Geochronology and geochemistry of the Pola de Allande granitoids (northern Spain): their bearing on the Cadomian-Avalonian evolution of northwest Iberia

1998 ◽  
Vol 35 (12) ◽  
pp. 1439-1453 ◽  
Author(s):  
Javier Fernández-Suárez ◽  
Gabriel Gutiérrez-Alonso ◽  
George A Jenner ◽  
Simon E Jackson
Keyword(s):  
Inductively Coupled Plasma ◽  
Trace Element Composition ◽  
Variscan Belt ◽  
Calc Alkaline ◽  
Northern Spain ◽  
Isotopic Signatures ◽  
Magmatic Arc ◽  
Inductively Coupled ◽  
Plasma Mass Spectrometry ◽  
Northwest Iberia

The Pola de Allande pre-Variscan tonalite-granodiorite plutons are located in the Narcea Antiform, at the boundary zone between the Cantabrian and west Asturian Leonese zones of the Iberian Variscan belt. These granitoids were intruded into a Neoproterozoic siliciclastic sedimentary sequence with subordinate volcanic intercalations and were subsequently overprinted by Variscan thrust-related shear deformation. U-Pb laser ablation inductively coupled plasma - mass spectrometry (ICP-MS) dating of zircons from two plutons yielded concordant ages of intrusion of 605 ± 10 and 580 ± 15 Ma. To the authors' knowledge, this is the first reported U-Pb Cadomian-Avalonian age for igneous rocks in this section of the Iberian Variscan belt. These intrusions are coeval with the main episode of dominantly calc-alkaline magmatic activity related to Cadomian-Avalonian subduction. Major and trace element composition of the granitoids is characteristic of I-type high-K calc-alkaline granitoids generated in continental arc settings, and are comparable to those of coeval granitoids in other areas of the Cadomian-Avalonian belt. Sr and Nd isotopic signatures indicate that the genesis of the Pola de Allande granitoids involved either mixing of mantle melts of Cadomian extraction with an older enriched crust (Eburnean-Icarthian, i.e., ca. 2 Ga old crust) or melting of a mafic infracrustal protolith with a Grenville age (ca. 1.2 Ga) mantle extraction. The Neoproterozoic sediments, hosting the Pola de Allande granitoids and present in large areas of northwest Iberia, may represent the back-arc basin of the subduction complex in which the Avalon composite terrane constituted the main magmatic arc.

Major- and trace-element composition of REE-rich turkestanite from peralkaline granites of the Morro Redondo Complex, Graciosa Province, south Brazil

2010 ◽  
Vol 74 (4) ◽  
pp. 645-658 ◽  
Author(s):  
F. C. J. Vilalva ◽  
S. R. F. Vlach
Keyword(s):  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Alkali Feldspar ◽  
Trace Element Composition ◽  
Inductively Coupled ◽  
Coupled Substitution ◽  
Plasma Mass Spectrometry ◽  
Compositional Variations ◽  
End Members ◽  
South Brazil

AbstractTurkestanite, a rare Th- and REE-bearing cyclosilicate in the ekanite–steacyite group was found in evolved peralkaline granitesfrom the Morro Redondo Complex, south Brazil. It occurswith quartz, alkali feldspar and an unnamed Y-bearing silicate. Electron microprobe analysis indicates relatively homogeneous compositions with maximum ThO2, Na2O and K2O contentsof 22.4%, 2.93% and 3.15 wt.%, respectively, and significant REE2O3 abundances(5.21 to 11.04 wt.%). The REE patterns show enrichment of LREE over HREE, a strong negative Eu anomaly and positive Ce anomaly, the latter in the most transformed crystals. Laser ablation inductively coupled plasma mass spectrometry trace element patterns display considerable depletions in Nb, Zr, Hf, Ti and Li relative to whole-rock sample compositions. Observed compositional variations suggest the influence of coupled substitution mechanisms involving steacyite, a Na-dominant analogue of turkestanite, iraqite, a REE-bearing end-member in the ekanite–steacyite group, ekanite and some theoretical end-members. Turkestanite crystals were interpreted as having precipitated during post-magmatic stages in the presence of residual HFSE-rich fluidscarrying Ca, the circulation of which wasenhanced by deformational events.

scholarly journals U–Pb age and Lu–Hf signatures of detrital zircon from Palaeozoic sandstones in the Oslo Rift, Norway

2013 ◽  
Vol 151 (5) ◽  
pp. 816-829 ◽  
Author(s):  
MAGNUS KRISTOFFERSEN ◽  
TOM ANDERSEN ◽  
ARILD ANDRESEN
Keyword(s):  
Detrital Zircon ◽  
Inductively Coupled Plasma ◽  
Late Carboniferous ◽  
Isotopic Signatures ◽  
Inductively Coupled ◽  
Source To Sink ◽  
Icp Ms ◽  
Plasma Mass Spectrometry ◽  
Isotope Analyses ◽  
Multiple Episodes

AbstractU–Pb and Lu–Hf isotope analyses of detrital zircon from the latest Ordovician (Hirnantian) Langøyene Formation, the Late Silurian Ringerike Group and the Late Carboniferous Asker Group in the Oslo Rift were obtained by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Overall the U–Pb dating yielded ages within the range 2861–313 Ma. The U–Pb age and Lu–Hf isotopic signatures correspond to virtually all known events of crustal evolution in Fennoscandia, as well as synorogenic intrusions from the Norwegian Caledonides. Such temporally and geographically diverse source areas likely reflect multiple episodes of sediment recycling in Fennoscandia, and highlights the intrinsic problem of using zircon as a tracer-mineral in ‘source to sink’ sedimentary provenance studies. In addition to its mostly Fennoscandia-derived detritus, the Asker Group also have zircon grains of Late Devonian – Late Carboniferous age. Since no rocks of these ages are known in Fennoscandia, these zircons are inferred to be derived from the Variscan Orogen of central Europe.

scholarly journals Typomorphic Characteristics of Pyrites from the Shuangwang Gold Deposit, Shaanxi, China: Index to Deep Ore Exploration

Minerals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 383
Author(s):  
Wang ◽  
Liu ◽  
Wang ◽  
Zeng ◽  
Liu ◽  
...  
Keyword(s):  
Gold Deposit ◽  
Inductively Coupled Plasma ◽  
Gold Mineralization ◽  
Trace Element Composition ◽  
Central China ◽  
Western Qinling ◽  
Inductively Coupled ◽  
Contour Maps ◽  
Plasma Mass Spectrometry ◽  
P Type

The large Shuangwang gold deposit (>80 t gold) is located in the Western Qinling Orogen (WQO) of central China. It is an orogenic-type gold deposit hosted in an NW-extending breccia belt in the Devonian Xinghongpu Formation. Gold mineralization of the Shuangwang deposit is featured by hydrothermal breccia ores with strata fragments cemented by hydrothermal minerals dominated by ankerite, quartz, and pyrite with minor amounts of calcite and albite. Pyrite is the major gold-hosting sulfide and the most abundant ore mineral. Crystal habits, thermoelectricity, and trace-element composition of pyrites from the main ore-forming stage of the Shuangwang gold deposit were studied by microbinocular, BHTE-06 thermoelectric coefficient measuring instrument, and high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). Spatial distribution of the above data for pyrites was delineated by contour maps of morphology index, P-type frequency, and primary halo elements (e.g., supraore halo elements Ba and Sb; near-ore halo elements Pb, Zn, and Cu; and subore halo elements Co, Mo, and Bi). Based on the above results, four target areas (areas between prospecting lines 0 and 1, between lines 14 and 18 below orebody KT9; areas between prospecting lines 30 and 34, between lines 44 and 46 below orebody KT8) were put forward for deep gold exploration in the future. These targets are consistent with the depth extrapolation of proven gold orebodies, indicating the practicality of typomorphic characterization of pyrites as vector to deep/concealed gold orebodies. The effectiveness of the pyrite typomorphic parameter for deep gold prediction seems to be chemical composition, crystal habits, and then thermoelectricity.

scholarly journals Old subcontinental mantle zircon below Oahu

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
John D. Greenough ◽  
Sandra L. Kamo ◽  
Donald W. Davis ◽  
Kyle Larson ◽  
Zhen Zhang ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Lithospheric Mantle ◽  
Inductively Coupled Plasma ◽  
Prolonged Storage ◽  
Ionization Mass ◽  
Isotopic Signatures ◽  
Inductively Coupled ◽  
Mantle Evolution ◽  
Plasma Mass Spectrometry ◽  
Continental Lithospheric Mantle

AbstractOur understanding of mantle evolution suffers from a lack of age data for when the mantle geochemical variants (mantle components) developed. Traditionally, the components are ascribed to subduction of ocean floor over Earth history, but their isotopic signatures require prolonged storage to evolve. Here we report U-Pb age results for mantle-derived zircon from pyroxenite xenoliths in Oahu, Hawaii, using laser ablation inductively coupled plasma mass spectrometry and isotope dilution - thermal ionization mass spectrometry. The zircon grains have 14 million-year-old rims, Cretaceous cores, and Proterozoic Lu-Hf model ages which are difficult to reconcile with transport of the pyroxenites in the Hawaiian mantle plume because the ages would have been reset by high temperatures. We suggest the zircons may have been preserved in sub-continental lithospheric mantle. They possibly reached Oahu by asthenospheric transport after subduction at Papua New Guinea or may represent fragments of sub-continental lithospheric mantle stranded during Pangean breakup.

scholarly journals Episodic Precipitation of Wolframite during An Orogen: The Echassières District, Variscan Belt of France

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 923 ◽  
Author(s):  
Loïs Monnier ◽  
Jérémie Melleton ◽  
Olivier Vanderhaeghe ◽  
Stefano Salvi ◽  
Philippe Lach ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Time Lag ◽  
Rare Metal ◽  
Crustal Thickening ◽  
Variscan Belt ◽  
Massif Central ◽  
Magmatic Arc ◽  
Inductively Coupled ◽  
History Of ◽  
Middle Carboniferous

Monazite and rutile occurring in hydrothermally altered W mineralizations, in the Echassières district of the French Massif Central (FMC), were dated by U-Pb isotopic systematics using in-situ Laser ablation-inductively coupled plasma–quadrupole mass spectrometry (LA-ICP-MS). The resulting dates record superimposed evidence for multiple percolation of mineralizing fluids in the same area. Cross-referencing these ages with cross-cutting relationships and published geochronological data reveals a long history of more than 50 Ma of W mineralization in the district. These data, integrated in the context of the Variscan belt evolution and compared to other major W provinces in the world, point to an original geodynamic-metallogenic scenario. The formation, probably during the Devonian, of a quartz-vein stockwork (1st generation of wolframite, called wolframite “a”; >360 Ma) of porphyry magmatic arc affinity is analogous to the Sn-W belts of the Andes and the Nanling range in China. This stockwork was affected by Barrovian metamorphism, induced by tectonic accretion and crustal thickening, during the middle Carboniferous (360 to 350 Ma). Intrusion of a concealed post-collisional peraluminous Visean granite, at 333 Ma, was closely followed by precipitation of a second generation of wolframite (termed “b”), from greisen fluids in the stockwork and host schist. This W-fertile magmatic episode has been widely recorded in the Variscan belt of central Europe, e.g. in the Erzgebirge, but with a time lag of 10–15 Ma. During orogenic collapse, a third magmatic episode was characterized by the intrusion of numerous rare-metal granites (RMG), which crystallized at ~310 Ma in the FMC and in Iberia. One of these, the Beauvoir granite in the Echassières district, led to the formation of the wolframite “c” generation during greisen alteration.

Discovery of a Neoproterozoic granite in the Northern Alxa region, NW China: its age, petrogenesis and tectonic significance

2015 ◽  
Vol 153 (3) ◽  
pp. 512-523 ◽  
Author(s):  
WEN ZHANG ◽  
VICTORIA PEASE ◽  
QINGPENG MENG ◽  
RONGGUO ZHENG ◽  
TONNY B. THOMSEN ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Calc Alkaline ◽  
Alkaline Pluton ◽  
Crustal Rocks ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Tectonic Significance ◽  
Southern Central ◽  
Plasma Mass Spectrometry ◽  
Very High

AbstractA Neoproterozoic granite (Western Huhetaoergai granite) from the Northern Alxa region, southern Central Asia Orogenic Belt (CAOB) is first recognized by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb zircon dating (889±8 Ma). It is a highly fractionated potassium-rich calc-alkaline pluton with lowεNd(t) (−2.6 to −1.1) and high (87Sr/86Sr)t(0.727305–0.735626), and is probably derived from a mantle source and assimilated crustal rocks with very high87Sr/86Sr. Regional geology implies that it may reflect the existence of a microcontinent, and the formation of the Western Huhetaoergai granite is related to the assembly of Rodinia.

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