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Microgranitoid enclaves are common in granitic plutons worldwide, occurring individually and in homogeneous or heterogeneous swarms. Three plutons in the central Sierra Nevada batholith contain swarms with mostly heterogeneous suites of enclaves in the intermediate composition range, and occur in a number of two-dimensional shapes, specifically as dikes, small rafts, lenses, pipe/vortices and large...
The Fornos de Algodres Complex (FAC) comprises several intrusions of late-post-tectonic Hercynian granitic rocks ranging in composition from hornblende granodiorites and quartz monzodiorites, through coarse porphyritic biotite granites and two-mica granites (coarse-, medium- and fine-grained), to muscovite-rich leucogranites. Field and regional constraints show that the emplacement of this large,...
The Proterozoic Pomovaara Granite Complex in northern Finland comprises three separate highly magnetic granite stocks. They are discordant, apparently unfoliated and according to isotope data, a significant Archaean component characterizes the source of these granites. The three stocks are aligned in an array parallel to major trans-crustal faults as interpreted from both aeromagnetic and gravity...
Strongly peraluminous (SP) granites have formed as a result of post-collisional processes in various orogens. In `high-pressure' collisions such as the European Alps and Himalayas, post-collisional exhumation of overthickened crust (>50 km), heated by radiogenic decay of K, U and Th during syn-collisional thickening, produced small- to moderate-volume, cool (<875 o C) SP granite melts...
The Jalama pluton (JP) is one of the best examples of the late Hercynian two-mica granites of the Central-Iberian Zone (CIZ) of the Hesperian Massif (Spain and Portugal). This pluton is a multiphase intrusion that consists of three intrusive units: (1) the external unit (EU) comprises three main facies [a two-mica coarse-grained porphyritic granite (PG), a two-mica coarse-grained equigranular granite...
Tonalitic, granodioritic and monzogranitic enclaves occur in the Hercynian peraluminous porphyritic biotite granite and biotite-muscovite granite from the Nelas region. Some variation diagrams show linear trends, but others show dispersion. The enclaves generally have closely similar isotopic signatures to those of the host granites. They contain xenocrystic plagioclase with the same composition as...
The Oetmoed Granite-Migmatite Complex (OGMC), Central Damara Orogen, Namibia, consists of grt- and crd-bearing S-type granites and hbl- and titanite-bearing A-type granites that intruded into crd-sil-Kfs-bearing metasedimentary rocks, stromatic migmatites and nebulites. Stromatic migmatites formed by limited in situ partial melting of metapelites under H 2 O-saturated conditions at ~700 ...
The solubility of Ti- and P-rich accessory minerals has been examined as a function of pressure and K 2 O/Na 2 O ratio in two series of highly evolved silicate systems. These systems correspond to (a) alkaline, varying from alkaline to peralkaline with increasing K 2 O/Na 2 O ratio; and (b) strongly metaluminous (essentially trondhjemitic at the lowest K 2 O/Na...
The Rio Espinharas pluton, northeastern Brazil, belongs to the shoshonitic series and consists mainly of syenogranite, quartz–monzonite and porphyritic quartz–monzonite, but diorite, quartz–monzodiorite, quartz–syenite and microsyenogranite also occur containing microgranular enclaves, except for the diorite. Most variation diagrams of rocks, amphiboles, biotites and allanites show linear trends,...
The Agua Boa and Madeira igneous complexes at the Pitinga mine were emplaced into acid volcanic rocks of the Paleoproterozoic Iricoume Group, and host major tin, rare-metal (Zr, Nb, Ta, Y, REE) and cryolite mineralization. The igneous complexes are elongate NE-SW and each is composed of three major facies that, in order of emplacement, include porphyritic and equigranular rapakivi granite and biotite...
The Bandombaai Complex (southern Kaoko Belt, Namibia) consists of three main intrusive rock types including metaluminous hornblende- and sphene-bearing quartz diorites, allanite-bearing granodiorites and granites, and peraluminous garnet- and muscovite-bearing leucogranites. Intrusion of the quartz diorites is constrained by a U-Pb zircon age of 540+/-3 Ma.Quartz diorites, granodiorites and granites...
Extensive, mainly acidic peraluminous magmatism affected the Tuscan Archipelago and the Tuscan mainland since late Miocene, building up the Tuscan Magmatic Province (TMP) as the Northern Apennine fold belt was progressively thinned, heated and intruded by mafic magmas. Between 3.8 and 1.3 Ma an intrusive complex was built on Larderello area (Tuscan mainland) by emplacement of multiple intrusions of...
In the granitic rocks of the Western Carpathians, xenotime-(Y) occurs both as a late-stage magmatic mineral, and as a secondary post-magmatic phase. Magmatic xenotime occurs with monazite and displays minor compositional zonation involving Si, Th and U. The source of elements for the formation of secondary xenotime-(Y) in the granitic rocks results from leaching of P and (Y+REE), mainly from zircon...
A comprehensive survey of the accessory-mineral assemblages in Variscan granites of the German Erzgebirge and Pan-African granites from Jordan revealed the occurrence of intermediate solid solutions of the tetragonal thorite–xenotime–zircon–coffinite mineral group with partially novel compositions. These solid solutions preferentially formed in evolved and metasomatically altered, P-poor leucogranites...
The Mesozoic geology of SE China is characterized by widespread Jurassic to Cretaceous igneous rocks consisting predominantly of granites and rhyolites and subordinate mafic lithologies. However, the tectonic regime responsible for the inland Jurassic granites remains controversial. We report here U–Pb zircon ages, geochemical and Sr–Nd–Hf isotopic data for the Nankunshan alkaline granite and the...
In the southernmost Dom Feliciano Belt of Uruguay, highly fractionated calc-alkaline granites, mildly alkaline granites, shoshonitic volcanics, and peralkaline intrusions and volcanics are spatially and temporal associated with the evolution of shear zones. Four representative magmatic unites of this diverse association were petrographic and geochemically investigated: the Solís de Mataojo Complex,...
Various petrologists have suggested that K-feldspar megacrysts grow in granites that are extensively crystallized, even at subsolidus conditions. However, experimental evidence indicates that, though K-feldspar nucleates relatively late in the crystallization history, abundant liquid is available for development of large crystals. A great deal of evidence, involving many different factors, favours...
The hypothesis that granites (sensu lato) commonly undergo extensive grain-shape changes (“recrystallization”) during cooling is not supported by microstructural evidence, especially the abundance of non-truncated zoning patterns in mineral grains. Regional metamorphic felsic gneisses that have undergone extensive neocrystallization/recrystallization at amphibolite facies conditions (which some have...
The pre-Variscan basement of Iberia contains two contrasting associations of silicic igneous rocks, one composed of intermediate to felsic peraluminous rocks with ages clustering around 486 Ma, and the other dominated by felsic peralkaline rocks considered to be of similar age. The most voluminous manifestation of peralkaline magmatism is the Galiñeiro Igneous Complex, mainly consisting of A1-type...
The crust in southern Mongolia is part of the Central Asian Orogenic Belt, a vast accretionary orogen that records the opening and closure of the Palaeo-asian Ocean in the late Proterozoic to Palaeozoic. The crustal evolution of the region is revealed in basement inliers that also contain intrusion-related porphyry ore bodies that are important mineral exploration targets. The Saykhandulaan inlier...
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