Showing papers in "Global geology in 2012"

Zircon U-Pb ages of Khanka Lake granitic complex and its geological implication

Abstract: Khanka Lake granitic complex is located in the southeastern margin of Jiamusi Massif,mainly composed of granodiorite,monzogranite and syenogranite.Zircon U-Pb dating by LA-ICP-MS technique indicates that the Yangtianzhainanshan and Shuangzishan plutons were emplaced with ages of 257±2 Ma and 215~212 Ma,respectively.The spatial and temporal distribution of granitoids reveals that they were related to the subduction of the Paleo-Asian oceanic plate and the post-collisional extensional environment of northeastern China.Considering other previously dating of granitic rocks,we proposed that the Jiamusi Massif and Khanka Massif commonly experienced three stages of magmatism in large scale(the Early Paleozoic,Permian and Triassic).The two massifs should be considered to constitute a single crustal entity.

Ore genesis and molybdenite Re-Os dating of Dashihe molybdenum deposit in Dunhua,Jilin

Abstract: Dashihe deposit is one of the large-size molybdenum deposits recently discovered in the southern margin of Xiaoxinganling——Zhangguangcailing molybdenum metallogenic belt.Deep ore bodies in this deposit are located in the top of porphyaceous granodiorite,veinlet-disseminated in shape.The near-surface ore bodies mainly occurred in the low-grade metamorphic rocks as molybdenite-bearing quartz veins.Molybdenum mineralization was controlled by the explosive breccia pipe and the fissures,and the mineralization and alteration are obvious in zonaition,belonging to porphyry molybdenum deposit.Re-Os dating of five molybdenite samples collected from the shallow ore bodies showed that the model ages as 182.1± 2.7 Ma~191.9±2.6 Ma,with the weighted mean age of 186.7±5.0 Ma,and MSWD=11.8,which indicates the deposit formed in Early Yanshanian.Combined with other obtained lithogenic and metallogenic ages from the Xiaoxinganling——Zhangguangcailing molybdenum metallogenic belt,it can be inferred that 160~190 Ma is a concentrated period for large-scale molybdenum mineralization of this belt.The content of Re in the molybdenite is 3.549~4.362 μg·g-1,indicating ore-forming materials derived from crustal sources.Comprehensive analysis showed that the Dashihe deposit might be resulted by the large-scale mineralization events of the Early Yanshanian in the area,and formed in the tectonic environment during the superposition and transformation of Paleo-Asian and Circum-Pacific tectonic domains.

Geological and geochemical characteristics and genesis of ferromolybdenum deposit in Wudaoling,Heilongjiang Province

Abstract: Wudaoling ferromolybdenum deposit is a typical skarn deposit in Lesser Xing'an range-Zhangguangcai range metallogenic belt.Orebodies are hosted in skarn zone between pyritized quartz porphyry,alterated product of alkali-feldspar granite,with tuffaceous sandstone and acid tuff of Wudaoling Formation.The mineral assemblage of skarn was composed of garnet,diopside,actinolite and epidote,etc.The orebodies are irregular in shape,and characterized by branch and composite form.The types of ores included molybdenum,iron and pyrite ores.The alkali-feldspar granite and quartz porphyry closely related to mineralization,are metaluminous-peraluminous in nature,belonging high potassium calc-alkaline I-type granties.The granties were enriched in LILE(such as Rb,K,U) and depleted in HFSE(such as P,Ti),which was compatible with the geochemical characteristics of subduction granites.LA—ICP—MS U—Pb zircon dating showed that the formation age of quartz porphyry and alkali feldspar granites were 193.6±1.1 Ma and 193.9±1.3 Ma,respectively.Combining with regional geological evolution characteristics,the authors suggested of that the formation of Wudaoling ferromolybdenum deposit was related to the extended environment after subduction of the ancient Pacific Plate.The metallogenic epoch was Early Jurassic(186±2 Ma) and genesis belonged to skarn type.

Geochemical characteristics and tectonic significance of Late Carboniferous volcanic rocks in Benbatu Formation of Sonid Youqi,Inner Mongolia

Abstract: The volcanic rocks of Benbatu Formation in Sonid Youqi mainly consist of basaltic-andesite and andesite with a little daciteZircon U——Pb isotopic dating reveals the andesite formed in 3009±16 MaThe volcanic rocks generally belong to the tholeiitic series with low K and comparatively high Fe in geochemical characteristicsTrace elements are characterized by REE weak fractionation,incompatible elements(Th,U,La,Ce) enrichment and HFSE(Nb,Ta,Ti) depletion,which is similar to the StKitts island arc volcanic rocksThe rocks of Benbatu Formation show Eu in negative anomaly and Sr in low content,indicating the magma evolution experienced plagioclase fractional crystallization,which also led to the rocks poor in Al and rich in NaThe volcanic rocks of Benbatu Formation in Sonid Youqi area originated from the partial melting by the subduction of mantle wedge,and the formation of the rocks is related to the subduction of Paleo-Asian Ocean plate

Present status of oil shale resource utilization in the world and its development prospects

Abstract: Because of the increasing of oil price and the shortage of conventional oil and gas resources,the oil shale of unconventional oil and gas resources may become the important oil complementary and alternative energy in the 21th century due to its rich resources,its economy and its feasibility of development and utilization.Approximately 70% of the proven reserves of the world's shale oil resources converted by oil shale is distributed in the United States followed by China,Russia,Brazil,Canada,Jordan,Australia and Estonia,etc.,while over 85% oil shale of China is in Jilin,Liaoning and Guangdong provinces.Along with the increasing attention on the development and utilization of oil shale,the oil shale reserves,shale oil production and economic value of oil shale have showed the growth trend,and the support of corresponding policy have also increased.

Conodonts and their age from Carboniferous Lujuantun Formation of Qijianfang section in Panshi,Jilin Province

Abstract: Conodonts are found in two samples collected from the upper part of Qijianfang section in Panshi of central Jilin Province,including Declinognathodus bernesge,D.inaequalis,D.noduliferous sensu lato and D.praenoduliferous.This fauna clearly indicated that the the sampled strata were the early Bashkirian of Late Carboniferous,precisely from the upper D.praenoduliferous zone to lower D.noduliferous zone.The intermediate line of Carboniferous was determined in the interval of the Lujuantun Formation in Jilin.

Discovery of Ordovician pluton in Abaga Banner, Inner Mongolia and its geological significance

Abstract: Geri Obo complex pluton in Abaga Banner is located in northern Hegenshan fault belt,and consists of quartz diorite,granodiorite and biotite monzogranite,in which the monzogranite is the major rocksBy LA——MC——ICP——MS zircon U——Pb dating,the monzogranite 206Pb/238U age was 449±30 Ma,showing the Late OrdovicianGeri Obo pluton had high-K calc-alkaline characteristics,and enriched in LREEThe trace elements were depleted in Ba,Sr,Nb,Ta,P,Ti,but enriched in Rb,Th,U,K,Nd and Zr,showing Geri Obo pluton formed in active continental margins,and might be related to the subduction event in southern Sonid zuoqi

Reverse time migration with source wavefield reconstruction and wavefield decomposition

Abstract: Reverse time migration has become a standard imaging tool of complex structure such as salt model,strongly steep reflector and nappe structure,for their high precision,adapting to strong velocity variation and being free of reflector angle.The imaging condition requires the source wavefield and receiver wavefield could be obtained simultaneously,which could result in storage shortage and tremendous I/O time when large-scale data is faced.The imaging condition could also arouse low frequency artifacts in wave propagation path.Thus,a RTM scheme is proposed.To the storage and I/O problem,we use source wavefield reconstruction to ensure that the source wavefield and receiver wavefield can be available simultaneously.It means that in the forward modeling of source wavefield,we only need to store the wavefield around the imaging region and that of the last two time slices as boundary condition and initial condition of reconstruction.This strategy could decrease storage and I/O requirements greatly.We also combine up-down,left-right going wavefield decomposition imaging condition with Laplace filter to remove the artifacts of RTM.This method works well in testing.The significance of this scheme is that it could improve the method of removing artifacts in RTM,which could help to deal with the complex geological structure and give a high-quality image,and with the use of source wavefield reconstruction,it can decrease the storage and I/O time of RTM greatly.

Characteristics and genesis of Neoarchean granitic complex in Xingcheng of western Liaoning

Abstract: Neoarchean granitic complex in Taili area of Xingcheng in western Liaoning,was an important part of Neoarchean granitic crust in North China craton,and divided into two types: the biotite-feldspar gneiss and granodioritic gneiss.All granodioritic gneiss was "fuzzy" in gradual transition without general characteristic of intrusive body.Granodioritic gneiss and biotite-feldspar gneiss mixed with eath other,indicating coordinated deformation or transitional relationship.Micro fabric research showed that the two types of gneiss can be divided into two different types of structural phase for each:native structure phase and neonatal structure phase.The content of neonatal structure phase was increasing and the native structure phase was decreasing gradually from biotite-feldspar gneiss to granodioritic gneiss.In major elements,the two types of gneiss had linear distribution trend in SiO2 with MnO,CaO,TiO2,Fe2O3 and MgO with similar characteristics in trace and rare earth elements.The granodioritic gneiss belongs to anatectic granite in genesis,and their source rocks might be a metamorphosed greywacke.

Geotectonic setting of Songliao block∶ reatriction from Paleozoic detrital zircon U——Pb dating

Abstract: The authors studied the detrital zircon aging from the Upper Paleozoic Zhesi Formation in southern Songliao block.The U——Pb dating of detrital zircon from the Zhesi Formation by LA——ICP MS technique showed 4 major age groups: 263~378 Ma(peak age as 274 Ma);405~547 Ma(peak age 515 Ma);660~974 Ma(peak age 923 Ma);and the fourth group including 1 165 Ma,1 369 Ma,1 476 Ma and 1 517 Ma.The youngest zircon age of 263±2 Ma represents the lower limit of the deposition age of the Zhesi Formation,in which the peak age 274 Ma is consistented with the ages of the surrounding volcanic rocks and island arc magmatic rocks in Dashizhai Formation.The peak age 515 Ma showed the age of the Pan-African metamorphic complex in NE China.The rest old ages reflect the information of basement in Songliao block.Considered the ages of the detrital zircon aging of the Upper Paleozoic strata such as the Tumenling Formation in northern Songliao block,Benbatu Formation in western Songliao block and Heilongong Formation in eastern Songliao block,it is suggested that the Songliao block had Archean and Proterozoic metamorphic basement,providing rich source of material for the Paleozoic sediments.The fact indicats that the Songliao block was more likely a stable micro continental block rather than long-term activities of orogenic belt.

Distribution of regional geochemical elements and combination anomaly method

Abstract: On the basis of comparing with single-element anomaly method,taking 1/200,000 geochemical exploration data of Baishan area in Jilin as the example,the authors studied the spatial quantitative combination anomaly model,established the medium-large scale factor Pan-Kriging model in this area,applied DEM to express 3D element spatial distribution model and gave out geological interpretation with multi-elements spatial distribution and spatial quantitative combination anomaly methods.The results showed the multi-spatial quantitative combination anomaly method was higher in accuracy,better in internal structure and correlation and more in geo-information than traditional single element method,especially the three-dimension expression of DEM was more intuitive.

Application of multivariate regression analysis method in porosity calulation of volcanic clastic rock

Abstract: Volcanic clastic rock reservoirs are complex in lithology and logging data,large in distribution regions,and multiple in layers,which lead to the difficulty on logging data determination.On the basis of accurately identification the lithological characters,the authors took the volcanic clastic reservoirs in Wuerxun-Bell depression of Hailar Basin as an example,did pretreatment of the logging data and calculated the theoretical skeleton parameters based on core analysis.Then,the authors applied multivariate regression method in porosity calculation and returned statistical formula based on the relationship among porosity with neutron,density and sound wave,which realized the porosity calculation of volcanic clastic reservoirs by multivariate regression method.The result was similar with porosity by core analysis(error=1.6%),and met the reservoir calculation requirement.

Ores genesis in Jinchuan Ni——Cu——(PGE) sulfide deposit: evidence from geochemistry of platinum group elements

Abstract: The authors studied the different types of ores in I and II mining areas of Jinchuan Ni——Cu——(PGE) sulfide deposit,and particularly the distribution pattern of platinum group elementsThe ∑PGE in disseminated ores,net-textured ores and massive ores reduced gradually with the same trend in the mining area of orebodies Nos24,1 and 2 from the west to the eastThe sulfide melt of massive ores had fuller PGE differentiation than disseminated ores and net-textured oresThe distribution of platinum group elements in massive ores showed that they were controlled by sulfide melt fractional crystallization,and the separation of monosulfide solid solution(MSS)The study showed that the disseminated ores were the results of rapid condensation and the in situ sulfide melting from the magma fractional crystallizationThe net-textured ores formed by the sulfide melt fractional crystallization in the deep segregationThe study of quantitative simulation showed that the massive ores in different orebodies formed by the varying degrees of MSS fractional crystallization excluding the role control of R-factor

Dynamic metamorphism of argillaceous rocks of Permian Linxi Formation in Linxi region,Inner Mongolia

Abstract: Linxi area in the middle of Inner Mongolia developed north-east trend tectonic belt near the Siramulen River suture,leading to dynamic metamorphism of partial Linxi Formation statra,and outside the belt was not subjected to dynamic metamorphism.In the dynamic metamorphic belt developed cleavage,and in the metamorphic mudstone and in the muddy siltstone occurred intense tectonic replacement.Intensity of deformation and metamorphism in the metamorphic belt is uneven with quartz veinlets penetrated.Some parts with strong deformation and metamorphism formed two-mica schist,and its metamorphic mineral assemblages is composed of Bt+Ms+Chl+Pl+Q,in which biotite is chemically composed of Fe2+(1.38%~2.63%),Mg2+(1.93%~2.47%) and K+(0.96%~1.38%);muscovite consists of Si4+(6.13%~6.78%),Al[Ⅳ](1.22%~1.87%) and K+(0.93%~1.46%).According to the estimation of the two-mica geothermometer,the PT condition of dynamic metamorphism are 0.3 GPa and 480 ℃.Some parts are only in brittle deformation,with no new metamorphic minerals occurced;and are only in deformation withnot metamorphism.The study of dynamic metamorphism provided the geological basis for the assessment of the Upper Paleozoic oil and gas resources in the Songliao Basin and its peripheral.

Two types of mineralization and genesis in Sarekoubu——Tiemurte area of Altay Xinjiang

Abstract: The Sarekoubu——Tiemurte deposits in southern Altay of Xinjiang occurred in metamorphic rocks of Lower Devonian Kangbutiebao Formation.The Zn——Pb(Cu) mineralization related to the Early Devonian marine volcanic deposition Zn——Pb(Cu) and the late Devonian——Early carbonifeneus quartz veins mineralization related to the collisional orogeny.The former is represented by the VMS type Tiemurte Zn——Pb(Cu) deposit,and the latter by the orogenic type Sarekoubu gold deposit,and the vein mineralization related to orogeny superposed in the VMS deposit.Based on the study and comparison of stable isotope characteristics of the two types of mineralization,combined with the deformation and metamorphism of mineralization and fluid inclusions,the authors discuss the metallogenic minerals,fluids and ore genesis.The carbonic(CO2-CH4——N2) fluids inclusions are widely developed in the sulfide quartz veins of the Sarekoubu deposit and the Cu-bearing quartz veins in late stage of Tiemurte deposit,indicating that the carbonic fluid inclusions are related to the hydrothermal fluid of collision orogeny.In the Tiemurte Zn——Pb(Cu) deposit,the δ34S values of sulfides in VMS ores range from-26.46×10-3 to-19.72×10-3,indicating that the sulfur mainly from the inorganic reduction and bacterial reduction of seawater sulfate.The δ34S of sulfides from late superimposed veins is closed to the δ34S values of sulfides in Sarekoubu gold deposit,indicating a deep source of sulfur in the ores.The δDH2O and δ18OH2O in the Sarekoubu gold deposit and Tiemurte Zn——Pb(Cu) deposit indicate the fluids in collision orogeny were related with the magmatic activity and metamorphism.δ13C values of CO2 in carbonic inclusions range from-21.15×10-3 to-7.51×10-3,and those of CH4 range from-34.11×10-3 to-28.38×10-3 in Sarekoubu gold deposit.Whereas,δ13C values from inclusions in late Cu-bearing quartz veins in the Tiemurte range from-8.02×10-3 to-6.99×10-3,δ13C show a deep source or magma source that is not related with marine volcanic sedimentary.

Zircon U-Pb age of Hulin Pluton in Heilongjiang Province and its geological implication

Abstract: A new zircon LA-ICPMS U-Pb data of hornblende-bearing granodiorite from Shiqingshan quarry in Hulin revealed that the Hulin Pluton was emplaced during Early Cretaceous(118 Ma).Petrography and geochemistry of the Pluton and geological evidence of regional tectonic evolution suggest that the formation of Hulin Pluton was related to the subduction of the Pacific Plate.

Mine environmental assessment by analytic hierarchy process——taking Fuxin mine as example

Abstract: On the basis of remote sensing investigation results in Fuxin mine,the authors do mine environmental assessment by analytic hierarchy process,analyze the weight through judgement matrixes,and then establish evaluation grade by weighted computing after consistency check.Mine geological remote sensing assessment system consisting of index,method and levels has been proposed,and taking Fuxin mine as an example to test the system.The result shows that the assessment data by the system were credible and reasonable.

Reserch on hydrocarbon accumulation condition and distributive regulation of Siberian platform,Russia

Abstract: Siberian platform of Russia has tremendous potential prediction in hydrocarbon but poor in exploration research.The platform is one of the important target areas of overseas hydrocarbon exploration and for the CNPC.On the basis of the types of tectonic units,the comprehensive analysis results of hydrocarbon accumulation condition,trap type and hydrocarbon distribution characteristics,show that the key factors that controlling the hydrocarbon distribution of Siberian platform are tectonic action and the characteristics of strata and source rocks;the model of hydrocarbon accumulation is characterized by being generated and reserved indigenously.Hydrocarbon reservoirs mainly distributed in uplifted areas of cratonic margin without shield and depressions of continental margin,the former hydrocarbon enriched layer lay in Permian-Jurassic,and the latter in Vendian-Cambrian.The main type of hydrocarbon reservoir is stratigraphical-structural composite.

Confirmation of Late Triassic A-type granite and their geochemical constraints on structural setting in eastern Heilongjiang

Abstract: The study of petrology and element geochemistry indicated that there were aluminous A-type granites during Late Triassic in the Wuying——Tangwanghe area of eastern Heilongjiang Province.The granites are composed of syenogranite-alkaline feldspar granites and alkaline granites,equivalent to the late-collision extension proposed by Liegeois,indicating the ending of orogenic event and the beginning of new interaplate environment.The whole rock Rb——Sr isochronal age shows the granites formed in Late Triassic,representing the post-orogenic extension of Jiamusi plate and Songnen——Zhangguangcai plate along with Jiayin-Mudanjiang suture zone during Late Triassic,which indicated the ending of the evolvement of Paleo-Asia Ocean structural zone,and the begining of eastern Heilongjiang into the interaplate evolution of littoral-Pacific structural zone.

Zircon LA-ICP-MS U——Pb dating of diorite-porphyrite from Sishanlinchang gold deposit in Heilongjiang and its geological significance

Abstract: Sishanlinchang ore deposit is a typical gold deposit in sulfide quartz vein type,and found in Bindong area in recent years.The authors studied the zircon of diorite-porphyrite closely related to mineralization,which results show that the zircon U——Pb dating in diorite-porphyrite can be inducted six groups i.e.1 057±9 Ma,199±2 Ma,144~148 Ma,115±2.7 Ma,111.6±1.7 Ma(n=6,MSWD=0.55,probability=0.77)and 107.3 ±2.8 Ma(n=3,MSWD=0.088,probability=0.92).Combined with considerations of the development of the regional thermal event of magma,the authors suggested that diorite magma emplaced in 115~107 Ma,and its evolution underwent the strong contamination by granitic rock in Mesoproterozoic and Early Jurassic.The mineralization occurred in the conversion stage from later Early Cretaceous to Late Cretaceous,and its metallogenetic and diagenetic background was related to mid-acid granitic magmatism by the subduction of the Pacific plate.

Unconformity characteristics and geological significance in key tectonic revolution stage of Tarim Basin

Abstract: Tarim Basin suffered seven key tectonic revolution stages since Ordovician,including the episode Ⅰ of middle Caledonian,episode Ⅲ of middle Caledonian,early Hercynian,late Hercynian,Indo-Chinese,middle Yanshan and late Yanshan-Himalayan,and generated seven important unconformities with different types and characteristicsThrough seismic profile recognition,logging analysis and core observation,the authors considered that these unconformities appeared in parallel,superimposed,folded,fault-folded,ancient karst and palaeo-erosion unconformities in typeAssociated with the evolution of the Tarim Basin,unconformities changed constantly in geometric shape,space and timeAccording to these changes,the authors considered that the unconformities were characterized by superimposition and composition in geometric shape,lamination and difference in space,and migration in timeThe unconformities characteristics in Tarim Basin had close relationship with tectonic movement,erosion time and palaeo-sedimentary environment

Characteristics of fluid inclusions and its significance for ore prospecting of the Ciweigou gold deposit in Yanbian Region

Abstract: The Ciweigou gold deposit is one of typical low-sulphidation epithermal gold deposits in NE China.In order to determine its physical and chemical conditions and ore-forming depth,the microthermometric and laser raman spectrum analysis of fluid inclusions in the quartz and calcite from the same auriferous quartz-calcite vein in different levels are carried out.There are major gas-liquid two-phase and small amount of liquid phase fluid inclusions in auriferous quartz-calcite vein.The homogenization temperature of the two-phase inclusions ranges from 112.2 ℃ to 377.7 ℃ and mainly from 200 ℃ to 240 ℃;the salinity ranges from 0.18%NaCl to 10.87%NaCl,and the average value is 3.43%NaCl;the density changes from 0.57g/cm3 to 1.00 g/cm3 and the average is 0.89 g/cm3.Together with the Raman spectra of gas phase in fluid inclusions,characteristics of the fluid inclusions show that the ore-forming fluid belongs to NaCl-H2O(CO2) hydrothermal system with low temperature,salinity and density.According to the microthermometric data,the value of ore-forming pressure can be estimated from 7.99 to 37.89 MPa and the mean value is 14.92 MPa.The depth of the mineralization is from 0.27 to 1.26 km,averaging 0.50 km.Based on the comparision between the Ciweigou deposit with other epithermal gold deposits,it can be concluded that the small denudation depth of the Ciweigou deposit demonstrates the preferable ore prospecting in this deposits.

Research and development of database management system for shallow geothermal energy resource based on C# and SharpMap

Abstract: Through the research and development for database management system,it is applied to the actual engineering of shallow geothermal energy resource database management system in XX region.Based on the analysis of the function and requirement for the database management system,every function of this system was accomplished with Microsoft Visual Studio 2008 as the developer platform,C# as the development language,and open sourced SharpMap as GIS tool of map operation.The system provides the tool for globally knowing the occurrence state of the shallow geothermal energy resource in XX region,and it is helpful for reasonable planning,developing,exploiting and managing the resource.

Characteristics of source rocks and their potential evaluation in Ta'nan sag of Tamtsag Basin,Mongolia

Abstract: The potential evaluation of source rocks is important for the oil and gas exploration,especially for the lithologic reservoir exploration,and should be considered many factors.Limited by the actual conditions of Ta'nan sag,the authors choose five indicators including hydrocarbon source rock thickness,organic carbon content,kerogen type,pyrolysis index and organic matter maturity,to evaluate the characteristics and hydrocarbon generation potential of source rocks in Early Cretaceous Tongbomiao-,Nantun-and Damoguaihe formations.The study of indicators show that the source rock characteristics are good in general for the studied area,in which the Nantun Formation is the best for source rocks,followed by the Damoguaihe Formaiton,and Tongbomiao Formation which is the worst.By the means of " direct multiplication",the authors comprehensively queued the nine sub-layers in this area according to the hydrocarbon generation potential of source rocks,the best source rocks developed in the SQ3-3 sub-layer in Nantun Formation and the worst source rocks developed in I oil group in Tongbomiao Formation.In sequence of the hydrocarbon generation potential of source rocks from best to worst is the SQ3-3,SQ3-2,SQ3-5,SQ3-1,SQ3-4,SQ4-1,II oil group,SQ4-2 and I oil group.

Geochemistry and petrogenesis of Weihe granites batholith in northern Zhangguangcai range

Abstract: The analysis of geology,petrography,major and trace elements,zircon Hf isotop data of Weihe granites batholith in northern Zhangguangcai range shows that the batholith is composed mainly of granodiorite,adamellite,orthoclase and aklali-feldspar granite with a few quartz diorite and tonalite.Intrusive contact relationship has been recognized among different rock types.Geochemical analysis shows that the granites are rich in silicon and potassium contents,belonging to quasi-aluminous and weakly peraluminous rocks(A/CNK=0.97~1.03).The alkaline(K2O+Na2O) is 6.56%~9.10% in contents,ascribed to high-K calc-alkaline series I-type granite.Rare and trace earth elements of the granites are rich in LREE,Rb,Th,U,K,Hf and depleted in Nb,Ta,P,Ti.Chondrite-normalized REE display moderate negative to slight positive Eu anomalies.Variable zircon Hf isotope composition(eHf(t)=(-6.68~+12.13,TDM2=464~1 675 Ma) shows that the magma origrinated from the basic crusts which accreted from depleted mantle during the Phanarozoic and Neoproterozoic,and assimilated older crust locally.

Organic geochemical characteristics and geological significance of oil shales in Dalazi Formation of Luozigou Basin

Abstract: The authors studied the organic geochemical parameters of oil shales from upper Dalazi Formation of Luozigou Basin by kerogen microscopy,rock-pyrolysis,GC and GC-MS analysis,and discussed the organic geochemical characteristics and geological significance of oil shales in Luozigou Basin.Oil shales were formed under sedimentary environment of fresh-slight saline water reduction,based on the analysis of some patameters including Pr/Ph ratio,gammacerane,pregnane,diasterane and diahopane.Comprehensive analysis of maceral microscopy,rock-pyrolysis and sterans(C27—C29) distribution showed that the oil shales organic matters were mixed source input in the studied area.Rock-pyrolysis,Ro,isomerized degree of sterane and C31 homoterpane,C29 morpane/C29 hopane,and Ts/Tm showed that the oil shales were immature to low mature in their evolutionary stage.

Yitonghe fault and its stability estimation

Abstract: The estimation on the distribution and risk of Yitonghe faults plays an important role in civil development and planning of Changchun CityBased on regional geological survey and geophysical data,the authors have confirmed that the Yitonghe faults distribute in north-south trending with west dipping and large dip angle,which was used the methods of surface electric survey,ground penetrating radar detection and reflection seismic surveyThrough the radar detection,the authors infer the Yitonghe faults as Quaternary active faults,cutting off the Cretaceous formations,and define the Yitonghe faults as high torsional faults in Yitonghe erosion valleySince Quaternary,especially the late Pleistocene,the Yitonghe faults have tended to stable,with small probability of moderate-strong earthquakes

Cenozoic petrified woods from Suranaree area of Nakhon Ratchasima,northeastern Thailand and their implication on paleoenvironment

Abstract: The Miocene-Pleistocene petrified woods are very abundant and well preserved in the area of Suranaree subdistrict,Nakhon Ratchasima,northeastern Thailand.Twenty three specimens of the petrified woods have been studied by the authors,and determined to comprise at least 17 species of 10 genera,including 13 eudicot angiosperm taxa assigned to 7 genera of 6 families.The taxa are Canarium sp.(Burseraceae);Terminalia sp.vel Combretum sp.,Terminalia sp.(Combretaceae);cf.Irvingia sp.(Irvingiaceae);Cynometroxylon holdeni,Cynometroxylon sp.,cf.Cynometroxylon spp.,cf.Millettia spp.(Leguminosae);Careya spp.(Lecythidaceae);and Azadirachta sp.(Meliaceae),etc.In addition,there are 4 taxa(incertae sedis) needed further study.The highly diverse paleoflora shows a close resemblance in the floristic characters to the modern flora of mixed deciduous,dry dipterocarp,and dry evergreen forests in northeastern Thailand,which implies that the paleoclimate in the area was probably tropical wet and dry,corresponding to the present climate but with higher humidity.

Experiment on dielectric property of LNAPL contaminated soil——a case study in quartz sand

Abstract: In order to study the dielectric property of light non-aqueous phase liquid(LNAPL) contaminated soil,the authors simulate LNAPL contaiminated soil by quartz sand(particle size 0.106～0.212 mm),diesel and water under laboratory condition,and then use the open-ended coaxial probe method to detect the dielectric constant in the contaiminated soil by high frequency electromagnetic wave(200 MHz～3 GHz) and analyze the change regulation of soil-water volume content with the relative dielectric constant.The experimental results showed that relative dielectric constant of non-saturated quartz sand raised with the increasing of volumetric water content and oil content,but the variation of dielectric constant was not obvious with the increasing of oil content when the sand was saturated.The relative dielectric constant of the contaminated non-saturated soil increased first,and tended to stable later as time prolonged.

Fluid inclusions and genesis of Daheishan molybdenum deposit in Jilin

Abstract: Daheishan super-large molybdenum deposit of Jilin is one of the porphyry molybdenum deposits in central Asia——Hinggan Mongolian orogenic belt.The ore bodies are yielded in the Yanshanian granodiorite porphyry and unequal particle granodiorite,and closely related with Toudaogou metamorphic volcanic rocks of Lower Paleozoic.The research on fluid inclusions showed that the samples mainly developed gas-liquid two-phase inclusions and daughter minerals-bearing three-phase inclusions in Daheishan deposit.The ore-forming fluids reflected a continuous evolution process,forming gas-liquid two-phase aqueous inclusions and daughter minerals-bearing three-phase inclusions in early-middle stage,and the homogenization temperatures between 300 ℃~460 ℃ and fluid salinity between 1.7 wt%~49.92 wt% NaCl eqv.In this stage,the fluids underwent decompression and boiling action and resulted in laege-scale mineral precipitation,which was also the main mineralization stage.In later stage,gas-liquid two-phase aqueous inclusions were developed mixing with meteoric water.The homogenization temperature is 196.5 ℃~300 ℃ and fluid salinity is 1.7 wt%~7.1 wt% NaCl eqv,belonging to H2O-NaCl system.Fluid boiling action was the main mechanism of metal sulfides precipitate.The Daheishan molybdenum deposit formed in the continental marginal arc environment.