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An innovative approach to peak gas storage in large urban areas – A hard rock natural gas cavern in New York City
Published in Bjørn Nilsen, Jørn Olsen, Storage of Gases in Rock Caverns, 2022
The dominant rock type is a gneiss. The gneiss is a thinly foliated rock comprised principally of in-grained quartz, biotite, and feldspar with variable small amounts of garnet, pyrrhotite and probably magnetite. It is believed that the gneiss belongs to the Hartland Formation. This unit originated as sedimentary rock of probably Precambrian age which was metamorphosed to its present state in late Ordovician time.
Lexicon of lithostratigraphic units for the Sudan
Published in J.R. Vail, Lexicon of Geological Terms for the Sudan, 2022
A heterogeneous group of rocks of varying mineralogy and texture unified by a complex tectonic history occurs in the extreme south-west of South Darfur Province. Widespread quartzo-feldspathic gneisses, rich in biotite and/or muscovite, in which sillimanite is present, and also hornblende garnetiferous amphibolite. The unit was defined by Hunting Geology and Geophysics (1969b), and said to be synonymous with the Older Plains Group of previous workers.
Assessment of the Visual Disaster of Land Degradation and Desertification Using TGSI, SAVI, and NDVI Techniques
Published in Shruti Kanga, Suraj Kumar Singh, Gowhar Meraj, Majid Farooq, Geospatial Modeling for Environmental Management, 2022
B. Pradeep Kumar, K. Raghu Babu, M. Rajasekhar, M. Ramachandra
The geology of Anantapur district has been compiled from the GIS reports and other available data from the district Gazetteer, and the geological materializations in the Anantapur district can broadly be alienated into distinct and well-marked groups; an older group of metamorphic rocks has its place to the Archean and younger group of sedimentary rocks belonging to the Proterozoic age. The study is being mainly composed of hornblende biotite gneiss, biotite gneiss, and migmatites. Some part in the south western side is composed of grey granite or pink granite (Figure 14.2).
Two belts of HTLP sub-regional metamorphism in the New England Orogen, eastern Australia: occurrence and characteristics exemplified by the Wongwibinda Metamorphic Complex
Published in Australian Journal of Earth Sciences, 2020
K. Jessop, N. R. Daczko, S. Piazolo
Grade increases to the north against the Shacks Mylonite Zone (Figure 19). The northern half of the area contains typical accretionary complex rock types of psammitic and pelitic metasedimentary rocks mixed with meta-basalts, meta-cherts and minor calc-silicate lenses that have been metamorphosed to migmatite gneiss, amphibolite and quartzite. The gneiss contains segregations, veins and irregular intrusions of S-type granitic rocks formed by partial melting of the metasedimentary rocks (Morand, 1993). Large grains of muscovite coexist with quartz and K-feldspar in the gneisses and have been interpreted as part of a prograde assemblage (Leitch et al., 1993). Psammitic metasedimentary rocks contain quartz, biotite, plagioclase, muscovite, and sillimanite. In addition, pelitic sedimentary rocks contain K-feldspar and almandine-garnet (Leitch et al., 1993; Morand, 1993). Cordierite has not been recorded, possibly because of the quartz-rich nature of the protolith Shoalwater Formation sedimentary rocks. Amphibolites are predominantly hornblende and plagioclase with subordinate titanite, clinopyroxene and almandine garnet.
Cleaning up the record – revised U-Pb zircon ages and new Hf isotope data from southern Sweden
Published in GFF, 2021
The bulk of the Eastern Segment is instead totally dominated by gneisses of TIB-2 age (1710–1660 Ma, n = 55). There are a couple of rocks with somewhat older ages (“TIB-1.5”), including the 1725 Ma gneissic monzonite south of Alvesta (sample 86011), and a few rocks with ages going down to 1600 Ma (n = 4). Four of the gneiss samples in this study (76314, 85015, 85017, 85019) fall within the 1690 to 1700 Ma range, which seems to be the period of most intense magmatism within the future-to-be Eastern Segment, to judge from the number of age data falling in that interval (n = 19). The two coarser-grained gneissic granitoids at Mölle and Skäralid (84093 and 85018) yield slightly younger ages between 1680 and 1690 Ma (for which interval n = 16).
Compositional characteristics of mineralised and unmineralised gneisses and schist around the Abansuoso area, southwestern Ghana
Published in Applied Earth Science, 2023
Raymond Webrah Kazapoe, Olugbenga Okunlola, Emmanuel Arhin, Olusegun Olisa, Daniel Kwayisi, Elikplim Abla Dzikunoo, Ebenezer Ebo Yahans Amuah
The unmineralised gneisses are of two varieties based on mineralogical composition. These are the Biotite gneiss and Hornblende-Biotite gneiss. Generally, the gneisses are medium-grained and are weakly to strongly foliated. The biotite-gneiss is composed of quartz, plagioclase, microcline, and biotite (Figure 2(a)). Cubic to slightly elongated sulphide minerals can be observed. The biotite and elongated opaque minerals define the foliation and mineral elongation (Figure 2(a)). Quartz is anhedral, exhibits undulose extinction, appears recrystallised, and occurs as either coarse crystals or medium-grained, elongated aggregates. Plagioclase and microcline are subhedral to anhedral and weakly altered to sericite. The biotite shows very weak alterations mostly into chlorite. The hornblende-biotite gneiss is foliated with compositional banding of felsic bands alternating with mafic bands. In general, this rock is composed of hornblende, biotite, garnet, plagioclase, quartz, and microcline (Figure 2(b)). The first three minerals comprise the mafic bands whereas the latter three comprise the felsic bands. The mineral assemblage is structurally competent although individual grains are slightly elongated, broken, or cracked. The garnet and microcline in some samples are very coarse and poikilitic with inclusions of quartz and occasional biotite (Figure 2(b,c)). Associated with the garnet and often occurring within the foliation are subhedral to cubic opaque sulphide minerals. Hornblende has partially altered to epidote whereas the feldspars and biotite have partially altered to sericite and chlorite, respectively. Quartz is elongated and exhibits undulose extinction.