate interval consists of limestone breccia, which has a variably matrix-supported and less common clast-supported texture. Clasts in the matrix-supported parts are predominantly fine-grained massive limestone and fossiliferous limestone but include a small number of well-rounded trachyandesite clasts and minor phenocryst fragments. Clast-supported limestone breccia consists of intervals up to 10 m wide in which fine-grained limestone has a finely fractured but essentially intact texture. These intervals were interpreted by Simpson (2014) as probable large slide blocks that were transported downslope with more fragmented limestone and minor volcanic clasts in subaqueous debris flows. The limestone breccia contains two (0.5 and 1 m wide) intervals of massive to diffusely laminated coarse-grained volcaniclastic sandstone that is composed of intermediate lava clasts, plagioclase and altered ferromagnesian crystals and minor limestone clasts.