The occurrence of massif-type anorthosite intrusions is a widespread Proterozoic phenomenon. They are usually associated with gabbroic, charnockitic, and granitic rocks, comprising the so-called anorthosite-mangerite-charnockite-granite (AMCG) suite.
This study concentrates on the northwestern part (over an area of 80 km 2) of the 10–20-km-wide and >100-km-long, strike-slip ductile WNW–ESE-trending ASZ (Fig. 1).Outcrops in the study area comprise charnockite, quartzofeldspathic garnet-biotite gneiss with intercalations of migmatitic garnet gneiss and biotite gneiss, and granite.
From the 1.93 Ga syn-collision leucogranite (garnet-bearing granite), the 1.88–1.85 Ga post-collision A-type granites and charnockites (the granite–charnockite suite), and the1.85–1.77 Ga intraplate basaltic rocks (Li 1997 and Xiang et al. 2008) in the region, a Paleoproterozoic orogenic cycle can be deciphered in the Cathaysia Block. The ...
In order to understand the genesis of charnockite and its genetic relationship with S-type granite in DSGC, we conducted in situ zircon SIMS U-Pb dating and Hf-O isotopes analyses as well as monazite U-Th-Pb dating based on detailed petrographical and mineral chemical analyses, in combination with applications of newly …
Charnockite is similar to granite in its outward appearance. It is a hypersthene-quartz-feldspar rock resembling 1. and 2. Platy quartz does not exist and can be used to distinguish it from 1. In ...
The major lithologic unit – the granitoids can be subdivided into TTG, charnockite, Closepet granite and anatectic granites/migmatites. The charnockite near Salem has two types of occurrence: one is massive, garnet-free and plutonic, crystallized at ~2560 Ma, and the other is gneissic, garnet-bearing and incipient, metamorphosed at …
The Friersdale Charnockite is thus younger than the 1090 ± 9 Ma Straussburg Granite at the 66% (or la) confidence level although the ages overlap at the 95% (or 2a) confidence level.
Charnockite is a granofels that contains orthopyroxene, quartz, and feldspar.Charnockite is frequently described as an orthopyroxene granite. Granites are felsic rocks that usually contain no or very little pyroxene. …
The Luyashan intrusion in the northernmost segment of the Lüliang Complex (Fig. 2) is composed of weakly gneissic rocks previously classified as enderbite, charnockite, massive quartz monzonite, rapakivi granite and alkali-feldspar granite (Zhao et al., 2008, Liu et al., 2006, Liu et al., 2012).
Contacts between granite, quartz mangerite, and charnockite are usually transitional without clear-cut evidence of intrusion sequence. Smaller intrusions comprising solely charnockite or granite were also recorded. Dykes and small stocks represent mafic rocks with local evidence of mingling interaction with granite (Fig. 3 e–h).
Harker variation diagrams for CaO and TiO2 in the Nicholson "s Point granite. The charnockite samples are shown as filled symbols and the garnet biotite granite as open symbols. garnetiferous rocks (mean S content = 194 ppm; standard deviation = 44) (Fig. 7, Table 2). There are no significant differences in the values of 8~80 between the ...
Pudukkottai region in the northeastern part of the Madurai Block exposes the garnetiferous pink granite that intruded the biotite gneiss. Charnockite patches are associated with both the rock types. Rb–Sr biotite and Sm–Nd whole-rock isochron ages indicate a regional uplift and cooling at ∼550 Ma. The initial Nd isotope ratios ( ε Nd t = − …
Occur- rences of granite-charnockite complexes with charnockitic alteration of surrounding rocks are most readily explained by volatile-associ- ated processes. The common CO2-rich fluid inclusions of charnockites could have a more direct interpretation than the incidental role suggested by some workers (Hollister, 1988). Summary …
Samples of both the Walker Top Granite and charnockite from the larger xenolith in the western part of the roadcut were collected for U-Pb geochronology. Walker Top Granite zircons range from 200 to 675 μm long and 75–280 μm wide and have aspect ratios between 2:1 and 6:1. The grains are commonly euhedral to subhedral, acicular, …
The pluton shows compositional gradients from primitive orthopyroxene-bearing granite (charnockite) at stratigraphically low levels to relatively evolved orthopyroxene-free granite at stratigraphically high levels. Deviation of whole-rock compositions from metasediment-sourced experimental melts, and step-zoned …
Geochemically, the charnockite suite shows compositional variation from monzonite through granodiorite to granite, and based on Q-A-P classification, the rocks correspond to Opx-bearing granite (charnockite), granodiorite (opdalite or charnoenderibite), and monzodiorite (jotunite).
The Varberg–Torpa charnockite–granite association (Varberg, SW Sweden) consists of the magmatic Varberg charnockite (1399 ± 6 Ma) and the Torpa granite (1380 ± 12 Ma). The Torpa granite is both continuous and, based on its whole-rock geochemistry, synmagmatic with the Varberg charnockite. The granite body also contains a number …
The mineralogy and petrology of the charnockite and surrounding granite are the same except for the presence of orthopyroxene ± clino-pyroxene in the charnockite. In addition, the charnockite is ...
A particularly enigmatic example of charnockite-granite relations is found in southern Karnataka State. The outcrop of the Closepet Granite, a linear 250-km-long complex of intrusive granites, crosses the lower-grade craton from north to south and impinges upon the charnockitic terrane (Fig. 1). At this petrologic juncture, a charnockitic ...
Igneous rocks (granite and charnockite) are known to contain minerals that can trap naturally occurring radioactive elements like uranium and thorium. When these elements decay, they release radiation in the form of alpha, beta, and gamma particles [8]. Typical granite is chemically composed of 70–77 %
Schematic summary of a possible model for generation of Grenvillian anorthosite–mangerite–charnockite–granite suites. Following either lithospheric delamination or convective thinning of the lithosphere resulting from crustal thickening related to Elzevirian orogenesis, the hot asthenosphere rises towards the base of the …
In the case of the Varberg-Torpa charnockite-granite association, investigation of the mineralogy, mineral chemistry, petrology, whole rock data, and fluid inclusions from both the Varberg ...
The major lithologic unit – the granitoids can be subdivided into TTG, charnockite, Closepet granite and anatectic granites/migmatites. The charnockite near …
granite, coarse- or medium-grained intrusive igneous rock that is rich in quartz and feldspar; it is the most common plutonic rock of the Earth's crust, forming by the cooling of magma (silicate melt) at depth. …
Igneous charnockites are characterised by distinctively high abundances of K 2 O, TiO 2, P 2 O 5 and LIL elements and low CaO at a given SiO 2 level compared to …
the Charnockite-Granite Association (C.G.A.), which includes both charnockitic and non-charnockitic components, outcrops in the Varberg area of south-west Sweden". This complex was
Above the granite sheet is a nebulitic contact between an area of charnockite and gneiss in which charnockite has begun to develop. well as K reported from the northern portion of the granite
Imaging the complete orogenic cycle during Paleoproterozoic in the Cathaysia Block from a granite–charnockite suite • 1.93 Ga leucogranite generated under collisional setting in a thickened crust. Collision and subsequent post-collisional extension related with the assembly of supercontinent Columbia
Download: Download full-size image Fig. 1. (a) Schematic map showing distribution of the late Permian–Triassic granite east of the South China Block (modified after Gao et al., 2014a, Wang et al., 2005).Insert shows distributions of principal continental blocks of present-day Southeast Asia and the South China Fold Belt in South China …
Schematic summary of a possible model for generation of Grenvillian anorthosite–mangerite–charnockite–granite suites. Following either lithospheric …
