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Primary water and oxygen isotope composition are important tools in tracing magma source and evolution. Metamictization of zircon due to U-Th radioactive decay may introduce external secondary water to the crystal, thereby masking the primary water and oxygen isotope signature. Recently, Raman-based screening has been established to select the low-degree metamict zircons. However, such an approach may not be appropriate for ancient samples, in which nearly all zircons are metamict. It was reported that thermal annealing can potentially heal crystals and retrieve primary water content and δ18O information from metamict zircons, given the weaker hydrogen bond of secondary water than that of primary water. Heating experiments at temperatures of 200–1000 °C over a period of 2–10 h reveal that annealing can effectively recover primary water and oxygen isotopes from metamict zircons. Primary water in crystalline and metamict zircons remains intact when heated at 4 h, which represent the optimal annealing treatment condition. Hydrothermally altered zircon is an exception. It only yields the minimum estimate of its primary water contents at 600 °C over a period of >4 h, probably due to partial primary water loss during metamictization for hydrothermal zircons. Moreover, the proportion of low-δ18O (700 °C. This study therefore provides the basis for applying zircon water and δ18O proxies to geologically ancient samples.

Water content and oxygen isotopes in zircon provide crucial constraints on magma source and process, yet they can be significantly modified by zircon metamictization, which causes secondary water absorption into the zircon crystal and the concomitant oxygen isotope changes. Therefore, it is imperative to develop a screening scheme to select the least-metamict zircons for the analyses. We propose a screening scheme based on our study on the Suzhou A-type granite (South China) through integrating Raman spectroscopy, water and trace element measurements, and oxygen isotope analysis. The results show that the primary water content is retained in zircon when the full-width at half maximum (FWHM) is 1007 cm−1 of ν3(SiO4) vibration band, while the primary δ18O is preserved at 1005.5 cm−1 Raman shift. Changes in trace element concentrations in Suzhou zircons are different from previous observations in metamict zircons but most likely related to magma evolution, which implies that trace elements are insensitive to metamictization. Primary δ18O in Suzhou zircons (4.5–6.0‰) fall into the mantle range, indicating a dominant mantle contribution to Suzhou granites. Primary water content was estimated at ca. 650–1400 ppm, significantly higher than those of typical I-type granite (400–736 ppm) and upper mantle-derived zircons (81–177 ppm). The high primary zircon water content was not controlled by the sub-solidus process, temperature, pressure, and cation charge balance but considered to reflect the high-water content in melts. This suggests a hydrous origin for the Suzhou A-type granite, which challenges the conventional view of anhydrous petrogenesis for A-type granites.

Several highly-enriched 28Si crystals were produced to enable a better determination of the Avogadro constant through removing the uncertainty associated with the abundance determination of the minor isotopes 29Si and 30Si.

The origins of the Mesozoic low-δ18O A-type granites in eastern China are quite controversial. A new “low-δ18O” granite, the Taohuadao alkaline (A1-type) granite from the Zhoushan archipelago, offshore from Zhejiang, is reported in this study. Integrated in situ analyses of Hf-O-Li isotopes in zircon are used to provide insights on the petrogenesis and evolution of this granite, and low-δ18O granites in general. Three types of zircon have been recognized in Taohuadao samples: zircon with sector/oscillatary zoning (Type 1), disturbed zoning (Type 2) and extremely high-U (Type 3) grains. Data are carefully screened for radiation damage and post-magmatic alteration and only Type 1 zircon represents a magmatic origin. In Type 1 zircons, Type 1a with normal mantle δ18Ozrn value of 5.23‰ has a positive δ7Li value (2.0 ± 3.3‰), while Type 1b has a δ18O value of ∼4.81‰ and highly variable negative δ7Li values (−31.9‰ to −0.3‰). In contrast to the O-Li isotopes, zircon is quite homogeneous in terms of Hf isotopes (eHf(t) = −3.5 ± 1.7), suggesting that the Taohuadao A1-type granites were derived from a simple source. Our results show that the magmatic zircon δ18Ozrn values are negatively correlated with Hf content but positively correlated with Zr/Hf ratio in zircon, which indicates that fractional crystallization plays an important role in producing the slightly low δ18O signature. The anhydrous nature of the A1-type granites suppressed the crystallization of biotite and hornblende, while low oxygen fugacity is responsible for insufficient precipitation of magnetite, both of which drive the later differentiates towards slight depletion in 18O. Therefore, we suggest a ferrogabbro-type fractional crystallization may have played a major role in producing the chemical and oxygen isotopic variations of the Taohuadao A1-type granite and accounts for ∼0.5‰ 18O-depletion. The extremely depleted δ7Li in Type 1b zircons is most likely a result of diffusion-driven fractionation. Mantle-like O-Li isotopes and very low Li abundance in zircon suggest a predominantly mantle origin with little, if any, involvement of continental crustal materials in the granite. Thus the Taohuadao A1-type granite was most likely produced by intensive fractionation of reduced, anhydrous basaltic melts, rather than by mixing of mantle- and crustally-derived melts as previously thought.

Gravitational stress in general and microgravity (µg) in particular are regarded as major stress factors responsible for immune system dysfunction in space. To assess the effects of alternating µg and hypergravity (hyper-g) on immune cells, the attachment of peripheral blood mononuclear cells (PBMCs) to adhesion molecules under flow conditions and the antigen-induced immune activation in whole blood were investigated in parabolic flight (PF). In contrast to hyper-g (1.8 g) and control conditions (1 g), flow and rolling speed of PBMCs were moderately accelerated during µg-periods which were accompanied by a clear reduction in rolling rate. Whole blood analyses revealed a “primed” state of monocytes after PF with potentiated antigen-induced pro-inflammatory cytokine responses. At the same time, concentrations of anti-inflammatory cytokines were increased and monocytes displayed a surface molecule pattern that indicated immunosuppression. The results suggest an immunologic counterbalance to avoid disproportionate immune responses. Understanding the interrelation of immune system impairing and enhancing effects under different gravitational conditions may support the design of countermeasures to mitigate immune deficiencies in space.

Wireless communication technology continues to advance at a rapid pace, and researchers have made tremendous progress in extending single-input single-output (SISO) systems to multiple-input multiple-output (MIMO) systems such as IEEE 802.11n, WiMAX, and LTE. However, a MIMO system requires a detector circuit to separate received data. To reduce the number of comparators required, the method of modified merge sort is proposed, and the results are compared with those of five sorting algorithms. This modified merge sort requires approximately 56% fewer comparators than a bitonic merge sort and approximately 46% fewer comparators than an odd-even merge sort. When implemented in a TSMC 0.18-μm process, the proposed chip demonstrates a throughput of up to 1200 Mbps at an operating frequency of 150 MHz.

Zircon is widely used in geochronology and as an isotopic tracer in igneous processes. However, the use of isotopic data obtained from zircon requires evaluating of processes that might compromise the robustness of its isotopic systems. In this study we have assessed how different U contents and degrees of metamictization have affected the SIMS U–Pb and oxygen-isotope signatures of zircon–quartz pairs from the U-rich A-type granites from Suzhou (southern China). Our SIMS results show that zircons with low U concentrations define a U–Pb age of 126.1 ± 0.5 Ma and homogeneous mantle δ18O values of 5.34 ± 0.46‰ (2SD). In contrast, zircons with high U contents show a positive correlation between U concentration and U–Pb ages (123–157 Ma) and a negative correlation between U concentration and δ18O values (range from 5.3 to 3.7‰). These observations are integrated with Raman spectra and oxygen-isotope analyses of coexisting quartz to reveal that the anomalously high U–Pb ages and low δ18O values reflect the degree of radiation damage to the zircons (quantified by radiation dose in displacements-per-atom, Ddpa). The older SIMS U–Pb ages are a direct result of the matrix effect caused by metamictization, whereas the low δ18O values result from interaction with OH-bearing fluids, the infiltration and diffusion of which was facilitated in the radiation-damaged areas. Coexisting quartz preserves primary O-isotope signatures of the magma better than high-U zircon, and thus provides a constraint for zircon oxygen-isotope values. This study demonstrates that it is essential to evaluate the degree of radiation damage before/after carrying out dating or oxygen-isotope analysis on zircons with high U contents. The results indicate that for the Suzhou pluton, Ddpa

Adakites, or adakitic rocks, in a broad sense, have been used to describe a large range of igneous rocks with the common feature of high Sr/Y and La/Yb ratios that can be achieved though different mechanisms. Among them, the continental, or C-type, adakitic rocks are particularly controversial in terms of their sources and genesis. In this study we revisit both Cu–Au ore-bearing and barren “C-type adakitic rocks” in the Lower Yangtze River Belt (LYRB) of central eastern China, including comprehensive analyses of their in-situ zircon Hf–O isotopes, whole-rock geochemistry and Sr–Nd isotopes. These “C-type adakitic rocks” consist of monzodiorite, granodiorite and quartz monzonite that are classified as shoshonitic to high-K calc-alkaline series according to their chemical compositions. They are characteristically high in potassium (K 2 O = 2.4–4.5%, K 2 O/Na 2 O = 0.6–1.3), with continental crust-like isotopic compositions, i.e., whole-rock eNd(T) = − 3.9 to − 7.7, initial 87 Sr/ 86 Sr = 0.7054–0.7085, zircon eHf(T) = 0 to − 11, and δ 18 O = 6‰ to 9‰. The ore-bearing and barren rocks are cogenetic. Fractional crystallization of hornblende, titanite, magnetite and apatite played a major role in their chemical variations, with the ore-bearing rocks being more felsic (SiO 2 = 63.3–69.6%) and higher in Sr/Y (41.2–75.6) than the barren rocks (SiO 2 = 57.3–65.0%, Sr/Y = 30.4–51.8). All these geochemical and isotopic features, in combination with regional geological data, suggest that the LYRB “C-type adakitic rocks” were unlikely to have been formed by melting of either a thickened and/or delaminated lower continental crust, or an altered oceanic crust as previously thought. These rocks are in general akin in geochemistry and isotopes to the Archean sanukitoids and the Setouchi high-Mg andesites in Japan, and are thus interpreted as being formed by melting of an enriched mantle source metasomatized by dewatering from a delaminated flat-slab. The flat subduction of an oceanic plateau and its subsequent delamination and foundering since the early Mesozoic beneath southeastern China ( Li and Li, 2007 ) thus not only explain the temporal and spatial propagation of widespread Yanshanian igneous rocks regionally since ca. 195 Ma, but also the formation of a series of enigmatic “adakitic” rocks in the region, including the LYRB potassium-rich rocks that were inappropriately called the “C-type adakitic rock” by previous workers.

We report here the first integrated U–Pb dating and hafnium–oxygen isotope analyses of detrital zircon grains from sedimentary and volcaniclastic rocks in the Neoproterozoic Nanhua Basin, central South China. These data provide vital information on the depositional cycles of the Cryogenian strata and their bearings on the breakup of the Rodinia supercontinent, and the characteristics of Precambrian crustal growth in the South China Block and neighboring continents. Zircon SIMS U–Pb ages indicate that the Qingshuijiang Formation was deposited at 772 ± 5 Ma and the Fanzhao Formation was deposited between 800 and 770 Ma. The onset time of the Sturtian (Jiangkou) glaciation is constrained to be no older than 730 Ma. Together with compilations of all available high precision zircon U–Pb data on tuff beds in the Nanhua Basin, our work demonstrates that the Cryogenian deposition in South China began at about 850 Ma and had three depositional cycles at ca. 850–820 Ma, 820–720 Ma and 720–635 Ma. Hf isotope analyses and U–Pb dating, combined with existing O isotope analyses, of detrital zircon have revealed three striking features for grains with 1.0–0.7 Ga ages: (1) about 22% of total analysed grains have Hf isotope compositions that plot between the new continental crust and depleted mantle growth curves; (2) about 80% of zircon grains have δ18O values below 6.5‰; and (3) 950–700 Ma is the most dominant age group in the total of 1616 concordant detrital zircon ages from the Cryogenian sedimentary rocks. The Early Neoproterozoic (1.0–0.7 Ga) thus appears to have witnessed significant juvenile crustal growth in South China. In addition, zircon analyses of the Cryogenian sedimentary rocks revealed 3.2–2.9 Ga and possibly 2.7–2.4 Ga as two additional episodes of juvenile crust growth in South China and neighboring continents.

Late Permian to Triassic (“Indosinian-aged”) orogenesis and associated magmatism are widespread in southeastern China, but their causes and significance to the regional geodynamic evolution are highly controversial. We report in this study integrated in situ U–Pb, Hf and O isotope analyses of detrital zircons from the Middle to Late Permian sediments in southeastern China, and use these data to decipher the sedimentary provenances, regional magmatic barcode and crustal evolution processes. A total of 409 concordant U–Pb zircon analyses on five sedimentary samples exhibits four major age peaks at ca 1870 Ma, ca 445 Ma, ca 370 Ma and ca 280 Ma, one “broad” age group of ca 1180–960 Ma, and two subordinate peaks at ca 2530 Ma and ca 800 Ma. All the Archean-aged detrital zircons are oval in shape with clear abrasive imprints, indicating long-distance transport and/or multi-cycled sedimentary processing from unknown Archean sources. In contrast, detrital zircons of the remaining age groups are mostly euhedral to subhedral crystals, suggesting short-distance transport. Zircon ages of ca 1870 Ma, ca 1180–960 Ma, ca 800 Ma, ca 445 Ma and ca 280 Ma are coeval with exposed magmatic rocks in the Cathaysia Block of southeastern China. The ubiquitous existence of ca 280 Ma detrital zircons in the studied sediments implies a widespread occurrence of Early Permian magmatic rocks in southeastern China coastal region. In situ Hf and O isotope analyses of detrital zircons reveal periods with growth of juvenile continental crust at ca 1870 Ma, ca 1400 Ma, ca 1140–940 Ma, ca 445 Ma and c. 280 Ma, alternating with reworking and recycling of continental crust at ca 1200 Ma, ca 830 Ma and ca 370 Ma. The ca 280 Ma detrital zircons display coherent, negative correlations between eHf(T) and δ18O values, indicating that their igneous source rocks probably formed with reworking of ancient supracrustal materials by mantle-derived magmas in an active continental margin. This interpreted ca 280 Ma magmatic event in an active continental margin is coincident with the remarkable change in regional palaeogeography from a carbonate platform in Carboniferous-earliest Permian time to an elongated uplift along the southeastern coastal regions in mid-Early Permian. Therefore, the early Indosinian tectonism and magmatism in southeastern South China most likely reflect the formation of a continental arc by the subduction of the Paleo-Pacific plate in the Early Permian.

The middle-lower reaches of the Yangtze River is one of the most important metallogenic belts in China, hosting numerous Cu–Fe–Au–Mo deposits. Previous chronological and geochemical investigations mostly focused on the magmatic rocks and associated deposits in the lower reaches of the river, but the timing and genesis of the Cu–Au–(Mo) mineralized porphyries in the middle reaches are yet to be well constrained. In this study we carried out precise SIMS U–Pb zircon age determinations for a number of Cu–Au–(Mo) mineralized porphyries and barren granitoid intrusions in the Jiurui and Edong mining districts in the middle reaches of the Yangtze River valley. Our new age results reveal two discrete magmatic and mineralization events at ca. 145–146 Ma and ca. 140 Ma in the study area. The ca. 145–146 Ma granitoids signify the start of the Cretaceous magmatism in the Yangtze River Metallogenic Belt, coinciding temporally with a regional tectonic switching from a Late Jurassic transpressive tectonic regime to an earliest Cretaceous extensional regime in eastern China.

To understand the behavior of Li in zircon, we have analyzed the abundance and isotopic composition of Li in three zircon standards (Plešovice, Qinghu and Temora) widely used for microbeam analysis of U-Pb ages and O-Hf isotopes. We have mapped Li concentration ([Li]) on large grains, using a Cameca 1280HR Secondary Ion Mass Spectrometer (SIMS). All zircons have a rim 5–20 μm wide in which [Li] is 5 to 20 times higher than in the core. Up to ~20‰ isotopic fractionation is observed on a small scale in the rims of a single zircon grain. The measured δ7Li values range from –14.3 to 3.7‰ for Plešovice, –22.8 to 1.4‰ for Qinghu and –4.7 to 16.1‰ for Temora zircon. The [Li] and δ7Li are highly variable at the rims, but relatively homogenous in the cores of the grains. From zircon rim to core, [Li] decreases rapidly, while δ7Li increases, suggesting that the large isotopic variation of Li in zircons could be caused by diffusion. Our data demonstrate that homogeneous δ7Li in the cores of zircon can retain the original isotopic signatures of the magmas, while the bulk analysis of Li isotopes in mineral separates and in bulk-rock samples may produce misleading data.