Geoscience

Microbial Mats from the Mesoproterozoic Carbonates of the North China Platform and Their Potential for Hydrocarbon-Generation

SHI Xiao-Ying ZHANG Chuan-Heng JIANG An-Qing LIU Juan WANG Yi LIU Dian-Bei

2008, 22(5): 669-682.

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In the region from Jixian County of Tianjin City to Xinglong County of Hebei Province in eastern Yanshan, the sedimentary structures which present the spindle-shaped crack on the surface are widely developed in the fine clastic strata of the of the Changcheng Group of the Mesoproterozoic, and they have been explained as the metazoan trace fossils or the seismic-induced liquefied veins etc. The structures always co-exists with the palimpsest ripples, the wrinkle structures,and so on. The preliminary studies indicate that the spindle-shaped cracks might be the products of degasing and dewatering of the sediments during early diagenesis, which are caused by the seal of overlying microbial mat, thus, they can be grouped into the category of the microbially induced primary sedimentary structures （the matground structures）. Spindle-shaped cracks and the other matground structures provide an important evidence to reconstruct the sedimentary environment of the Precambrian. These structures also illuminate the metabolism diversity and enormous biomass of microbes in the Precambrian on the earth surface, and thus form important marks in the sedimentary records.

Rb-Sr and Sm-Nd Isotopic Compositions of the Kangding Complexes and Their Significances

CHEN Yue-Long WANG Zhong LUO Zhao-Hua LI Da-Feng DIAO Dun-Xiang

2008, 22(5): 707-714.

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Through systematic measurement of Rb-Sr and Sm-Nd isotopic compositions in three sets of hornblende, biotite, plagioclase, K-feldspar separates extracted from tonalite，biotite-hornblende-plagioclase gneiss, and hornblende leptite and their correspond whole rocks in the Kangding-Mianning area, Sichuan Province,together with U-Pb ages of zircons in the rocks, the results indicate that their original crystallization ages of magmas cannot be ascertained by Rb-Sr and Sm-Nd isotopic systematics because of complicated history of formation and metamorphism. Fitted~700 Ma isochrones by Rb-Sr and Sm-Nd isotopic compositions of mineral separates and their whole rocks suggest metamorphism age of amphibolitesupperamphibolite facies. Because of partial resetting of Sm-Nd isotopic system during the processes, Sm-Nd isochrones give rise to older meaningless mixed age usually. The Kangding complexes had not experienced metamorphism of granulitic facies after magma crystallization. The lenticular granulitic bodies may be the relict products of metamorphosed oceanic crustal component after partial melting during subduction of newly formed oceanic crust underneath the Yangtze craton in Neoproterozoic period by the Rodinia super-continent’s break-off. The metamorphosed oceanic crustal rocks, previously underplating mafic rocks, and metamorphosed felsic basement rocks of the Yangtze craton began to partially melt when the subducted oceanic plate was broken off and up-welling of asthenospheric material. TTG(tonalite-trondjemite-granodiorite)association was formed by mixing of dominant(>70%)magma derived from partial melting of metamorphic mafic rocks with that from partial melting of metamorphic felsic basement rocks.

Nd Isotopic Compositions of Basement Rocks, Granitoids and Basalts from Middle-Eastern Inner Mongolia: Implication for the Regional Crustal Evolution

WANG Zhong LI Da-Feng LIU Jin-Bao CHEN Yue-Long HOU Jing-Xie LI Wei PI Jiao-Hui LIN Yu

2008, 22(5): 715-723.

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Twenty one samples，including basement rocks, granitoids and basalts from the west segment of the North China Craton and the Xing-Meng Orogen, Inner Mongolia were chosen to study their Nd isotopic compositions. Through the comparison of their Nd depleted mantle model ages, it is indicated that the Xing-Meng Orogen and North China Craton show overall different features. The Nd depleted mantle model ages of the rocks from the Xing-Meng Orogen are generally lower than those in the west segment of the North China Craton in Inner Mongolia. The Nd depleted mantle model ages of the Xilinhot Block are between the ones in the North China Craton and the Xing-Meng Orogen. The samples’t^_DM values indicate that the accretion of the North China Craton in Inner Mongolia primarily occurred before Mesoproterozoic; in contrast, the accretion of the Xing-Meng Orogen in Inner Mongolia predominantly began at Neoproterozoic. The evolution diagram of ε_Nd values with time from the north margin of the North China Craton suggests that both reworking of old crust and crustal accretion dominated the regional crust in Mesoproterozoic and Hercynian periods. The accretion rate of the Xing-Meng Orogen shows that its crustal accretion primarily occurred at 1,000-700 Ma and the later formed igneous rocks show the involvement of the old crustal components.

Ordovician Magmatic Arc Stratum of the Middle Qilian Block

WANG Yong-He JIAO Yang-Quan LI Jian-Xing LEI Gui-Xia

2008, 22(5): 724-732.

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Seduction-collision of the Caledonian tectonic belt in the Qilian unit formed in the Ordovician period. By geologic mapping, analysis of environment of sedimentation and study of rock geochemistry, it is considered that the rock formation of Late Ordovician epoch in Yeniutai, Subei County is the important part of magmatic arc of the northern margin in the western part of the middle Qilian block. Companied with the intermediate-acid intrusive rocks of Late Ordovician volcanic arcs, this stratum is mainly composed of slightly metamorphosed basic and intermediate volcanic rocks and conglomerate, sandstone, slate and a few fossil-bearing limestones from bottom of peaceful and deep water reducing environment of marine facies to the upper of alongshore underwater river-estuarine environment with alluvial-fluvial sedimentary sandwiched in the upper part. Material source is the magmatic arc intrusive rock, volcano-sedimentary rock and antiquity crystalline basement in the neighbor area, which reflects a progradational sequence in ascending order with lower water and shrinkage of the basin. The transformations of volcanic rock in ascending order are from basic to middle volcanic rock,from tholeiite of island arc sodium alkaline basalts to potassium alkaline basalts, from extravasations facies to burst facies, generally reflecting the characteristic of mature magmatic arc volcanic rock assemblage which is related to extrusion of the tectonic environment. The assemblage of magmatic arc stratum,intrusive rock and tectonic-ophiolitic mélange belt suggests characteristic of the continental margin proximal of Late Ordovician oceanic crust in west section of northern Qilian Mountains southdipping.

Genesis of Garnet Skarn of the Xiekeng Cu-Au Deposit in Qinghai Province

WANG Xing XIAO Rong-Ge Yang-Li-Peng WANG Bin

2008, 22(5): 733-742.

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According to the traditional mineral deposit geological data, skarn is only formed from intermediate-acid magma contacting and replacing carbonate, but skarn original rocks are not pure carbonates and their compositions of some skarn original rocks are close to those of skarn in recent studies, so the traditional genesis of skarn deposit would be further investigated. Xiekeng Cu-Au deposit, Xunhua County, Qinghai Province, which was found in 1990's, is a garnet-skarn-type and garnet-diopside-skarn-type deposit. Petrochemical characteristics and geochemical characteristics of rare earth elements and trace elements of the mineralized skarn are rather similar to those of the marlitic-sedimentary and pyroxene-diorite-type magmatic rocks, therefore, this kind of skarn is not the traditional skarn but the skarn which is formed by auto-metamorphism of magmatic rock and marliticsedimentary in the hydrothermal process by systematically studying on the geochemical characteristics of the skarn.

Physical-Chemical Conditional Evolution of Ore-forming Fluid in the Damoqujia Gold Deposit in Jiaodong Peninsula

GUO Chun-Ying GAO Bang-Fei ZHANG Jing WANG Qiang-Fei GONG Qiang-Jie XU Hai-Jun

2008, 22(5): 743-750.

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In the Damoqujia gold deposit, fluid inclusions can be divided into three types, namely aqueous inclusion, CO₂-rich inclusion and brine inclusion. The former two types dominate, while the last one is rare. For aqueous inclusions, the homogenization temperatures vary from 98 ℃ to 376 ℃ with salinities varying from 0.53% to 8.28 % and the homogenization pressures are below 50×105 Pa. For CO₂-rich inclusions, the whole homogenization temperatures range from 255 ℃ to 348 ℃ with salinities varying from 2.42% to 11.43% and homogenization pressures are from 1,000×10⁵Pa to 2,500×10⁵Pa; the CO₂homogenization temperatures vary from 23.0 ℃ to 32.4 ℃ which indicates the existence of CH₄ or H₂S. The oreforming depth was estimated at about 1 km, based on homogenization temperatures of pure CO₂ inclusions assuming hydrostatic pressure. At about 270 ℃, the homogenization pressures decrease rapidly, indicating that the fluid system experienced a decompression boiling process near 270 ℃; at the same time, the salinity and density of ore fluid varied remarkably. Therefore, it is proposed that decompression boiling and related ore fluid dramatic change in physical and chemical properties are responsible for gold deposition in Damoqujia.

REE Geochemical Characteristics of Fluorite in Fuxin Metallogenic Region and Its Geological Implications

YANG Zi-Rong LIU Jing-Dang SUN Xiang WANG Wen-Wu XU Da-De WANG Yong-Chun

2008, 22(5): 751-756.

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In order to research the metallogenic characteristics of the Fuxin fluorite ore area,the paper discusses the REE geochemical characteristics. The results show that fluorites occur in Early Permian, Late Triassic and Late Jurassic granite with negative Ce anomaly and three types of the REE distribution patterns such as negative, normal and positive Eu anomaly for fluorite. The content of REE in fluorite does not increase with the fluorite content in the country rocks. The granite which interuded in late period is rich in light REE. Total REE content decreases gradually and the REE distribution pattern evolves from depleted Eu to enriched Eu from the early period to the late period. The content of SO₂^-4 in the mineral fluid inclusions and the liquid composition reduction parameter existing in Early Permian and Late Triassic indicate that ore-forming fluid has evolved from deoxidized condition to oxidized condition. The ore-forming material sources originate from the granite.

Discussions on Reliability of the Decrepitation Technique Applied in Fluid Inclusion Studies:Taking the Jiangxi Dajishan Tungsten Deposit as An Example

XU Wen-Gang ZHANG De-Hui XI Bin-Bin ZHANG Wen-Huai SHI Niang-Hua

2008, 22(5): 757-765.

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As a prospecting method, acoustic decrepitation technique could provide a rapid and simple mean of identifying the barren and mineralized quartz veins. However, the method has not gained routine acceptance and development because of its semi-quantitative nature and possible difficulties in decrepigram interpretation. In order to discuss the reliability of the decrepitation technique, microthermometry is applied to determine the decrepitation temperature of fluid inclusions in quartz samples collected from Dajishan tungsten deposit in Jiangxi Province. The microthermometry data indicate that the decrepitated temperature is anti-related with the size of fluid inclusions and the decrepitated peak in decrepigram is overlapped by decrepitation of all these three types of fluid inclusions. The results show that the decrepitation technique is reliable in exploration applications and should be used widely.

Time-spatial Developing Features of Co-existed Inherited and Neogenic Structures and Their Implications for Oil-gas Exploration

TUN Gen-Yao Liang-Xin XIE Zhou

2008, 22(5): 766-778.

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China and neighbouring continent is a composite one, resulted from amalgamation of microcontinents and blocks by multiple orogenies. According to the orientations, the younger structures can be classified into two basic kinds: inherited and neogenic structures. There is a complicated spatial relation of the both, and the intensity of neogenic structure’s developing varies from place to place. For oil-gas exploration in the Cenozoic basins in East China, for example, the North Jiangsu and Bohai Bay basins where the NE structure was inherited one and the NEE structure was neogenic, the optimized targets might be neogenic structure superimposed the inherited ones. For the Mesozoic basins in middle-eastern China, such as the Erlian and Poyang basins, it should attend to, in addition to finding the neogenic structure superimposed the inherited ones, the oil-gas adjustment and later secondary reservation caused by occurring of the neogenic structure. The marine sedimentary basin was generally superimposed by continental basin, where multi-generation and multi-orientation neogenic structures developed and controlled the lithologic and structural oil-gas pools respectively. For example, there occurred two generations (NW- and NE-orientations respectively) of neogenic structures in the northeastern Sichuan Basin. To take structural study as the key link, to strengthen analyses on the neogenic structures, and to synthesize the works on source, migration and reservation, the theory of basin-orogeny coupling will guide concretely the oil-gas exploration practice.

Constraints the Depth and Geometry of the Subsurface Detachment Fault from Parameters of Propagation Anticline: Geometrical Model and It’s Applied to Thin-skinned Thrust in Chongqing Area, South China

ZHANG Bing Ya-Dan-Beng Song-Hong-Lin Zhang-Wei-Chen Xu-Ping Wei-Guo-Qiang JIN Zhe-Long

2008, 22(5): 779-786.

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A geometrical model, which utilizes an assemblage of parameters of propagation anticline to constraint the depth and geometry of the blind detachment fault,is figured in this paper based on both balanced geosection principles and previous studies. The parameters measured from anticline in this model include backlimb angle, interlimb angle, the height of anticline, the width of the anticline and the thickness of the layer upwards point fault tip. The calculation could be practiced using software ZB1.0, which was programmed in VC⁺⁺, and gives results of the detachment fault, including ramp dip angle, fault-parallel distance, strata draught and the deepth of flat. Parameters of anticline, which are from seismic and geological sections of the Cizhuya propagation anticline, respectively, give the consistent depth and dip angle of detachment fault at 8.10-8.63 km and 29°-45°. The depth indicates the detachment fault along the bottom of Cambrian, while the dip angle suggests a medium dip for the fault ramp. The results are also consistent with the regional geological estimation, and thus proved that the geometrical model is practicable to petroleum exploration and subsurface structures in this area.

Coal Reservoir Characteristics and Perspective and Target Areas for CBM in the Anyang-Hebi Coalfield, North China

LIU Da-Meng TAO Yan-Bin LIU Zhi-Hua SHANG Da-Zhen TANG Shu-Heng CHE Yao HUANG Wen-Hui

2008, 22(5): 787-793.

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Based on the coal quality, maceral, coal facies, micro-fracture, liquid nitrogen isotherm adsorption/desorption and mercury-injection analyses, the occurrence conditions and generation geological characteristics of coalbed methane (CBM),coal reservoir physical characteristics, CBM resource and it’s exploration and exploitation prospect in the Anyang-Hebi coalfield have been systematically studied. The in-place CBM resource was calculated using the fuzzy mathematics and stacking analysis of GIS (geographic information system) method. The results show that the in-place CBM resources and the resource abundance in the Anyang-Hebi coalfield are about 1,115.×10⁸ m³and 1.18×10⁸m3/km² respectively, which are very favorable for CBM exploration and development. The optimum target areas in this coalfield are located in the No.4 mine to No.8 mine districts of middle coalfield and around Shuiyezhen town in the northern coalfield, where the coal reservoirs have a huge coal thickness and a high CBM resource abundance,a good burial depth, well-connected pore-fracture systems, and a high permeability resulting from the local tectonic stress.

High Resolution Sequence Framework,Depositional Pattern and Litho-Stratigraphic Traps of Hanjiang Formation in Panyu Uplift,Pearl River Mouth Basin

DONG Wei LIN Chang-Song QIN Cheng-Gang XIE Li-Hua YANG Xiao-Fa CUI Li-Xie ZHANG Bo

2008, 22(5): 794-802.

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Panyu uplift is an important oil and gas-bearing district of the Pearl River Mouth Basin. Hanjiang Formation in the area can be divided into three thirdorder sequences, which are bonded by unconformities characterized by truncation or onlap contacts and its relevant conformity surfaces. Based on the flooding surfaces of the forth-order cycles, they can be subdivided into eleven forthorder sequences or systems tracts. The upper two forthorder sequences of the SQhj1 sequence consist of two sets of deltaic deposits showing progradational foresets. The lowstand systems tracts of the SQhj2 mainly include incised valley fills and lowstand wedges. Seismic sedimentology and paleo-geomorphology analysis, based on the 3D seismic data and combined with logging-restricted data, has revealed the facies distribution and revolution of important forth-order sequences in the area. The deltaic mouth bar and underwater distributary channel sandstones of the highstand systems tracts, incised channel and lowstand wedge deltaic sandy bodies and shoreline or beach sandbars comprise the major reservoirs in the study area. They are capped by overlying transgressive mudstones,so favorable reservoir and seal assemblages are formed. The economically important litho-stratigraphic traps could be formed around the onlap slope belts and the low slope or slope-break zones.

The Quantitative Study Method and Its Application to Dongdaohaizi Fracture Belt in Baijiahai Uplift,Junggar Basin

LIANG Quan-Qing LIU Shen HE Xiao-Hu WANG De-Jie WANG Xiao-Dong

2008, 22(5): 803-809.

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The vertical sealing ability of fault is mainly controlled by the closed degree of fault fracture and the lithology of fault filling material. According to quantitative calculation of positive stress on fault plane and shale percentage contents, the fault vertical sealing factor (F^_vs) is defined as the product of normal stress on fault plane and shale percentage contents of fault filling material. The vertical sealing ability of fault can be quantitatively evaluated by the parameter. The article applies the parameter to Dongdaohaizi fracture belt on Baijiahai uplift in Junggar Basin, sets up the vertical sealing criterion for oil and gas,quantitatively evaluates the fault sealing property and analyses its control effect. As a result, it can be proved that the vertical sealing factor is an efficient index in studying the vertical sealing ability of fault.

The Study on Heterogeneity of Delta Front Reservoir of PI Formation in the South of Xingshugang, Daqing

ZHANG Yan LIN Jing-Long SHU Tan HAO Lan-Yang

2008, 22(5): 810-816.

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When the oilfield major reservoirs are in the high water period, replacing the major reservoirs by the non-major reservoirs becomes an inevitable trend. The reservoirs of delta frontal sub-faces are taken as non-major reservoirs because of strong non-homogeneous. To improve reserve’s producing degree, it is necessary to describe fine reservoir heterogeneity, and to ascertain the law of residual oil distribution, then to guide the oilfield development adjustment plan. In this paper, the characteristics of reservoir of delta frontal sub-faces of PI Formation in the south of Xingshugang are studied with the data of dense well pattern and rock-mineral identification. The delta frontal sub-faces can be divided into lobate delta frontal subfaces, branched delta frontal sub-faces and sheeted delta frontal sub-faces. The genetic types of sand bodies in different sedimentary envivonments are analyzed in detail, and the distribution and space-matching relationship of different sand bodies are studied. The micro-pore structure type is studied on the base of the thin section analysis,so the reservoir heterogeneity is studied including plane heterogeneity,interlayer heterogeneity,in-layer heterogeneity and microcosmic characteristic. The influence of reservoir heterogeneity remained oil is analysed, and enrichment position of remained oil in reservoir of different delta frontal sub-faces is pointed out at last.

Genetic Type and Distribution of the Oils in the Nanpu Depression, Bohai Bay Basin

LI Su-Mei JIANG Zhen-Hua DONG Ru-Xia WANG Xu-Dong

2008, 22(5): 817-823.

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A great quantity of oils were discovered recently in both the foreshore and onshore of the Nanpu Depression, Bohai Bay Basin. Totally 67 oil and oil sand samples were collected to perform detail conventional geochemical analysis to unravel differential characteristics and classify genetic types for the oils. Four groups of the oils in the depression are recognized, including (1)onshore oils produced from Es₃ interval, characterized by high abundance of 4-methyl steranes but low level of oleanane and low methylphenanthrene indices.Also the oils have a relatively higher degree of thermal maturity; (2)onshore oils produced from Es1 to Ed and Ng to Nm. They have converse features of the group-I with widely secondary alteration by water washing and biodegradation for most of the oils from Ng to Nm; (3)offshore oils from Ed interval, which are differentiated from onshore oils with relatively high ratios of gammacerane to C₃₀hopane and steranes to hopanes; (4) oils from Ordovician burial hill, which have apparent low contents of steranes and terpanes but high content of pregnane, tricyclic terpane and diasteranes, indicate relatively high thermal evolution of the oils. It is expected that there are several favored source rocks developed in both onshore and offshore regions of the Nanpu Depression, and there is a better quantity of Es₁ to Ed source rocks offshore than to onshore. Great petroleum potential in the depression was suggested after our study.

The Research of Deliverability Well Test Interpretation of Yaha Condensate Gas Reservoir,Xinjiang

JIANG Man-Qi Xiao Xiang-Jiao LI Bao-Zhu HU Yong-Le YANG Sai-Yu OU Yang-Ting

2008, 22(5): 824-828.

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Yaha condensate gas reservoir of Xinjiang is the biggest gas reservoir explored in our country, and it has developed very well since it was put into production. Yaha condensate gas reservoir is in the period of complete retrograde condensation now, when the production is affected greatly, and the contradiction in the course of production has also been exposed gradually. This paper used the way of modern well test, and the well test interpretation software of Saphir of KAPPA corporation to analyse 9 wells’ build-up testings of pressure, deliverability testing data of the Yaha condensate gas,the rules of deliverability and the effect of retrograde condensation on deliverability. We draw the conclusions as follows: （1）when the permeability in the reservoir is higher than 20×10^-3μm² and the tested production is more than 250 thousand cubic meters,negative slope appears; （2）because of retrograde condensation effect, most of the well test models are the radial composite models. These conclusions will play an important role on understanding the gas field production performance,enhancing the research of dynamic detection technology,and gaining the good gas injection and remarkable economic benefit.

Environmental Impacts and Sustainable Developments of Magnesium Smelting Industry in China: A Review

MA Hong-Wen CAO Ying JIANG Yun TUN Xiu-Wen LIU Yu-Qin

2008, 22(5): 829-837.

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Dolomite and magnesite ores with high quality are both abundant in China, giving rise to an excellent resource background to develop magnesium smelting industry. At the end of the last century, China became the largest country in the world for the production and exportation of primary magnesium produced by the Pidgeon process, at the higher expense of energy and dolomite resource consumptions, and the local environmental quality. During the social and economic developments, China is currently facing the growing challenges in energy, mineral resources, and the environments. It is highly demands to develop magnesium smelting industry sustainable, instead of the Pidgeon process widely used nowadays. Using high quality dolomite ores as the raw materials, it is the optimal technical choice that primary magnesium is produced by the carbothermic reduction process with the developed procedure in this paper, i.e.,at the first, dolomite ore is calcined into dolomitic lime, and then, the magnesium oxide is separated from calcium oxide in the lime, and further, reduced by carbon to primary magnesium, while the calcium oxide is used to produce light-weight calcium carbonate as a coproduct. Compared with the Pidgeon process, the suggested technique has such advantages as a higher availability of dolomite resources, higher efficiency of energy consumptions, and completely clean processes.Under the current social and economic situations in China, this innovative technique system will definitely lead the magnesium smelting industry going forward to a sustainable development, and therefore, satisfying the requirements to develop the country with saving the mineral resource and the environmental kindness.

Specific Surface Area and Pore Size Distribution of 13X Zeolite Molecular Sieves

BAI Feng MA Hong-Wen

2008, 22(5): 838-844.

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The specific surface area and pore size distribution of the hydrothermally synthesized 13X zeolite molecular sieves from calcined potassium feldspar powder from 95 ℃ to 100 ℃ were experimentally investigated in this paper.The results showed that the specific surface area of the synthetic 13X zeolite molecular sieves changed from 747.40 to 621.50 m²/g.The total volumes changed from 0.344,70 to 0.393,70 cm³/g.The micro-pore volume ratio，the pore size being less than 2.5 nm of the 13X zeolites，highly reached the range from 81.33% to 84.70% in small and medium scale of experimental samples of SXZ-10g and SXZ-1kg；while the micropore volume ratios of extend scale of experimental samples of SXZ-10kg were from 67.90% to 67.98%.The micro-pore volume was an important factor of high specific surface area and high adsorption capability of 13X zeolite molecular sieves.

Thermodynamic Analysis and Experiments on Sintering Reactions of High Alumina Flyash

LI Ge MA Hong-Wen TAN Dan-Jun JU Dan BANG Hui SU Shuang-Jing

2008, 22(5): 845-851.

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The possible reactions of high alumina flyash with sodium carbonate and calcium carbonate as flux agent were studied during the sintering processes. According to the results of thermodynamic calculations and the flyash-sodium carbonate sintering experiments, contrasting the energy consumption, material resource consumption and the expellant of the greenhouse gas CO₂ during the two sintering processes,it demonstrates that the procedure could be the least consumptions of the mineral resources and energy, the least expellant of the greenhouse gas CO₂, and that the terminal products with high value could be manufactured when sodium carbonate is taken as the flux agent. It is therefore feasible that the procedure suggested in this paper is hopeful industrialized both in economic benefits and environmental kindness.

Preparation and Pb²⁺ Immobilization Behaviors of Blast Furnace Slag Based Geopolymer

NI Jian-Di CHEN Wen-Yan XIE Shu-Feng CHEN Yun-Fa

2008, 22(5): 852-856.

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Geopolymer, with good mechanical properties, was prepared using blast furnace slag(BFS) and calcinated kaolin clay. The synthesis tests of slag based geopolymer are done based on four different slag contents (20%, 40%, 60%, 80%),curing regime( 20 ℃) and curing time(1 d,3 d,7 d,28 d)The testing results showed that the geopolymer mortar containing 80% slag exhibited the highest mechanical strength in 28 d curing. The compressive strength of slag based geopolymer mortar is 65 MPa. Additionally, infrared(IR), Xray diffraction(XRD) techniques are used to characterize the microstructure of the slag based geopolymer paste. The analytical data indicated that significant depolymerization of the silicate or aluminosilicate networks occurred, then significant polymerization occurred. Immobilization behaviors of slag based geopolymer in presence of Pb²⁺also is carried out. The geopolymer was prepared by using Pb²⁺ solution,and the compressive strengths were tested in 28 d curing. The Pb²⁺ content had influenced on the development of compressive strength of geopolymer, but the compressive strength in 28 d did not change observably. The leaching tests were employed to investigate the immobilization behaviors of the slag based geopolymer. The leaching tests showed that the slag based geopolymer can effectively immobilize Pb²⁺content, and the immobilization rate reached 99.9%.

Hazard and Control Measures of Radon and Its Progenies in the Environment

CHENG Ye-Xun

2008, 22(5): 857-868.

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This paper briefly reviews the research history of the lung cancer due to Radon and its progenies in the past hundreds years, then presents the relationship between risk of lung cancer and radon and its progenies inbreathed by uranium miners. It focuses on radon concentration indoor, in subsurface constructions and in spring water worldwide. It suggests that it is essential to do the research on the geological sources of radon in the environment and how to control radon level indoor,and furtherly it also presents the approaches of controlling radon indoor and the significance of protection human health.

Investigation of Radioactivity in Qiangtang Basin and Its Southeast Outside Area, Tibet

XIE Fa-Wang FANG Mao-Long WANG Shu-Gong

2008, 22(5): 869-876.

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Qiangtang basin is located in the middle of QinghaiTibet Plateau, where the weather is atrocious and the uranium geologic research was little. This paper primarily presented the radioactive characteristics about the strata in Qiangtang basin and the granite in southeast outside of basin based on the following data,radioactivity gamma.ray spectrum survey in field, some chemical analysis data of granite, car.borne gamma.ray spectrometry made by other geological department, and a few regional investigation material so on. Studies show that the Middle and Upper Jurassic Xueshan Formation, Quemocuo Formation and Xiali Formation have fairly high uranium content,their average uranium content in the northeast slope zone are 4.12×10^-6,4.06×10^-6 and 3.68×10^-6,respectively. In the northern Qiangtang depression, the average uranium content for Xiali Formation is 7.75×10^-6, and 5.93×10^-6 for Suowa.Xueshan Formation. From the viewpoint of spatial variation, the average uranium content of strata in the south of northern Qiangtang depression is higher than that in the north. While in northeast slope zone, the average uranium content is characterized by high in the middle and the north, and low in the south. These data and analysis results in this paper can be served as the significant radioactive basis for analyzing the geological condition of uranium ore.formation in Qiangtang basin.

Formation Mechanism of the Ground Collapse in Minedout Area of Coalmine Underlying Loose Loess Deposit

WANG Hui LI Zhi-Yi YANG Wei-Min WEI Lu

2008, 22(5): 877-883.

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Based on field investigation and lab tests, the ground collapse characteristics of mined-out area along Qingdao-Lanzhou express highway has been studied. The formation mechanism of the ground collapse has been discussed further. The research shows that the ground collapse represents collapse hole, earth fissure and sinking basin,and the distributing rule is not good. The ground collapse is obviously hysteretic comparing with coal seam excavate. The main reason of ground collapse is that coal seams are buried low,and the two zones are through the earth’s surface. Because the loose loess overlaying coal seam has unique structure and certain structural strength, it would not break down immediately. The tensile crack would form firstly along loess vertical joints in loose bed, and then the crack would develop corrosion and erosion under the condition of ground water current action, and the tensile crack would extend to form collapse hole finally.

Getting Information of Attitude of Rock Joints with Ultrasonic Borehole Televiewer

WANG Shu-Li LI Hui-Xun YANG Xiao-Jun

2008, 22(5): 884-888.

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Information and 3D images for attitudes of layers have been got with ultrasonic borehole televiewer（BHTV） in geotechnical investigation. Borehole information of rock mass fractures in seven drillholes was derived by BHTV in a underground oil storage cavern. It includes scatter plots of poles and rose maps of dip direction for structure plane with depth, dip direction, strike direction, integrality and line intensity of jointing, 3D core images, 3D borehole wall images, joint pole maps and rose maps of jointing. The statistical characteristics of these maps and images are analyzed, the results reveal that BHTV is a valuable tool for geotechnical investigation.

Magnetic Influence of Quartz Tail-sands on the Dry Top Soil and Its Environmental Implications

LI Yong LI Hai-Yan

2008, 22(5): 889-894.

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Magnetic measurements have been undertaken on quartz tailsands, dry top soil, tailsandsinfluenced top soil and town top soil of Fengyang,Anhui. Results show that magnetic properties of the four kinds of samples are evidently different. Although magnetite dominates the susceptibility of the four kinds of samples, there are some maghemites in dry top soil, some iron hydroxides （e.g.lepidocrocite） in quartz tail-sands and town top soil and some iron hydroxides （e.g.lepidocrocite）, maghemite in tailsandsinfluenced top soil. The content of magnetite in the town top soil is apparently more than that in the other three kinds of samples. The content of magnetite in the tail-sands-influencedtop soil is between that in the quartz tail-sands and dry top soil. Magnetite grains of town top soil is finer than 1μm; those of quartz tail-sands are larger than 0.1μm, and those of dry top soil are smaller than 0.1μm, while those of tail-sands-influenced top soil are between those in the quartz tail-sands and in the dry top soil. Negative correlation lies between the susceptibility and the frequency dependence susceptibility of town top soil, positive correlation lies between those of dry top soil, while no evident correlation lies between those in the tail-sands-influenced top soil. Under the effect of industry processes and traffic, town top soil shows magnetic enhancement. However, the producing of quartz sands results in magnetic reduction of top soil. This is due to less magnetic minerals in quartz sands than that in the dry soil.

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