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In this paper isotopic (Sr, Nd, and Pb) and geochemical data are discussed with the aim of developing a model for the evolution of the magmatic system of Vulcano (Aeolian Arc, Italy). The magmatism at Vulcano is shoshonitic in affinity. The Vulcano products display, throughout the stratigraphic sequence, repeated variations in the isotope ratios ( 87 Sr/ 86 Sr=0.70426-0.70524;...
Leucocratic A-type granites of the Proterozoic Damara orogen, Namibia are a distinctive groups of rocks based on their mineralogical, chemical and isotopic characteristics. A-type granites can be distinguished from the leucocratic S-type granites on the basis of Fe-rich amphibole and biotite and higher abundances of Zr, Nb, Y and LREE but lower values of 87 Sr/ 86 Sr ...
In a 60 Ma interval between the Late Carboniferous and the Late Permian, the magmatic arc associated with the cordilleran-type New England Fold Belt in northeast New South Wales shifted eastward and changed in trend from north-northwest to north. The eastern margin of the earlier (Devonian-Late Carboniferous) arc is marked by a sequence of calcalkaline lava flows, tuffs and coarse volcaniclastic sedimentary...
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...
Young (≤3Ma) lavas from volcanic centers along a 75-km N–S transect from northern Madeira Island to a submarine volcanic field 55km south of Madeira exhibit distinct spatial geochemical variations. From south to north along this transect, there is a general decrease in Fe(8) (total Fe as FeO normalized to MgO=8wt.%), K(8), Pb isotope ratios and Zr/Hf and an increase in Al(8) and Nd isotope ratios,...
The Victoria Valley Batholith, a granite–rhyolite complex of unusual composition, was emplaced in the Grampians–Stavely Zone of western Victoria at 396 Ma. Petrographic and geochemical features of the suite share important similarities with A-type magmas and we propose that they be classified as such. The close association between metaluminous to weakly peraluminous A-types and peralkaline granites...
The Cretaceous Okhotsk–Chukotka volcanic belt (OCVB) is one of the largest subduction-related volcanic provinces of the Earth. It is thought to be related with the subduction of paleo-Pacific plates under the collage of terranes of NE Asia accreted during Jurassic and Early Cretaceous time. The OCVB comprises a remarkably high portion of silicic rocks, up to 80–90% in some segments. Within the Central...
The petrography, mineralogy and geochemistry of two macroscopically distinct drill core samples of what was previously identified as a potentially diamondiferous kimberlitic rock from the Wekusko Lake area (central Manitoba, Canada) were examined in detail. The rock shows an inequigranular, uniform to segregation texture arising from the presence of abundant macrocrysts (partly or completely chloritized...
Granitoids varying in composition from biotite–amphibole granodiorite to monzogranite with rapakivi textures have recently been recognized in the Qinling orogen (central China). The granitoids are magnesian, calc-alkalic and metaluminous (A/CNK=0.71–0.95). They contain many mafic to intermediate microgranular enclaves. The enclaves are quenched mafic melts in granitic host magma as evidenced by fine-grained...
The Beiminghe (BMH) iron ore in the southern part of the Taihang Mountain (TM), Hebei province, is one of the largest skarn iron deposits in China. Here we report phlogopite 40 Ar– 39 Ar and zircon U–Pb age data, as well as sulfur, lead, and He–Ar isotope geochemistry of pyrite from the ores and skarnitized rocks in the deposit in an attempt to constrain the timing and mechanism of...
Silhouette and North Islands in the Seychelles represent an alkaline plutonic–volcanic complex, dated at 63 to 63.5Ma by U–Pb zircon and 40 Ar/ 39 Ar methods. This magmatism coincides with the final stages of the cataclysmic Deccan Traps continental flood volcanism in India (67 to 63Ma), and thus a causal link has been suggested. Recent reconstructions have placed the Seychelles islands...
This paper presents the results of an investigation carried out on young volcanic rocks from the Gedemsa and Fanta 'Ale complexes, located in the Main Ethiopian Rift, the site of an intense magmatism since Eocene–Oligocene. The earlier NW–SE direction of extension of the Rift, which generated NE–SW trending faults, rotated around E–W in Quaternary times, and produced the still active N to N–NE Wonji...
The origin of spatial variations in the geochemical characteristics of volcanic rocks erupted in the Andean Southern Volcanic Zone (SVZ) has been studied by numerous researchers over the past 40years. Diverse interpretations for along-strike, across-strike, and small-scale variations have been proposed. In this paper, we review geochemical data showing along-strike geochemical variations and address...
40Ar–39Ar age, whole-rock chemical, and Sr–Nd isotope data are presented for the post-collisional, Eocene (51.3–44.1Ma)-aged volcanic rocks from the Bafra (Samsun) area in the western part of the Eastern Pontides (N Turkey) aiming to unravel their sources and evolutionary history. The studied Eocene volcanic rocks can be divided into two groups: analcime-bearing (tephritic lava flows and dykes) and...
The Cuddapah basin (CB) is one of a series of Proterozoic basins that overlie the Archaean cratons of India, and contains a unique stratiform carbonate-hosted uranium mineralisation. In the present work, we discuss stable (C, O) and radiogenic (Nd, Sr) isotope systematics of carbonates of the Papaghni sub-basin in order to understand uranium ore forming processes and geodynamic evolution of the CB...
Fayalite-bearing felsic (FBF) magmatic rocks are a special type of granitic rocks with controversial origins. A suite of fayalite- and ferrosilite-bearing subvolcanic rocks, namely, the Xishan FBF rocks in South China, is investigated in this study. The Xishan FBF rocks have high SiO2 contents of 69–70wt.%, high K2O/Na2O ratios of 1.71–1.95, and high FeOt/(FeOt+MgO) ratios of 0.88–0.89. Fayalite (Fo=7...
Results of a comprehensive geochemical study (major and trace elements, and isotopes of Sr, Nd, Pb, Hf) of Cretaceous volcanic rocks from the Chukotka area in northeastern Russia are presented. Synthesis of available geological and geochronological data suggests diachronous onset of activity of the Okhotsk–Chukotka volcanic belt (OCVB), the largest magmatic province in the region. The OCVB consists...
The link between the Kerguelen large igneous province and several moderately-voluminous magmatic domains emplaced on continental crust near the relict triple junction of eastern Gondwana remains tentative. In particular, linking Sr–Nd–Pb isotopic ratios of the 90,000km2 submerged Naturaliste Plateau at the relict triple junction of eastern Gondwana to the Kerguelen LIP were difficult due to previous...
The Qiman Tagh of the East Kunlun Orogen, NW China, lies within the Tethysides and hosts a large W–Sn belt associated with the Bashierxi monzogranite. To constrain the origin of the granitic magmatism and its relationship with W–Sn mineralization and the tectonic evolution of the East Kunlun Orogen and the Tethys, we present zircon U–Pb ages and Hf isotopic data, and whole-rock compositional and Sr–Nd–Pb...
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