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Melt inclusions within forsterite-rich olivine crystals in two mixed magmas from the Indonesia–Australia collision zone provide information on the primary melts formed within this tectonic environment. Although whole rock Sr, Nd and Pb isotope data show a strong influence of subducted continental material, the melt inclusion major and trace element compositions are only subtly different from typical...
In the southern zone of the Eastern Pontides, an isolated small (~1.5 km 2 ) outcrop of plagioleucitites occurs in the Aşutka thrust sheet. Field relations constrain the timing of volcanism between Maastrichtian and late Paleocene. The plagioleucitites consist of clinopyroxene, analcime (former leucite), Ti-magnetite, plagioclase, sanidine, apatite and accessory biotite. The rocks are represented...
A variety of high Ba–Sr granites and syenites is intruded into the Caledonian terrane of the Northern Highlands of Scotland. Volumetrically rather small, the plutons display a considerable range of compositions from ultramafic and mafic to granitic and syenitic. Most intrude Proterozoic Moine metasediments, though some are exposed within the Moine Thrust Zone in the west, beyond which lies the Archaean...
Phase relations at 0.1 MPa over a range of oxygen fugacities (fO 2 ) from 1130 to 1350 °C on a volatile-free synthetic kimberlite analog composition show the crystallization sequence of olivine, monticellite, akermanite, perovskite, clinopyroxene, ulvopsinel and kirschteinite. At low pressures kimberlite liquids show limited change in Ca, Si, Al and Ti, but a large variation in Fe/Mg from...
Metamorphosed carbonatites, located in the Basal Complex of Fuerteventura, Canary Islands (Spain), contain unusual Ca-Nb-Zr disilicates. These mineral phases appear in different textural situations that have very different chemical compositions. More widespread Ca-Nb disilicates with minor Zr contents cover the whole range of cuspidine–niocalite solid solution. Disilicate crystals containing more...
New field, major and trace element and whole rock K–Ar data on the Neogene volcanic fields of northern Baja California (Jaraguay and San Borja) show that the calc-alkaline activity of the Comondú arc vanished around 11 Ma, following the end of the subduction of the young oceanic Farallon plate. It was immediately replaced by magnesian andesite volcanism, showing paroxysmal activities between 8.5 and...
Dehydroxylation of omphacites in eclogites from UHP Dabie-Sulu terrain has been investigated using a combined method of petrological observations, mineral chemistry, heat treatment, Mössbauer, and micro-FTIR spectroscopy. Progressive heating of omphacite in air up to 1100 °C results in complex, multi-stage processes involving oxidation and dehydrogenation at different temperatures. During heating,...
The Baimazhai deposit in Yunnan Province is one of the largest Cu–Ni sulfide deposits hosted in mafic–ultramafic intrusions in China. Concentrations of platinum-group elements (PGE) in massive sulfide ores and host rocks from Baimazhai were determined by using inductively coupled plasma mass spectrometry (ICP-MS) following nickel sulfide fire assay pre-concentration. The results show that the total...
We present comprehensive Sr–Nd–Pb isotope and element data for volcanic rocks from the southern Kyushu region in southwest Japan, and compare them with those around the Hishikari deposit, one of the largest epithermal gold mines both in size and grade in the circum Pacific. The majority of volcanic rocks collected in southern Kyushu belong to the medium-K series; however, those of the Hishikari area...
The Qinling is an important orogenic belt, which formed by the joining of the North China and South China blocks. The Shaxiongdong carbonatite–syenite complexes were emplaced at the southern margin of South Qinling and border the South China block. LA-ICPMS (Laser Ablation Inductively Coupled Plasma Mass Spectrometry) zircon U–Pb geochronology constrains the syenite emplacement age to be 441.8±2.2 Ma,...
The crystallization history of zoned K-feldspar phenocrysts in microgranular magmatic enclaves in the Karkonosze granite (SW Poland) reveals that the crystals grew in stirred coeval magmas of contrasting compositions. The growth mechanism and crystal compositions are investigated using cathodoluminescence and profiling by Electron Microprobe and Laser Ablation ICP-MS. These methods provide insight...
The Gangdese batholith emplaced from the Cretaceous to Eocene in southern Tibet has been widely regarded as the major constituent of an Andean-type convergent margin resulting from northward subduction of the Neo-Tethyan oceanic lithosphere under Asia. While the Gangdese batholith consists predominantly of calc-alkaline rocks, we identify from the eastern part of the batholith a suite of epidote-bearing...
The Dazi volcanic basin is located in the eastern segment of the Gangdese magmatic belt, south Tibetan collision zone. The compositions of Dazi Eocene (40–38 Ma) volcanic rocks range from picrite through basalt to basaltic andesite with low-K tholeiitic affinities. The primitive samples are characterized by high-MgO (6.34–14.35 wt.%) and compatible trace elements (Cr=131–844 ppm, Ni=45.2–268 ppm)...
Mantle xenoliths in the Quaternary Pali Aike alkaline basalts of southernmost Patagonia include lherzolites and harzburgites with and without garnet. The values of fO 2 for all xenoliths range from 0.33 logarithmic unit below the fayalite–magnetite–quartz buffer (FMQ−0.33) to FMQ+0.75, which overlap those for abyssal peridotites. The fO 2 data, together with the bulk rock and mineral...
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...
Ferropicrites and their differentiates make up a geochemically distinctive group of dikes that crosscut Jurassic continental flood basalts of the Karoo large igneous province at Vestfjella, western Dronning Maud Land, Antarctica. The Vestfjella ferropicrites can be divided into two geochemical types: The depleted ferropicrites have (La/Sm) N of 1.2–1.3, (Sm/Yb) N of 4.5, initial ε...
This paper describes the metamorphic evolution and the tectonic significance of the Aghil Range, a poorly known terrane located between Kunlun and Karakorum north of K2 in the framework of western Tibet. The Aghil Range consists of different units separated by syn- to late-metamorphic thrusts and post-metamorphic faults of similar attitude; among other units, the Surukwat Complex is a composite sequence...
Amphibole-bearing migmatites from north-eastern Sardinia, Italy, are characterized by tonalitic to granodioritic leucosomes made up of quartz, plagioclase, K-feldspar, biotite, ±amphibole, and garnet. The leucosomes show higher SiO 2 , Na 2 O, Sr and lower TiO 2 , Fe 2 O 3tot , MgO, MnO, P 2 O 5 , K 2 O and Rb content as compared to the...
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