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In the Central Iberian Zone (CIZ) of the Iberian Massif large volumes of granitoids were emplaced during the post-collisional stage of the Hercynian orogeny (syn- to post-D3, the last ductile deformation phase). Twelve granitic units and a quartz monzodiorite were selected for a U-Pb zircon and monazite geochronological study. They represent successive stages of the D3 event. The Ucanha-Vilar, Lamego,...
The emplacement history of the Voisey's Bay troctolite intrusion, that hosts the major Ni-Cu-Co sulfide deposit of the same name, has been studied using precise U-Pb geochronology of baddeleyite, zircon and apatite. The baddeleyite U-Pb ages of multiple drill core samples of troctolite and gabbro indicate that all of the mafic rocks studied from different components of the Voisey's Bay intrusion:...
Exposed blocks of lower crustal Archaean granulites separated by Palaeoproterozoic faults occur near the western boundary of the Karelian craton in central Finland. The southwesternmost granulite block in the study area, the Jonsa block, differs from other granulites by having younger zircon U-Pb and Sm-Nd T DM model ages. The U-Pb ages on zircons and monazites from leucosomes and mesosomes...
Zircon from a xenolite-rich carbonatite dyke on Telyachi island, near Kandalaksha on the Kola Peninsula, northwest Russia, have been analysed for U-Th-Pb to determine the age of the dyke and study the geological evolution of the Belomorides. Zircon from the ankeritic carbonatite, analysed by conventional isotope dilution, yielded a concordant U-Pb age of 380+/-7 Ma. This age is confirmed by SIMS U-Pb...
Coesite and omphacite inclusions have been identified for the first time as minute inclusions in zircon from amphibolite-facies granitic orthogneiss in the Sulu ultrahigh-pressure (UHP) metamorphic terrane of eastern China by Raman spectroscopy and microprobe analyses. The occurrences of these minerals in the voluminous granitic gneiss of Sulu support a regional and pervasive UHP metamorphic event...
Stepwise HF-dissolution experiments on five Archean zircon populations reveal very systematic patterns of Pb discrimination, releasing at one point Pb with artificially too-old 207 Pb/ 206 Pb ages. The experiments involved a first HF dissolution step for 1 h at room temperature and evaporation on a hot-plate that produces Pb with young 207 Pb/...
This study is an attempt to unravel the tectono-metamorphic history of high-grade metamorphic rocks in the Eastern Erzgebirge region. Metamorphism has strongly disturbed the primary petrological genetic characteristics of the rocks. We compare geological, geochemical, and petrological data, and zircon populations as well as isotope and geochronological data for the major gneiss units of the Eastern...
Field relations and whole-rock geochemistry indicate that magma mixing has been important in the genesis of the late Mesozoic I-type igneous complexes at Pingtan and Tonglu in SE China. Morphological and trace-element studies of zircon populations in rocks from each of these complexes have defined several distinct growth stages [Mineral. Mag. (2001)]. In-situ LAM-MC-ICPMS microanalysis shows large...
We have identified by laser micro-Raman spectroscopy that inclusions of coesite occur together with other eclogite-facies mineral phases within metamorphic zircons separated from the large eclogite body at Ulsteinvik-Dimnoy on Hareidland. This is the first identification of coesite from this portion of the northwestern Western Gneiss Region (WGR) and supports continuity of ultrahigh-pressure (UHP)...
There are two types of gneisses, biotite paragneiss and granitic orthogneiss, to be closely associated with UHP eclogite at Shuanghe in the Dabie terrane. Both concentration and isotope composition of bulk carbon in apatite and host gneisses were determined by the EA-MS online technique. Structural carbonate within the apatite was detected by the XRD and FTIR techniques. Significant 13 ...
The U–Th–Pb isotopic systematics of zircons from six sanukitoid intrusions in the Karelian Craton has been investigated, using the secondary ion mass spectrometer (SIMS).Our results show that Karelian sanukitoids formed between 2745 and 2705 Ma ago and that there is an age difference of about 30 Ma between sanukitoids in the eastern and western Karelia. Results for intrusions made up of a number of...
The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H 2 O. Accessory phase solubilities are not affected by the water content...
New high-resolution, secondary ion mass spectrometry U–Th–Pb data obtained from zircon and monazite from representative Variscan intrusions in the Balkan sector of the Variscan orogen (Central Bulgaria) constrain the ages of magmatism to the interval ∼315–285 Ma. The samples investigated are granitoids from two contrasting intrusive suites. Calc-alkaline granitoids of the first suite include the San...
In the Golfo Aranci high-grade metamorphic basement of NE-Sardinia (Italy), a fragment of the southern part of the Variscan chain, several metabasic rocks with relic eclogitic parageneses are interlayered with a dominant sequence of migmatitic paragneisses and felsic orthogneisses. Petrologic, geochemical and geochronological data on selected samples permitted the reconstruction of a long history...
Zircon crystals have been investigated from a gneiss area in the Central Erzgebirge, Bohemian Massif, where small occurrences/lenses of granulites (and sometimes eclogites) are located within amphibolite facies gneisses. Geological relationships indicate that leucocratic quartzofeldspathic rocks within the granulite boudins represent melts, whereas garnet-rich melanocratic rocks are considered restites,...
The Corsica-Sardinia batholith in the southern realm of the Hercynian belt of Europe shows evidence for gravitational collapse of this part of the mountain belt, causing major felsic and mafic magmatism. The latest intrusions are composed of leucomonzogranite and late metaluminous and alkaline granite, associated with tholeiitic layered complexes and dykes. Three dating methods on zircon (Pb-evaporation,...
Zircons from a nepheline-syenite of the Fuerteventura Basal Complex were dated by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). The age obtained from a total of 21 U–Th–Pb analyses is 25.4±0.3 Ma (2σ) indicating a late Oligocene–early Miocene crystallization. This age is consistent with new K–Ar ages on nepheline-syenites and pyroxenites, and contradicts previously published...
Growth of zircon with respect to that of garnet has been studied using a combination of petrography, U–Pb dating and oxygen isotope analysis. The aim is to document the mechanism and pressure–temperature conditions of zircon growth during metamorphism in order to better constrain the Tertiary metamorphic history of Naxos, Greece. Two metamorphisms are recognised: (1) an Eocene Franciscan metamorphism...
Contact metamorphism in the aureole of the 1322 Ma Makhavinekh Lake Pluton, northern Labrador, affected monazite and zircon in the adjacent 1850 Ma metapelitic gneisses. Transformation of regional garnet and sillimanite to lower-pressure symplectitic intergrowths of cordierite, orthopyroxene, and spinel was accompanied by resorption of inherited monazite inclusions in garnet coupled with the appearance...
The strongly peraluminous and P-rich, protolithionite and zinnwaldite leucogranites from Podlesí, western Krušné Hory Mts., Czech Republic, contain accessory zircon with extraordinary enrichment of several elements, which constitute trace elements in common zircon. Elements showing a not yet reported anomalous enrichment include P (up to 20.2 wt.% P 2 O 5 ; equivalent to 0.60 apfu,...
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