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The mechanism of formation of blueschist–eclogite belts and their space-time distribution are important in understanding the tectonics associated with convergent plate boundaries. Here we investigate the garnet-bearing blueschists from Rongma area of central Qiangtang in northern Tibet. The mineral assemblage in these rocks is characterized by porphyroblastic garnet set within a matrix of fine-grained...
The Paleozoic granites in the Chinese Altai are important for the study of tectonic evolution and crustal growth in the Central Asian Orogenic Belt (CAOB). Four representative peraluminous granitic intrusions were selected for systematic studies of zircon U–Pb and Hf isotopic compositions and whole-rock geochemical and Nd–Sr isotopic analyses. These rocks have high ASI (Alumina Saturation Index, Al...
Numerous Neoproterozoic mafic dykes, referred to as the Dashigou swarm, are identified in the central and southeastern parts of the North China craton (NCC). They are 305–010° trending dykes, with widths of ~10–100m and exposed lengths of several to >10km. Precise U–Pb isotope dilution thermal ionization mass spectrometry (ID-TIMS) measurements on baddeleyite grains separated from three dykes yield...
Irregular aggregates of monazite-(Ce) to monazite-(Nd), up to 150μm in diameter, have been found in graywackes from the Protivanov Formation, Drahany Upland, Czech Republic. Monazite aggregates enclose a variety of detrital and authigenic minerals. Textural evidences suggest that they are of authigenic origin and grew during very low-grade metamorphism at a maximum temperature ~200–300°C in relation...
A 600km long metabasite belt is exposed at the southern border of the Chugach terrane in southern Alaska, south of the Eocene Chugach Metamorphic Complex (CMC). In this contribution, we present petrologic and geochemical results for parts of this metabasite belt. The metabasites studied are amphibolite grade and their PT conditions are evaluated with hornblende–plagioclase thermometry and the average...
We report on the newly discovered lava flow that erupted in the Colli Albani Volcanic District, which is the most recent and, geochemically the most peculiar effusive event recognised in the entire ultrapotassic Roman Province (Central Italy).This lava flow is associated with the Monte Due Torri scoria cone, located approximately 5km south of the Albano hydromagmatic centre (69–36ka). The Monte Due...
The Baishiquan and Pobei Early Permian mafic–ultramafic intrusions were emplaced into Proterozoic metamorphic rocks in the Central Tianshan and the Beishan Fold Belt, northern Xinjiang, NW China. The Baishiquan intrusion comprises mainly gabbro, and mela-gabbro sills occurring within and along the margins of the gabbro body. In the Pobei intrusion, two distinct gabbroic packages, a lower gabbro and...
The Gaositai complex is a typical Alaskan-type intrusion, emplaced in the northern margin of the North China Craton at about 280Ma. It is a concentrically zoned intrusion, with dunite in the core, rimmed by wehrlite, clinopyroxenite and hornblendite outwards. To understand the chemical compositions of the parent magma to the ultramafic complex, and thus that of the mantle source, we conduct petrological...
The rocks of 2.87Ga Rio Maria sanukitoid suite of the eastern Amazonian craton include granodiorites, intermediate rocks, layered rocks and mafic enclaves. Their REE patterns and the behavior of Rb, Ba, Sr, and Y allowed the distinction of a granodioritic (granodiorite and intermediate rocks) and a monzonitic (mafic enclaves) sanukitoid series. Petrogenetic modeling indicated that the granodiorites...
A swarm of Late Triassic (220Ma) carbonatite dykes is emplaced into the deformed southern margin of the North China block (NCB) at Lesser Qinling, discontinuously extending for about 10km. The carbonatites are volumetrically minor, and their formation is related to collision between the South China block (SCB) and Qinling orogen, which led to the amalgamation of the NCB and SCB. The carbonatites are...
Early Mesozoic porphyritic intrusions in the Shangri-La region, southern Yidun terrane, SW China, are spatially associated with andesites and dacites. These intrusions are composed of diorite and quartz diorite, and are closely related to copper mineralization. LA-ICP-MS zircon U–Pb ages of the intrusions range from 230 to 215Ma. The associated andesites and dacites are interlayered with slates and...
Gneissoid granites were traditionally thought to be the components of the Precambrian basement in the eastern South China Block, but twenty-four gneissoid granite samples from the Wugong, northern Wuyi, southern Wuyi and Yunkai Domains gave zircon U–Pb ages of 424–456Ma, 410–457Ma, 426–438Ma and 415–450Ma, respectively. The existence of the abundant Kwangsian gneissoid granites, which have incorrectly...
The boundary between the Gondwana and Laurussia, or a terrane separated from it, is traced by a suture recording the closure of the Rheic ocean in the Pulur, Beyçam and Kurtoğlu areas of the eastern Sakarya Zone of Turkey. Pulur lherzolite has a lower Cr# [100Cr/(Cr+Al)=5−37] of the spinel and slightly enriched flat medium-heavy rare earth element (M-HREE) whole-rock pattern typical for those of the...
High pressure igneous rocks (tonalites), generated by partial melting of subducted basaltic rocks accreted to the mantle wedge, are present in the La Corea serpentinite-matrix mélange (eastern Cuba) as centimeter- to meter-sized blocks and as concordant to crosscutting veins within high-pressure parent amphibolite blocks. The slab melts have adakitic signatures, in agreement with formation after partial...
The Monviso ophiolite Lago Superiore Unit constitutes a well-preserved, almost continuous upper fragment of oceanic lithosphere subducted at c. 80km depth, thereby providing a unique opportunity to study mechanical coupling processes and meter-scale fluid–rock interactions occurring at such depths in present-day subduction zones. It is made of (i) a variably thick (50–500m) section of eclogitized...
The pseudosection modelling of two chemical systems (both metabasic and metapelitic) allowed to reconstruct the exhumation P–T path followed by the southern slope of the Monte Rosa nappe (Upper Gressoney Valley) during the Alpine orogenesis. The metamorphic evolution of the polymetamorphic basement complex from the Monte Rosa nappe is marked by texturally distinct mineral assemblages, defining four...
The ages of orthogneisses exposed in massifs of the Variscan chain can determine whether they are part of a pre-Neoproterozoic basement, a Neoproterozoic, Panafrican arc, or are, in fact, lower Paleozoic, and their isotopic compositions can be used to probe the nature of their source rocks, adding to the understanding of the types, distribution, and tectonic evolution of peri-Gondwanan crystalline...
Three samples of garnet–kyanite paragneiss from the Variscan Ulten Zone (Northern Italy) were studied in detail for U–Th–Pb monazite dating. Monazite in these gneisses is abundant, shows highly variable grain size and occupies different textural positions: within the matrix, as inclusion in garnet and kyanite, within apatite aggregates. Monazite shows different deformation features as a function of...
Cenozoic volcanic rocks are widespread in eastern China. These rocks have variable isotope compositions, reflecting different mantle sources under SE and NE China. In order to explore their PGE variations, chalcophile elements are determined for basalts from Leiqiong and Sanshui and andesites from Lianping in SE China. Basalts from Leiqiong have higher Ni (66–376ppm) and Cu (30–73ppm) contents than...
Late Mesozoic intrusive and volcanic rocks are widespread in the southeast Hubei Province, Middle–Lower Yangtze River Belt (YRB), East China. Detailed in situ zircon U–Pb and Hf isotope, elemental and Sr–Nd–Pb isotopic data are presented in this paper for Late Mesozoic volcanic rocks from the Jinniu Basin, YRB, aiming to constrain their age, petrogenesis, and tectonic implications. The Jinniu volcanic...
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