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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,...
Three holes were drilled in the northern (Dominique), central (Sophie) and southern (Naore) parts of the volcanic shield of Eiao island in the Marquesas archipelago, French Polynesia. These were continuously cored with an excellent recovery and reached depths of 500 m (Sophie) and 800 m (Dominique and Naore). K-Ar dating indicates that the volcanic sequence penetrated was emplaced between 5.52+/-0...
The Voisey's Bay Ni-Cu-Co sulfide deposit is located in Eastern Labrador, and transects the 1.85 Ga collisional boundary between interbanded garnet-sillimanite and quartzo-feldspathic paragneisses (Tasuiyak gneisses) of the Proterozoic Churchill Province to the west and granitic, intermediate and mafic orthogneisses of the Archean Nain Province to the east. The deposit is associated with an upper...
This study reports new geochemical and Sr-Nd-Pb isotopic data for Miocene to Quaternary basaltic to andesitic, dacitic, and rhyolitic volcanic rocks from the Huichapan caldera, located in the central part of the Mexican Volcanic Belt (MVB). The initial Sr and Nd isotopic ratios, except for one rhyolite, range as follows: 87 Sr/ 86 Sr 0.70357-0.70498 and 143...
The Sausfjellet pluton is made up of two intrusive units emplaced into high-grade metamorphic rocks of the Helgeland Nappe Complex of the Uppermost Allochthon in the Norwegian Caledonides. The eastern part of the pluton intruded marble and less voluminous calc-silicate and pelitic rocks. The western half is hosted predominantly by semi-pelitic migmatite with intercalated marble. Remelting of the migmatite...
The Monte Capanne pluton (Tuscan Magmatic Province, Elba Island, Italy) displays a great variety of magmatic products. Mafic microgranular enclaves (MME) are widespread and display variable size, texture and composition. Petrographic and mineralogical features highlight the importance of magma mixing in their genesis. In particular, patchy-zoned phenocrysts and corroded An-rich plagioclase are common...
The intrusive complex at Hortavær represents a magma transfer zone in which multiple pulses of gabbroic and dioritic magmas evolved along Fe- and alkali-enrichment trends. Extreme alkali enrichment resulted in nepheline-normative and sparse nepheline-bearing monzodioritic and monzonitic rocks. More evolved monzonitic and syenitic rocks are silica saturated and, in some cases, quartz bearing. Previous...
Deformed Hercynian peraluminous granitoids ranging from tonalite to granite crop out in the Rebordelo–Agrochão area, northern Portugal and some of them contain tonalitic and granodioritic enclaves. Variation diagrams of major and trace elements of the rocks, biotites and sphenes show fractionation trends. The most- and the least-deformed samples of granite and their biotites also define fractionation...
The Quaternary Acatlán Volcanic Field (AVF) is located at the western edge of the Trans-Mexican Volcanic Belt (TMVB). This region is related to the subduction of the Pacific Cocos and Rivera plates beneath the North American plate since the late Miocene. AVF rocks are products of Pleistocene volcanic activity and include lava flows, domes, erupted basaltic andesite, trachyandesite, trachydacite, and...
Calculations of fractional crystallization (FC) and assimilation fractional crystallization (AFC) at 11 kb for a variety of primitive magmatic compositions and a mafic assimilant demonstrate that none of them has a bulk composition suitable to be parental to massif anorthosites. Mafic compositions thought to be parental to massif anorthosites have Mg′ values of 0.6 to 0.4 and form coherent arrays...
We present new mineral and whole-rock compositions and Sr–Nd–Hf–Pb–O–H isotope data on samples from the Kangerlussuaq Alkaline Complex (∼1000 km 2 ) in central East Greenland, part of the North Atlantic Igneous Province. This complex mainly consists of the Kangerlussuaq Intrusion but includes at least 13 separate satellite intrusions emplaced in the uppermost crust close to the unconformity...
Kimberlite hosts two populations of olivine that are distinguished on the basis of grain size and morphology; the populations are commonly described genetically as xenocrysts and phenocrysts. Olivine xenocrysts or macrocrysts are thought to derive from disaggregation of mantle xenoliths whereas the smaller, euhedral olivine crystals are presumed entirely cognate to the kimberlite melt. Recent studies...
Lithic sedimentary xenoliths in magmatic pyroclastic deposits in the Rockeskyllerkopf Volcanic Complex of the Quaternary West Eifel volcanic field preserve evidence of the earliest stages of melting, reaction with and assimilation into their silica-undersaturated basanite host. The xenoliths have a 0.5–1.5 mm thick surface glaze of rhyolitic glass and internally have both silica-undersaturated and...
The Coyaguayma ignimbrite is a strongly peraluminous (SP), sillimanite, garnet-bearing silicic rhyolite which erupted in the northern Puna segment of the central Andean plateau in the Upper Miocene (~11Ma), a period that was characterized by the eruption of voluminous (100s to 1000s km 3 ) dacitic ignimbrites of high-K calc-alkaline affinity. In this region, the SP magmatic rocks are both...
In this paper, we study the geochronology, mineral chemistry, and whole-rock elemental, stable (O, C, D) and Sr-Nd isotopic data for alkaline ultrabasic–basic massifs of the Vitim alkaline province (Sayzhenski complex) in the Central Asian Orogenic Belt, near the boundary with the Siberian craton, to evaluate their petrogenesis and geodynamic significance. U-Pb zircon dating results in Early Paleozoic...
Assimilation of foreign material into a granitic magma body entails mixing between two end-member components: the initially solid assimilant, and the original magma, whose composition is mostly represented by a granitic liquid. In this study, we assess the interactions between a haplogranite liquid made to the composition of the minimum at 200MPa H 2 O (Ab 38.23 Or 28.72 Qtz...
Platinum-group minerals are the dominant control on the budget of platinum-group elements in ophiolitic chromitites. They vary widely in distribution, morphology, chemistry and Os-isotope compositions. Their distribution in different types of chromitites, and different microstructural sites within them may reflect the role of chromite as a physical ''collector'' of the platinum-group elements during...
Colli Albani is a quiescent caldera complex located within the Roman Magmatic Province (RMP), Italy. The recent Via dei Laghi phreatomagmatic eruptions led to the formation of nested maars. Albano Maar is the largest and has erupted seven times between ca 69–33ka. The highly explosive nature of the Albano Maar eruptions is at odds with the predominant relatively mafic (SiO 2 =48–52wt.%) foiditic...
The lack of consensus on the possible range of initial kimberlite melt compositions and their evolution as they ascend through and interact with mantle and crustal wall rocks, hampers a complete understanding of kimberlite petrogenesis. Attempts to resolve these issues are complicated by the fact that kimberlite rocks are mixtures of magmatic, xenocrystic and antecrystic components and, hence, are...
In the Michoacán-Guanajuato Volcanic Field, Quaternary monogenetic alkaline volcanism is mostly present in its northern sector in association with coeval calcalkaline volcanism. Their respective geochemical signatures reveal the existence of two suites of differentiated alkaline lavas, one with a typical OIB-like signature and another that displays intermediate characteristics with the coeval calcalkaline...
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