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Ma J.,Chinese Research Academy of Environmental Sciences | Zhou Y.,Sun Yat Sen University | Zhou Y.,Guangdong Provincial Key Laboratory of Geological Processes and Mineral Resource Survey
Journal of Environmental Sciences | Year: 2011

Soil samples from Huizhou and Zhanjiang, China were analyzed for 16 priority poly cyclic aromatic hydrocarbons (PAHs) with harmonized sampling, sample extraction and analysis quantification methods. The concentrations and sources of PAHs in soil samples of the two cities were compared. Almost all of the PAH components were detectable in 103 soil samples. The concentrations of {caret insertion point}PAHs ranged from 35.40 to 534.5 μg/kg in soil samples from Huizhou, and ranged from 9.50 to 6618.00 μg/kg in samples from Zhanjiang. Evident differences of concentrations, compositions and sources of PAHs in soils were observed between the two cities. The average concentrations of individual component and the sum of a group of PAHs in soil samples from Zhanjiang were significantly higher than those in Huizhou (P < 0.05). Phe, Flu, Pyr, Bbf and Baa were the dominant PAH components both in soil samples from Huizhou and Zhanjiang. Except for these five components, Bap, Up, Daa and Bgp were also the dominant PAH components in soil samples from Zhanjiang. Coal combustion and liquid fossil fuel combustion were the same sources of PAHs in the two cities with different contributions, and petroleum played a key role in PAHs release in Zhanjiang. © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Source

Zheng Y.,Sun Yat Sen University | Zheng Y.,CAS Guangzhou Institute of Geochemistry | Zheng Y.,Guangdong Provincial Key Laboratory of Geological Processes and Mineral Resource Survey | Li D.,CAS Guangzhou Institute of Geochemistry | And 3 more authors.
Geotectonica et Metallogenia | Year: 2015

The Ashele Cu-Zn deposit is located in the Ashele Devonian volcanic-sedimentary basin to the south of the Altay accretionary orogenic belt. The ore bodies are lens like hosted in the Ashele Formation. Orebodies show deformations concordant with the host rocks. The ore-forming process can be divided into two stages: the first VMS stage represented by banded and massive ores, while the second hydrothermal stage represented by Cu-polymatellic veins. Most of primary ores are preserved, but locally some veins cut across the earlier banded ores accompany with the coarse grains and pressure-solution, crushed, meta-porphyry, replacing textures, indicating metallic remobilization of primary VMS ores. Four types of fluid inclusions are distinguished, which include aqueous water (W-type), pure CO2 (PC-type), CO2-H2O (C-type) and daughter mineral-bearing (S-type). The primary fluid inclusions have homogenization temperatures of 220-280 ℃ and salinities of 4% to 8% NaCl equivalent. Gases in fluid inclusions are CO2, CH4 and N2. The low salinity and high CO2 content indicate the ore-forming fluid may be metamorphic fluid. The hydrostatic-lithostatic pressure of boiling fluid assemblage fluctuates is range of 85-295 MPa, corresponding to the depth of 8.5-10.9 km. Considering the regional tectonic evolution, we conclude that the VMS mineralization was formed in the arc-basin under extensional setting, whereas the late stage hydrothermal remobilization was formed in continental-arc collision setting. Therefore, the Ashele Cu-Zn deposit is a modified VMS deposit. ©, 2015, Science Press. All right reserved. Source

Zhang Y.,CAS Guangzhou Institute of Geochemistry | Zhang Y.,Sun Yat Sen University | Wang Y.,Sun Yat Sen University | Wang Y.,Guangdong Provincial Key Laboratory of Geological Processes and Mineral Resource Survey | And 8 more authors.
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | Year: 2015

It is generally accepted that the Jiangnan orogenic belt led to the amalgamation of the Yangtze with Cathaysia blocks during the Neoproterozoic period. However, its tectonic evolution and amalgamation timing are still in debate. This paper presents a set of new geochronological and geochemical data for the newly-identified Neoproterozoic high-Mg volcanics from Cihua (Jiangxi). LA-ICP-MS zircon U-Pb dating of the representative sample yields a weighted mean age of 832±12 Ma (n=16, MSWD=0.12), representing the eruption age of the andesite. Geochemical results indicate that they can be classified as high-Mg andesites with SiO2 ranging from 57.67% to 61.33%, MgO from 3.51% to 4.29% and Mg-number from 52 to 57. Their chondrite-normalized REE patterns exhibit a left-sloping pattern with enriched LREEs relative to HREEs. On the primitive mantle-normalized multi-element patterns, these samples have strong enrichment in LILE and depletion in HFSE with marked negative Nb-Ta, Ti and positive Th anomalies, similar to those of the typical arc volcanics. The generation of the volcanic rocks might have been attributed to an interaction of the subducted melt/fluid or sediment with the overlying refractory mantle, suggesting the central Jiangnan orogen was still on the subduction till ~832 Ma. It is concluded that the Jiangnan orogen consists of several branches with distinct amalgamation evolution. © 2015, Editorial Department of Earth Science-Journal of China University of Geosciences. All right reserved. Source

Tang L.,Sun Yat Sen University | Tang L.,Guangdong Provincial Key Laboratory of Geological Processes and Mineral Resource Survey | Chen H.,Sun Yat Sen University | Song J.,Sun Yat Sen University
Geosciences Journal | Year: 2016

Water molecules are adsorbed onto the surface and interlayer of clay minerals and form a film, which causes that pore pressure diffusion in clayey soils differs from that in granular material. In this paper, adsorbed water is classified into strongly adsorbed water and loosely adsorbed water, which provide a better understanding of the physical mechanisms of the adsorbed water. To investigate the impact of adsorbed water on pore pressure diffusion, a series laboratory tests were conducted, including the uplift pressure test, pore pressure diffusion test and adsorbed water content test. The experimental results implies that strongly adsorbed water can neither flow nor participate in pressure diffusion, but loosely adsorbed water shears at pressure gradients and participates in laminar flow. Therefore, as long as the dense clayey soil contains loosely adsorbed water, the pore pressure change at a local site can diffuse throughout the material. A concept called “loosely adsorbed water index (Ilo) is defined to characterize both the content and physical properties of loosely adsorbed water: (1) when Ilo ≥ 1, the peripheral water molecules of loosely adsorbed water layer essentially behave the same as free water; (2) as Ilo → 0, the physical properties of adsorbed water may evolve from a gel-like state to a solid-like state (strongly adsorbed water). According to the density of clay and the content of adsorbed water, the process of pore pressure diffusion can be divided into three modes: flow channels of free fluid, deformations of the adsorbed water layer and shear motions of the peripheral-adsorbed water molecules. Pore pressure response to additional water pressure strongly depends on the permeability, seepage path and boundary conditions. The time-lag effect of pore pressure diffusion should be considered in applications of effective stress in engineering. © 2016 The Association of Korean Geoscience Societies and Springer-Verlag Berlin Heidelberg Source

Zhang X.,Sun Yat Sen University | Zhang X.,CAS Guangzhou Institute of Geochemistry | Zhang X.,Guangdong Provincial Key Laboratory of Geological Processes and Mineral Resource Survey | Cawood P.A.,University of Western Australia | And 7 more authors.
Gondwana Research | Year: 2016

The Kenting Mélange on the Hengchun Peninsula, Taiwan, formed through tectonic shearing of subduction complex lithologies, probably within the plate boundary subduction channel between the Eurasian and Philippine Sea plates, with further deformation and exhumation in the Pliocene-Pleistocene during arc-continent collision. Field relations reveal a structural gradation from normal stratified turbidite sequence (Mutan Formation) through broken formation to highly sheared Kenting Mélange containing allochthonous polygenic blocks. This gradation is consistent with an increase of average vitrinite reflection values from ~. 0.72% in the Mutan Formation through ~. 0.93% in the broken formation to ~. 0.99% in the mélange, suggesting temperatures of at least 140. °C during formation of the Kenting Mélange. Zircons from gabbro in the Kenting Mélange are dated as 25.46. ±. 0.18. Ma, which together with geochemical data constrains the source to South China Sea oceanic lithosphere. In combination with the field relationships, vitrinite reflectance values, microfossil stratigraphy, and offshore geophysical data from S and SE Taiwan, we propose that the Kenting Mélange initially formed at the subduction plate boundary from off-scraped trench deposits. Minor Plio-Pleistocene microfossils (<. 5%) occur within the mélange in proximity to slope basin of equivalent age and were likely sheared into the mélange during out-of-sequence thrusting associated with active arc-continent collision, which in the Hengchun Peninsula commenced after 6.5. Ma. © 2015 International Association for Gondwana Research. Source

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