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Lexicon of lithostratigraphic units for the Sudan
Published in J.R. Vail, Lexicon of Geological Terms for the Sudan, 2022
A number of granite hills in the western part of the Qala En Nahl area of Kassala Province were mapped by Wilcockson and Tyler (1933) and grouped together as foliated porphyritic granites. Some are gneissic, whereas Beila is very coarse and pegmatitic. Plagioclase, microcline and some orthoclase are intergrown with quartz, and brown biotite and some hornblende are present. The granites post-date serpentinites and basic volcanic rocks of the Er Raqal Group and the Wad Wadeda Mafic Complex.
Minerals, rocks, discontinuities and rock mass
Published in Ömer Aydan, Rock Mechanics and Rock Engineering, 2019
Amphiboles are characterized by double chains of tetrahedra balanced by similar cations. They are monoclinic or orthorhombic and commonly found in igneous and metamorphic rocks. Asbestos is one of well-known amphibole mineral. Hornblende is a well-known mineral of the amphibole group.
Minerals, rocks and sediments
Published in Richard J. Chorley, Stanley A. Schumm, David E. Sugden, Geomorphology, 2019
Richard J. Chorley, Stanley A. Schumm, David E. Sugden
Hornblende ( (OH)2Ca2(Mg,Fe)6Al2Si7O22) is a complex mineral which is the most common representative of the amphibole group. It is formed by double silica tetrahedron chains (Figure 4.1C) linked by other ions (silica-oxygen ratio approximately 4:11).
Evaluation and speciation of heavy metals in the soil of the Sub Urban Region of Southern India
Published in Soil and Sediment Contamination: An International Journal, 2022
M. Sinduja, V. Sathya, M. Maheswari, P. Dhevagi, P. Kalpana, G. K. Dinesh, Shiv Prasad
The research area is situated in southwestern parts of the Vellore District of Tamil Nadu, covering around 781 sq. km (Figure 1). The temperature ranges from 18.2 to 36.8°C, with the hottest months being May and June. These regions lie in a part of the Palar river basin, and the drainage pattern is dendritic to semi-dendritic in nature. Generally, the climatic condition of this area is arid to semi-arid. Hence, groundwater is used for drinking, domestic, industrial, and agricultural purposes. The lithology of this region consists of three rocks, namely, Archean crystalline rocks (granite, epidote, hornblende gneiss), sedimentary rock (90%), and hard rock (10%). In addition, hornblende, Muscovite, Pyroxene, Plagioclase, Quartz, Microcline, and Biotite have been observed in the region (Figure 2).
Assessing groundwater quality and health risks of fluoride pollution in the Shasler Vagu (SV) watershed of Nalgonda, India
Published in Human and Ecological Risk Assessment: An International Journal, 2020
Narsimha Adimalla, Sudheer Kumar Marsetty, Panpan Xu
Shasler Vagu (SV) watershed is located in the southwest of Nalgonda district, India in between north latitudes from 16°55' to 17°00' and east longitudes from 78°45' to 79°10'. The study area falls in the Survey of India Toposheet Nos. 56 L/13 and 56 P/1 and covering an area of about 365 km2. Geologically, the study region is underline by Peninsular Gneissic Complex (PGC), and the dominant rock type are of granite and granite gneiss. Younger intrusive include gabbro, dolerite and hornblendite, apatite, pegmatite, quartz and epidote veins, and alluvium. Older metamorphic rocks include hornblende schists, amphibolites, banded magnetite quartzite, meta-basalt, and biotite schist. In the investigated area, biotite schist rock occurs as lenses, schlieren, and inclusion within the migmatitic gneisses. The exposures of biotite schist are oval shaped trending NNW-SSE in the study area. Low-grade metamorphosed basic igneous rock occurs as enclaves within the porphyritic granite, while banded magnetite quartzite is narrow bands trending NW-SE. Hornblende and amphibolite schist are mainly consisted of hornblende and plagioclase as an essential mineral, while quartz, sphene, sericite, and magnetite occur as accessory minerals. These rocks occur as elongated in N–S direction with vertical dip. The migmatite rocks are medium to coarse-grained in nature and are well exposed, while biotite gneisses are generally banded in nature and occur as sheets and inselbergs in low topographic areas (CGWB 2013; Sudheer Kumar et al. 2017).
New U–Pb zircon ages for the Glenroy Complex and McKnee Intrusives, southeast Nelson: strengthening links with northern Fiordland and constraining the timing of metamorphism
Published in New Zealand Journal of Geology and Geophysics, 2020
Matthew W. Sagar, James M. Palin, Liam A. Heath
Sample OU81904 is a medium-grained hornblende–biotite quartz monzodioritic (qz = 5%, or = 21%, ab = 40%, an = 13%) orthogneiss collected from the north side of Davis Creek, downstream from the upper-most fork in the creek. The gneissic foliation is defined by sub-millimetre- to millimetre-scale, discontinuous quartzofeldspathic and hornblende–biotite-rich bands, and parallel alignment of the long-axes of hornblende, biotite, and plagioclase. Hornblende forms subhedral–euhedral prisms, which consist of rims with dark-green/blue-green/pale-brown pleochroism (Z > Y = X) that grade into green-brown/dark green/pale-brown pleochroic cores. The pleochroic scheme indicates that the hornblende cores are enriched in Ti relative to the rims (e.g. Shelley 1975). Hornblende–quartz symplectites suggest the former presence of pyroxene. Biotite displays pale-brown–dark-brown pleochroism and is subhedral–euhedral. Anhedral–euhedral titanite is associated with hornblende and biotite, and its relative abundance is characteristic of this sample. Plagioclase typically forms subhedral grains and does not display either simple or multiple twinning, while anhedral K-feldspar commonly exhibits cross-hatch twinning. Some K-feldspar grains are perthitic and the cores of some plagioclase grains are preferentially altered, suggesting they are relatively enriched in anorthite. Quartz is anhedral and displays undulose extinction. Minor anhedral–subhedral epidote exhibits faint pleochroism (pale-yellow–white) and is also associated with hornblende and/or biotite. Accessory euhedral apatite grains are conspicuous.