Geoscience

Structural Style and Deformational Characteristics of the Thickskinned Thrust Belt in the Western Xuefeng Mountain

HONG Chang-Liang, YA Dan-Beng, ZHANG Bing, HU Yan-Bei, SHANG Shuang-Li

2011, 25(6): 1021-1031.

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A thickskinned thrust belt is located at the western edge of Xuefeng Mountain. The folds axis and faults are mainly NNE strike to the south portion of the thrust fault belt, and strike to NEE to the north. The basement of Proterozoic Banxi Group is occurred in large area of the thickskinned thrust belt. While the reasons why the basement strata — Banxi Group occurred in Xuefeng Mountain and the structural styles of the Banxi Group are the key problems to analyze the Mesozoic tectonic of South China. In this paper, we focused and studied the geometry and kinematics of the thickskinned thrust faults, and interpretation of the data of seismic section and magnetotelluric sounding along FenghuangHuaihua tectonic section. We recognized that the thickskinned thrust faults were activated and moved from southeast to northwest during the IndosinianYanshanian stage, and the faults dip to SE and the dip angles appear steep near surface, while to the underground they get together and turn to a main basement fault. The sub back thrust faults are popularly scattered in the hanging wall. The basement of Banxi Group and Early Paleozoic strata are involved in the over thrust fault belt, known as the thickskinned thrust, resulting into large occurrence of the besement of Banxi Group.

Evolution of Yanshanian Granites in Southern Marginal Region of North China Block：A Case Study of XiaoqinlingWaifangshan Area

WANG Zhen-Jiang , XU Jian-Chang, FENG Jian-Zhi , QI Dong-Mei, YANG Gang, SUN Wei-Zhi

2011, 25(6): 1032-1046.

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According to the time and space distribution characteristics of Mesozoic granites in XiaoqinlingWaifangshan area in southern marginal region of North China block，the forming process of the Mesozoic granites can be divided into 160-155 Ma(Ⅰ), 150-125 Ma（Ⅱ）, and 120-110 Ma（Ⅲ），not identical with largescale magmatic activity periods of North China. The geochemical evolution of the three periods of granites are special: geochemical characteristics of Ⅰ and Ⅲ periods of granites are very similar，and they are abnormally high content of K, obvious negative Eu anomaly and weak heavy rareearth fractionation, belonging to Atype granites. Ⅱ period of granite is metaluminousperaluminous and high potassium calcium alkaline series granite, and is rich in big ion lithophile element，such as K, U, and Th，lack in the high field element. P2O5 content decrease with the increasing of SiO2 content, belonging to Itype granite. For the contents of most samples, Sr content is more than 300.00×10^-6，Y content is less than 19.00×10^-6 and Yb content is less than 1.90×10^-6, showing the geochemical characteristics of adakite rock. From early to late period，Ⅰ,Ⅱ and Ⅲ periods of granites show the trend of Atype-Itype-Atype. I period of granite formed in local extensional environment under the extrusion tectonic background. Ⅱ period of granite formed in tectonic setting transition period，being the product of the lower crust melting led by thickening crust. Ⅲ period of granite formed from plate stabilization, lithosphere stretching, and decompression and melting of the lower crust rocks, after Yangtze and North China continental blocks fitting.

LA-ICP-MS U-Pb Dating of Detrital Zircons from the Marine VolcanicSedimentary Rock in the Northern Kamste，Eastern Junggar and Its Geological Significance

WANG Yi-Jian, LIU Hong-Jun, ZHOU Juan-Ping- , JU Hong-Jie

2011, 25(6): 1047-1058.

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There has been a controversy in zircon U-Pb ages of marine volcanicsedimentary detrital rock, which occurred in 10 km away from the northern Kamste in Eastern Junggar.Thus, the zircon U-Pb ages of detrital rock were measured by the LA-ICP-MS method.And 100 detrital zircons had been tested totally, of which 90 ages of these zircons are useful.The dating results have shown that: (1)the formation age of this rock stratum may be Early Carboniferous, because the deposition time was later than 333.2 Ma which has been limited by the youngest age of detrital zircon(2)There are multiple provenances for this rock stratum, which are proved by the contrast results between detrital zircon dating results and regional magmatic events as follows: Early Cambrian (523.1 Ma, 535.1 Ma)detrital zircons might source from Precambrian crystalline basement of Junggar, but need further research; MiddleLate Ordovician (440.0 Ma, 460.9 Ma) detrital zircons came from pyroclastic rocks of Huangcaopo Group; Early Silurian(429.3 Ma)detrital zircon might originate from the Lower Silurian stratum, which was deposited in the surrounding of this study area; Middle Devonian ((371.5±2.5) Ma)detrital zircons derived from the strata of Zhuomubasitao Formation and Wulusubasitao Formation; and Early Carboniferous ((336.4±0.8)-(353.5±0.7) Ma)detrital zircons stemmed from the stratum of Nanmingshui Formation.(3) In addition, there is a zircon aged 2,676.2 Ma having the harmonic degree of 99%, which has provided some basis for the possible existence of Precambrian ancient crystallization basement, but needs further evidence.

Geochemical Characteristics and Environmental Significance of Dengying Formation of Upper Sinian in Qiannan Depression

WANG Feng-Mo, CHEN Zi-Liao, LI Xian-Jing, CHENG Gang, HE Xun-Yun, XU Zheng-Yu, MA Li-Qiao, DONG Yong, HUANG Ling

2011, 25(6): 1059-1065.

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The dolomite deposited in the Dengying Formation of Upper Sinian in the Qiannan Depression.Based on the actual measurement the Yangtiaozhai section, Majiang, we used the geochemical analyses to discuss the sedimentary geochemistry characteristics and the palaeosedimentary environment significance of Dengying FormationsThe results indicated:(1)CaO and MgO remarkably positively correlated with each other；SiO₂negatively correlated with CaO and MgO; Sr negatively correlated with MgO, and positively correlated with Al₂O₃, K₂O, Na₂O, TiO₂, P₂O₅, TFe; V, Al₂O₃, K₂O, TiO₂, TFe and P2O5 positively correlated with each other; Mn weakly positively correlated with TFe. (2) The content of Sr and the value of 1,000×Sr/Ca increased with the depth of sedimentary water, regarded as the mark of the palaeobathymetric and succession boundary. (3)The analytic results of the ratios of Sr/Ba, MgO/Al₂O₃, MgO/CaO and V/(V+Ni) revealed that the palaeosedimentary environments of Dengying Formation is ocean sediments which was formed in reducing environment of continental sea in hot arid climate,and with the detrital material of terrigenous origin Especially, the second member of Dengying Formation was formed in the deepest water environment and the paleosalinity of the fifth member of Dengying Formation is the highest；The geochemical characteristics and the sedimentary environment are closely correlated, and the geochemical characteristics can be regarded as an important mark in the sedimentary phase analyses

Geochemical Characteristics of Trace Elements in the Marine Surface Sediments Outer Yangtze River Estuary

LA Xian-Hong, ZHANG Zhi-Xun, LI Ri-Hui, WANG Zhong-Bei, CHEN Xiao-Hui, HOU Fang-Hui

2011, 25(6): 1066-1076.

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This study analyzed the abundance of 25 trace elements in 187 pieces of marine surface sediments outer Yangtze River estuary using correlation analysis and Rmode factor analysis，and discussed the variation coefficient，and the source and distribution characteristics of trace elements in the sediments. Elements of Li,V,Cr,Co, Ni,Ga,Cu,Zn,Th and Rb have similar distributions, whereas Sr is negatively correlated with elements of Li,Cu, Pb, Zn, Th and Rb. The distribution of Sr in the southeast part of the study area reveals a clear link to source materials related to the biogenic process, whereas the distribution of Zr reflects the influence of materials from Yangtze River. The distributions of Cd and Mo are not obviously correlated with the type and granularity of sediments, but are mainly controlled by redox environment. The results of correlation analysis and Rmode factor analysis show that the sedimentation，grain size effect，marine biogenic process, redox environment and geological background of the source area play a dominant role in controlling the distribution of the contents of trace elements in marine surface sediments outer Yangtze River estuary.

GeologicalGeochemical Characteristics and Genesis of Changshanhao Gold Deposit in Inner Mongolia, China

DIAO Bai-Qing, LIU Jia-Jun, WANG Jian-Beng, DI Yu-Sheng, BANG Run-Min-2 Wang-Shou-Guang, CHEN Cun-Li

2011, 25(6): 1077-1087.

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Changshanhao gold deposit is a large metamorphic microclastic rock type gold deposit hosted in carbonaceous slates and phyllites of the MesoNeoproterozoic Bilute Formation of Bayan Obo Group in central Inner Mongolia. The gold ore bodies are tabular and lenticular and no clear boundary to wall rocks; the ores occur as sulfur veinlets or quartzsulfide veinlets deformed with strata in beddings, joints and fractures, which consist of simple minerals with weak alterations. The ore and wall rocks have the similar trace element geochemical feature. The ranges of ore ²⁰⁸Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁶Pb/²⁰⁴Pb, close to those of strata, are 37.430 8 to 38.979 2， 15.452 2 to 15.674 1 and 17.109 to 18.921 7，respectively. Goldbearing quartz veins mainly contain liquid fluid inclusion with homogenization temperature of 230 to 370 ℃ and salinity of 6.01% to 20.52% NaCl eqv. δD and δ¹⁸O of the fluid are -108‰ to -112‰ and 6.4‰ to 9.4‰. These geologicalgeochemical characteristics indicate that oreforming material and fluid come from strata. The authors infer that Changshanhao gold deposit is a sedimentmetamorphism mesotherm deposit, and the later magmatic activity had a little effect on the metallogenesis.

Characteristics and Geological Significance of Fluid Inclusions in the Shuangwang Gold Deposit, Shaanxi Province

LIU Bi-Zheng, WANG Jian-Beng, WANG Ge-Xin, LIU Jia-Jun-1, XIE Hai-Ying, CAO Rui-Rong, HUI De-Feng, CHENG Jian-Jun

2011, 25(6): 1088-1098.

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The Shuangwang gold deposit is located in the southwest of Taibai County, Shaanxi Province. It occurred in the Devonian strata of the Qinling orogenic belt. Systematic fluid inclusion study of hydrothermal minerals from No8, 7, 9, 5, 6 and 2 ore bodies shows that the inclusions of the Shangwang gold deposit had diversity of characteristics. The range of homogenization temperature of inclusions in early oreforming stage, main oreforming stage and late oreforming stage are from 300 to 463 ℃, 220 to 340 ℃, and 100 to 279 ℃ respectively. The characteristics of main oreforming stage fluid are low salinity content (21%-227% NaCl eqv), rich in CO2 and containing N2, CH4 and other gases. From east to west, the trapping pressure is gradually decreasing, and the open fluid system tends to be dominant. Mineralizing fluids were mixed fluids which mainly originated from magmatic and metamorphic water. At the later stage, some meteoric water joined into the fluid system. The diversity and evolution of fluid inclusions and a large number of breccia ores indicate that oreforming fluids of the Shuangwang gold deposit have the characteristics of fluid unmixing, the metallogenic pressure is from 100 to 170 MPa. Boiling caused by decreasing of fluid pressure is the most important reason of gold deposition.

Research of Metallotectonics and Tectonic Stress Field of Jinqingding Gold Deposit, Shandong Province

GAO Jian-Wei, DIAO Guo-Chun, MAO Xiao-Gong, TENG Chao, DONG Han-Wen, LI Qing-Rong, SONG Yu-Bei, LIU Zhen-Hao

2011, 25(6): 1099-1107.

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Jinqingding quartzvein type gold deposit is located in the central area of MupingRushan metallogenic belt. Based on the structural mapping, the analysis of paleotectonic stress inversion and the differential paleostress values, the authors studied the tectonic movement features and tectonic evolution history preliminarily. The new results show that the orecontrolling fault of this deposit has gone through three stages of activity, characterized by leftslip transgression before mineralization, rightslip extension transtension during mineralization and intrusion of lamprophyre, and leftslip transgression after mineralization. During the mineralization, the orecontrolling fault experienced a significant transformation of tectonic stress field, which expanded, and was filled with ore body. According to discussion of the metallogenic evolution mechanism, we regard that mineralization is restricted by many aspects, such as the directions of tectonic stress field, fault movement direction, fracture surface properties and so on, which results from coupling of multiple structure elements.

Geochemical Characteristics and Affecting Factors of the Unusually High Dibenzothiophenes Oils in the Tazhong Uplift

LI Su-Mei, ZHANG Bao-Shou, ZHANG Hai-Jie, CHENG Shi-Zhong, DIAO Meng

2011, 25(6): 1108-1120.

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Unusually high dibenzothiophenes (DBTs) oils were detected in the Tazhong Uplift, Tarim Basin, with the maximum absolute abundance up to 26,859 μg/g and relative abundance among the aromatic hydrocarbons recognizable up to 58.2%. The oil is usually situated in the Lower Ordovician in the No1 Fault Belt and the TZ4 and TZ1-6 wellblocks. An integrated geochemical approach was utilized in characterizing the oils. The results show that the type of source rock has an significant controlling on the distribution and abundance of DBTs. Normal DBTs were detected in pure dark mudstones and shales, whereas super high DBTs were observed in the source rocks with high content of sulphate. An increasing trend of the DBTs content was observed for the source rock and the related oils within normal oil window in the Dongying Depression. However, in the case of the Tazhong oils with high thermal maturity, there is an increasing and then decreasing trend with a breakpoint around 5,500 m, suggesting strong controlling of thermal evolution. It was also observed that biodegradation and waterwashing have an effect on DBTs in a varying degree, with an decreasing trend of DBTs concentration with increasing biodegradation. But it is unlikely that this kind of secondary alteration is one of the reasons responsible for the abnormal oils in the Tazhong region. It was detected that there is a positive relation between DBTs, H2S content (in associated gas), mercaptan and long chain alkylthiolanes in the high DBTs oils, which is recognized as productions of TSR. We believe there are several factors having an effect on the DBTs in the Tazhong oils. Thermal chemical alteration and TSR are suggested to be the essential factors responsible for the high DBTs in partial Lower Ordovician oils, and little possibility of a kind of special source rocks have caused the abnormal oils, although it could not be excluded at present. As to the oils in the Carboniferous in the TZ4 wellblock etc, we suggest that mixing of later charged deep oils with high DBT concentrations with earlier oils in situ is the most likely mechanism responsible for the abnormal DBT concentrations.

Recognition of Oil Source and Source Rocks in Zhu Ⅲ Depression

FU Ning, LI You-Chuan, SUN Jian-Xin, SUN Yu-Mei, XU Jian-Yong

2011, 25(6): 1121-1130.

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Thirtyseven crude oil samples and forty rock samples were analyzed by geochemistry analysis methods of GCMS，carbon isotopic and light weight hydrocarbons for the further exploration research of Zhu Ⅲ depression. Based on the results, comprehensive comparison between oil source and hydrocarbon source rocks was done again and new cognition was gained. The results showed that the deep lacustrine facies source rock of Wenchang Formation is the major source rock of Wenchang B sag in Zhu Ⅲ depression, rather than the shoreshallow lacustrine facies source rock; and the swamp facies source rock of Enping Formation is the major source rock of Wenchang A sag in Zhu Ⅲ depression. The main contributions of the crude oil were deep lacustrine facies source rock of Wenchang Formation in Wenchang B sag (Structure WC19-1 and WC19-2), swamp facies source rock of Enping Formation in Wenchang A sag(Structure WC9-1, WC9-2, WC9-3, WC14-3, WC11-2). The crude oil in west Qionghai uplift (Structure WC13-1、WC13-2、QH18-1、QH23-1) primarily came from the deep lacustrine facies rocks of Wenchang Formation in Wenchang B sag, while that in east Qionghai uplift (Structure WC19-6N、WC7-2、WC7-3、WC8-3) mainly came from source rocks of Enping Formation in Wenchang A sag. Two episodes of hydrocarbon filling had taken place in the study area.

Oil & Gas Migration Characteristic and Model for Sha-2 ember of he Shahejie Formation in Shengbei Fault Zone, Dongying Sag

CENG Jian-Hui, SUN Tie-Jiang, GUO Kai- , ZHANG Yong-Wang

2011, 25(6): 1131-1136.

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The geological and geochemical research results indicate that fault activities of Shengbei fault zone in Dongying Sag have an important effect on oil & gas migration and accumulation of Sha-2 ember of the Shahejie Formation. Oil and gas generated from the source rocks in the lower part of Sha-2 ember of the Shahejie Formation and the upper part of Sha-4 ember of the Shahejie Formation migrate vertically into Sha-2 ember of the Shahejie Formation along Tuo 94 fault and the northsouth fault independently during the fault activities, and then migrate laterally in Sha-2 ember of the Shahejie Formation and accumulate in the saddle of Shenglicun anticline and Tuozhuang anticline.

Type of Petroleum Migration Pathway System and Accumulation Model in Langgu Depression，Jizhong

WANG Zong-Li, LUO Jiang, LI Qing-Li, LI Xiang-Yang, XIE Jing, DIAO Lei, CUI Qiang-Qiang

2011, 25(6): 1137-1144.

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Based on the problems that the reservoir formation mechanism of Langgu Depression is not clear and the hydrocarbon migration pathway system is indefinite currently， this paper filters parameters of affecting hydrocarbon migration and pathway， and emphasizes on the relationship between wax content， oil field water salinity and buried depth. Combining with its vertical assembling pattern， three petroleum migration pathway system types are summarized: A type(conventional chromatography)，B type(express pathway)，C type(porefracture)， and the spatial distribution features of diverse reservoirs at various structural belts are studied. The control over the depth， scale and categories of reservoir and petroleum phase by pathway system types is researched. Finally， according to scheme of classification of migration pathway system， four models of hydrocarbon accumulation are established and petroleum accumulation unit is determined. It can provide significant information for the oil and gas reservoir simulation， exploration direction and exploration target prediction.

Correspondence Between High Frequency Sequences and Milankovitch Cycles of Yaojia Formation in Daqing Placanticline

SUN Yang, FAN Ta-Liang, FU Liang-Tong, WANG Hai-Rong, HU Xiao-Lan

2011, 25(6): 1145-1151.

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Ten typical well cores were observed to study highfrequency sequence classification of Daqing Yaojia Formation in this paper. As a result, 98 ultrashortterm cycles, 33 shortterm cycles, 9 midterm cycles and 3 longterm cycles were identified. Meanwhile, this paper analyzed the Milankovitch Cycles, based on the natural gamma curves of those wells. The result showed that Milankovitch Cycles were well preserved in the strata of Yaojia Formation. The thickness of longperiod cycles caused by eccentricity ranges from 2.679 m to 3.972 m, the thickness of midperiod cycles caused by obliquity cycles ranges from 1.379 m to 2.131 m and the thickness of shortperiod cycles caused by precessions ranges from 0.601 m to 0.901 m. There is a good consistency between highfrequency sequences and Milankovitch Cycles. The midcycle, shortcycle and ultrashortterm cycles of highfrequency sequence are corresponding respectively to the longperiod eccentricity, shortperiod eccentricity and the precession cycle of Milankovitch Cycles. Lake level change caused by the change of Earths orbit is a major controlling factor of the formation of highfrequency sequences.

Preliminary Discussion of Simulation Experiments on the Mechanical Compaction and Physical Property Evolution of Sandstones

CAO Ying-Chang, XI Ke-Lai, WANG Jian, YUAN Guang-Hui, YANG Tian

2011, 25(6): 1152-1158.

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In order to simulate the physical property change of sedimentary strata in the diagenetic process, a set of new equipment was designed and applied to simulate the mechanical compaction using different modern sediments. Results of the experiments show that the porosity and permeability are not regularly changing during compaction, and it can be divided into two sections, ie. a sudden change section at early stage and a uniform change section at later stage. In the uniform change section, the porosity decreases with the increase of the depth, and they have an exponential relationship; the permeability also decreases with the increase of the depth, and they have an exponentiational relationship; the porosity and permeability also have an exponential relationship. When the sandstone only experiences mechanical compaction, for the sediments with same source and separation, the more coarse of grain size is, the slower of compaction rate is, and the porosity and permeability will be larger; for the sediments with the similar source and grain size, the poorer sorting is, the quicker compaction rate is, and the porosity and permeability will be less. During the uniform change section, the porosity reduction per 100 meters is also different for different lithofacies in sandstones. The porosity reduction per 100 meters is the least in well sorted medium sandstone, followed by that in well sorted fine sandstone and well sorted siltstone, then that in medium sorted coarse sand, and that in poorly sorted pebbly sandstone is the largest.

An Unsteady State Computation Model of Fractured Horizontal Well Coupling with Reservoir

CENG Fan-Hui, Guo-Jian-Chun, YIN Jian

2011, 25(6): 1159-1166.

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In order to calculate productivity of hydraulic fracture horizontal wells precisely, considering the reservoir seepage, borehole wall inflow, fracture and perforation flows mutual influence, an unsteady state computation model of fractured horizontal well coupling with reservoir was established based on the superposition principle. Calculation results showed that compared to the horizontal well production only from fractures, the difference of that from fractures and perforations was great early and later decreased slowly. Because of mutual interference, different location fractures had different flow rates and the centralfracture production was lower than that of the outerfracture. The production of the fractures with horizontal well bore center symmetry was unequal due to the influence of well bore friction. Along with the fractures length increased, the horizontal well production increased. As the conductivity increased, the fractures production increased, while the perforations production decreased and the horizontal well production increased. With the longer perforation length, the interference of perforations and fractures interference became stronger, so the single perforation production reduced, while the perforation number increased, the horizontal well production increased. As the deepening of perforation depth, the horizontal well yield increased.

Applying Audiomagnetelluric Method to the Study of Megadune Structure and Formation in Badain Jaran Desert, Inner Mongolia

LIN Wei, JIN Qing

2011, 25(6): 1167-1173.

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Badain Jaran Desert has a rare group of megadunes in the world; the audiomagnetelluric(AMT) method was used to study the structure of megadunes in Badain Jaran desert. The audiomagnetelluric data was processed by nonlinear conjugate gradients method, and the resistivity sections of megadunes were obtained. There is a apparent lowresistivity zone existing in the deep of the section, and a certain scale highresistivity zone in the central of the megadunes. It is inferred that the formation of megadunes is related to the stabilized northwest wind, continuous groundwater replenishment and the special environment. The groundwater rises through transpiration and is obstructed by calcareous layers in the ancient sand dunes, then is evaporated from the bottom of the leeward slope; the water vapor is condensed on the surface of sands which roll down from the top of dunes, enhancing the ability to resisting wind erosion of sands, thus the sand dunes get larger and larger as time goes by, turning to megadunes.

Density Inversion of Typical Watersaturated Sandstones with Multivariate Statistical Analysis in Multidimensional Space

ZHANG Yan, NIU Bin-Hua, SUN Chun-Yan, GUO Ji-Liang, SUN Xun

2011, 25(6): 1174-1179.

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The combination of measured data，rock physics and multivariate statistical analysis in multidimensional space is helpful for interpreting the data quantitatively and reduces the prediction risk of reservoir framework and fluid information. Densities of quartz, clay and fluid were inversed with the density, clay content and measured porosity pressure of typical watersaturated sandstone samples (Dehua Hans G group sandstone samples) in this paper. It reveals that the inversion result is consonant with the real situation. The correlation coe
fficient between fitting density and measured density can reach 0985,5. The highlight of this density inversion method is the combination of multivariate statistical analysis in multidimensional space and the law of mass conservation. Compared to traditional binary regression method in two dimensional space, this method could not only avoid the effect of singular point in regression analysis, but also get fitting density which has more significant correlation with measured density. The relative error between the inversed mean value and measured value is about 2%, and the reliable result indicates that this method is reasonable and effective.

Density Calculation and Reservoir Identification of Gas Hydrates

GU Ji-Hui, NIU Bin-Hua, SUN Chun-Yan, GUO Ji-Liang, SUN Xun, LIU Sai-Sai

2011, 25(6): 1180-1186.

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The occurrence of gas hydrate reservoirs is a special environment that belongs to the multiple phases. The use of twophase porous medium theory can fully take into account the structure of the medium, the special nature of the fluid and gas that fill the pores among the mineral framework, the relationship between the properties of the parts and the entirety, which can accurately describe the actual stratigraphic structure, the attributes of strata, and the dynamic response of seismic waves in the rock. This study proposed a rock physics model based on the solid property of gas hydrate and the characteristics of the geological conditions, and constructed the equations of forward, reverse and bidirectional linear regression to calculate density. Taking sites of 991 A, 995 A in ODP Leg 164 as examples, the densities of gas hydrate and framework were calculated with rock density based on this model. The calculated values of the density of gas hydrates are from 0858,2 to 1055,6 g/cm3. After the calculated values were corrected, the framework densities in different depths were derived, and the distribution of favorable hydrate reservoir was identified. This study provides a new rock physics model for the research on gas hydrates.

Statistical Analysis of Factors Affecting the Thermal Conductivity of Silty Clay and Fine Sand in Beijing Area

LUAN Yang-Bei, WEI Mo-Shun, ZHENG Gui-Sen, JI Xin-Nan

2011, 25(6): 1187-1194.

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With shortages of energy and increasing awareness of environmental protection, the limited resources of shallow underground space have been rapidly developed and utilized. It is very important to master the variation of thermal physical parameters of rock and soil for using limited underground thermal energy efficiently and reasonably. Based on the thermal physical properties test of rock and soil in the geological prospecting projects of Beijing plain shallow geothermal energy resources, this paper analyses statistically the factors affecting the thermal conductivity of the silty clay and fine sand. The statistical results show that the average thermal conductivity of silty clay is 174 W/(m·K), and the average thermal conductivity of fine sand is 155 W/(m·K) and that the variation trend of these thermal conductivity rates is clear with the variation of the natural water content, natural density and porosity, with increasing water content the thermal conductivity decreases. The variation trends are listed as following: the thermal conductivity increases with increasing density; the thermal conductivity reduces with increasing porosity; the best thermal conductivity is of about 20% water content in silty clay and 15% in fine sand; because the differences of samples in geological structural position, sedimentary environment, sedimentary history, material composition of rock and soil and composition microstructure affect the combination of the heat transfer, the thermal conductivity and water content in different areas, even in the same areas, have different fitting equations but the same variation trend.

Distribution Characteristics of Groundwater Environmental Isotopes in a Multilevel Basin in Arid Area of the Northwestern China and Their Indication

SUN Qi, TU Xiang, ZHOU Xun, CHEN Jian-Jie, GAO Wei-Chao

2011, 25(6): 1195-1200.

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The study area is located in the arid area in the Northwestern China and two levels of water storage basins exist. The firstlevel basin receives the lateral recharge from the southern mountain area. Spring discharge from the firstlevel basin flows into and recharges the next basin, at the same time groundwater in each levels of basin receives recharge from direct precipitation and indirect infiltration of flood flow. Based on hydrogen and oxygen isotope mixture formula, the precipitation amount accounts for 60% of the total recharges, of which, direct recharge from precipitation is estimated 21%, and recharge from flood flow is estimated 79%. Lateral recharge from the mountain area is about 40%. The secondlevel basin receives 38% recharge from precipitation, and the upstream spring discharge accounts for 62%. The quantity of tritium indicates that the se
condlevel basin is not affected by present precipitation. Using the piston model and the complete mixing model, the age of shallow groundwater in the firstlevel basin is estimated to range from 32 to 60 a.

Simulation Study of Hydraulic Connection Between the Polluted River and Groundwater in a Riparian Zone

LIU Li-Ya, HE Jiang-Chao, WANG Dun-Jie, ZHANG Cuan

2011, 25(6): 1201-1206.

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This study specified a polluted riparian zone of Sui River, Huaibei in Anhui Province to research the effect of common surface pollutant sources on groundwater. Based on a field investigation, pumping test and slug test in the polluted riparian zone, a systemic study was carried out in respect of hydrodynamic. Processing Modflow was used to establish the hydrogeology model, we can discriminate the hydraulic connection among the polluted river, the deep aquifer and the shallow aquifer, according to the situation of water exchange among subregions. The results of simulation demonstrated that there was no obvious hydraulic connection between the polluted river and the shallow aquifer, and the hydraulic connection between the deep aquifer and the shallow aquifer was weak.

Archaeal Diversity Analysis for the Two Hot Springs in Chengde Area of China

HAO Chun-Bo, ZHANG Li-Na, LI Sai-Yuan, ZHOU Xun, FENG Chuan-Beng, FANG Bin

2011, 25(6): 1207-1213.

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The archaeal diversity of two hot springs with different temperature in Chengde area of China was investigated using 16S rDNA clone library. The results showed that the archaea in the Shanwanzi hot spring A12 (74.5 ℃) belonged to two phyla: Crenarchaeota and Euryarchaeota, but the archaea in the Qijia hot spring A14 (61.4 ℃) belonged to Crenarchaeota only. Based on sequence similarity, a total of 3 phylotypes or operational taxonomic units (OTUs) were obtained from A12 sample, while the archaeal sequences in A14 sample could be classified into 10 phylotypes. The biodiversity difference between the two samples revealed that the temperature might be an important factor to affect the level of archaeal diversity in hot springs. The major physiological function of archaea in sample A12 was methanogenesis through anaerobic acetate fermentation. On the contrary, the most archaea in sample A14 were closely related to ammoniaoxidizing archaea, indicating that their dominant physiological function was aerobic ammonia oxidation.

Quantification Research on Condensation Water on Qianxi Temple of Longmen Grottoes

FANG Yun, HUANG Xuan, WANG Xiao-Dong, ZHANG Ao, CHEN Jian-Beng, YANG Gang-Liang, FAN Zi-Long-

2011, 25(6): 1214-1218.

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Longmen Grottoes were carved in the carbonate rocks, which are severely eroded by water, and condensation water disease is the nonignorable problem. Qianxi Temple is a typical cave of Longmen Grottoes which have being suffered by the condensation water. The quantitative collection test of condensation water is an important tool to evaluate condensation water disease and to analysis the condensation water formation mechanism. The condensation rate and the amount of condensation water were determined by a special experimental facility at the site of Qianxi Temple in 2010. The tests mainly included the calibration test of the experimental facility and the quantification test of condensation water. From the calibration test, the curvilinear relationship between testing time and the error of the experimental facility was obtained; the condensation rate was derived by the quantification collection test at the different periods.The results reveal that the experimental error and testing time could be fitted into the linear relationship. In 2010, the amount of condensation water is 200.68 kg at Qianxi Temple, which is a considerable amount; the condensation rate is the fastest in morning and the slowest at evening. The annual amount of condensation water fluctuated from 2006 to 2010 according to the analysis of previous research achievements, for the amount of condensation water varied with the annual climate change. Since 2008, the amount of condensation water has increased. The condensation rate of the Dazu Carved Stone which is located in the south is the fastest, and the Yungang Grottoes in the north is the slowest, and the Longmen Grottoes is situated between the this difference corresponds to the grottoes respective geographical position and the climatic conditions.

Organic Modification and Drilling Fluid Properties of Bentonite

HU Ji-Liang, DAO Shi-Xian, FU Fan, WANG Cheng-Biao

2011, 25(6): 1219-1222.

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Polymer A was synthesized by aqueous solution polymerization used acrylic acid and acrylamide with potassium persulfate as initiator. Organic modified bentonite sample was prepared by mixing extrusion method with polymer A as an organic modifier.The structure and morphology of the sample were examined by Xray diffraction (XRD), Fourier transform infrared spectroscopy(FT-IR) and scanning electron microscopy (SEM).The results show that the crystal spacing of the organic modified bentonite changes from 1.269 to 1.322 nm, and the organic modified bentonite still maintains the layered structure with organic groups in the layer.The organic modified bentonite was successfully prepared.Drilling fluids were prepared by this organic modified bentonite to study the fluid loss property and other properties.When the mass fraction was 4%, the viscosity of the drilling fluid was 5.5 mPa·s, and the fluid loss and lubrication coefficient were 13 mL and 0.13, respectively. The results show that the fluid loss and lubrication coefficient of the drilling fluid of organic modified bentonite reduce greatly and the rheology improves, compared with drilling fluid of ordinary sodium bentonite.

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