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The modification of the Archaean lithospheric mantle root beneath the eastern North China Craton (NCC) has been noticed. However, the degree of modification and the characteristics of metasomatic agents for the NCC lithospheric mantle are still unclear. Here, we compile the geochemistry and 87Sr/86Sr and 143Nd/144Nd isotope ratios of Cretaceous primitive basalts (Yixian, Sihetun, Fangcheng and Feixian) from the eastern NCC and estimate the inputs of subduction-related elements into the Archaean lithospheric mantle beneath the NCC. These basalts show primitive (high MgO, Cr and Ni contents) and arc-like geochemical features (enrichments in LILEs and depletions in HFSEs) that indicate that the mantle sources were modified by fluids related to subducted crustal materials. Substantial proportions of subduction-mobile elements (e.g. ~95% Ba and ~90% Th) transferred to the basalt sources via hydrous melts. Thus, a large volume of fluids transferred into the lithospheric mantle. The data support the model that the NCC Archaean lithospheric mantle was weakened by hydrous melts, which resulted in a fusible weakened lithospheric mantle. Preliminary lithospheric thinning was induced by the extension of the NCC resulting from trench retreat of the Paleo-Pacific plate at ~140-120 Ma. Then, decompression melting of the lithospheric mantle caused pervasive melts in the weakened lithospheric mantle, resulting in the lithospheric mantle having a low viscosity comparable to the asthenospheric mantle, which principally reduced the lithospheric mantle. [ABSTRACT FROM AUTHOR]

Ophiolite provides key information on subduction–accretion processes along convergent plate margins. The Wunuer ophiolite in the Great Xing'an Range of NE China was considered to be an accreted fragment of the Palaeo‐Oceanic Plate. Based on field investigation, we evaluate the petrotectonic assemblages, geochemical features, and formation age of the ophiolite, which comprises gabbro, diabase, metabasalt, and radiolarian bedded chert with serpentinized amphibole‐pyroxene peridotites. Zircon U–Pb dating shows ages of 346 ± 6 Ma and 341 ± 6 Ma suggesting the timing of formation of the ophiolite as Early Carboniferous. The ophiolitic mafic rocks in Wunuer can be divided into two types based on their geochemical features. Type I is characterized by high Ti and low Al, with weakly negative Nb‐Ta and positive Pb anomalies and low light rare earth elements (LREE). These rocks display MORB‐like features, and correspond to partial melting product of depleted mantle. Type II has low Ti, high Al, notably negative Nb‐Ta and positive Pb anomalies, and is obviously enriched in LREE, large‐ion lithophile elements (LILE), and depleted in high‐field‐strength elements (HFSE), characterized by IAB‐like features, and may be formed by partial melting of more depleted mantle, which was strongly metasomatized by subduction fluids, resulted in high LILE/HFSE. The two types of ophiolites belong to SSZ type, obviously influenced by subduction, and their tectonic setting is inferred to be within a spreading ridge in a back‐arc basin. Combined with regional geological background, the Wunuer ophiolite probably represents a shrinking ocean basin and may be the late product of the long‐term and mature back‐arc basin, related to the terminal stage of ridge spreading within the back‐arc basin. [ABSTRACT FROM AUTHOR]

Granitoids and their hosted microgranitoid enclaves (MEs) can provide crucial information in understanding the evolution of granitoids and continental crustal growth. The Guyong pluton in central Tengchong Block is mainly composed of monzogranites and abundant coeval MEs (76 Ma). This study reports their petrological, geochemical, and Sr–Nd, zircon U–Pb, and Lu–Hf–O isotopic features to shed light on their petrogenesis and the evolution of the Neo‐Tethys. The Guyong MEs have low SiO2 (56.88–69.61 wt%) and high MgO (1.04–3.91 wt%) contents. They have typical igneous textures and are characterized by similar mineral assemblages, chondrite‐normalized rare earth element diagrams, and Sr–Nd and zircon Hf–O isotopic compositions (εHf(t) of −9.0 to −2.3, δ18O of 6.57–8.07) with their host monzogranites, indicating that they are cognate. The acicular apatite and fine‐grained texture and geochemical characteristics suggest that the MEs were generated in a rapid cooling and crystallization process at the margin of magma conduit. The Guyong monzogranites have high SiO2 contents (70.79–74.24 wt%) and low MgO contents (0.24–0.78 wt%). They are calc‐alkalic and weakly peraluminous and show characteristics of I‐type granites. The geochemical and isotopic compositions of the Guyong monzogranites and MEs suggest that they were produced by partial melting of the metasedimentary and meta‐igneous rocks from the Proterozoic Gaoligong metamorphic complex. The Late Cretaceous magmatism in the central Tengchong Block is correlated with the northward subduction of the Neo‐Tethys. [ABSTRACT FROM AUTHOR]

More than 80% of Chinese opera performances today are presented by privately run professional folk troupes, mostly in rural areas—Chinese theatre's best kept secret. These performances are rarely noticed by Chinese theatre scholars. There are more than 30 such troupes in Quangang District, Fujian province, which has a population of 300,000. [ABSTRACT FROM AUTHOR]

The Tengchong‐Lianghe tin metallogenic district in western Yunnan is an important tin mineralization area in the Sanjiang Tethyan Metallogenic Domain from southwestern China. The Lailishan deposit is one of the largest tin deposits in this district and spatially and temporally associated with Eocene granites. LA‐MC‐ICP‐MS cassiterite U–Pb dating (49.8 ± 2.6 Ma) suggests that the tin mineralization is coeval with the Lailishan granites. The contact between the monzogranite and the syenogranite is gradual and both are weakly peraluminous, with high SiO2, Al2O3, and total alkali contents. They are characterized by negative Eu anomalies and the depletion in high‐field‐strength elements and enrichment in large‐ion lithophile elements. Compared with the monzogranite, the syenogranite is more evolved and exhibit 'tetrad effect'. The Lailishan monzogranite was probably derived from the partial melt of the ancient crustal basement from the Tengchong Block under syn‐collisional tectonic setting. The syenogranite was cogenetic with monzogranite and experienced the process of fractional crystallization. The mineralization process is divided into three successive mineralization stages (I–III) in this study. These stages are characterized by the coarse‐grained cassiterite and high temperatures (216–337°C), light brown or colourless cassiterite and moderate temperatures (160–243°C), and dark brown cassiterite and low temperatures (116–199°C) of ore‐forming fluids, respectively. From the Stage I to later stages, both the δ18OH2O and δDSMOW values of fluids are decreasing and shift from magmatic water towards meteoric water, indicating that the ore‐forming fluids derived from granitic melts and mixed over time with meteoric water with the decrease of temperature. The δ34S values of pyrites and pyrrhotites (2.4–5.9‰) and Pb isotopic compositions for pyrites from Lailishan deposit (206Pb/204Pb = 18.687–19.402) are similar with those of Lailishan granites. We propose that the Lailishant in deposit is derived from the Lailishan granites. [ABSTRACT FROM AUTHOR]

The Early Cretaceous igneous complexes in the north flank of the North China Craton (NCC) provide a window to investigate the Mesozoic magmatism in the NCC. Here we report the precise timing of Early Cretaceous magmatism and magma petrogenesis of the different rock types in the north flank of the NCC based on petrology, mineral chemistry, geochemistry, zircon geochronology and Sr-Nd isotopes. Zircon U-Pb dating reveals that the Shouwangfen complex was crystallized at 130–128 Ma. The rocks display enrichment in large ion lithophile elements (LILE) and LREE, and depletion in high field strength elements (HFSE) and HREE, with relatively high Sr/Y and La/Yb values, typical of subduction-related magmatic rocks. The mafic microgranular enclaves show typical igneous textures, acicular apatites, sieve-texture of plagioclase phenocrysts and overgrowth of amphibole around the pyroxene, corresponding to magma mixing and mingling and thermal exchange. The quartz monzonites display normal zoning of the plagioclase, low and homogeneous εNd(t) values and linear co-variations in two-component diagrams. The quartz monzodiorites are characterized by high and homogeneous εNd(t) values. Petrologic feature and geochemical data suggest that the quartz monzonites represent lower crustal magma with minor contribution of enriched melt of the sub-continental lithospheric mantle (SCLM), followed by fractional crystallization. The mafic microgranular enclaves were sourced from enriched SCLM, followed by mixing and mingling with the host quartz monzonitic magma. The quartz monzodiorites are mainly SCLM-derived and subsequently mixed with lower crust melts. The high water contents (≥3%) of these Early Cretaceous igneous complexes suggests a hydrous SCLM beneath the NCC. The Early Cretaceous igneous complexes formed within an extensional tectonic setting which were related to the retreat and dehydration of the paleo-Pacific slab. The hydration of the lithosphere induced extensive crust-mantle interaction and large-scale water-rich magmatism, leading to lithospheric thinning in the NCC during the Mesozoic. [ABSTRACT FROM AUTHOR]

Whole-rock and Sr–Nd–Pb isotopic composition data, zircon Hf isotopic data and zircon U–Pb ages were obtained for the Late Triassic porphyries in the Zhongdian arc, eastern Tibet. These porphyries are intermediate and metaluminous and are enriched in large ion lithophile elements and depleted in high field strength elements. Moreover, they have weak negative Eu anomalies, high Sr and Ba contents, and high Sr/Y ratios. Different mineral geothermobarometers suggest that the porphyries in the Zhongdian arc crystallized at c. 640–829 °C and pressures of 2.1–2.8 kbar at depths shallower than 8 km. The porphyries have a calculated water content of 4.47–4.94 wt % and a relatively high magmatic oxygen fugacity. These porphyries were emplaced mainly at 230–203 Ma with a peak at 218–215 Ma. The Sr–Nd–Pb–Hf isotope data suggest that the porphyries in the Zhongdian arc were derived from a mixed melt of 50–65 % asthenospheric mantle and 35–50 % eclogite from the western Yangtze lower crust that experienced low-degree partial melting of 2–10 %. Subsequent fractional crystallization resulted in the decreasing trends of the major- and trace-element contents. The high Sr/Y and La/Yb values are the result of the low degree of partial melting of the western Yangtze lower crust rather than fractional crystallization, because no linear relationship was noted between Sr/Y or La/Yb and SiO2. The mixed melts from the lower crust and asthenospheric mantle provided a fertile magma source, and subsequent fractional crystallization under the favourable magmatic conditions of high water content and high oxidation state resulted in the formation of the porphyry Cu–Au deposits. [ABSTRACT FROM AUTHOR]