Geoscience

Temporal-Spatial Evolution of Metallogenic Systems and Its Significance to Mineral Exploration

ZHAI Yu-sheng,WANG Jian-ping,DENG Jun,PENG Run-min,LIU Jia-jun

2008, 22(2): 143-150.

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Metallogenic systems are an important component of the mega-earth system. Their formation and distribution are controlled by the evolution of the earth system. Different metallogenic systems formed at different stages of the geological history are the products of earth system evolution. These systems also document the evolutional processes of the earth to a certain extent. As located in the junction of three tectonic metallogenic domains such as the PalaeoAsia, the Tethys-Himalaya and the circum-Pacific plates, the China continent underwent very complex tectonic evolutional processes. So the superimposition between metallogenic systems is obvious in China. This constitutes one of main regional metallogenic features of China. Spatial distribution of metallogenic systems is controlled by the unevenness of dynamics of the earth system. For example, different metallogenic systems occurred in divergent, convergent, and transformational tectonic regimes in palaeocontinental margins. Ore-forming depth, evolution and preservation depth of a metallogenic system depend on the evolution of tectonic setting. Analysis of ore-bearing probability of structural layers is an effective way to estimate probable ore deposit types and mineral resource potential in a region. The concept of concealed ore belt, which is put forward in this paper, will enlarge prospecting target from concealed ore deposit to concealed ore belt. Therefore it constitutes an important progress of regional metallogeny and mineral exploration.

A New Example of Unconformity-Related Endogenic Metallization: the Yinan Au-Cu-Fe Deposit in Shandong Province, China

GU Xue-xiang, DONG Shu-yi, WANG Yin-hong，HU Gui-Zeng, DU Shu-hao，JIAO Peng

2008, 22(2): 151-161.

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The Yinan skarn and hydrothermal type Au-Cu-Fe deposit in Shandong Province occurs in the contact zone of the intermediate-acidic composite intrusions of the Yanshanian age and their surrounding wall rocks. In the recent years, two new ore layers have been discovered on the unconformity surface between the Archean and Neoproterozoic as well as in the overlying Neoproterozoic cover rocks. Locally in the Archean basement rocks below the unconformity, Au and Cu mineralization has also been observed. The unconformity-controlled orebodies are typically layer- or sheet-like and laterally continuous and flat, with a normal depth of 430-650 m beneath the surface. Tectonically as an unstable and weak zone, the unconformity surface and the overlying interfaces between mechanically different strata are ready to be fractured and glided during later tectonic activity and magmatic intrusion, thus resulting in the filling and mineralization of magmas and related hydrothermal fluids. Meanwhile, the unconformity surface is usually served as a geochemical barrier, and the marked difference in chemical composition between the cover rocks （pebbled sandstone, sandstone and shale interbedded with argillaceous limestone） and the basement rocks （granite gneiss and amphibolite） may also have played an important role in the unconformity mineralization. The veinlet and disseminated Au and Cu mineralization in the Archean basement rocks may be related to the extensional cleavages in the basement caused by the detachment of the unconformity surface. The discovery of the unconformity related mineralization in the Yinan deposit is of great significance to the study of metallogenesis and exploration both in the mine and in the entire western Shandong Province.

Rare Earth Element and Trace Element Geochemistry of Shalagang Antimony Deposit in the Southern Tibet and Its Tracing Significance
for the Origin of Metallogenic Elements

QI Xue-xiang ，LI Tian-fu，YU Chun-lin

2008, 22(2): 162-172.

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Shalagang antimony deposit of the southern Tibet occurs in carbonaceous slate, pelitic siltstone and silicalite in the Jiabula Formation of the Lower Cretaceous, and diabase in Yanshanian and gabbro in Himalayanian. The ore bodies are controlled by E-W striking interlayer faults and S-N striking faults. The weakly country rock alteration distributed along the ore bodies with symmetrical plane and zone. Analytic results show the REE patterns of the carbonaceous slate and silicalite are similar to that of the upper crust and shale in Paleozoic and Mesozoic. The REE patterns of the gabbro with LREE depleted, HREE enriched and slightly Eu depleted flat curves are different from that of Yanshanian diabase in the southern Tibet with LREE enriched and without Eu abnormal curves. The strong enrichment and high fractionation of LREE, moderate depletion of Eu and strong depletion of Ce in the Chondritenormalized REE patterns of the antimony ores are different from those of hydrothermal fluid and exhalite from the black- and white- smoker chimney within Mid-Atlantic Ridge, North Atlantic seawater and Woxi Sedex type W-Sb-Au deposit, but the Chondrite-normalized REE patterns of the antimony ores have the strong reversed change with that of Himalayanian gabbro. Furthermore, the characteristics of strongly negative anomaly of Nb and positive anomaly of Ce and Ba in the trace element MORB-normalized spider diagram for antimony ores show the similar to and different from those for Himalayanian gabbro, carbonaceous and silicalite. The sulfur isotopic compositions of sulfides from Shalagang antimony deposit （δ³⁴S）range from-2.6‰ to-4.1‰ besides 10.3‰ and-41.6‰. All above show the metallogenic elements were mostly derived from the Himalayanian magma and less from adjacent rocks. The δD and δ¹⁸O_H2O are-151‰ to-166‰ and 9.4‰ to 12.3‰，respectively, which show the ore-forming fluid was the mixed solution of postmagmatic hydrothermal and underground water.To sum up, Shalagang antimony deposit, which is an epithermal type,formed in Miocene and was related to the formation of the southern Tibet detachment system. The metallogenic elements are mostly derived from Himalayanian gabbroic magma, and less from the adjacent rocks. The water in the metallogenic fluid is derived from Himalayanian postmagmatic solution and underground water.

The Metallogenic Epoch and Source of Ore-forming Materials of the Xiaodonggou Porphyry Molybdenum Deposit, Inner Mongolia

QIN Feng, LIU Jian-ming, ZENG Qing-dong, ZHANG Rui-bin

2008, 22(2): 173-180.

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The Xiaodonggou porphyry Mo deposit is located in the southern part of Da Hinggan Mountains, with a distance of 25 km from the Xarmoron River huge fault northward.The Sr-Nd isotope and Pb isotope analyses of the Xiaodonggou intrusion show that the value of ⁸⁷Sr/⁸⁶Sr(t) ranges from 0.705,0 to 0.705,5, and εNd（t） ranges from-2.4 to -2.8.Re-Os isotopic age dating for six molybdenite sampled from the major orebody gives an isochron age of (138.1±2.8) Ma, indicating that this deposit formed in the early Cretaceous.Pb isotope analyses results show that the rock and ore-forming materials of the Xiaodonggou porphyry molybdenum deposit are from different sources.The rock-forming materials are from juvenile crust materials originating from subducted oceanic crust, while the ore-forming materials are from mantle fluid.Considering the tectonic history of this area, we explain the origin of the Xiaodonggou porphyry Mo deposit as following: as the Da Hinggan Mountains began to raise in the early Cretaceous, delamination of the lithosphere, upwelling of the materials from the asthernosphere, underplating of basic magmas and mantle fluid led the lower crust rocks melting, following with more mantle fluid entering the magma room.Carrying the mantle fluid,magma uplifted along the EW, NE huge fault and evolved into granite rich in silicate and potash,then invaded into the Permian strata and finally precipitated into Mo deposit.

Geology and Geochemistry of the Kangding-Luding Metamorphosed Intrusions and Implication for Tectonic Setting

LI Zhi-hong，LUO Zhao-hua，CHEN Yue-long2，ZHAO Jun-xiang

2008, 22(2): 181-189.

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The Kangding-Luding metamorphosed intrusions are distributed in northwestern margin of the Yangtze block. On the basis of the field geological characteristics, petrography, mineralogy and geochemistry, we demonstrate that rock types include gabbro, quartzdiorite, tonalite, granodiorite, adamellite, syenogranite, in which intermediate acid rocks are majority; The rocks are dominantly moderate-K calc-alkaline series; Components of plagioclase include albite, oligoclase and andesine, hornblende and biotite exist extensively; The intrusions have calc-alkaline differential trend in major element compositions. Their trace elements show typical geochemical characteristics of island arc setting; REE patterns are of slightly rightinclined type; On the diagram of tectonic settings, they are mainly located at the range of VAG. Above mentioned characteristics suggest that the Kangding-Luding metamorphosed intrusions were formed at the magmatic arc setting.

SHRIMP U-Pb Ages of Zircon in the Gneiss of Erqisi Tectonic Belt in Altay, Xinjiang, and Their Geological Significances

LIU Guo-ren, QIN Ji-hua, ZHAO Zhong-he, XUE Hong-mei,ZHANG Li-wu, HE Li-xin

2008, 22(2): 190-196.

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It is a long debate on the age of the middle- and high-metamorphic rocks of Erqisi tectonic belt in Altay,Xinjiang.The middle- and high-metamorphic rocks have been regarded as the Kemuqi Group, Lower- and Middle-Proterozoic erathem, and the Fuyun Group, Upper-Proterozoic, yet other research disagree.The age of the gneiss in Erqisi tectonic belt especially follows much interesting.According to the studies of the petrography, major- and trace-element chemistry, and zircon SHRIMP U-Pb ages of the gneiss in this paper, we suggest that the gneiss is similar to diorite and/or quartzdiorite in chemical compositions, and should be ortho-gneiss and the magma products in post-collision.Zircon U-Pb ages range from 350 Ma to 295 Ma, and ten spots yield a concordant mean U-Pb age of(326±6)Ma, indicating that they are Carboniferous intrusions.Furthermore, no Precambrian zircon has been documented in our measurements, which strongly argue against that the gneiss in Erqisi is Precambrian.Combining previous studies and our own data, we suggest that the middle- and high- metamorphic rocks in Altay could be of different ages.

Genesis and Geologic Significance of Late Triassic Monzonitic Granite in Jinshantun,the Southeast of Xiao Hinggan Mountains

HAN Zhen-zhe,ZHAO Hai-ling,SU Shi-jie,LANG Hai-tao,YU Rong-wen,YIN Zhi-gang

2008, 22(2): 197-206.

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Late Triassic porphyritic-like monzonitic granite association,nearly northern and southern trend, are widely distributed in the area of Jinshantun,the southeast of Xiao Hinggan Mountains.Dark microgranular dioritic enclaves and medium-basic dikites swarm are wide-spreadly distributed in these rocks.Through the study of the macroscopic and microscopic feature and geochemistry of mediumbasic dikites,the pluton and its enclaves, the enclaves mainly present perfectly round shape,displaying the feature of apparently plastic flow,having representative magma structure, acicular apatite and containing K-feldspar,quartz megacryst of host rock, having apparent characteristic of magma mingling genesis enclaves.Medium-basic dikites swarm of the pluton have diversified shapes, and they present mini wave-like or flat contact with granite,show feldspar phenocryst of host rock, display synhypomagmatic dyke swarm that is formed by crustmantle magmatic mixing.The above study suggest that Late Triassic monzonitic granite have obvious genetic feature of magma mingling,and their formation are probably in connection with underplating of basic magma, under the mechanism of postcollisional extensional dynamics.

Cenozoic Lithosphere Tectonic Detachments, Magmatism and Earthquake in Eastern China

WANG Ya-mei, WAN Tian-feng

2008, 22(2): 207-229.

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It is a suitable method to roughly determine partial detachment in lithosphere or at the bottom of lithosphere, used by data of magmatic source depth at strong magmatism areas in eastern China.In the North Sinian stage（Eocene-Oligocene）, partial tectonic detachments mainly occurred at the intersection among the bottom of lithosphere and pre-existing NW or N-E and NNE striking lithospheric faults.In the Himalayan stage（Miocene-Early Pleistocene）, detachments widely occurred at the intersection among the bottom of lithosphere and three NE and NNE trending lithospheric faults（Taihangshan, Tan-Lu and southeast coastal of China）.In the Neotectonic stage（since Middle Pleistocene） according to the seismic data, detachments mainly occurred near Moho discontinuity and intermediate crust, with sheety-like, but not in south China.The recent gravity gradient zone is the division line between continental and oceanic lithosphere mantle, also indicates the division of the strong and weak area of magmatism, migrating eastwards at most about 200 km, compared with that from Cretaceous to present.Therefore, the authors suggested that tectonic detachment was occurred by main brench faults, and the type, characteristics and distribution of magmatic rocks and earthquakes were controlled by the detachments, occurred at the intersection area of the faults and different tectono-spheres in the lithosphere.Neither mantle plume nor hot magma uplifting widely existed, and no large-scale extension-thinning process occurred in eastern China lithosphere during Cenozoic.

Tectonic Evolvement Function to Oil and Gas Pool's Reformation in Xuanhan-Daxian Area, Northeastern Sichuan Basin

TANG Da-qing,WANG Li-jun,ZENG Tao,FENG Xing-lei

2008, 22(2): 230-238.

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Xuanhan-Daxian area in northeastern Sichuan basin is one of the most important areas for the petroleum exploration in south China, it has been investigated for many years,and in 2003 it has been proved to be a new area which has plentiful petroleum resource by the well Puguang 1.Based on detailed interpretation of about 500 km2 of three-demension seismic data and tectonic characteristics in northeastern Sichuan basin, according to the structure evolution profile and the similar features of two typical reservoirs of Puguang and Maobachang, the formation and stack of the structure styles in different stages and different stress fields have been studied, Puguang and Maobachang structural traps have their early prototype in later Indosinian Movement epoch, forming in later Yanshanian Movement epoch, being reconstructed in Himalayan Movement epoch. The reconstruction of Himalayan Movement to early carbonate rock reservoirs has been analyzed, especially the reforming function of the evolution of fault and fold system. The research shows that the Himalayan Movement has played a great important role in the structural geometry, tectonic evolution characteristics, fault system and reservoir-cap rock conditions of the carbonate rock reservoirs such as Puguang and Maobachang in Xuanhan-Daxian area.

Analysis on Forming Conditions of Lithologic Trap in Liushagang Formation, Weixinan Depression of BBW Basin

LIU Zhen, TAN Zhuo, CAI Dong-sheng, LIU Ming-quan, FU Dong-yang

2008, 22(2): 239-246.

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Weixinan Depression is a typical dustpan-like rift in BBW Basin, which has experienced three tectonic movements in Paleogene, displays polycyclic sedimentary characteristics, develops several sets of source-reservoir-cap rock associations. According to the analysis on Paleogene stratigraphic framework using sequence stratigraphy, sequences in the second section of Liushagang Formation and in lower and upper sequences of the first section of Liushagang Formation are the main sequences in which lithologic traps were developed. The development and formation of lithologic traps were strictly controlled by different system tract types in third order sequences of Paleogene. The detailed performances are: lithologic traps mainly developed in lowstand system tract and lacustrine transgressive system tract of sequence in the second section of Liushagang Formation, in lowstand system tract of lower sequences in the first section of Liushagang Formation and in highstand system tract of upper sequences in the first section of Liushagang Formation. Abundant sedimentary system types resulted from multisource filling were important to the formation of various lithologic traps. Nearshore underwater fan lithologic trap, fan delta lithologic trap which developed in steep slope belt, turbidite channel lithologic trap in gentle slope belt and sublacustrine fan lithologic trap which developed in sag belt are favorable targets.

Play Analysis and Profitable Exploration Area Evaluation of Lower Sandstone Section of Silurian in Tarim Basin

ZENG Qing-bo，FAN Tai-liang ，LIU Cong，LI De-quan，QU Ying-jie

2008, 22(2): 247-254.

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The long exploration history has proved that Silurian system of Tarim Basin, with good reservoirseal grouping and affluent oil and gas sources, provides a bright prospect for future exploration. Guided by the theory of play and combined with the exploration practice of Tarim Basin, the lower sandstone section of Silurian is divided into three plays, which include Tazhong, Tadong and Tahe areas. The marginal probability method is also introduced into the comprehensive analysis on the secondary plays in each play. The results show that the values of marginal probabilities of the secondary plays in Tazhong area where the reservoirseal grouping and the traps are well developed, are high enough to be ranked as the Ⅰ—Ⅱ level area of profitable exploration. As for Tadong and Tahe areas, the traps developed well, but the conditions of reservoirseal grouping are not good,and the marginal probabilities of the secondary plays are relatively low, so the secondary plays can be classified as the Ⅱ—Ⅲ level profitable exploration area.

Study on Sequence Stratigraphy in Clastic Rocks and Volcanics Mixing Accumulated Formation—Taking Jiamuhe Formation in the Northwestern Margin of the Junggar Basin as An Example

ZHU Yan-he ，YAN Yao-min ，WANG Ying-min ，ER Chuang ，LI Yang-yang

2008, 22(2): 255-264.

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The foreland thrust belt in northwestern margin of the Junggar Basin is a significant region to research basinrange coupling and development of sedimentary system of western area of Junggar Basin. Jiamuhe Formation in Permian is mixing accumulated formation which contains volcanics, volcanoclastic and clastic rocks. Volcanics stratigraphic unit and clastic rock stratigraphic unit have the generalized origin relation, which are Smith formation and with cycles. According to the difference of lithologic character, there are clastic rock area, volcanics and clastic rock mixed area and volcanics area. In different areas, we apply different ways to find some types of unconformity surfaces generated by tectogenesis, volcanic activity or fluctuation of lakelevel and used as sequence boundaries. In clastic rocks area, unconformity surfaces in seismic profiles are represented as a truncation, a baselap, a bidirectional downlap, a toplap or an incised valley; In the mixed area, a truncation belt; while in the volcanics area, a truncation formed by relatively falling of lakelevel. So we can identify different unconformity surfaces by seismic, drilling and log data, and then divide sequences in different sedimentary environments by correlation rules based on volcanic eruption types, volcanic cycle features and sedimentary cycle features.

Source Analysis of Oils from the Ordovician in the Shoal Zone, Nanpu Sag, Bohai Bay Basin

ZHAO Yan-de, LIU Luo-fu, ZHANG Zhi-huan, WANG Xu-dong，MEI Ling, LI Yan，CHen lei

2008, 22(2): 264-272.

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The Ordovician Formation is the main oil reservoir of deep strata in the Nanpu oilfield in the northern Huanghua depression, Bohai Bay basin.At present, there are some different points of views about the distribution of the source rocks contributing to this reservoir.The geochemical characteristics of saturated hydrocarbons and carbon isotopes in source rocks, crude oils and extracts in some sandstones from oilbearing strata in the regional interest areas have been investigated in this paper.The contribution of source rocks in the first and third members of Shahejie Formation to petroleum accumulation in the reservoirs of the Ordovician Formation, Dongying Formation in the region has been discussed too.The results show that the crude oils in the reservoir of the Ordovician Formation mainly derived from the source rocks in the third member of Shahejie Formation.

REE Geochemical Characteristics and Their Geological Signification in Silurian,West of Hunan Province and North of Guizhou Province

LI Shuang-jian, XIAO Kai-hua, WO Yu-jin, LONG Sheng-xiang, CAI Li-guo

2008, 22(2): 273-280.

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The sediments of Silurian in South China are main detrital rocks, which were formed at the end of Caledonian. A set of high quality source rocks developed at the bottom of Silurian. It has an important signification to reveal the palaeoenvironment and tectonic setting for this sequence. The systemic analysis of geochemistry indicates that the amount of REE of Silurian in West of Hunan Province and North of Guizhou Province is high. The ratios of LREE/HREE and LaN/YbN show that the differentiation of LREE and HREE is obvious. The REE distribution patterns are characterized by rich in LREE and obviously negative Eu abnormity. The Ce_anom can be used to reveal redox of palaeo-ocean. The reduction in Early Silurian is strong with high Ce_anom, which is advantageous for organic preservation and the formation of good quality source rocks. The differential degree of REE can also be used to reflect the sedimentary rates. The Lan/Ybn values decrease gradually from bottom to top in Silurian. The sedimentary rate at the bottom of Silurian is lower than that of upper sequence, so it is more favorable for organic accumulation and preservation. According to the characteristics of REE and their ratios, combined with achievements in palaeogeography, it can be drawn that provenance of the study area comes from Xuefeng and Qianzhong palaeouplifts, and the source rocks are granites and sedimentary rocks.

Satellite Monitoring for 2004-06-22 Landslide in the Pali River,Tibet

WANG Zhi-hua，XU Qi-de

2008, 22(2): 281-287.

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2004-06-22 Landslide is located at the middle part of the Pali River Basin which is in the western end of Tibet,China, and is near the China-India boundary. Taking multi-temporal high resolution satellite data as the RS information and DEM derived from Orbview as the geographical control,digital landslide technique has been adopted to study and monitor 2004-06-22 Landslide activities. Satellite image interpretation reveals that before landslide occurred the part of slope had already been the dangerous rocks before sliding,surrounding by fractures and nearly separating with slope, 2004-06-22 Landslide is considered as a high-speed slide activity of bedrock bedding, which is calculated as 63.7×104 m3 in volume by the use of RS+GIS.Satellite monitoring shows that each part of the landslide has not changed during 35 months from Sep.,2004 to Jul.,2007, and there is no any new landslide activity occurring during this period. 2004-06-22 Landslide is a natural gravity erosion process in the high mountain narrow canyon and intensive recent tectonic activity area, it has fully released energy, so apart from some unloading and adjusting activities surrounding the landslide， other landslides would not occur nowadays.

Activity of JianshanziKalun Fault in Changchun City

SHENG Jian, BO Jing-shan, NAI Lei , ZHANG Yu

2008, 22(2): 288-293.

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JianshanziKalun fault is an important fault which runs through the Changchun City. Former study on this fault was just based on physiognomy and hydrogeological data. The location, extending direction, orientation and activity of JianshanziKalun fault was acquired by remote sensing technique,electrical method, shallow seismic exploration, ground penetrating radar and united boring hole section. The result of investigation revealed that JianshanziKalun fault had been inactive since MiddlePleistocene epoch.

Study on Identification of Altered Wall-rock in Areas of DifferentVegetation Coverages Based on Remote Sensing

SHEN Li-xia，LIU Li-ping，SU Xin-xu，ZHU Yan，ZHAO Fang

2008, 22(2): 293-298.

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Compared with other geological information, alteration is usually weak information, and because of the interference of the vegetation and coverage, the extraction of the alteration information by remote sensing is very difficult. In order to know how to get detail information about alteration in areas of different vegetation coverages through remote sensing, this paper chooses three areas to extract the alteration information, which are the exposed base rock area in the desert of east Inner Mongolia （Wengen District）, mid-coverage plain area in the middle-north Inner Mongolia （Dalaimiao District）,and high coverage forest and plain area in the northeast Inner Mongolia （Pogelu Mountain Area）. Based on the study of the method for extraction of alteration anomalies from the TM data, we can conclude that （1） in the exposed base rock area, band ratio process and principal component analysis are better in extraction of the alteration information; （2） in the mid-vegetation plain area, it is better to firstly pre-process by masking, and then use principal component analysis; （3） and in the high vegetation coverage forest and plain area, the alteration information can be partly extracted by the methods of de-vegetation, masking and ratio-principal component. This paper made some contributions for the alteration information extraction in areas of different vegetation coverages by remote sensing techniques.

Accuracy Verification of Evapotranspiration Result Using Hydrological Budget Method—A Case Study of the Zhangye Basin

JIN Xiao-mei, WAN Li, LIANG Ji-yun

2008, 22(2): 299-303.

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Among many methods of evapotranspiration （ET） estimation, surface energy balance system （SEBS） is one of the widely used methods in recent years. Based on the land surface energy balance theory, SEBS is applied to estimate land surface turbulent flux and the relative evapotranspiration at different scales using visible light,near and far infrared satellite remote sensing data, the insitu meteorological data or the product of atmospheric numerical model.Combining with hydrological data and remote sensing data, this paper estimated the regional evapotranspiration of the Zhangye basin using SEBS, and verified the accuracy of evapotranspiration result based on the principle of hydrological budget. The result indicates that the evapotranspiration by SEBS is consistent with that by hydrological budget method, which verified the accuracy of SEBS in basin evapotranspiration estimation.

Characteristics and Ecological Risk of Heavy Metals in Overlying Water,Suspended Particles and Bed Mud in the Inner Mongolia Stretch of the Yellow River

ZHAO Suozhi，LIU Li-ping，WANG Xi-kuan，LI Shi-bao，ZHU Suo, ZHENG Ping, ZHANG Qing，

2008, 22(2): 304-312.

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Samples of overlying water, suspended particles and bed mud in the Inner Mongolia stretch of the Yellow River were collected systemically and their heavy metal element contents were analysed. Using methods of geo-accumulation and the potential ecological index,the heavy metal concentration, contamination degree and ecological risk of overlying water, suspended particles and bed mud along the Yellow River were studied. The results indicate that concentrations of the suspended particles are generally higher than those of the bed mud except As concentration. The results by geo-accumulation index method show that suspended particles and bed mud are in the state of no-pollution to mid-pollution, and suspended particles are polluted more seriously than the bed mud. The results by potential ecological index method indicate that heavy metal ecological hazard of bed mud and suspended particles are in a state of light-pollution. The evaluation results of the geo-accumulation index method and the potential ecological index method are almost identical.

Removal of Volatile Chlorinated Hydrocarbons in Water by Supported Nanoscale Pd/Fe Particles

SHANG Hai-tao,LI Zhi-ling, YANG Qi, XI Hong-bo, HAO Chun-bo

2008, 22(2): 313-320.

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Control of chlorinated hydrocarbons pollution has gradually become the top research field in modern world. In order to investigate the removal ability of chlorinated hydrocarbons, the most widely existent pollutants, dichloroethylene（1.1-DCE） and Lidane（γ-HCH）were chosen as the aim pollutants,and the synthetical supported nanoscale Pd/Fe were chosen as the reaction medium. The supported Pd/ Fe bimetallic catalysts were made by the procedures of impregnation, liquid reduction, and reductive precipitation. The grain size of palladium and iron are at the nanoscale by the transmission electron microscope. The Fe/ Pd systems proved to be very effective, and the removal rate of 1.1-DCE and γ-HCH in 2 hours respectively reached about 85% and 100%. The removal of 1.1-DCE and γ-HCH in water by the supported Pd/Fe bimetallic catalysts follows the pseudofrist order kinetics with the halflife t1/2 of 1.31 h and 0.34 h. The amount of Pd/ Fe, Pd/ Fe ratio, pH and reaction temperatures are the most important factors that affect the removal efficiency and there is little relationship with the initial concentration. During the reactions, H₂，coming from eroded Fe，may be the main reducer. Pd is a good hydrogenation catalyst and it formed a high concentration reaction phase in the surface of Pd/Fe-Al₂O₃particles which accelerated the reaction rate.

Effect of Groundwater on Vegetation Growth in Yinchuan Plain

SUN Xian-chun, JIN Xiao-mei，WAN Li

2008, 22(2): 321-324.

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Vegetation is one of the important indices to reflect the status of regional eco-environment， and the groundwater has significant impact on vegetation growth. Located in arid northwestern area, Yinchuan plain is the important industrial and agricultural base in Yellow River basin, and its condition of natural ecoenvironment is typical in northwest China. Combined with MODIS-NDVI and groundwater monitoring data, this paper studied the relation between groundwater and vegetation in Yinchuan plain from large scale. The relation curve between depth of groundwater and NDVI change rate was fitted based on least square method. The impact of groundwater on vegetation growth was analyzed quantitatively and the suitable depth of groundwater for the vegetation growth was discussed in this study. The result indicated that the vegetation growth is best as the depth of groundwater is 3 m, the suitable range of depth of groundwater for the vegetation growth is between 1 and 5 m. The impact of groundwater depth on vegetation is gradually weak if the depth of groundwater is larger than 5 m and the impact is zero if the groundwater depth is larger than 8 m.

Distribution Characteristics of Extractable Organic Matter in Atmospheric PM₁₀ in Beijing

DONG Xue-ling，LIU Da-meng，YUAN Yang-sen，CHE Rui-jun

2008, 22(2): 325-332.

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PM₁₀ is one of the most important forms of air pollution, and its harmful organic compounds can be absorbed into the human body to result in different diseases, and to impact the human living environment.In the PM10 samples collected in different function zones of Beijing during four seasons of 2005, the extractable organic matter（EOM） was obtained by ultrasonic extraction and separated into saturated hydrocarbon, aromatics, non-hydrocarbons and asphaltenes, the content and distribution of EOM show that the annual average concentration of organic compounds in PM10 was 41.39 μg/m3, being 1.4 times higher than that in cleanliness district Ming Tombs site.The organic pollution level in winter was the most serious,the mass concentration of organic compound in PM10 was 6704 μg/m3, which was 1.2, 2.1 and 4.5 times higher than that in spring, autumn and summer, respectively.The concentration order of organic compositions is non-hydrocarbons,asphaltenes,aromatics and saturated hydrocarbon, indicating that organic pollution of Beijing city mainly results from coal-burning.The concentration of EOM was various in different function zones, presenting industrial or commercial zones>living or traffic zones>cleanliness zone, but during four seasons the variety of EOM was different. The contribution of pollution sources to different percentages of EOM depended on different function zones.

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