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东昆仑骆驼峰地区中晚三叠世花岗岩年代学、地球化学及构造意义 预览
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作者 顾焱 钱烨 +3 位作者 李予晋 赵梦琪 刘雷 孙丰月 《矿产勘查》 2019年第4期724-736,共13页
骆驼峰地区位于东昆仑造山带昆北弧后裂陷带,其内发育大量记录古特提斯洋演化的岩浆岩。本文对该地区花岗闪长岩和钾长花岗岩进行了年代学和地球化学研究,用以限定古特提斯洋的构造演化。LA-ICP-MS锆石U-Pb测年结果表明花岗闪长岩形成... 骆驼峰地区位于东昆仑造山带昆北弧后裂陷带,其内发育大量记录古特提斯洋演化的岩浆岩。本文对该地区花岗闪长岩和钾长花岗岩进行了年代学和地球化学研究,用以限定古特提斯洋的构造演化。LA-ICP-MS锆石U-Pb测年结果表明花岗闪长岩形成于中三叠世(233Ma),钾长花岗岩形成于晚三叠世(218Ma)。花岗闪长岩和钾长花岗岩分属于中钾钙碱性-高钾钙碱性系列和钾玄岩系列,A/CNK值为0.92-1.02,具有偏铝质花岗岩类属性。两类岩石均具有负铕异常、稀土总量低、轻稀土明显分馏和铕弱异常的特点。花岗闪长岩富含大离子亲石元素、亏损高场强元素,具有火山弧花岗岩特征,为古特提斯洋俯冲消减作用的产物。钾长花岗岩具有相对较高Nb、Ta和Rb含量,显示出同碰撞花岗岩的特征,暗示古特提斯洋在早三叠已经闭合进入陆陆碰撞阶段。两类岩石记录了古特提斯洋俯冲到消亡的构造体制的转换。 展开更多
关键词 年代学 地球化学 构造体制转换 骆驼峰地区 东昆仑
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Subduction zone geochemistry 预览
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作者 Yong-Fei Zheng 《地学前缘:英文版》 CAS CSCD 2019年第4期1223-1254,共32页
Crustal recycling at convergent plate boundaries is essential to mantle heterogeneity.However,crustal signatures in the mantle source of basaltic rocks above subduction zones were primarily incorporated in the form of... Crustal recycling at convergent plate boundaries is essential to mantle heterogeneity.However,crustal signatures in the mantle source of basaltic rocks above subduction zones were primarily incorporated in the form of liquid rather than solid phases.The physicochemical property of liquid phases is determined by the dehydration behavior of crustal rocks at the slab-mantle interface in subduction channels.Because of the significant fractionation in incompatible trace elements but the full inheritance in radiogenic isotopes relative to their crustal sources,the production of liquid phases is crucial to the geochemical transfer from the subducting crust into the mantle.In this process,the stability of specific minerals in subducting crustal rocks exerts a primary control on the enrichment of given trace elements in the liquid phases.For this reason,geochemically enriched oceanic basalts can be categorized into two types in terms of their trace element distribution patterns in the primitive mantle-normalized diagram.One is island arc basalts(IAB),showing enrichment in LILE,Pb and LREE but depletion in HFSE such as Nb and Ta relative to HREE,The other is ocean island basalts(OIB),exhibiting enrichment in LILE and LREE,enrichment or non-depletion in HFSE but depletion in Pb relative to HREE.In either types,these basalts show the enhanced enrichment of LILE and LREE with increasing their incompatibility relative to normal mid-ocean ridge basalts(MORB).The thermal regime of subduction zones can be categorized into two stages in both time and space,The first stage is characterized by compressional tectonism at low thermal gradients.As a consequence,metamorphic dehydration of the subducting crust prevails at forearc to subarc depths due to the breakdown of hydrous minerals such as mica and amphibole in the stability field of garnet and rutile,resulting in the liberation of aqueous solutions with the trace element composition that is considerably enriched in LILE,Pb and LREE but depleted in HFSE and HREE relative to normal M 展开更多
关键词 SUBDUCTION zone BASALTS Element mobility Geochemical differentiation CRUSTAL METASOMATISM MANTLE GEOCHEMISTRY
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Ophiolites of the Central Asian Orogenic Belt:Geochemical and petrological characterization and tectonic settings 预览
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作者 Harald Furnes Inna Safonova 《地学前缘:英文版》 CAS CSCD 2019年第4期1255-1284,共30页
We present a compilation of published data(field,petrography,ages and geochemistry)from 73 ophiolitic complexes of the Central Asian Orogenic Belt.The ophiolitic complexes,ranging in age from Neoproterozoic to Triassi... We present a compilation of published data(field,petrography,ages and geochemistry)from 73 ophiolitic complexes of the Central Asian Orogenic Belt.The ophiolitic complexes,ranging in age from Neoproterozoic to Triassic.have been geochemically classified as subduction-related and subductionunrelated categories applying recent,well-established discrimination diagrams.The subductionunrelated category is further subdivided into Mid-Ocean Ridge type(MOR),a common rift-drift stage and Plume type,and the subduction-related category is subdivided into Backarc(BA),Forearc(FA).Backarc to Forearc(BA-FA)and Volcanic Arc(VA)types.The four subduction-related types define highly different geochemical features,with the BA and FA types defining end members showing subduction influence of 10%-100%and 90%-100%subduction influence,respectively,and the two other types(BAFA and VA)define values between the two end members.The subduction-related category comprises79%of the examined ophiolites,of which the BA type ophiolites is by far the dominant group,followed by the BA-FA type,and with FA and VA types as subordinate groups.The Neoproterozoic and Ordovician complexes exhibit the highest,whereas those of Silurian age exhibit the lowest subduction-influence.Of the remaining 21%subduction-unrelated ophiolites,the MOR type dominates.Both the subductionrelated and subduction-unrelated types,in particular the latter,are commonly associated with alkaline basalts taken to represent ocean island magmatism.Harzburgite,dunite,gabbro and basalt are the common lithologies in all ophiolite types,whereas the BA-FA,FA and VA types generally contain intermediate to felsic rocks,and in the FA type boninites occur.The subduction-related ophiolites types generally show low metamorphic grade,whereas greenschist.amphibolite and blueschist grades occur in the subduction-unrelated and BA types.The highly different subduction contribution(from 0 to 100%in the MOR and FA,respectively),attest to variable dips of the subducting slab,as well as variable flux of s 展开更多
关键词 GEOCHEMICAL classification Subduction-unrelated UNITS Subduction-related UNITS SUBDUCTION fingerprint Intra-plate MAGMAS Arc erosion
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Identification model of geochemical anomaly based on isolation forest algorithm 预览
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作者 SHANG Yinmin LU Laijun KANG Qiankun 《世界地质:英文版》 2019年第3期159-166,共8页
The methods for geochemical anomaly detection are usually based on statistical models, and it needs to assume that the sample population satisfies a specific distribution, which may reduce the performance of geochemic... The methods for geochemical anomaly detection are usually based on statistical models, and it needs to assume that the sample population satisfies a specific distribution, which may reduce the performance of geochemical anomaly detection. In this paper, the isolation forest model is used to detect geochemical anomalies and it does not require geochemical data to satisfy a particular distribution. By constructing a tree to traverse the average path length of all data, anomaly scores are used to characterize the anomaly and background fields, and the optimal threshold is selected to identify geochemical anomalies. Taking 1∶200 000 geochemical exploration data of Fusong area in Jilin Province, NE China as an example, Fe2O3 and Pb were selected as the indicator elements to identify geochemical anomalies, and the results were compared with traditional statistical methods. The results show that the isolation forest model can effectively identify univariate geochemical anomalies, and the identified anomalies results have significant spatial correlation with known mine locations. Moreover, it can identify both high value anomalies and weak anomalies. 展开更多
关键词 ISOLATION FOREST model GEOCHEMICAL ANOMALY ROC CURVE Youden index
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Comprehensive geochemical/hydrochemical and geo-thermometry analysis of Unai geothermal field,Gujarat,India
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作者 Manan Shah Anirbid Sircar +3 位作者 Nahid Shaikh Karan Patel Darshan Sharma Dwijen Vaidya 《中国地球化学学报:英文版》 EI CAS CSCD 2019年第1期145-158,共14页
The knowledge of water temperature produced from a geothermal reservoir and its composition is of utmost importance in designing utilization strategies,the surface production facilities and in selecting the material t... The knowledge of water temperature produced from a geothermal reservoir and its composition is of utmost importance in designing utilization strategies,the surface production facilities and in selecting the material to be used.Unai hot springs are located in the southern part of Gujarat,India with discharge temperatures varying from 51 to 56℃.With the aim of developing Unai as a potential geothermal field and exploiting it in the future,geochemical and geothermometrical study was undertaken.The samples were collected from various Unai geothermal location and analysis of chemical composition of water obtained from different wells was done.The concentration of Silica,carbonate and ions like Na and C1 have been analyzed to delineate the path of water movement in the subsurface and classify the reservoir based on the enthalpy.The ratio of the concentration of ions like Na+ and K+ and the relative proportions of various sets of ions were also used to characterize the geothermal reservoir and the reservoir fluid by the use of ternary diagrams.Na-K-Ca,Chalcedony,quartz,and Silica geo-thermometers have been studied.The present study also envisages the importance of graphical representations like Piper diagram,Scholler etc.to determine variation in hydrochemical facies and to understand the evolution of hydrochemical processes in the Unai geothermal field respectively.The study yields the conclusion that the reservoir under consideration is a low enthalpy reservoir with temperature ranging from 60 to 80 ℃. 展开更多
关键词 GEOTHERMAL ENERGY Hydrochemical GEOCHEMICAL Geothermometery RENEWABLE ENERGY
Jurassic granitoid dike in Luodian,Guizhou Province:discovery and geological significance
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作者 Mingjin Zhu Aiguo Nie +2 位作者 Yazhou Tian Xinsong Wang Jun Sun 《中国地球化学学报:英文版》 EI CAS CSCD 2019年第1期159-172,共14页
In this paper,the Jurassic granitoid dike that intrudes into Permian diabase was reported in Luokun,Luodian County,south Guizhou.Zircon LA-ICP-MS U-Pb dating of the granitoid dike yielded an age of 164.3±2.4 Ma w... In this paper,the Jurassic granitoid dike that intrudes into Permian diabase was reported in Luokun,Luodian County,south Guizhou.Zircon LA-ICP-MS U-Pb dating of the granitoid dike yielded an age of 164.3±2.4 Ma with the εHf(t)range from +7.8 to +12.1.The high contents of SiO2 (65.2%-66.8%)and total alkali (Na2O +K2O:9.01%-9.95%),and low contents of Mg,Fe,Ca,P and Ti show the characteristics of alkali-rich granite.The total contents of rare earth elements range from 289.90 to 394.23 ppm.The Rb,Ba,K,Th,U and other LILE,Ta,Sr,P,Ti are enriched,and heavy rare earth elements are depleted.Petrogeochemical characteristics show that the dike was derived from a partial melting of newly-grown basaltic crust,and contaminated by crustal materials before experiencing strong fractional crystallization.The dike was formed in the intraplate post-oro-genic extension stage and indicates that parental magma rose to the shallow crust through a fault.This provides new evidence of tectonic and mantle-crest magmatic activities and may contribute to regional Au mineralization in southern Guizhou and neighboring areas. 展开更多
关键词 JURASSIC GRANITOID DIKE GEOCHEMICAL characteristics GEOCHRONOLOGY Luodian Guizhou province
Sedimentary and geochemical characteristics of the Triassic Chang 7 Member shale in the Southeastern Ordos Basin,Central China
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作者 Jing-Wei Cui Ru-Kai Zhu +1 位作者 Zhong Luo Sen Li 《石油科学:英文版》 SCIE CAS CSCD 2019年第2期285-297,共13页
The Ordos Basin is the largest petroliferous basin in China, where the Chang 7 Member shale serves as the major source rock in the basin, with an area of more than 100,000 km2 So far, sedimentary and geochemical chara... The Ordos Basin is the largest petroliferous basin in China, where the Chang 7 Member shale serves as the major source rock in the basin, with an area of more than 100,000 km2 So far, sedimentary and geochemical characterizations have rarely been conducted on the shale in shallow(< 1000 m) areas in the southeastern part of the basin, but such characterizations can help identify the genesis of organic-rich shale and promote the prediction and recovery of shale oil. In this paper,several outcrop sections of the Chang 7 Member in the Tongchuan area were observed and sampled, and sedimentary and geochemical characterizations were conducted for the well-outcropped YSC section. The study results show that the Chang7 Member shale is widely distributed laterally with variable thickness. The organic-rich shale is 7-25 m thick in total and exhibits obvious horizontal variation in mineral composition. In the eastern sections, the shale contains organic matter of TypeⅡ2-Ⅲ and is low in thermal maturity, with high clay mineral content, low K-feldspar content, and no pyrite. In the western sections, the shale contains Type Ⅱ1 organic matter and is low in thermal maturity, with high clay mineral, K-feldspar, and pyrite contents. The YSC section reveals three obvious intervals in vertical mineral composition and organic abundance.The Chang 7 Member organic-rich shale(TOC > 10%) contains mainly sapropelite and liptinite, with Type Ⅱ kerogen. It is generally characterized by a hydrocarbon potential of more than 70 mg/g, low maturity, and shallow-semideep lacustrine facies. In the western sections, the shale, still in a low maturity stage, has a higher hydrocarbon potential and is optional for shale oil recovery. However, the Chang 7 Member shale in the study area is highly heterogeneous and its shale oil recovery is practical only in the organic-rich intervals. 展开更多
关键词 ORDOS Basin CHANG 7 MEMBER oil Organic-rich SHALE SEDIMENTARY CHARACTERISTICS Geochemical CHARACTERISTICS
Geochemistry,Paleoenvironment and Mechanism of Organic-Matter Enrichment in the Lower Silurian Longmaxi Formation Shale in the Sichuan Basin,China 预览
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作者 CHEN Zhipeng CUI Junping +4 位作者 REN Zhanli JIANG Shu LIANG Xing WANG Gaocheng ZOU Chen 《地质学报:英文版》 SCIE CAS CSCD 2019年第3期505-519,共15页
To investigate the mechanism of the organic-matter enrichment in the Lower Longmaxi Formation shale,the geochemistry and total organic carbon(TOC)of the Longmaxi Formation black shales in the Jiaoshiba,Zhaotong,and We... To investigate the mechanism of the organic-matter enrichment in the Lower Longmaxi Formation shale,the geochemistry and total organic carbon(TOC)of the Longmaxi Formation black shales in the Jiaoshiba,Zhaotong,and Weiyuan areas of the Sichuan Basin were analyzed.Paleoproductivity proxy parameters(Babio,Siex,and Ni/Al),clastic influx proxies(TiO2 and Ti/Al),redox indices(V/Cr,Ni/Co,V/(V+Ni),and U/Th),and hydrothermal indicators(Fe,Mn,and Y concentrations;Fe/Ti ratio and a Ni-Zn-Co diagram)were employed to decipher the paleoenvironment of the Lower Longmaxi Formation shales.TiO2 and Ti/Al indicated low terrigenous detrital influx in all three areas.However,Babio,Siex,and Ni/Al indicated high productivity in the Jiaoshiba area.V/Cr,Ni/Co,and U/Th indicated higher oxygen content with larger fluctuations in the Zhaotong and Weiyuan areas.Fe,Mn,and Y concentrations and the Fe/Ti ratio implied greater active hydrothermal activity in the Weiyuan area.These heterogeneities were considered to be closely related to the paleoenvironment and paleogeography,and the large basement faults that developed during the Chuanzhong paleo-uplift could have provided vents for deep-hydrothermal-fluid upwelling.The redox indices(V/Cr,Ni/Co,and U/Th)and a paleoproductivity proxy(Ni/Al)displayed a significant correlation with the TOC,suggesting that both excellent preservation conditions and high paleoproductivity were the controlling factors for the enrichment of organic matter in the Longmaxi Formation shale.There was no obvious correlation between the clastic influx proxy(Ti/Al)and the TOC due to the extremely low supply of terrigenous debris.The hydrothermal indicator(Fe/Ti)was negatively correlated with the TOC in the Weiyuan area,indicating that hydrothermal activity may have played a negative role in the accumulation of organic matter.This study suggests that the enrichment of organic matter in the Longmaxi Formation marine shale varied according to the paleogeography and sedimentary environment. 展开更多
关键词 geochemical index organic-matter ENRICHMENT PALEOGEOGRAPHY hydrothermal fluid Sichuan Basin
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Geochemical evaluation of low salinity hot water injection to enhance heavy oil recovery from carbonate reservoirs
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作者 Ji Ho Lee Kun Sang Lee 《石油科学:英文版》 SCIE CAS CSCD 2019年第2期366-381,共16页
Although low salinity water injection(LSWI) has recovered residual oil after the conventional waterflood, highly viscous oil has remained in heavy oil reservoirs. Hot water injection is an economic and practical metho... Although low salinity water injection(LSWI) has recovered residual oil after the conventional waterflood, highly viscous oil has remained in heavy oil reservoirs. Hot water injection is an economic and practical method to improve oil mobility for viscous oil reservoirs. It potentially controls temperature-dependent geochemical reactions underlying the LSWI mechanism and oil viscosity. Therefore, this study has modeled and evaluated a hybrid process of low salinity hot water injection(hot LSWI) to quantify synergistic effects in heavy oil reservoirs. In comparison to seawater injection(SWI) and LSWI, hot LSWI results in more cation ion-exchange(Ca2+ and Mg2+) and more wettability modification. Hot LSWI also reduces oil viscosity. In core-scaled systems, it increases oil recovery by 21% and 6% over SWI and LSWI. In a pilotscaled reservoir, it produces additional oil by 6% and 3% over SWI and LSWI. Probabilistic forecasting with uncertainty assessment further evaluates the feasibility of hot LSWI to consider uncertainty in the pilot-scaled reservoir and observes enhanced heavy oil production. This study confirms the viability of hot LSWI due to synergistic effects including enhanced wettability modification and oil viscosity reduction effects. 展开更多
关键词 Low SALINITY WATER INJECTION Hot WATER INJECTION WETTABILITY modification GEOCHEMICAL reaction Viscosity reduction
Arsenic variability and groundwater age in three water supply wells in southeast New Hampshire 预览
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作者 Joseph P. Levitt James R. Degnan +1 位作者 Sarah M. Flanagan Bryant C. Jurgens 《地学前缘:英文版》 CAS CSCD 2019年第5期1669-1683,共15页
Three wells in New Hampshire were sampled bimonthly over three years to evaluate the temporal variability of arsenic concentrations and groundwater age.All samples had measurable concentrations of arsenic throughout t... Three wells in New Hampshire were sampled bimonthly over three years to evaluate the temporal variability of arsenic concentrations and groundwater age.All samples had measurable concentrations of arsenic throughout the entire sampling period and concentrations in individual wells had a mean variation of more than 7 μg/L.The time series data from this sampling effort showed that arsenic concentrations ranged from a median of 4 mg/L in a glacial aquifer well (SGW-65) to medians of 19 μg/L and 37 μg/L in wells (SGW-93 and KFW-87) screened in the bedrock aquifer,respectively.These high arsenic concentrations were associated with the consistently high pH (median ≥- 8) and low dissolved oxygen (median <0.1 mg/L) in the bedrock aquifer wells,which is typical of fractured crystalline bedrock aquifers in New Hampshire.Groundwater from the glacial aquifer often has high dissolved oxygen,but in this case was consistently low.The pH also is generally acidic in the glacial aquifer but in this case was slightly alkaline (median =7.5).Also,sorption sites may be more abundant in glacial aquifer deposits than in fractured bedrock which may contribute to lower arsenic concentrations.Mean groundwater ages were less than 50 years old in all three wells and correlated with conservative tracer concentrations,such as chloride;however,mean age was not directly correlated with arsenic concentrations.Arsenic concentrations at KFW-87 did correlate with water levels,in addition,there was a seasonal pattern,which suggests that either the timing of or multiple sampling efforts may be important to define the full range of arsenic concentrations in domestic bedrock wells.Since geochemically reduced conditions and alkaline pHs are common to both bedrock and glacial aquifer wells in this study,groundwater age correlates less strongly with arsenic concentrations than geochemical conditions.There also is evidence of direct hydraulic connection between the glacial and bedrock aquifers,which can influence arsenic concentrations.Correlations bet 展开更多
关键词 ARSENIC VARIABILITY GEOCHEMICAL time series Age tracers GROUNDWATER age MODELING
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Geochronology and Geochemistry of Li(Be)-Bearing Granitic Pegmatites from the Jiajika Superlarge Li-Polymetallic Deposit in Western Sichuan, China
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作者 Hongzhang Dai Denghong Wang +2 位作者 Lijun Liu Yang Yu Jingjing Dai 《地球科学学刊:英文版》 SCIE CAS CSCD 2019年第4期707-727,共21页
Strategic emerging minerals such as lithium,beryllium,niobium and tantalum are the most important rare metals currently,especially with the increasing demand of emerging industries on rare metals in China.The Jiajika ... Strategic emerging minerals such as lithium,beryllium,niobium and tantalum are the most important rare metals currently,especially with the increasing demand of emerging industries on rare metals in China.The Jiajika deposit with a complete Li-Be-Nb-Ta metallogenic series is the largest pegmatite type rare metal deposit in China at present.In this paper,systematic researches of geochronology and petrogeochemistry were carried out to understand the genetic relationships between mineralization and magma evolution in the Jiajika deposit,which might be helpful to further rare-element prospecting in Songpan-Garze area.Zircon LA-ICP-MS U-Pb dating yields a concordia age of 217±1.1 Ma and a weighted mean 206 Pb/238 U age of 217±0.84 Ma for the aplite from the No.308 pegmatite.Cassiterite LA-MC-ICPMS dating yields concordant ages of 211±4.6 Ma for the No.308 pegmatite vein and198±4.4 Ma for the No.133 pegmatite vein,indicating that the rare metal mineralization mainly occurred in the Late Indosinian Period,further suggesting that the granites,aplites and pegmatites in Jiajika formed during a relatively stable stage after the intense orogeny of the Indosinian cycle.The rare metal-bearing granitic rocks and pegmatites show a clear linear relationship between A/CNK and A/NK and are enriched in total alkalis and depleted in CaO,FeO,MnO,MgO,Ba and Sr.All barren rocks and mineralized rocks feature similar rare earth element and trace element geochemical patterns.Thus,these characteristics indicate that the aplites and pegmatites represent the highly differentiated products of the two-mica granite(MaG)in this area,which is the most likely parent magma.During the evolution of magma,strong alkali metasomatism occurred between the melt phase and the volatile-rich fluid phase;as a result,large-scale rare metal mineralization occurred in certain structural zones of the pegmatite veins in the Jiajika deposit. 展开更多
关键词 GRANITIC pegmmatites rare mmetals METALLOGENIC EPOCH geochemical characterizatiion Jia ajika
Distribution Patterns of Major and Trace Elements andProvenance of Surface Sediments on the ContinentalShelf off Western Guangdong Province andNortheastern Hainan Island 预览
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作者 GE Qian XUE Z. George +3 位作者 YE Liming XU Dong YAO Zhigang CHU Fengyou 《中国海洋大学学报:英文版》 SCIE CAS CSCD 2019年第4期849-858,共10页
A coupled approach based on grain size and geochemical elements is used to trace the provenance of surface sediments and to confirm the distribution patterns of grain size and elements on the continental shelf off wes... A coupled approach based on grain size and geochemical elements is used to trace the provenance of surface sediments and to confirm the distribution patterns of grain size and elements on the continental shelf off western Guangdong Province and northeastern Hainan Island. The mean grain size ranges from 0.05 φ to 7.28 φ with a mean value of 5.60 φ. The average concentra- tions of major elements descend in the order of SiO2 > Al2O3 > CaO > Fe2O3 > K2O > MgO > Na2O > TiO2 > P2O5 > MnO, while those of trace elements exhibit a descending order of Sr > Rb > Zn > V > Cr > Pb > Ni > Cu > As > Cd. On the basis of the distribution patterns of elements and results of statistical analysis, the study area is classified into three zones. Zone I locates on the continental shelf off western Guangdong Province, and the sediments are mainly from Pearl River, Taiwanese rivers, and small rivers nearby. Zone II locates in the eastern exit of Qiongzhou Strait and the coastal area off Leizhou Peninsula, and the sediments are mainly from the ero- sion products of Qiongzhou Strait and Hainan Island. Zone III locates off the eastern Hainan Island and the continental shelf deeper than 50 m isobaths, and the sediments are mainly from Hainan Island and coral reef. The influence from open water should also be considered. Results indicate that the grain size is the main controlling factor for major and trace element contents and that anthropo- genic impact and biological activity also play an important role in the distribution of these elements. 展开更多
关键词 grain size GEOCHEMICAL elements WESTERN Guangdong Province NORTHEASTERN HAINAN ISLAND controlling factor
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城市规划中土地质量地球化学评价的应用 预览
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作者 方志雷 《中小企业管理与科技》 2019年第16期102-104,共3页
论文综述了城市规划体系和土地质量地球化学评价体系的现状和难点,介绍了土地质量地球化学评估技术方法和分级标准的最新成果,并以某行政区为研究实例,在土地质量地球化学调查、质量评估的基础上,对该行政区的土地利用总体规划(2010-202... 论文综述了城市规划体系和土地质量地球化学评价体系的现状和难点,介绍了土地质量地球化学评估技术方法和分级标准的最新成果,并以某行政区为研究实例,在土地质量地球化学调查、质量评估的基础上,对该行政区的土地利用总体规划(2010-2020年)的规划方案提出相应调整意见。 展开更多
关键词 土地质量 地球化学 城市规划 分级标准
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青海督冷沟地区万保沟群火山岩地球化学特征 预览
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作者 延立波 《矿产勘查》 2019年第2期174-180,共7页
分布于青海督冷沟一带的万保沟群火山岩,是一套浅变质基性—中基性火山岩组合,以基性熔岩为主,通过对样品的综合分析,其主量元素特征表明该套火山岩主要为洋岛拉斑玄武岩系列,有向板内拉斑玄武岩过渡的趋势,稀土元素特征显现出与E型洋... 分布于青海督冷沟一带的万保沟群火山岩,是一套浅变质基性—中基性火山岩组合,以基性熔岩为主,通过对样品的综合分析,其主量元素特征表明该套火山岩主要为洋岛拉斑玄武岩系列,有向板内拉斑玄武岩过渡的趋势,稀土元素特征显现出与E型洋中脊玄武岩或P型洋中脊玄武岩相似,微量元素特征则表明万保沟群玄武岩与其中的板内拉斑玄武岩更为接近,综合来看万保沟群火山岩应属洋岛型玄武岩。 展开更多
关键词 万保沟群 地球化学 火山岩 督冷沟 东昆仑
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Impact of residual zircon on Nd-Hf isotope decoupling during sediment recycling in subduction zone 预览
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作者 Chen Zhang M.Santosh +3 位作者 Qun Luo Shu Jiang Luofu Liu Dongdong Liu 《地学前缘:英文版》 CAS CSCD 2019年第1期241-251,共11页
The subduction factories in convergent plate margins exert crucial control on recycling terrestrial components and returning to the overlying crust.The Nd and Hf isotopic systems provide potential tracers to evaluate ... The subduction factories in convergent plate margins exert crucial control on recycling terrestrial components and returning to the overlying crust.The Nd and Hf isotopic systems provide potential tracers to evaluate these processes.Here we present a case where these isotopic systems are decoupled in a suite of granites from the Chinese Altai,showing a wide range ofεHf(t)values(from-4.7 to+10.8)in contrast to a limited range ofεNd(t)values(from-5.8 to-1.9).The zircon xenocrysts occurring frequently in these rocks show markedly negativeεHf(t)values(from-34.3 to-6.5)and positiveδ^7Li values(from+12.5 to+18.2).We propose a model to explain the observed relationship between residual zircon and Nd-Hf isotope decoupling.We suggest that the Altai granites originated from partial melting of subducted slab components under relatively low temperature conditions which aided the residual zircon from oceanic sediments to inherit and retain a significant amount of 177Hf in the source,thereby elevating the 176Hf/177Hf ratio of the melt,and decoupling from the 143Nd/144Nd ratio during the subsequent magmatic processes.Our study illustrates a case where sediment recycling in subduction zone contributes to decoupling of Nd and Hf isotopic systems,with former providing a more reliable estimate of the source characteristics of granitic magmas. 展开更多
关键词 ND and Hf isotope SYSTEMATICS Subduction TECTONICS Oceanic SEDIMENT melting Geochemical RECYCLING Chinese ALTAI
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滇东南白垩纪高分异S型花岗岩研究进展
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作者 许赛华 任涛 +2 位作者 吕昶良 石伟民 王彩艳 《矿物学报》 CAS CSCD 北大核心 2019年第2期149-165,共17页
滇东南地区广泛出露白垩纪花岗岩,面积超过500km2。在岩体周缘形成了众多金属矿床,如世界级的个旧Sn-Cu多金属矿床、都龙Zn-In-Sn多金属矿床、南秧田超大型W矿床等,使其成为国内地球科学研究的热点地区。本文系统收集了前人近年来公开... 滇东南地区广泛出露白垩纪花岗岩,面积超过500km2。在岩体周缘形成了众多金属矿床,如世界级的个旧Sn-Cu多金属矿床、都龙Zn-In-Sn多金属矿床、南秧田超大型W矿床等,使其成为国内地球科学研究的热点地区。本文系统收集了前人近年来公开发表的滇东南典型白垩纪花岗岩体(个旧、薄竹山和老君山)的地球化学数据,综合地质和地球化学分析表明滇东南白垩纪3个大型花岗岩体为高分异S型花岗岩,系统的年代学数据表明滇东南白垩纪岩浆活动与成矿主峰期发生在77~95 Ma。Sr、Nd、Hf同位素均显示该花岗岩岩浆主要来源于华夏板块元古代基底物质的部分熔融,综合分析后本研究初步认为滇东南地区晚白垩纪大规模的酸性岩浆活动是对晚三叠世华南板块与印支板块碰撞造山后伸展环境的响应。 展开更多
关键词 高分异S型花岗岩 晚白垩纪 研究进展 地球化学 滇东南
Fluvial sediments in the Alagxa Plateau as a dust source: iron mineralogical and geochemical evidence
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作者 WANG Youjun JIA Jia +2 位作者 LU Hao LU Caichen XIA Dunsheng 《干旱区科学:英文版》 SCIE CSCD 2019年第2期217-227,共11页
The Alagxa Plateau, in the margin of the northeastern Tibetan Plateau, is one of the most important dust source areas in East Asia, and the widespread sandy desert in the area is important both as a reservoir and a so... The Alagxa Plateau, in the margin of the northeastern Tibetan Plateau, is one of the most important dust source areas in East Asia, and the widespread sandy desert in the area is important both as a reservoir and a source of eolian silty. The northeastern margin of the Tibetan Plateau is one of the most actively-growing mountain belt on earth, and has large amounts of debris, with masses of fine grained material, which were continuously mobilized and deposited in the Alagxa Plateau by rivers, forming broad alluvial fans. It is possible that the role of fluvial sediments as a source of silty dust in the Alagxa Plateau has been underestimated. In this study, we test this hypothesis by investigating the iron mineralogical and geochemical characteristics of the fluvial sediments and the surface material of the sandy desert in the Alagxa Plateau, and comparing them with paleo-eolian dust deposits(loess) in the adjacent Chinese Loess Plateau(CLP) to investigate the possible linkages among the fluvial sediments, sandy desert and the last glacial loess of the CLP. The results show that sandy desert typically have high contents of goethite, and high ratios of goethite to hematite, similar to the fluvial sediments in the Alagxa Plateau. Based on the major element characteristics, field investigations and the results of previous studies, we found a genetic link between the silt component of the fluvial sediments and the sandy desert in the Alagxa Plateau with high value of Gt(goethite) and similarity of the Gt/(Hm(hematite)+Gt) ratio. But the silt component of the sandy desert main come from the adjacent fluvial sediments. The iron mineralogical characteristics(χ(magnetic susceptibility), χARM(anhysteretic susceptibility), SIRM(saturation isothermal remanent magnetization) and SIRMAF100 mT(SIRM demagnetized at 100 mT)) of the CLP samples overlap with those of the fluvial sediments in the Alagxa Plateau, but there is a mismatch with the sandy desert samples. This suggests that the fluvial sediments are the source of a larg 展开更多
关键词 FLUVIAL sediments silty DUST SANDY DUST iron MINERALOGICAL and GEOCHEMICAL characteristic Alagxa PLATEAU
A Model of Hydrothermal Dolomite Reservoir Facies in Precambrian Dolomite,Central Sichuan Basin,SW China and its Geochemical Characteristics 预览
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作者 GU Yifan ZHOU Lu +3 位作者 JIANG Yuqiang JIANG Chan LUO Mingsheng ZHU Xun 《地质学报:英文版》 SCIE CAS CSCD 2019年第1期130-145,共16页
Hydrothermal mineral assemblages and related hydrothermally enhanced fracturing are common in the Precambrian Dengying Formation of Central Sichuan Basin.Petrographic and geochemical analyses of core samples show that... Hydrothermal mineral assemblages and related hydrothermally enhanced fracturing are common in the Precambrian Dengying Formation of Central Sichuan Basin.Petrographic and geochemical analyses of core samples show that the hydrothermal dolomite reservoirs of Dengying Formation consist of four main types of pores in the reservoir facies.These include:1)hydrothermal dissolution vug(or pore),2)intercrystalline pore,3)residual inter-breccia vug(or pore),and 4)enlarged dissolved-fracture.There are three different fabrics dolomite in hydrothermal dolomite reservoirs,namely,saddle dolomite,fine-medium dolomite and micritic dolomite.Micritic dolomite is the original lithology of host rock.Saddle dolomite with curved or irregular crystal faces was directly crystallized from hydrothermal fluids(average temperature 192°C).Fine-medium dolomites are the products of recrystallization of micritic dolomite,resulting in abnormal geochemical characteristics,such as slight depletion ofδ18O,significant enrichment of Mn-Fe and 87Sr/86Sr,and positive Eu anomaly.A model for the distribution of various hydrothermal dolomite reservoir facies is proposed here,which incorporates three fundamental geological controls:1)extensional tectonics and tectono-hydrothermal events(i.e.,the Xingkai Taphrogenesis of Late Sinian-Early Cambrian,and Emei Taphrogenesis of Late Permian),2)hydrothermal fluid storage in clastic rocks with large thickness(e.g.,Nanhua System of Chengjiang Formation and part of Doushantuo Formation),and 3)confining bed for hydrothermal fluids(such as,the shale in Qiongzhusi Formation).The supply of hydrothermal fluid is critical.Large basement-rooted faults and associated grid-like fracture system may function as the channels for upward migration of hydrothermal fluid flow.The intersection of the above-mentioned faults(including the conversion fault),especially transtensional sags above negative flower structures on wrench faults can serve as a key target for future hydrocarbon exploration. 展开更多
关键词 HYDROTHERMAL DOLOMITE reservoir FACIES geochemical characteristics PRECAMBRIAN Dengying Formation central Sichuan Basin
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晚三叠世昌都盆地构造背景及对成煤作用的控制
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作者 曹代勇 宋时雨 +2 位作者 马志凯 彭扬文 乔军伟 《地学前缘》 EI CAS CSCD 北大核心 2019年第2期169-178,共10页
位于西藏东部的昌都盆地是经历石炭纪、二叠纪以及三叠纪多期成煤盆地叠合改造形成的构造盆地,其中以晚三叠世巴贡组含煤地层分布最为广泛。三叠纪时期,盆地两侧的金沙江洋盆与澜沧江洋盆相继闭合,区域构造背景复杂,是决定成煤古地理条... 位于西藏东部的昌都盆地是经历石炭纪、二叠纪以及三叠纪多期成煤盆地叠合改造形成的构造盆地,其中以晚三叠世巴贡组含煤地层分布最为广泛。三叠纪时期,盆地两侧的金沙江洋盆与澜沧江洋盆相继闭合,区域构造背景复杂,是决定成煤古地理条件的首要因素。不同的构造背景形成特定的岩浆岩石类型和构造-岩浆岩组合。昌都地体两侧晚三叠世火山岩的地球化学特征分析表明,昌都盆地东缘双峰式火山主要受伸展应力控制,形成裂陷,造成地形起伏大,区域沉降幅度大,沉积速率快,不利于发育稳定的成煤环境。盆地西缘与澜沧江洋壳俯冲相关的侵入岩发育,反映在挤压应力背景下形成坳陷,相对简单的基底构造为发生持续稳定的聚煤作用提供了良好的古地理环境。在后期构造作用的控制下,连续的煤层多被错断,呈角度不一、大小悬殊的单斜断块或褶皱产出,在巴贡、夺盖拉等地保存有具工业价值的煤矿点。 展开更多
关键词 昌都盆地 构造背景 地球化学 成煤 构造控煤
大同市新荣区石墨矿岩石地球化学特征及物源分析
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作者 赵越 刘敬党 梁天意 《辽宁工程技术大学学报:自然科学版》 CAS 北大核心 2019年第2期136-140,共5页
大同新荣区石墨矿床是山西石墨矿集区的重要组成部分,针对前人对该地区缺乏石墨岩石地球化学、原岩及沉积环境等问题,本文野外地质调查结合岩石地球化学研究方法,对大同新荣区石墨矿床矿区地质特征、矿床特征、矿石质量、矿石地球化学... 大同新荣区石墨矿床是山西石墨矿集区的重要组成部分,针对前人对该地区缺乏石墨岩石地球化学、原岩及沉积环境等问题,本文野外地质调查结合岩石地球化学研究方法,对大同新荣区石墨矿床矿区地质特征、矿床特征、矿石质量、矿石地球化学特征、围岩地球化学特征进行了系统研究.研究结果表明:从矽线石榴片麻岩、石榴浅粒岩到石榴混合花岗岩,SiO2、CaO成分含量逐渐增加,其它成分基本都是逐渐降低,K2O、Na2O以浅粒岩最高,混合岩化作用强弱不同,化学成分迁移的差异;片麻岩、浅粒岩和混合花岗岩三种含矿岩石具有同源性,均显示陆壳沉积岩石特征.研究结论为进一步探讨大同新荣区石墨床成矿过程提供了新的依据. 展开更多
关键词 石墨资源 地球化学 沉积环境 同源性 成矿时代
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