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Li X.-H.,CAS Institute of Geology and Geophysics | Li Z.-X.,Curtin University Australia | Li W.-X.,CAS Guangzhou Institute of Geochemistry
Gondwana Research | Year: 2014

The South China Block, consisting of the Yangtze and the Cathaysia blocks, is one of the largest Precambrian blocks in eastern Asia. However, the early history of the Cathaysia Block is poorly understood due largely to intensive and extensive reworking by Phanerozoic polyphase orogenesis and magmatism which strongly overprinted and obscured much of the Precambrian geological record. In this paper, we use the detrital zircon U-Pb age and Hf isotope datasets as an alternative approach to delineate the early history of the Cathaysia Block. Compilation of published 4041 Precambrian detrital zircon ages from a number of (meta)sedimentary samples and river sands exhibits a broad age spectrum, with three major peaks at ~2485Ma, ~1853Ma and ~970Ma (counting for ~10%, ~16% and ~24% of all analyses, respectively), and four subordinate peaks at ~1426Ma, ~1074Ma, ~780Ma and ~588Ma. Five of seven detrital zircon age peaks are broadly coincident with the crystallisation ages of ~1.89-1.83Ga, ~1.43Ga, ~1.0-0.98Ga and ~0.82-0.72Ga for known igneous rocks exposed in Cathaysia, whereas, igneous rocks with ages of ~2.49Ga and ~0.59Ga have not yet been found. The Hf isotopic data from 1085 detrital zircons yield Hf model ages (TDM C) between ~4.19Ga and ~0.81Ga, and the calculated εHf(t) values between -40.2 and 14.4. The Archean detrital zircons are exclusively oval in shape with complicated internal textures, indicating that they were sourced by long distance transportations and strong abrasion from an exotic Archean continent. In contrast, the majority of detrital zircons in age between ~1.9 and ~0.8Ga are euhedral to subhedral crystals, indicative of local derivation by short distance transportations from their sources. The oldest crustal basement rocks in Cathaysia were most likely formed by generation of juvenile crust and reworking of recycled Archean components in Late Paleoproterozoic at ~1.9-1.8Ga, rather than in the Archean as previously speculated. Reworking and recycling of the continental crust are likely the dominant processes for the crustal evolution of Cathaysia during the Mesoproterozoic to Neoproterozoic time, with an intervenient period of significant generation of juvenile crust at ~1.0Ga.Precambrian crustal evolutions of the Cathaysia Block are genetically related to the supercontinent cycles. By comparing detrital zircon data from Cathaysia with those for other continents, and integrating multiple lines of geological evidence, we interpret the Cathaysia Block as an orogenic belt located between East Antarctica, Laurentia and Australia during the assembly of supercontinent Columbia/Nuna at ~. 1.9-1.8. Ga. The Cathaysia Block amalgamated with the Yangtze Block to form the united South China Block during the Sibao Orogeny at ~. 1.0-0.89. Ga. The Laurentia-Cathaysia-Yangtze-Australia-East Antarctica connection gives the best solution to the paleo-position of Cathaysia in supercontinent Rodinia. The significant amount of ~. 0.6-0.55. Ga detrital zircons in Cathaysia and West Yangtze have exclusively high crustal incubation time of >. 300. Ma, indicating crystallisation from magmas generated dominantly by crustal reworking. This detrital zircon population compares well with the similar-aged zircon populations from a number of Gondwana-derived terranes including Tethyan Himalaya, High Himalaya, Qiangtang and Indochina. The united South China-Indochina continent was likely once an integral part of Gondwanaland, connected to northern India by a "Pan-African" collisional orogen. © 2014 International Association for Gondwana Research.

Chen H.,CAS Guangzhou Institute of Geochemistry
Ore Geology Reviews | Year: 2013

Although the sources of the ore metals remain problematic in most Iron-oxide Cu and Au (IOCG) deposits, external sulphur, either from surficial basinal brines and seawater (e.g., Central Andean and Carajás deposits) or from formation water and metamorphic fluids (e.g., the Cloncurry deposits), or introduced by magmatic assimilation of metasedimentary units (e.g., Phalaborwa), has been documented in many major Cu-rich IOCG centres. However, only the evaporite-sourced fluids yield diagnostically high δ34S values (i.e., >10‰), while sedimentary formation water or metamorphic fluids commonly have lower values and are less clearly distinguishable from magmatic fluids, as in the Cloncurry deposits in which the involvement of external fluids is revealed by other evidence, such as noble gas isotopes. On the basis of these arguments, IOCG deposits could be redefined as a clan of Cu (AuAgU) deposits containing abundant hypogene iron oxide (magnetite and/or hematite), in which externally-derived sulphur probably plays an important role for the Cu (AuAgU) mineralization. In this definition, all "Kiruna-type" magnetite deposits, hydrothermal iron deposits (e.g., skarn Fe deposits) and magnetite-rich porphyry CuAu and skarn CuAu deposits are excluded. Two subtypes of IOCG deposits are recognized on the basis of the predominant iron oxide directly associated with the Cu (Au) mineralization, whether magnetite or hematite. Neither magnetite- nor hematite-rich IOCG deposits show any preference for specific host rocks, and both range in age from Neoarchean to Pleistocene, within a broad tectonic environment. © 2012 Elsevier B.V.

Xu Y.-G.,CAS Guangzhou Institute of Geochemistry
Geochimica et Cosmochimica Acta | Year: 2014

Major, trace element and Sr-Nd-Pb isotopic data of basalts emplaced during 90-40Ma in the North and Northeast China are compiled in this review, with aims of constraining their petrogenesis, and by inference the evolution of the North China Craton during the late Cretaceous and early Cenozoic. Three major components are identified in magma source, including depleted component I and II, and an enriched component. The depleted component I, which is characterized by relatively low 87Sr/86Sr (<0.7030), moderate 206Pb/204Pb (18.2), moderately high εNd (~4), high Eu/Eu* (>1.1) and HIMU-like trace element characteristics, is most likely derived from gabbroic cumulate of the oceanic crust. The depleted component II, which distinguishes itself by its high εNd (~8) and moderate 87Sr/86Sr (~0.7038), is probably derived from a sub-lithospheric ambient mantle. The enriched component has low εNd (2-3), high 87Sr/86Sr (>0.7065), low 206Pb/204Pb (17), excess Sr, Rb, Ba and a deficiency of Zr and Hf relative to the REE. This component is likely from the basaltic portion of the oceanic crust, which is variably altered by seawater and contains minor sediments. Comparison with experimental melts and trace element modeling suggest that these recycled oceanic components may be in form of garnet pyroxenite/eclogite. These components are young (<0.5Ga) and show an Indian-MORB isotopic character. Given the share of this isotopic affinity by the extinct Izanaghi-Pacific plate, currently stagnated within the mantle transition zone, we propose that it ultimately comes from the subducted Pacific slab.Eu/Eu* and 87Sr/86Sr of the 90-40Ma magmas increases and decreases, respectively, with decreasing emplacement age, mirroring a change in magma source from upper to lower parts of subducted oceanic crust. Such secular trends are created by dynamic melting of a heterogeneous mantle containing recycled oceanic crust. Due to different melting temperature of the upper and lower ocean crust and progressive thinning of the lithosphere, the more fertile basaltic crustal component is preferentially sampled during the early stage of volcanism, whereas the more depleted gabbroic lower crust and lithospheric mantle components are preferentially sampled during a late stage. This model is consistent with a protracted destruction process of the lithosphere beneath eastern China. The presence of significant recycled oceanic crust components in the 90-40Ma basalts highlights the influence of Pacific subduction on the deep processes in the North China Craton, which can be traced back at least to the late Cretaceous. This, along with the conjugation of crustal deformation pattern in this region with the movement of the Pacific plate, makes the Pacific subduction as a potential trigger of the destruction of the North China Craton. © 2014 Elsevier Ltd.

Cheng H.,CAS Guangzhou Institute of Geochemistry
Critical Reviews in Food Science and Nutrition | Year: 2010

Considerable knowledge has been accumulated on the volatile compounds contributing to the aroma and flavor of yogurt. This review outlines the production of the major flavor compounds in yogurt fermentation and the analysis techniques, both instrumental and sensory, for quantifying the volatile compounds in yogurt. The volatile compounds that have been identified in plain yogurt are summarized, with the few key aroma compounds described in detail. Most flavor compounds in yogurt are produced from lipolysis of milkfat and microbiological transformations of lactose and citrate. More than 100 volatiles, including carbonyl compounds, alcohols, acids, esters, hydrocarbons, aromatic compounds, sulfur-containing compounds, and heterocyclic compounds, are found in yogurt at low to trace concentrations. Besides lactic acid, acetaldehyde, diacetyl, acetoin, acetone, and 2-butanone contribute most to the typical aroma and flavor of yogurt. Extended storage of yogurt causes off-flavor development, which is mainly attributed to the production of undesired aldehydes and fatty acids during lipid oxidation. Further work on studying the volatile flavor compounds-matrix interactions, flavor release mechanisms, and the synergistic effect of flavor compounds, and on correlating the sensory properties of yogurt with the compositions of volatile flavor compounds are needed to fully elucidate yogurt aroma and flavor. © Taylor and Francis Group, LLC.

Yang J.F.,CAS Guangzhou Institute of Geochemistry
Journal of environmental science and health. Part. B, Pesticides, food contaminants, and agricultural wastes | Year: 2011

The distribution and occurrence of 15 antibiotics in surface water of the Pearl River System (Liuxi River, Shijing River and Zhujiang River) and effluents of four wastewater treatment plants (WWTPs) were investigated in two sampling events representing wet season and dry season by using rapid resolution liquid chromatography-electrospray tandem mass spectrometry (RRLC-MS/MS) in positive ionization mode. Only eight antibiotics (sulfadiazine, sulfapyridine, sulfamethazine, sulfamethoxazole, trimethoprim, roxithromycin, erythromycin-HO and norfloxacin) were detected in the water samples of the three rivers and the effluents. The detection frequencies and levels of antibiotics in the dry season were higher than those in the wet season. This could be attributed to the dilution effects in the wet season and relatively lower temperature in the dry season under which antibiotics could persist for a longer period. The levels of the detected antibiotics in different sites are generally in a decreasing order as follows: Shijing River ≥WWTP effluent ≥Zhujiang River ≥ Liuxi River. Risk assessment based on the calculated risk quotients showed that only erythromycin-HO and roxithromycin detected in the Pearl Rivers might have adverse effects on aquatic organisms.

The present invention discloses a gradually-ascending spiraled passive sampler for measuring sediment-water diffusion flux of organic polutants, which comprises a sediment pore-water sampler and a water sampler arranged above the sediment pore-water sampler, wherein a plurality of sediment sampling units are vertically arranged in the sediment pore-water sampler, and the water sampler is provided with a plurality of water sampling units arranged transversely along the vertical direction in sequence.

Disclosed is an application of dealuminated Y type zeolite in degrading organic pollutants in water under microwave induction. The dealuminated Y type zeolite, with the cation being H+ and a mol ratio of SiO2 to Al2O3 being 60, is applied to degrading the organic pollutants in the water under microwave induction. The degrading rate of atrazine is up to 67.40 nmol/min under the radiation of 700 W microwave (2.450 GHz) at the laboratory simulation condition.

Cheng H.,CAS Guangzhou Institute of Geochemistry | Hu Y.,Stanford University
Environmental Pollution | Year: 2010

As the most widely scattered toxic metal in the world, the sources of lead (Pb) observed in contamination investigation are often difficult to identify. This review presents an overview of the principles, analysis, and applications of Pb isotopic fingerprinting in tracing the origins and transport pathways of Pb in the environment. It also summarizes the history and current status of lead pollution in China, and illustrates the power of Pb isotopic fingerprinting with examples of its recent applications in investigating the effectiveness of leaded gasoline phase-out on atmospheric lead pollution, and the sources of Pb found in various environmental media (plants, sediments, and aquatic organisms) in China. The limitations of Pb isotopic fingerprinting technique are discussed and a perspective on its development is also presented. Further methodological developments and more widespread instrument availability are expected to make isotopic fingerprinting one of the key tools in lead pollution investigation. © 2009 Elsevier Ltd. All rights reserved.

Cheng H.,CAS Guangzhou Institute of Geochemistry | Hu Y.,Stanford University
Bioresource Technology | Year: 2010

With rapid economic growth and massive urbanization, China faces the problem of municipal solid waste (MSW) disposal and the pressing need for development of alternative energy. Waste-to-energy (WTE) incineration, which recovers energy from discarded MSW and produces electricity and/or steam for heating, is recognized as a renewable source of energy and is playing an increasingly important role in MSW management in China. This article provides an overview of the WTE industry, discusses the major challenges in expanding WTE incineration in China, namely, high capital and operational costs, equipment corrosion, air pollutant emissions, and fly ash disposal. A perspective on MSW as a renewable energy source in China is also presented. Currently, only approximately 13% of MSW generated in China is disposed in WTE facilities. With the significant benefits of environmental quality, the reduction of greenhouse gas (GHG) emissions, and government policies and financial incentives as a renewable energy source, WTE incineration industry is expected to experience significant growth in the coming decade and make greater contribution to supplying renewable energy in China. © 2010 Elsevier Ltd. All rights reserved.

This invention discloses a kind of method to remove organic pollutants through coupling microwave degradation based on microporous mineral adsorption. It consists of the following major steps: Fill hydrophobic porous mineral adsorbent into the adsorption column to adsorb organic pollutants in the organic wastewater, and start up the microwave generator after the adsorbent reaches saturation so that the organic pollutants adsorbed inside the adsorption column can be degraded under microwave induction. With the alternative operation and regeneration of two adsorption columns, the organic wastewater can be treated continuously. In the invention, with the technologies of microwave-induced degradation through hydrophobic microporous mineral coupling adsorption, organic pollutants can be removed from water efficiently, and the degradation process and carrier can be circulated. The pollutants can be mineralized into non-toxic and harmless micromolecular substance completely.

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