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Variability of hydraulic fracturing rock stress measurements and comparisons to triaxial overcoring results made in the same borehole
Published in Katsuhiko Sugawara, Yuzo Obara, Akira Sato, Rock Stress, 2020
C. Andersson, R. Christiansson
The Äspö HRL – Oskarshamn area is located within the same granitic area. The rock is 1.6–1.8 billion years (Rhen et al. 1997) and is a part of the Scandinavian shield. The rock type around the boreholes at Äspö HRL mainly consists of a rather homogenous Quartz-monzodiorite called Äspö diorite. There are also smaller volumes of Småland granite. The main difference in mineral composition between Äspö diorite and Småland granite is that the Småland granite has a higher amount of quartz and potassium feldspar, while the diorite is richer in dark minerals. The granite has a lighter reddish color. The difference in rock mechanics properties between the two rock types is small. The mechanic properties have been described by for example (Nordlund et al. 1999). Sparsely distributed feldspar crystals in the Äspö diorite with the size of 15–20 mm can randomly influence the results of uniaxial testing.
Plutonic Rocks
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
The rocks comprising El Capitan are typical of the entire Yosemite region and of the Sierra Nevada Mountains overall. Yosemite is a mosaic of many different intrusive bodies that formed over millions of years, including some additional rock types not seen in El Capitan’s face. Figure 6.19 shows a sample of the Half Dome Granodiorite. It crops out just a few kilometers east of El Capitan on the north side of the valley in the Royal Arches and North Dome. The Royal Arches are prominent in Figure 6.5; North Dome is the rounded peak above the Arches. This granodiorite also crops out on the opposite side of the valley from the Arches, at Glacier Point. Farther east, it forms the vertical cliff face of Half Dome itself, seen in Figure 6.5. The granodiorite is medium to coarse grained and contains conspicuous plates of biotite and crystals of hornblende. It is the youngest of the major plutonic rocks in the region. The granite, granodiorite, tonalite, quartz monzonite, and quartz monzodiorite found in Yosemite are all considered granitoids, and this explains why sometimes the imprecise name granite is used for all of them. Other rocks—including quartz diorite, diorite, and gabbro (none of which are granitoids)—are present too, but in lesser amounts and are not called granite.
Principles of Petrological Analysis of Igneous Rocks
Published in O.A. Bogatikov, R.F. Fursenko, G.V. Lazareva, E.A. Miloradovskaya, A. Ya, R.E. Sorkina, Magmatism and Geodynamics Terrestrial Magmatism Throughout the Earth’s History, 2020
The intrusive equivalents of the potassic moderately alkaline (shoshonite– latite) series are represented by subalkaline and gabbro–monzonite intrusions, recorded from the Kurile Islands and Japan (Tsvetkov, 1984). They make up the thick, sill-like bodies of the southern group of the Kuriles (Tanfilieva and Zeleny, etc.) and the Nemura Peninsula of Japan. They exhibit some layering features: from orthoclase-olivine gabbroids at the base, to monzonite, monzodiorite and syenite in the upper parts of the sills. Monzonite is the dominant rock type. Melt crystallization took place under near-surface conditions, as suggested by the spatial association with shoshonite lavas and pyroclastics.
Geochemical characteristics and structural setting of lithium–caesium–tantalum pegmatites of the Dorchap Dyke Swarm, northeast Victoria, Australia
Published in Australian Journal of Earth Sciences, 2023
B. R. Hines, D. Turnbull, L. Ashworth, S. McKnight
The Banimboola Quartz Monzodiorite is an Early Devonian I-type plutonic intrusion, demonstrating an elongate northeast trend and is located east of the Dorchap Range (Figure 2; Morand et al., 2005). The Banimboola Quartz Monzodiorite is primarily composed of subhedral plagioclase, hornblende, biotite and clinopyroxene phenocrysts, with minor orthoclase and interstitial quartz and accessory sphene and apatite. Several smaller felsic and mafic dykes and multiple intrusive phases are associated with the Banimboola Quartz Monzodiorite, including aplitic and microgranitic porphyry dykes, commonly associated with a pervasive potassic alteration overprint. Seven biotite and hornblende K–Ar dates from the Banimboola Quartz Monzodiorite suggest a dominant intrusion age of 408 ± 16 Ma, although the possibility of an additional intrusive phase at 394 ± 7 Ma is also indicated (Richards & Singleton, 1981).