Ferromagnesian silicate association in S-type granites: the Darongshan granitic complex (Guangxi, South China)

2008 ◽  
Vol 179 (1) ◽  
pp. 13-27 ◽  
Author(s):  
Bernard Charoy ◽  
Pierre Barbey
Keyword(s):  
South China ◽  
Granulite Facies ◽  
Coarse Grained ◽  
Magma Ascent ◽  
Granulite Facies Metamorphism ◽  
Rock Types ◽  
Microgranular Enclaves ◽  
Mafic Microgranular Enclaves ◽  
Type Granite ◽  
Granite Complex

Abstract The late Indosinian Darongshan granite complex (Guangxi Province, South China) consists mainly of three plutons (Taima, Jiuzhou and Darongshan), with coarse-grained to subvolcanic rock types. There is a rough mineral evolution from the western to the eastern part of the complex, with ferromagnesian magmatic silicates sequentially distributed : Opx+Crd±Bt (Taima), Opx+Grt+Bt+Crd (Jiuzhou) and Bt+Crd (Darongshan). Restitic, cumulative or xenocrystic minerals (mainly Crd with fibrolite+spinel inclusions, Grt and probably Opx in some cases) are also encountered. Mineralogical, chemical and isotopic compositions of the granites suggest that the three plutons derive from a source dominated by a reduced, immature greywacke-psammite series, which has experienced high-amphibolite to granulite-facies metamorphism. This S-type granite complex is considered to result from various degrees of melting at different crustal levels by biotite dehydration-melting in a high T (800° to 950°C), low P (400–600 MPa) metamorphic environment. Abundant granulite-facies metasedimentary enclaves with refractory compositions are considered as xenoliths entrapped during magma ascent. The presence of scarce mafic microgranular enclaves and the high temperatures needed for melting could suggest that heat may have been partly contributed by mantle-derived magmas.

scholarly journals Protolith-Related Thermal Controls on the Decoupling of Sn and W in Sn-W Metallogenic Provinces: Insights from the Nanling Region, China

2019 ◽  
Vol 114 (5) ◽  
pp. 1005-1012 ◽  
Author(s):  
Shunda Yuan ◽  
Anthony E. Williams-Jones ◽  
Rolf L. Romer ◽  
Panlao Zhao ◽  
Jingwen Mao
Keyword(s):  
South China ◽  
Bulk Rock ◽  
Rare Metals ◽  
The West ◽  
Metallogenic Province ◽  
Peraluminous Granites ◽  
Microgranular Enclaves ◽  
Mafic Microgranular Enclaves ◽  
The World ◽  
Zircon Saturation

Abstract The Nanling region of South China hosts the largest W-Sn metallogenic province in the world, accounting for more than 54% of global tungsten resources as well as important resources of tin and rare metals. An important feature of this province, which is shared by a number of other W-Sn metallogenic provinces, is that W deposits occur separately from Sn and Sn-W deposits, with the latter concentrated in the western part of the region (especially along the deep, NE-trending Chenzhou-Linwu fault) and the W deposits to the east of them. All the deposits are associated with ilmenite series, peraluminous granites. However, the granites associated with the Sn and Sn-W deposits can be distinguished from the W granites by their higher bulk-rock εNd values and their higher zircon εHf values. Most importantly, the Sn and Sn-W granites are characterized by higher zircon saturation temperatures (800 ± 20°C) than the W granites (650°–750°C). The Sn and Sn-W granites also contain abundant mantle-derived mafic microgranular enclaves, whereas such enclaves are rare in the W granites. A model is proposed in which the protolith to the W granites released W to the melt as a result of the breakdown of muscovite. The temperature of melting, however, was too low for biotite to melt. In the west, particularly along the Chenzhou-Linwu fault (the location of the Sn and Sn-W deposits), higher temperatures enabled the breakdown of both muscovite and biotite and the consequent release of both Sn and W to form Sn and Sn-W granites. This model, which is based on differences in the protolith melting temperature and thus mobilization temperatures for Sn and W, is potentially applicable to any Sn-W metallogenic province in which the Sn and Sn-W deposits are spatially separated from the W deposits.

scholarly journals The Candoglia Marble and the “Veneranda Fabbrica del Duomo di Milano”: A Renowned Georesource to Be Potentially Designed as Global Heritage Stone

2019 ◽  
Vol 11 (17) ◽  
pp. 4725 ◽  
Author(s):  
Dino ◽  
Borghi ◽  
Castelli ◽  
Canali ◽  
Corbetta ◽  
...  
Keyword(s):  
Cultural Heritage ◽  
Anthropogenic Activities ◽  
Close Correlation ◽  
Granulite Facies ◽  
Coarse Grained ◽  
Granulite Facies Metamorphism ◽  
Alpine Area ◽  
Facies Metamorphism ◽  
Nw Italy ◽  
Silicate Layers

Marbles from Alpine area have been widely employed to build and decorate masterpieces and buildings which often represent the cultural heritage of an area (statuary, historic buildings and sculptures). Candoglia marble, object of the present research, is one of the most famous and appreciated marbles from Alpine area; it has been quarried since Roman times in the Verbano-Cusio-Ossola (VCO; Piemonte – NW Italy) extractive area. Candoglia Marble outcrops are present as lenses within the high-grade paragneisses of the Ivrea Zone, a visible section of deep continental crust characterised by amphibolite- to granulite-facies metamorphism (Palaeozoic period). Candoglia calcitic marble (80–85% CaCO3 and the 15–20% other minerals) shows a characteristic pink to gray colour and a coarse-grained texture (>3 mm): frequent centimetre-thick dark-greenish silicate layers (mainly represented by diopside and tremolite) characterize the texture of the marble. It has been largely used in local rural constructions and historical buildings, but its most famous application has been (and still is) for the “Duomo di Milano” construction (fourteenth century). The Veneranda Fabbrica del Duomo di Milano carried out the anthropogenic activities dealing with the Candoglia marble exploitation; it has to be highlighted that the company have managed the Marble exploitation during the last seven centuries and that the quarry itself is a tangible sign of the development of extraction and heritage in the VCO area. Candoglia marble can be recognized as a significant example of a “Global Heritage Stone Resource”: its exploitation from quarry to building (the Duomo di Milano) well represents the close correlation between stone and cultural heritage, between georesources and humankind development

Stable coexistence of grandidierite and kornerupine during medium pressure granulite facies metamorphism

1995 ◽  
Vol 59 (395) ◽  
pp. 327-339 ◽  
Author(s):  
C. J. Carson ◽  
M. Hand ◽  
P. H. G. M. Dirks
Keyword(s):  
Granulite Facies ◽  
Crustal Thickening ◽  
Coarse Grained ◽  
Granulite Facies Metamorphism ◽  
Larsemann Hills ◽  
Facies Metamorphism ◽  
Peak Metamorphism ◽  
Isothermal Decompression ◽  
The Stability ◽  
New Occurrences

AbstractPetrological and mineral chemical data are presented for two new occurrences of co-existing borosilicate minerals in the Larsemann Hills, East Antarctica. The assemblages contain kornerupine and the rare borosilicate, grandidierite (Mg,Fe)A13BSiO9. Two distinct associations occur: (1) At McCarthy Point, 1–10 mm thick tourmaline-kornerupine-grandidierite layers are hosted within quartzofeldspathic gneiss; and (2) Seal Cove, where coexisting kornerupine and grandidierite occur within coarse-grained, metamorphic segregations with Mg-rich cores of cordierite-garnet-spinel-biotite-ilmenite and variably developed plagioclase halos. The segregations are hosted within biotite-bearing, plagio-feldspathic gneiss. Textural relationships from these localities indicate the stability of co-existing kornerupine and grandidierite.The grandidierite- and kornerupine-bearing segregations from Seal Cove largely postdate structures developed during a crustal thickening event (D2) which was coeval with peak metamorphism. At McCarthy Point, grandidierite, kornerupine and late-tourmaline growth predates, or is synchronous, with F3 fold structures developed during a extensive granulite grade, normal shearing event (D3) which occurred prior to, and synchronous with, near-isothermal decompression. Average pressure calculations on assemblages that coexist with the borosilicates at Seal Cove, indicate the prevailing conditions were 5.2–5.5 kbar at ∼ 750°C for formation of the grandidierite-kornerupine assemblage.

scholarly journals Geoquímica das Rochas Máficas Toleíticas da Suíte Pós-Colisional Paulo Lopes, Neoproterozóico do Sul do Brasil

2005 ◽  
Vol 32 (2) ◽  
pp. 69 ◽  
Author(s):  
LUANA MOREIRA FLORISBAL ◽  
LAURO NARDI ◽  
MARIA DE FÁTIMA BITENCOURT ◽  
LEANDRO MENEZES BETIOLLO
Keyword(s):  
Coarse Grained ◽  
Main Body ◽  
Chronological Order ◽  
Orientation Field ◽  
Rapid Crystallization ◽  
Magmatic Rocks ◽  
Microgranular Enclaves ◽  
Mafic Microgranular Enclaves ◽  
Basic Rocks

The Paulo Lopes Suite (SPL), composed of the Paulo Lopes Granite (GPL), Garopaba Granitoids (GG) and Silveira Gabbro (GS), is an association of contemporaneous acid and basic rocks, comprising monzo and syenogranites associated to basic dikes, with abundant mafic microgranular enclaves, interpreted as co-mingling products. The contacts between the granitoids and the basic rocks are evidences of coeval and interactive magmas. The Silveira Gabbro occurs in the study area as a main body and several narrow dikes of NNE orientation. Field relations define a chronological order of magmatic events, where the GPL is the first magmatic pulse and, while steel partially crystallized, was intruded by mingled magmas, represented by the GG and the GS. The basic components are medium-grained, equigranular rocks, with subophitic and ophitic textures. The centre of the main body contains medium- to coarse-grained, equigranular rocks, where agglomerates of early-formed clinopyroxene and plagioclase crystals are found. In the chilled margins, they are microporphyritc rocks of aphanitic groundmass, indicative of rapid crystallization. The Silveira Gabbro rocks are composed of labradorite-andesine, orthopyroxene, augite, pigeonite, olivine (occasionally serpentinized), Fe-hornblende and magnesian hornblende, red biotite, magnetite, ilmenite, apatite, and baddeleyite. The composition is tholeiitic, similar to the high-Ti-P basalts of the Serra Geral Formation. Their high contents of K, Rb, Sr and Ba, as well as negative anomalies of Nb and Ta in multielemental diagrams are similar to the ones observed in magmatic rocks from mature arcs or post-collisional environments. The Neoproterozoic basic rocks may be discriminated from the ones belonging to the Cretaceous Serra Geral Formation by their higher contents of alcalis, Cs, U, Th, and by their fractionated REEpatterns, expressed in the La/LuN ratio. The associated granitoids are structural and compositionally compatible with the ones found in post collisional settings, which indicates that the SPL magmatism developed in such environment.

Reaction textures and metamorphic evolution of sapphirine–spinel-bearing and associated granulites from Diguva Sonaba, Eastern Ghats Mobile Belt, India

2014 ◽  
Vol 152 (2) ◽  
pp. 316-340 ◽  
Author(s):  
DIVYA PRAKASH ◽  
DEEPAK ◽  
PRAVEEN CHANDRA SINGH ◽  
CHANDRA KANT SINGH ◽  
SUPARNA TEWARI ◽  
...  
Keyword(s):  
Granulite Facies ◽  
Coarse Grained ◽  
Eastern Ghats ◽  
Metamorphic Rocks ◽  
Mobile Belt ◽  
Granulite Facies Metamorphism ◽  
Facies Metamorphism ◽  
Isothermal Decompression ◽  
Eastern Ghats Mobile Belt ◽  
Prograde Path

AbstractThe Diguva Sonaba area (Vishakhapatnam district, Andhra Pradesh, South India) represents part of the granulite-facies terrain of the Eastern Ghats Mobile Belt. The Precambrian metamorphic rocks of the area predominantly consist of mafic granulite (±garnet), khondalite, leptynite (±garnet, biotite), charnockite, enderbite, calc-granulite, migmatic gneisses and sapphirine–spinel-bearing granulite. The latter rock type occurs as lenticular bodies in khondalite, leptynite and calc-granulite. Textural relations, such as corroded inclusions of biotite within garnet and orthopyroxene, resorbed hornblende within pyroxenes, and coarse-grained laths of sillimanite, presumably pseudomorphs after kyanite, provide evidence of either an earlier episode of upper-amphibolite-facies metamorphism or they represent relics of the prograde path that led to granulite-facies metamorphism. In the sapphirine–spinel-bearing granulite, osumilite was stable in addition to sapphirine, spinel and quartz during the thermal peak of granulite-facies metamorphism but the assemblage was later replaced by Crd–Opx–Qtz–Kfs-symplectite and a variety of reaction coronas during retrograde overprint. Variable amounts of biotite or biotite+quartz symplectite replaced orthopyroxene, cordierite and Opx–Crd–Kfs–Qtz-symplectite at an even later retrograde stage. Peak metamorphic conditions of c. 1000°C and c. 12 kbar were computed by isopleths of XMg in garnet and XAl in orthopyroxene. The sequence of reactions as deduced from the corona and symplectite assemblages, together with petrogenetic grid and pseudosection modelling, records a clockwise P–T evolution. The P–T path is characteristically T-convex suggesting an isothermal decompression path and reflects rapid uplift followed by cooling of a tectonically thickened crust.

The relationship between crustal magmatic underplating and granite genesis: an example from the Velay granite complex, Massif Central, France

1992 ◽  
Vol 83 (1-2) ◽  
pp. 235-245 ◽  
Author(s):  
B. J. Williamson ◽  
H. Downes ◽  
M. F. Thirlwall
Keyword(s):  
Country Rock ◽  
Granulite Facies ◽  
Massif Central ◽  
Granulite Facies Metamorphism ◽  
Magmatic Underplating ◽  
Granite Complex ◽  
Partial Melts ◽  
Crustal Xenoliths ◽  
Lower Crustal ◽  
The Relationship

ABSTRACTThe Velay granite pluton (Massif Central, France) is the youngest (304 ± 5 Ma) and largest (∼6,900 km2) of the major Massif Central monzogranites/granodiorites and was formed nearly 50 Ma after the cessation of Hercynian continental collision (Pin & Duthou 1990). It is a highly heterogeneous pluton consisting of I-type, high-Sr granites (Sr = 500-900 ppm) with low (+35 to +41) and high (-3 to -5), at its centre, grading into S-type and mixed I-S-type heterogeneous granites of more normal Sr content (100–420 ppm) and higher (+40 to +210) and lower (-3·8 to -7.3) at its margins.The metasedimentary lower crust of the Massif Central was underplated/intruded by mafic mantle-derived magmas between 360 Ma and 300 Ma. From 300-280 Ma (Downes et al. 1991) underplating led to partial melting and granulite facies metamorphism of the underplated material (represented by felsic and mafic meta-igneous lower crustal xenoliths, = –11 to +112, = +2·2 to 8·2, Downes et al 1990). The partial melts assimilated mainly schist but also felsic gneiss and older granite country rock material ( = +100 to +300, = - 5 to -9) to produce the heterogeneous granites. Plagioclase and biotite were accumulated at the base of the intrusion which was intruded to high levels to form the high-Sr granites.

scholarly journals The impact of the Pan-African-aged tectonothermal event on high-grade rocks at Mount Brown, East Antarctica

2020 ◽  
Vol 32 (1) ◽  
pp. 45-57 ◽  
Author(s):  
Xiaochun Liu ◽  
Bin Fu ◽  
Qiuli Li ◽  
Yue Zhao ◽  
Jian Liu ◽  
...  
Keyword(s):  
Granulite Facies ◽  
New Mineral ◽  
High Grade ◽  
Garnet Porphyroblasts ◽  
Granulite Facies Metamorphism ◽  
Rock Types ◽  
Pan African ◽  
Mineral Phases ◽  
The Impact ◽  
Tectonothermal Event

AbstractThis study presents monazite and rutile U–Pb and hornblende and biotite 40Ar/39Ar geochronological data for high-grade rocks of the eastern Grenville-aged Rayner orogen at Mount Brown in order to analyse the extent and degree of Pan-African-aged reworking. Monazite from paragneiss yields U–Pb ages of 910 Ma for larger granular grains and 670–630 Ma for smaller globular beads around garnet porphyroblasts or hosted by symplectites. Rutile from leucogneiss yields U–Pb ages of 520–515 Ma. Hornblende and biotite from different rock types yield 40Ar/39Ar plateau ages of 744 and 520–505 Ma, respectively. Combining these results with published zircon U–Pb age data suggests that granulite facies metamorphism occurred at 910 Ma, with a local low-temperature fluid flow event at 670–630 Ma and thermal reworking at 520–505 Ma. The older age of 744 Ma may reflect cooling or partial resetting of the hornblende 40Ar/39Ar system, indicating that Pan-African-aged reworking did not exceed temperatures much higher than the hornblende Ar closure temperature. These data also suggest that the complete isotopic resetting of some minerals may occur without the growth of new mineral phases, providing an example of the style of reworking that is likely to occur in polymetamorphic terranes.

Lithostratigraphy of the Mesoproterozoic Twakputs Gneiss

2021 ◽  
Author(s):  
S. Doggart ◽  
P.H. Macey ◽  
D. Frei
Keyword(s):  
South Africa ◽  
Granulite Facies ◽  
Biotite Granite ◽  
Main Phase ◽  
Coarse Grained ◽  
Zircon Dating ◽  
Chemical Variability ◽  
Type Granite ◽  
Penetrative Foliation ◽  
Ubiquitous Presence

Abstract The Twakputs Gneiss is a garnetiferous, K-feldspar megacrystic, biotite granite-granodiorite orthogneiss. It represents a major unit in the Kakamas Domain of the Mesoproterozoic Namaqua-Natal Metamorphic Province extending about 250 km between Riemvasmaak in South Africa and Grünau in southern Namibia. The Twakputs Gneiss occurs as foliation-parallel, sheet-like bodies tightly infolded together with granulite-facies paragneisses into which it intrudes along with a variety of other pre-tectonic granite and leucogranite orthogneisses. These rocks were subsequently intruded by late-tectonic garnet-leucogranites, granites and charnockites. The Twakputs Gneiss is a distinctive unit characterised by large ovoid to elongate megacrysts of twinned perthitic K-feldspar, set in a coarse-grained matrix of garnet, biotite, quartz and feldspar. It contains a penetrative foliation defined by the alignment of K-feldspars and streaks of biotite that developed during the main phase D2 of the Namaqua Orogeny (~1.2 to 1.1 Ga). The foliation and an accompanying elongation lineation are more intensely developed along lithological contacts, especially at the margins of the mega-scale F3 domes and basins that refold the regional fabrics. U-Pb zircon dating of the Twakputs Gneiss has yielded concordia ages of between ~1192 and 1208 Ma. Whole-rock geochemistry shows consistent major, trace and REE elemental trends, and thus reflect chemical variability from a single fractionating magma. The Twakputs Gneiss has a granitic to granodiorite composition and is strongly peraluminous. The geochemistry and the ubiquitous presence of garnet and pelitic xenoliths indicate an S-type granite protolith. The Twakputs Gneiss is the most voluminous and widespread member of the Eendoorn Suite which comprises seven textural variants of garnetiferous, K-feldspar-megacrystic granitoid orthogneiss of the same age.

scholarly journals The Qârusuk dykes: post-Nûk, pre-Qôrqut granitoid magmatism in the Godthåb region, southern West Greenland

1983 ◽  
Vol 112 ◽  
pp. 101-112
Author(s):  
V.R McGregor ◽  
D Bridgwater ◽  
A.P Nutman
Keyword(s):  
Granulite Facies ◽  
Ductile Deformation ◽  
Granitoid Magmatism ◽  
Granulite Facies Metamorphism ◽  
Regional Deformation ◽  
Mineral Assemblages ◽  
Similar Character ◽  
Granite Complex ◽  
Chemical Character ◽  
Shear Belt

The Qarusuk dykes are minor intrusions of granitic and trondhjemitic gneiss emplaced in the Godthåb region between 2700 and 2600 Ma ago. They post-date the Nuk gneisses and their subsequent regional deformation and metamorphism but pre-date the essentiaUy post-tectonic Qôrqut granite complex. They are associated in time and commonly in place with intense ductile deformation concentrated in distinct belts along which there was considerable movement of fluids accompanied by retrogression of earlier mineral assemblages. Outside the Godthåb district dykes of similar character post-date the regional c. 2800 Ma granulite facies metamorphism. The dykes are siliceous with low Fet + Mg0 and high Na20 + K20. Variation in Na2O/K2O is at least in part attributed to exchange between magma and percolating fluids. Non-magmatic controls are thought to affect trace element (including REE) and isotopic compositions. The overall chemical character is consistent with derivation by partial melting of sialic rocks associated with the influx of hydrous fluids associated with shear belt formation.

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