Table of Content

20 March 2007, Volume 21 Issue 3

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Engineering Geology and Environmental Geology

U-Pb Isotopic Dating of Zircons from Porphyry Granite of the Fenghuoshan Mts., Northern Tibetan Plateau and Its Geological Significance

WU Zhen-han, YE Pei-sheng, HU Dao-gong, ZHANG Wei, ZHOU Chun-jing

2007, 21(3):  435-442. 

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Porphyry granites were genetically related to regional thrusting in the Fenghuoshan Mts., northern Tibetan Plateau. Both the granite emplacement and thrusting occurred in Oligocene, a key period of regional tectonic evolution according to field geological data. The porphyry granite and dark xenolith within the granite were sampled in northern Fenghuoshan Mts., and minerals of the samples were identified in detail by using microscope. SHRIMP U-Pb isotopic dating of zoned zircons from magmatic crystallization of the samples gives two groups of ages. Mean age of one group of U-Pb isotopic ages is (34.5±1.4)Ma, representing time of partial melting of the crust and formation of granitic magma. Mean age of another group of U-Pb isotopic ages is (27.6±0.5)Ma, representing time of granitic magma emplacement into the Yaxicuo group. Porphyry granite intruded in 27.6 Ma in northern Fenghuoshan Mts. belongs to the youngest granite complex outcropped in north Tibetan Plateau. U-Pb isotopic dating of the porphyry granite and its xenolith provides important time constrains for Cenozoic stratigraphic system, regional thrusting and plateau uplift.

The Discovery of Shoshonitic Magma Rocks in the Wucun Area in Zhejiang Province and Its Ore-seeking Significance

LU Cheng-zhong

2007, 21(3):  443-450. 

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Field geological, petrological and elementary geochemical studies reveal that the volcanic rocks, subvolcanic rocks and Muchen pluton of Xishantou Formation in the Wucun area in Zhejiang Province, which were formerly identified as calcicolous alkaline series rocks, should be typical shoshonitic rocks. These rocks are rich in alkali(Na₂O+K₂O=7.80％-11.48％) and kalium(K₂O/Na₂O=1.10-1.67), and poor in titanium(TiO₂=0.22％-0.88％) and ferrum(FeO+Fe₂O₃=2.91％-6.36％), also they have a relatively high content of aluminum (15.39％-18.24％), a moderate content of SiO₂ (56.96％-69.02％), and high ratios of Ce/Yb (27.29-38.19), Ta/Yb(0.32-0.74) and Th/Yb (4.76-7.72). Besides, they abound in macroion lithopile element and light rare earth element. All these are petrological geochemical features of shoshonitic rock series. The Wucun area is rich in mineral resources, its mineral deposit symbioses closely with shoshonitic magma rocks both in time and in space, and the shoshonitic magma rocks are its rock-forming matrix. These are important signs for ore-seeking petrology.

The Discovery and Geological Significance of an Early Paleozoic Ophiolite Mélange Belt in the Huoshishan Part of Beishan Mountain, Gansu Province, China

WANG Li-she , YANG Jian-guo, XIE Chun-lin, WANG Yu-xi

2007, 21(3):  451-456. 

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This paper aims to introduce the strange ophiolite mélange of the Huoshishan area of Beishan Mountains.The authors discovered the ophiolite mélange in the fieldwork in 2006,which are composed of exotic blocks and schiefers such as serpentinization peridotite schiefers,pyroxenite schiefers,basalt schiefers,siliceous-rocks and matrix.The matrix is located in Gongpoquan Group,which is made up of lots of metamorphic tuffaceous sandstones,little andesite and carbonate.Most of exotic blocks and matrix have metamorphosed.The Huoshishan ophiolite mélange occurs between the Hongliuhe and Niujuanzi ophiolite mélange,and the petrochemical and geochemical characteristics are similar to that of Honliuhe.Consequently,this research indicates that Huoshishan ophiolite mélange perhaps belong to Hongliuhe-Niujuanzi ophiolite mélange belt.The discovery of ophiolite mélange is important for study of the Paleozoic tectonic background of Beishan area.

Application of Mineral Paragenesis Analysis to the Research of Very Low-grade Metamorphism: Taking Well Hongcan No.1 in Songpan-Aba Area as an Example

TANG Yan, SANG Long-kang, LIU Rong, YU Ji-shun, YUAN Yan-ming

2007, 21(3):  457-461. 

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Illite crystallinity has been used as a primary index for subdividing very low-grade metamorphic zone since 1967 after Kübler who measured illite crystallinity by use of XRD and subdivided very low-grade metamorphic zone according to illite crystallinity first. However, Kübler indexes which are used to subdivide metamorphic grade are various among geologists. Therefore a combined research with petrology study is needed in order to solve such dispute. This paper attempts to apply the conventional method of mineral paragenesis analysis to the metapelites in Well Hong-can No.1 in Songpan-Aba area within a depth of  5,975 meters. The result reveals that these rocks have undergone high anchimetamorphism. Stilpnomelane, which is believed as an indicator mineral for anchimetamorphism in metapelite, cannot occur because of the limitation of bulk composition. However, they didn't reach epimetamorphism yet, the preservation of combination gas is still possible. Comparing with petrological evidences, we found the illite crystallinity index scheme proposed by Kisch(1990) is comparatively accorded with the true situation of this area. It is believed that applying mineral paragenesis analysis in the research on very low-grade metamorphism is crucial to solve such index dispute, and moreover, it is very useful for guiding thin section observation and the X-ray diffraction phase analysis.

Ichnofossils from the Middle Jurassic Mali Formation in Biru County, Northern Tibet, and Their Environmental Significance

WANG Qing-shan, WANG Gen-hou, LI Shang-lin, MA Bo-yong, YANG Xiao-gang

2007, 21(3):  462-468. 

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The paper describes eight ichnospecies from the Middle Jurassic Mali Formation in Biru County, northern Tibet: Beaconites biruensis ichnosp. nov. is characterized by non-divarication aclinic burrow with slick, thinner pipe wall and crescent back-packing structure, Bifungites cf. hanyangesis Yang is characterized by dumbbell-shape burrow on bedding surface, Biruichnus maliensis ichnogen. et ichnosp. nov. is characterized by burrow with columned thick wall divarication showing reticulation, Cruziana ichnosp is long and narrow ichnofossils showing two leaf-shaped, Micatuba cf. verso Chamberlain is more divarication burrow  system formed into upright pipe with many actinomorphic and different diameters, Palaeophycus ichnosp.is crooked or slight cylindrical burrow paralleling bedding surface, Treptichnus cf. bifurcus Miller is three-dimensional burrow system showing flexuous and saw-shape, Rhizocorallium ichnosp is simple U-shaped burrow paralleling or showing small angle with bedding surface, web-shaped structure. Middle Jurassic Mali Formation from Biru County, Tibet  contains a variety of lenticular bedding, wave bedding and vein bedding which all called tidal bedding, also  can be seen erosion structure, main lithology of the upside is aubergine coarse sand and arkose which belong to littoral sedimentation. The ichnofossils from the Mali Formation have predominance of shallow repichina and pascichnia, also can be seen feeding burrow and crawling mark, besides, the position from ichnofossils can be seen small interference ripple,the makers of the trace fossils lived in the shore environment with low to middle energy.

Trace Fossils from the Lower Member and the Lower Upper Member of the Ediacaran Doushantuo Formation at Weng'an, Guizhou, China

WANG Yue，XU Yi-fan

2007, 21(3):  469-478. 

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The Weng'an biota, a well-preserved phosphatized fossil Lagerstatten, from the Upper Member of the Neoproterozoic Ediacaran Doushantuo Formation at Weng'an County, Guizhou Province (E107°23′03″, N27°00′56″), including various multicellular organisms, has been attached to the study of early metazoan and embryos of metazoan. In the horizon of the lower of the Weng'an biota yielded and under it, three trace fossils are found: Wenganichnus nanbaoensis(ichnogen.et ichnosp.nov.), a slight curving tube with liner and lunate backfill-structure; Doushantuoichnus curvatus(ichnogen.et ichnosp.nov.), an epichnion bearing a central groove with small across ridges and some leafshaped bulges on the both sides of the central groove; ?Planolites ichnosp., a long linear-form ichnofossil wandering on the bedding surface and differing from the host rock. The characteristics of the trace fossils show they are produced by animal, no sedimentary structures. Their makers may be bilateral symmetric worm-form animals that could have fore/hind and dorsal/ventral differentiation and could be ability to move along an orientation. The egg and embryo fossils from the Weng'an biota may be oviposited by soft-body metazoan that is uneasily preserved. The eggs and embryos, in shallow-water with a high-energy environment, were conveyed and deposited in seafloor together with sediments, and then the dormant eggs and embryos buried in sediments are preserved.

Evolution of Brachiopod Diversity of the Late Middle Permian in the Hechuan Area of Chongqing

ZENG Yong, ZHANG Xin

2007, 21(3):  479-483. 

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Analysis of the evolution of species diversity based on brachiopod fossils of the Maokou Formation strata in the Hechuan area in Chongqing city indicates that the Lopingian Epoch incident in this region occurrs in the Late Permian. According to the integrated index of brachiopod species diversity  and the brachiopods evolutionary process, this paper concludes that the Lopingian Epoch incident in this region is composed of two phases. In the first phase， genus extinction rate was 42.9% and the species extinction rate was 60%. Rates of the second phase were 42.9% and 66.7% respectively. Before the both extinctions, two courses of expansion in species diversity occurred, and the coming probability of new species in the first course was 75%. Probability of new species in the second course was 77.8%. Whether the species were extinct or radiant, the rate of the second was higher than that of the first time.

Microbiostratigraphy and Paleoclimate Change from Upper Qingshankou to Lower Yaojia Formations in Well Xu-22 of Daqing Oilfield

CUI Ying，XI Dang-peng，WAN Xiao-qiao

2007, 21(3):  484-490. 

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Detailed sample collections and descriptions have been made from upper Qingshankou to lower Yaojia formations in well Xu-22 of Daqing Oilfield. The thickness of collected well core is 12.20 m. Careful identification and analysis on sporopollen and ostracods fossils have been carried out. Microbiota from the upper part of Qingshankou Formation refers to a deepwater and disoxidation environment. There are large amount of ostracods and other biota. The sporopollen Cythidites is dominant. This shows a relatively warm and moist climate. The color of upper layers turns light, the granularity turns large and the fossil abundance reduces rapidly. This shows the lake became shallower, the climate was drier and heater, and the creatures were suffered by disaster. At the boundary of 1,612.90 m, ostracods completely vanished, and the sporopollen number decreased. Sediments in upper layers become coarse and red. This shows that the lake was shallow, maybe in a delta-silted phase. The climate became more and more dry and heat, and fluctuated frequently, and fossils were rare. Generally, at the boundary, the climate turned to drier and heater from moist and warm conditions; the water became shallower and more fluctuant upwards; as a result, biota declined their abundance rapidly under the climate change.

Metamorphic Structural Sequence of Carboniferous and Its Underlying Strata in Kangmar Region of Southern Tibet

YU Tao，ZHOU Zhi-guang，LIU Chang-feng，LIANG Ding-yi

2007, 21(3):  491-497. 

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 The Kangmar region is located in the central southern Lhagoi Kangri tectonic belt of the Kangmar-Lhunze stratigraphic area. Large amount of work has been done  at the formation of Kangmar dome，but the sequence of Carboniferous and underlying strata is still obscure.  It causes the geological history of Lhagoi Kangri tectonic belt before Carboniferous being missing. Based on great deal of data on paleontology, stratigraphy, and rock assemblages obtained during the 1∶250,000 geological survey in Gyangze-Yadong region,   the present authors  restudied the Carboniferous and underneath strata in this region, and a new stratigraphic sequence has been set up.  It is in ascending order, the Ordovician Langba Group(POl), Ordovician Zeguo Group(Oz)and Lower Carboniferous Guzi Formation(C₁g). The Lower Carboniferous Guzi Formation(C₁g)is underlying unconformably the Early Permian Polinpu Formation(P₁p)by extensional unconformity contact, and overlying the Ordovician Zeguo Group(Oz)by a detachment fault.  Pre-Ordovician Langba Group(POl)contacts Ordovician Zeguo Group(Oz)by extensional unconformity, and separates the underlying Kangmar rock mass by a detachment fault.

The Late Cenozoic Activity of the Zhoucheng-Qingshui Fault Zone in Northwest Yunnan Region

HAN Shu-qin, CHEN Qing-lai, ZHANG Yong-shuang, SHI Lin

2007, 21(3):  498-504. 

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The northward convergence of India into Asia over the past 50 m.y. has led to the development and lateral extrusion of thickened crust. On the basis of velocity field constrained by GPS measurements, the Chuandian active crustal block adjusts the crustal lateral extrusion movement by clockwise rotation on a background of southeastward movement. The block exhibits a relatively homogenous movement at rates 19 mm/a and decreases to be 13-14 mm/a across the NE-striking faults such as Lijiang fault. The fact suggests that NE-striking faults have prevented the movement of active crustal block.Field observations collected recently show that the Zhoucheng-Qingshui fault zone, located in the interior of the Chuandian active crustal block, is an important component of the active tectonics. The fact that the early fault trace well preserved in riverine-lacustrine deposit and covered by the Xigeda Group deposited during the Pliocene suggests that the faulting onset in Early Pliocene. Many phenomena indicate the Zhoucheng-Qingshui fault zone is characterized by sinistral strike-slip faults with the component of normal or thrust along the fault zone striking NE45°during Quaternary. Age results of Thermoluminescence (TL) and Electronic Spin Resonance (ESR) indicate that the fault zone reactive during Mid-Pleistocene, and its activity has become weak since Late Pleistocene. The fault prevented southeastward movement of active crustal block. A long-term slip-rate of 0.1 mm/a of deformation on this fault, derived from the cumulative offset and Pliocene lacustrine deposit, is much slower than that of the Chuandian active crustal block, which suggests that the Zhoucheng-Qingshui fault zone isn't a significant factor in accommodating of the continued southward movement of the active crustal block.

Study on the Tectonic Events of East-Kunlun Orogenic Belt and  Prototype about West-South Qadam Basin during Mesozoic and Cenozoic

NI Jin-long, WANG Jin-cao, ZHOU Li, ZHAO Xiao-hua, LIU Dong, SONG Zhao-jun

2007, 21(3):  505-510. 

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There was much contention about the prototype of west-south Qadam basin because of its complex geology background. Based on the basin-range coupling theory, the tectonic geology events during Mesozoic and Cenozoic  were determined from the point that East Kunlun orogenic belt and westsouth Qadam basin were in a  common stress field, combining with versatile data and filed geology review. On the base of above named studies, the formation and reconstruction about the prototype of west-south Qadam were discussed .  The conclusions are as follows: Firstly, East Kunlun orogenic belt and west-south Qadam basin had suffered many periods of press and stretch events.  Among them, East Kunlun orogenic belt underwent perhaps postorogenic stretch during Lower and Middle Jurassic that might be the direct cause of the prototype of west-south Qadam basin during Mesozoic. Secondly, the pull-part geology background and the right-slip of Kunbei and Altun faults might be the main mechanism of prototype of Qadam basin during Cenozoic. Finally, the prototype basin was reconstructed by multi-episode press events during Mesozoic and Cenozoic.

Study on Marine-erosion Topography and Deposits in Xichong Bay,Shenzhen

TENG Jian-bin, SHEN Jian-wei, KEVIN Pedoja

2007, 21(3):  511-517. 

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 By field techniques of topographic surveys of Holocene beach and platform profiles in Xichong Bay，3 abrasion platforms including the presently eroding one are detected. According to the altimeter and tide tables, all altitudes are given in meters above mean sea level. The sand profile were divided into 6 layers and samples of seashells collected from the sand profile were performed 14C dating. Specimens of beachrock were examined using microscopy on thin sections. We conclude that although the rock of the platforms is granite which is hardly carved,the abrasion features,especially the platform, can be interpreted as an evidence of Holocene sea level. The altitudes of the beachrock and the platform represent that the mean sea level around 2,000 yr is at least 2.0 m higher than present mean sea level. We also point out a proposal on how to assess the eustatic sea-level movement and tectonic vertical motion of northern coast of South China Sea.

Characteristics of Relatively Earlier Formation of the Lithologic Oil Accumulation in Erlian Basin，Inner Mongolia

LIU Zhen, LIU Jun-bang, GAO Xian-zhi, XIN Hai-yan, XIAO Wei, XU Zhao-hui

2007, 21(3):  524-531. 

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Based on the hydrocarbon accumulation conditions of Erlian basin, integrated analyses including burial history, thermal history and characteristics of diagenetic fluid inclusions of oil reservoir in three main depressions are conducted, and in terms of quantitative analysis of homogenization temperature of fluid inclusions, the formation stages of the oil accumulations are determined. The results indicate that most of the lithologic oil accumulation of the three main depressions in Erlian basin eventually formed in Early to Mid Cretaceous, and compared with most structural oil accumulation in the basin the lithologic ones represent the characteristic of relatively earlier formation period. Early generation of lithologic traps coupled with early hydrocarbon charges make the early formation of oil accumulation possible. These two factors may also be the main elements for relatively earlier lithologic accumulation formation which is favorable for the forming of giant oil accumulations.

The Comparative Study on Organic Geochemical Characters of the Mesozoic Source Rocks in T₃y and J₂y of Zhenyuan in Ordos Basin

HAN Zong-yuan, MIAO Jian-yu, BU Zhan-qi

2007, 21(3):  532-537. 

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Depending on subsurface samples and test data, the authors use analytic methods of Rock-Eval, microscopic observation, organic elemental analysis, vitrinite reflectance and biomarkers comparatively to analyse the organic geochemical characters of the Mesozoic source rocks in T₃y and J₂y of Zhenyuan in Ordos Basin. The multidisciplinary analyses indicate that the source rocks of T₃y and J₂y have high organic content, high generating capability of liquid hydrocarbon. The kerogens of source rocks are mainly humic kerogen. Organic matters are now in the maturation period of hydrocarbon generation and have already come into the generative window. Organic matters of T₃y were accumulated and preserved in the reducing environment of lacustrine facies, and organic matters of J₂y in weak-reducing environment of shallow lacustrine and paludal facies. So source rocks of T₃y are much better than those of J₂y.

The Distribution Character and Development Model of Hydrocarbon Source Rocks of Lower Palaeozoic，the Eastern North China

CHENG Jin-xiang，JIAO Yang-quan，YAN Jia-xin，WU Li-qun，LING Hui-xi ，LIU Hua，

2007, 21(3):  538-545. 

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Researching the hydrocarbon source rocks of Lower Palaeozoic in North China is very important to the pre-Tertiary oil-gas strategic precinct. From the point of view of sedimentology，the type, quality evaluation, genesis and development model of hydrocarbon source rocks in the study area were analysed according to the statistics of parameters  TOC(%)，S₁+S₂ and bitumen “A”. The research shows: there are preferable hydrocarbon source rocks in the Lower-Majiagou Formation，the Upper-Majiagou Formation and the Fengfeng Formation of Ordovician, whose mean TOC values are 0.183％, 0.21％ and 0.181％ respectively; The high quality hydrocarbon source rocks develop in Lower Cambrian and distribute in the limited region, whose mean TOC value is 6.46% and max TOC value is 11.2%. According to the rock types, the hydrocarbon source rocks in North China can be divided into two series, the claystone type source rock in Lower-Cambrian and the carbonatite type source rock in Lower-Middle Ordovician. The genesis of hydrocarbon source rocks lies on sedimentary environment: claystone type source rock develops in the shallow-sea continental shelf and carbonatite type source rock is controlled by the tidal flat and restricted platform. The study of spatial distribution rule of hydrocarbon source rocks finds that Hefei basin is the potential developed region of claystone type source rock and Dongpu depression, Linqing depression and Jizhong depression are the ones of carbonatite type source rock. These results can provide a lot of effective geological information of the pre-Tertiary oil-gas strategic precinct in the eastern North China.

Quantificational Analysis of the Geologic Agent Affecting Gas Content of Coal Seam Unmined:Taking the 14^# Coal Seam of Xiaonan Coal Mine of Tiefa Basin  as An Example

ZHANG Zhen-wen, GAO Yong-li, DAI Feng-hong, LIU Guo-xing, FEI Xian-jun

2007, 21(3):  546-550. 

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The study of gas content and influencing factor of the coal seam unmined is an important fundamental research. We take the 14# coal seam of Xiaonan coal mine of Tiefa basin as an example and analyse the geologic agent systematically which influences the gas content. We make a study of each influencing factor, establish the gray connection model and calculate the degree of association of the influencing factors by using the gray connection method. The result indicates that the main geologic agent which influences the gas content of the 14^# coal seam of Xiaonan coal mine is the grade of coal metamorphism, the geologic structure, the coal seam thickness, and the depth of the coal seam. We also forecast the gas content by multiple regression. This study provides a scientific method about studying the gas content of the coal seam unmined and provides the basic data about the safe mining.

Expressions of Density Parameters of Biot Medium with Differential Density

NIU Bin-hua, SUN Sheng, SUN Chun-yan, HUANG Xin-wu, LI Jia

2007, 21(3):  551-555. 

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This paper involves a discussion about the expressions of density parameters of the Biot medium. Firstly, it gives the field equations of seismic wave propagation in the Biot medium. Secondly, it defines the differential density by the difference between two densities of the Biot medium under open-pore and close-pore conditions, and these densities are derived from the kinetic energy equations. This differential density emphasizes the average macroscopical state of porous media and avoids the details about the pore shape. Lastly, the expressions of density parameters of the Biot medium in terms of the differential density are presented in this paper. The discussion about these expressions that deepens the understanding of these densities especially points out that the negative feature of the coupling density is the result of the restriction between the negative feature of the kinetic energy and the equilibrium of inertial forces.

Paleomagnetism Characteristics of Triassic in Songpan-Aba Block and Its Kinematic Indication

HE Deng-fa，ZHUANG Zhong-hai，MA Yong-sheng

2007, 21(3):  556-563. 

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Up to now, no paleomagnetic data has been reported on the Bayankala folded belt, which is an upside-down triangle area located among the Yangze, North China, Tarim, and Qiangtang-Changdu blocks. The paleomagnetic study on Songpan-Aba continental block is to provide with quantitative data for its localization during geological history and to be a basis for oil and gas resources evaluation. The sampling spots are around the four micro-blocks such as the southern structural belt(Motianling area and Ruo'ergai area), and the central structural belt(Taohe area) of west Qinling structural zone , the Markang composite syncline belt of the Bayankala structural zone(Bayankala folded zone). The sampling is centered around the Triassic rocks. There are 57 sampling spots and 376 core samples in all. By the analysis and calculation of the measured data of the core samples, the paleomagnetic pole location for the Taohe, Bayankala, Motianling, and Ruo'ergai blocks(with the later two blocks located between the former two blocks)has been acquired. These micro-blocks are located at north latitude 49.5° to 58.5° and east longitude 191.4° to 202.9°. The paleo-latitude of the Taohe and the Bayankala micro-blocks in Late Triassic is the same as north 26.2°, which indicates that the four micro-blocks separated by the faults had combined to be a larger block in Late Triassic. The variation in the paleo-latitude during Triassic for the Taohe and the Bayankala micro-blocks shows the north 13.4° and north 11.3° of the two blocks respectively in Early Triassic have changed to the same north 26.2° in Late Triassic. Meanwhile, the two blocks have anticlockwise rotated approximately 40° and 16° respectively from Early Triassic to Late Triassic with their northward movement.

Study on Feasibility of Using Backscattering of Slowly Decaying High-frequency Electromagnetic Wave in Electromagnetic Method

ZHANG Rui ,WEI Wen-bo

2007, 21(3):  564-569. 

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Normal electromagnetic method usually uses low-frequency to explore, which has less resolving power to meet request. Slowly decaying wave is a kind of electromagnetic waves which use special function as their sources. They not only have the quality of slow decay,but also narrow beam and focused energy, which are widely used in military and communication. For these qualities, when they are used in geophysical exploration, the depth and resolution of investigation can be improved. This paper particularly focuses on the theory and implementation of how to inverse underground structure by comparing incident wave and scattering wave, and recording the spare time of the waves,and forward calculations for igneous,metamorphic and sedimentary rocks are carried out to verify the feasibility.

Transfer and Ecosystem Effects of Lead Contamination in Dabaoshan Mine Tailings, Northern Guangdong

FU Shan-ming,ZHOU Yong-zhang,ZHANG Cheng-bo,DING Jian,DOU Lei,ZHAO Yu-yuan

2007, 21(3):  570-577. 

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Mining activities have caused severe soil environment changes in Dabaoshan Mine, Guangdong, Southern China. The acid mine drainage and heavy metal ions drained directly into the Hengshihe river, which contaminated severely the ecological environment along the river. The tailings, soils, sludges, water and plants are regarded as whole ecosystem, the environmental responses of whole ecosystem to acid mine drainage and heavy metal ions are investigated. The lead in river water came from the tailings, and the lead concentration  isaffected distinctly by the pH value of water. River sludges can accumulate stably lead of water in high pH value water, but it should be released from the deposits when the pH value of water is low, forming the secondary contamination. The lead concentration in soils is affected by pH value and  granularity of soils. The high lead concentration in plants is related with the total lead in soils, and is affected by the pH value of soils, thus increasing soils’ pH value can reduce lead concentration in plants by improving irrigation water quality.

Numerical Simulation on Migration and Transformation of Nitrobenzene in Riverside Groundwater Field

ZHANG Wen-jing，LIN Xue-yu，SU Xiao-si

2007, 21(3):  578-583. 

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Based on simulated experiment research, this paper discusses the main rules and effect factors of nitrobenzene's transport and fate in riverside groundwater field. And based on the data of the simulated experiment, the numerical model of nitrobenzene's migration and transformation in riverside groundwater field has been built. The simulated result has indicated that the adsorption capability of nitrobenzene transporting in silt medium is better than that in sand medium. The adsorption coefficients of silt medium and sand medium are 0.526 cm³/g and 0.123 cm³/g respectively. Moreover, nitrobenzene's biodegradation rate constants of silt medium and sand medium  are 0.043 h^-1 and 0.002 h^-1 respectively. This study has indicated that the numerical simulated result of experiment is better, then it can be used in field simulation and forecast in the near further.

Reaction Mechanism of 13X Zeolite Crystallization with K-feldspar Powder as Raw Materials

ZHANG Xi-huan, MA Hong-wen,BAI Feng

2007, 21(3):  584-590. 

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The synthesis of 13X zeolite with K-feldspar powder as raw materials is characterized by XRD, SEM, IR, chemical analysis and Raman spectroscopy. The investigation discovers the inducement period, the crystal period of the crystallizing process and the average growth speed of 13X zeolite grains. The experimental results demonstrate that the reactive mixture is firstly transformed into aluminosilicate gels, and then the gels is transformed into 13X zeolite crystal grains while synthesizing 13X zeolite from the aluminosilicate precursor prepared by baking the K-feldspar powder. 13X zeolite has already appeared before the mixture all transforming into the aluminosilicate gels. The growth of 13X zeolite is mainly in the aluminosilicate gels, which is a process of putting the aluminosilicate gels structure in order while the liquid participates in the formation of 13X zeolite. [TO₄] tetrahedrons of the aluminosilicate gels connect each other to form the framework of 13X zeolite. A model for the formation of 13X zeolite is proposed, which involves that silicate ions and aluminate (or ferrite) ions polymerize to double six-membered rings, the secondary building unit, then the double sixmembered rings interconnecting to SOD cages, and then SOD cages further interconnecting to form the framework of 13X zeolite.