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Wang L.-J.,Geological Survey of Jiangsu Province | Wang L.-J.,Nanjing University | Wang L.-J.,Macquarie University | Griffin W.L.,Macquarie University | And 3 more authors.
Gondwana Research

A combined study of Lu-Hf isotopes and U-Pb ages for detrital zircons from sedimentary rocks can provide information on the crustal evolution of sedimentary provenances, and comparisons with potential source regions can constrain interpretations of paleogeographic settings. Detailed isotopic data on detrital zircons from Neoproterozoic sedimentary rocks in the northern part of the Yangtze Block suggest that these rocks have the maximum depositional ages of ~ 750. Ma, and share a similar provenance. In their source area, units of late Archean (2.45 to 2.55. Ga) to Paleoproterozoic (1.9 to 2.0. Ga) U-Pb ages made up the basement, and were overlain or intruded by magmatic rocks of Neoproterozoic U-Pb ages (740 to 900. Ma). Hf isotopic signatures of the detrital zircons indicate that a little juvenile crust formed in the Neoarchean; reworking of old crust dominates the magmatic activity during the Archean to Paleoproterozoic, while the most significant juvenile addition to the crust occurred in the Neoproterozoic. Only the Neoproterozoic zircon U-Pb ages can be matched with known magmatism in the northern Yangtze Block, while other age peaks cannot be correlated with known provenance areas. Similar zircon U-Pb ages have been obtained previously from sediments along the southeastern and western margins of the Yangtze Block. Thus, it is suggested that an unexposed old basement is widespread beneath the Yangtze Block and was the major contributor to the Neoproterozoic sediments. This basement had a magmatic activity at ~ 2.5. Ga, similar to that in North China; but zircon Hf isotopes suggest significant differences in the overall evolutionary histories between the Yangtze and North China. © 2012 International Association for Gondwana Research. Source

Yang L.,Wuhan University | Yang L.,Geological Survey of Jiangsu Province | Jin M.,Wuhan University | Tong C.,Wuhan University | Xie S.,Wuhan University
Journal of Hazardous Materials

This study reported a well controlled laboratory experiment of high concentration PAHs solute, containing fluorene, phenanthrene, fluoranthene and pyrene, through a nearly homogeneous soil column to reveal sorption and desorption behavior of these four PAHs in soil. The duration of the experiment was 64 days and the flow rate through the soil column was a constant which equals to 2000mLd-1. The result showed that the mechanism of isothermal sorption and desorption of fluorene can be perfectly described by the Langmuir model, and the correlation coefficients were greater than 0.997. The first-order Lagergren and the Bangham equation can precisely describe the rate of sorption of PAHs, while the rate of desorption can be represented by the second-order kinetics model. The results of the desorption experiment indicated that the desorption hysteresis of fluorene was evident. Few phenanthrene, fluoranthene and pyrene were desorpted to the aqueous phase for the chemical bond with the clay minerals. The most important process determining the behavior of PAHs in soils and their availability to further transformations was the sorption to soil solids with further sequestration and desorption to the aqueous phase. © 2012. Source

Gao R.,Chengdu University of Technology | Xiao L.,Wuhan University | Wang G.,Wuhan University | Wang G.,China University of Geosciences | And 3 more authors.
Acta Petrologica Sinica

West Junggar, as a crucial part of the Central Asian Orogenic Belt (CAOB), has been paid a lot of attention by numerous scholars. Six ophiolitic melange belts, numerous granitoids and mafic-intermediate dyke swarms outcrop in West Junggar, indicating how complex the Paleozoic tectonic evolution of West Junggar is. Although a great of improvements has been made, there are still many controversies, such as the formation time, rock assemblages and petrogenesis of diverse ophiolitic melanges, the petrogenesis, tectonic setting and thermal mechanism of the I-tvpe and A-tvpe granitoids, the geochronology, petrogenesis, tectonic background and paleo-stress regime of mafic-intermediate dyke swarms, the Paleozoic geochonological structure, the tectonic setting, the Phanerozoic crustal growth, the basement and tectonic evolution of West Junggar, and so on. The author collects the reported data and summarizes on the ophiolitic melange. Paleozoic granitoids and intermediate-mafic dyke swarms in West Junggar. Combining with the geological survey and geochemical work, we put forward several cognitions; ( 1 ) Daerbute and Karamay ophiolitic melanges that are derived from high degree partial melting of spinel-bearing Iherzolite, are formed in back-arc tectonic setting related with subduction. (2) C1 granitoids are the outcomes of subduction, C2-P1 are generated in post-collisional background, while P2 granitoids are formed in within-plate setting. (3) The petrogenesis of I-tvpe granitoids are subduction-related, while the A-tvpe granitoids and mafic- intermediate dyke swarms are post-collisional background-related. (4) The A-tvpe granitoids are derived from the high degree of fractionated crystallization after the lower crust partial melting induced by upwelling mantle. Geochemically, the mafic-intermediate dyke swarms are featured as adakitic rocks or sanukite, which are most possibly from partial melting of remnant oceanic slab metasomatised by fluids or melts. (5 ) The mafic-intermediate dyke swarms are formed a little later than that of the host granitoid, both of which are formed in post-collisional background in C2-P1 , suggesting a Paleozoic stress regime with near North-South direction extension. (6) The Paleozoic tectonic settings of West Junggar are oceanic basin system in Devonian, subdiction in Early Carboniferous, post-collisional setting in Late Carboniferous-Early Permian and within-plate setting in Middle-Late Permian. Source

Chang Y.,Nanjing University | Wu J.,Nanjing University | Liu L.,Geological Survey of Jiangsu Province
Journal of Hydrology

Spring hydrograph, especially the recession curve, is widely used to understand the internal information of the karst aquifer. However, how the turbulent conduit network influences the spring hydrograph is still unclear. Generally, the spring hydrograph could be divided into the early portion from the point recharge and late portion from the diffuse recharge. In this paper, MODFLOW-CFP is used to understand the influence of turbulent conduit on the spring hydrograph from the diffuse recharge and different influences of the turbulent and laminar conduit on this spring hydrograph. And then, a conceptual model is used to further interpret it. Based on the analysis results, the influence of turbulent conduit on the spring hydrograph from the point recharge is also discussed. For the spring hydrograph from the diffuse recharge, when ignoring the storage variation of the conduit network, the turbulent conduit just influences the early recession curve and this influence decreases with the spring discharge or rainfall intensity until it disappears. When the spring hydrography is strongly reshaped by the storage of the turbulent conduit network, only the early recession behavior is influenced by the turbulent conduit network as well. However, the laminar conduit network has a strongly influence on the whole recession behavior. The late exponential recession coefficient decreases with the conduit diameter and conduit storage. These different influences of turbulent and laminar conduit on the spring hydrograph are mainly caused by their different flow characteristics. Although the turbulent conduit could also strongly influence the early spring hydrograph from the point recharge, the late spring hydrograph is mainly controlled by diffuse recharge and the influence from the turbulent conduit may also disappear. © 2015 Elsevier B.V. Source

Xiao S.,Virginia Polytechnic Institute and State University | Shen B.,Peking University | Tang Q.,Virginia Polytechnic Institute and State University | Kaufman A.J.,The Interdisciplinary Center | And 3 more authors.
Precambrian Research

Thick carbonate successions of Proterozoic age were deposited in the Huaibei and Huainan regions along the southern margin of the North China Block. These successions, including the Huaibei Group in the Huaibei region and the Huainan and Feishui groups in the Huainan region, have been correlated with the Qingbaikou Group, which outcrops in the Jixian area of North China and is the eponymous succession of the Qingbaikouan System (traditionally regarded as 1000-800Ma). Recently, it has been shown that lower Qingbaikouan strata in the Jixian area may be as old as 1300-1400Ma. By correlation, the Huaibei, Huainan, and Feishui groups may include Mesoproterozoic strata, but these units have also been interpreted as Tonian or Cryogenian-Ediacaran-Cambrian in age. These contradictory age interpretations hamper our ability to explore the rich paleontological and sedimentary records preserved in these rocks and to assess paleogeographic reconstructions. In this report, we describe new microfossils and stable isotope data (δ13Ccarb, δ18Ocarb, δ34SCAS) from the Huaibei, Huainan, and Feishui groups. Possible vase-shaped microfossils from the Jiayuan Formation of the lower Huaibei Group and characteristic early Neoproterozoic acritarchs (particularly Trachyhystrichosphaera aimika) from the Gouhou and Liulaobei formations are consistent with a Tonian age for the Huaibei and Huainan groups. Similarly, carbon isotope trends in the Huaibei, Huainan, and Feishui groups are comparable with Tonian δ13Ccarb patterns in South Australia and Laurentia, with a plateau of moderately positive (1-5‰) values followed by pronounced negative δ13Ccarb excursion in the Gouhou Formation, which may be equivalent to the Bitter Springs anomaly in South Australia. δ34SCAS values of the Huaibei Group are mostly 25-40‰, similar to values from the stratigraphically equivalent Jingeryu Formation in the Jixian area. Overall, the combination of biostratigraphic, chemostratigraphic, and available radiometric data suggests that the Huaibei, Huainan, and Feishui groups are early Neoproterozoic (Tonian) in age. © 2014 Elsevier B.V. Source

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