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Elemental Compositions of Clinopyroxenes from Southern Okinawa Trough Basalt:Implications for Magmatism and Structural Environment in an Initial Back-Arc Basin
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作者 GUO Kun ZHAI Shikui +3 位作者 FAN Di ZHANG Xia ZHANG Yu ZHU Zhimin 《Journal of Ocean University of China》 SCIE CAS CSCD 2024年第3期643-653,共11页
The major and trace elemental compositions of clinopyroxene from basalt were used to characterize the nature of the primitive magma and structural environment beneath the southern Okinawa Trough(SOT),which is an initi... The major and trace elemental compositions of clinopyroxene from basalt were used to characterize the nature of the primitive magma and structural environment beneath the southern Okinawa Trough(SOT),which is an initial back-arc basin at a continental margin.The clinopyroxenes in the basalt were augite with variable Mg^(#)contents(73.37-78.22).The regular variations in major oxide contents(i.e.,CaO,FeO,TiO_(2),and Cr)with decreasing Mg#implied that the clinopyroxenes evolved from being enriched in Mg,Ca,and Cr to being enriched in Fe and Ti.The clinopyroxenes had relatively low rare earth element concentrations(7.51×10^(-6) to 12.68×10^(-6))and negative Eu anomalies(δEu=0.67-0.95).The Kd_(cpx) values of clinopyroxenes(0.2-0.26),which were used to examine whether the clinopyroxene was equilibrated with its host basalt,demonstrate that these clinopyroxene phenocrysts were not captured crystals but were instead produced by crystallization differentiation of the magma.The calculated clinopyroxene crystallization temperatures showed a narrow range of 990-1061℃,and their crystallization pressures ranged from 2.0 to 3.2 kbar.The geochemistry features of these clinopyroxenes indicated that the parent magma belonged to the subalkaline tholeiitic magma series and suggested that the magma experienced crystallization differentiation of olivine,plagioclase,and clinopyroxene,where the crystallization of plagioclase occurred earlier than that of clinopyroxene.Combined with geophysical data,this research on primitive magma and its crystallization differentiation from clinopyroxene indicates that the SOT is in the stage of‘seafloor spreading’and that basaltic rocks produced from tholeiitic magma represent the generation of oceanic crust. 展开更多
关键词 trace elements CLINOPYROXENES southern Okinawa trough seafloor spreading back-arc basin
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Geochemical characterization of Cretaceous sandstones from the Southern Benue Trough, Nigeria 被引量:9
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作者 Odigi M.I. Amajor L.C. 《Chinese Journal Of Geochemistry》 EI CAS 2009年第1期44-54,共11页
Geochemical studies of sandstones from the three lithostratigraphic successions in the southern Benue Trough of Nigeria were undertaken for a geochemical characterization of the sandstones, and to assess their strati-... Geochemical studies of sandstones from the three lithostratigraphic successions in the southern Benue Trough of Nigeria were undertaken for a geochemical characterization of the sandstones, and to assess their strati-graphic and source evolution. Major and trace elements data were obtained from outcrop sandstone samples. The SiO2/Al2O3, Fe2O3/K2O ratios and CaO contents have been used to characterize the Cretaceous sandstones into Al-rich and high and low Fe2O3/K2O ratio sandstones. Results indicate that there are geochemical features that display stratigraphic trends across the succession from the Asu River Group, Eze-Aku Group to the proto-Niger Delta succession which may imply a discontinuous evolution from different source terrains of Precambrian and Mesozoic ages that supplied the sediments. The Asu River Group sandstones have lower SiO2, Al2O3, Fe2O3 and higher MgO; the Eze-Aku sandstones have higher TiO2, CaO, alkalis and lower MgO while the proto-Niger Delta sandstones have higher SiO2, Al2O3, Fe2O3 and lower alkalis and CaO. These discontinuities signify the influence of tectonic impulses that af- fected the southern Benue Trough during the Cretaceous time. Changes in ratios of TiO2/Al2O3, Fe2O3, Cr and Zr suggest an increasingly mafic contribution to the depositional basin with time. The chemical index of alteration increases with time, possibly suggesting that a more intense weathering regime in the hinterland developed with time. 展开更多
关键词 地球化学 特征 储层沥青 烃源岩 对比
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Mineralogy,geochemistry,and sulfur isotope characteristics of sediment-hosted hydrothermal sulfide minerals from the southern Okinawa Trough 被引量:2
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作者 Yamin Yang Zhigang Zeng +5 位作者 Xuebo Yin Xiaoyuan Wang Shuai Chen Haiyan Qi Zuxing Chen Bowen Zhu 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2021年第10期129-143,共15页
Studies of the mineralogy and sulfur isotope composition of sediment-hosted hydrothermal sulfide minerals in cores are important for understanding the seafloor mineralization environment and material source and recons... Studies of the mineralogy and sulfur isotope composition of sediment-hosted hydrothermal sulfide minerals in cores are important for understanding the seafloor mineralization environment and material source and reconstructing the hydrothermal history.However,the source of ore-forming materials and the history of hydrothermal activity in the southern Okinawa Trough(SOT)remain unclear.Here,the mineralogy and sulfur isotope characteristics of sulfides from gravity core HOBAB4-S2,collected between the Yonaguni Knoll IV hydrothermal field(HF)and the Tangyin HF,was investigated.Enrichments in Zn(up to 321×10^(-6)),Cu(up to73.7×10^(-6)),and Pb(up to 160×10^(-6))and the presence of pyrite,galena,pyrrhotite and minor sphalerite and chalcopyrite provide evidence for the input of hydrothermal materials into the sediments.The pyrite morphologies include disseminated cubic,pentagonal dodecahedron,and framboidal forms.Except for minor framboidal pyrite,euhedral pyrite from core HOBAB4-S2 is mainly of hydrothermal origin with Co/Ni ratios>1 and S/Fe atomic ratios<2 in the Cu-Zn-Pb-rich layers.The occurrences of hexagonal pyrrhotite,high-Co(up to0.17%)pyrite and high-Fe sphalerite indicate that the hydrothermal precipitates formed at medium-high temperatures and low-sulfur fugacity(f S_(2))environments.The δ^(34) S values of sulfides(0.21‰–3.45‰)with low-f S_(2) mineral assemblages(e.g.,pyrrhotite±high-Fe sphalerite)in the core are significantly lower than those of magmatic rocks and seawater,indicating possible incorporation of previously formed biogenic sulfur in the sediment.Combined with the age model of the core,it is suggested that hydrothermal activity likely began in the Tangyin HF before AD 1445–1483 and that at least three active episodes may have occurred since then. 展开更多
关键词 MINERALOGY sulfur isotopes sediment-hosted hydrothermal sulfides southern Okinawa trough
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NotesBenthic foraminiferal distribution in surface sediments along continental slope of the southern Okinawa Trough: dependance on water masses and food supply 被引量:1
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作者 向荣 李铁刚 +2 位作者 杨作升 阎军 曹奇原 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2003年第1期133-144,共12页
Benthic foraminiferal analysis of 29 samples in surface sediments from the southern Okinawa Trough is carried out. The results indicate that benthic foraminiferal abundance decreases rapidly with increasing water dept... Benthic foraminiferal analysis of 29 samples in surface sediments from the southern Okinawa Trough is carried out. The results indicate that benthic foraminiferal abundance decreases rapidly with increasing water depth. Percentage frequencies of agglutinated foraminifera further confirm the modern shallow carbonate lysocline in the southern Okinawa Trough. From continental shelf edge to the bottom of Okinawa Trough, benthic foraminiferal fauna in the surface sediments can be divided into 5 assemblages: (1) Continental shelf break assemblage, dominated by Cibicides pseudoungerianus, corresponds to subsurface water mass of the Kuroshio Current; (2) upper continental slope assemblage, dominated by Cassidulina carinata , Globocassidulina subglobosa, corresponds to intermediate water mass of the Kuroshio Current; (3) intermediate continental slope assemblage, dominated by Uvigerina hispi-da, corresponds to the Okinawa Trough deep water mass above the carbonate lysocline; (4) lower continental slope- trough bottom assemblage, dominated by Pullenia bulloides, Epistominella exigua and Cibicidoides hyalinus, corresponds to deep water mass of the Okinawa Trough; and (5) trough bottom agglutinated assemblage, dominated by Rhabdammina spp. , Bathysiphon flavidus, corresponds to strongly dissolved environment of the trough bottom. The benthic foraminiferal fauna in the southern Okinawa Trough are controlled jointly by water masses and food supply. Water temperature, oxygen concentration and carbonate dissolution of the water masses are important controlling factors especially for the continental shelf break and trough bottom assemblages. The food supply also plays an important role in these benthic foraminiferal assemblages along the western slope of the Okinawa Trough. Both the abundance and the 5 assemblages of benthic foraminifera correspond well to the organic matter supply along the continental slope and a lateral transport of TSM (total suspended matter) and POC (particulate organic carbon) from the shelf break to the deep water is also an important food supply for benthic fauna in this region. 展开更多
关键词 Benthic foraminifer southern Okinawa trough DISSOLUTION KUROSHIO food supply
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Magma Evolution Processes in the Southern Okinawa Trough:Insights from Melt Inclusions 被引量:1
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作者 ZHANG Yujiao ZHAI Shikui 《Journal of Ocean University of China》 SCIE CAS CSCD 2021年第6期1383-1397,共15页
The Okinawa Trough is an initial back-arc basin that is influenced by the subduction of the Philippine Sea Plate and develops on the continental crust.The Okinawa Trough is a natural laboratory for the study of basin ... The Okinawa Trough is an initial back-arc basin that is influenced by the subduction of the Philippine Sea Plate and develops on the continental crust.The Okinawa Trough is a natural laboratory for the study of basin evolution,magmatism,and crustmantle processes in the early stage of back-arc spreading.Melt inclusions are small droplets of magma that are captured during the mineral crystallization process and can record the geochemical composition changes during magma evolution.In this study,the geochemical compositions of melt inclusions in host plagioclases of two volcanic rock samples at Station nos.9-1 and 9-2 from the southern Okinawa Trough are systematically analyzed.Based on previous studies,the origin and evolution of magma and the introduction of subducting materials in the study area are discussed.Results show that melt inclusions are characterized by the relative enrichment of large-ion lithophile elements,depletion of high-field-strength elements,and slight enrichment of rare earth elements.Indeed,the subduction of the Philippine Sea Plate introduced sediment-derived melts and fluids into the magma source area of the southern Okinawa Trough.Subsequently,4%to 5%partial melting of the hydrated mantle produces basaltic magma.The melt inclusions of andesite and dacite investigated in this study were formed by fractional crystallization of basaltic magma.Finally,the crystallization of plagioclase,pyroxene,and magnetite occurred during the late stage of magma evolution.The temperature-pressure data show that the melt inclusions in plagioclase have two capture periods:one is at temperatures above 1250℃and the other is at temperatures between 1180℃and 1200℃.The capture pressure of the inclusions at temperatures between 1180℃and 1200℃is between 5.6 kPa and 6.1 kPa,corresponding to the depth of 15–17 km below the seafloor.The geochemical characteristics of major and trace elements in inclusions show that the samples from two stations(i.e.,9-1 and 9-2)have similar or identical magma source areas.However,the crystallization differentiation reflected by inclusions in sample 9-1 is more obvious than that in sample 9-2.The inclusions were captured during magma evolution and were not contaminated by crustal materials. 展开更多
关键词 melt inclusions magma evolution processes contamination of crustal materials introduction of subducting materials the southern Okinawa trough
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A Comparative Study of Element Cycling in the Soil-Plant System: A Case Study of Shaly and Calcareous Soils, Southern Benue Trough, Nigeria 被引量:1
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作者 T. N. Nganje C. I. Adamu 《International Journal of Geosciences》 2014年第4期453-463,共11页
This study focused on the cycling of major and trace elements in the soil-plant system in parts of Southern Benue Trough, Nigeria. Surface soil samples and cassava crop samples were collected from cultivated farmlands... This study focused on the cycling of major and trace elements in the soil-plant system in parts of Southern Benue Trough, Nigeria. Surface soil samples and cassava crop samples were collected from cultivated farmlands underlined by shaly and calcareous soils and were analysed using standard techniques. The results show that shaly soils are relatively acidic (pH, 4.8 - 6.6) with high level of organic matter content (OM, 3.2% - 8.7%) compared to calcareous soils (pH, 5.6 - 7.2;OM 1.6% - 7.0%). The soils are enriched in elemental composition relative to the world average abundances in soil. The maximum levels of K, Al, and Zn were obtained from shaly soils. The computed accumulation factors are generally <1. Elemental levels decreased in the plant parts in the order tuber > leaf > stem. Significant correlation was obtained between elemental associations of calcareous surface soils compared to that of shaly soils. R-mode factor analysis revealed the controls of soil geochemistry to include lithology, anthropogenic and environmental factors. A stepwise linear regression analysis identified soil elemental component, pH and organic matter as some of the factors influencing soil-plant metal uptake. 展开更多
关键词 Soil Plant System CYCLING of Elements CALCAREOUS SOILS Shaly SOILS southern Benue trough NIGERIA
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EXAMINATION OF THE RELIABILITY OF THE JMA SEISMIC OBSERVATION NETWORK AROUND THE SOUTHERN OKINAWA TROUGH
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作者 陈佐林 杨作升 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 1994年第2期114-119,共6页
After the establishment of the seismic observation network of southern Okinawa in August,1988 by the JMA(Japan Meteorological Agency),many hypocenters of earthquakes have been located.However,due to the small number o... After the establishment of the seismic observation network of southern Okinawa in August,1988 by the JMA(Japan Meteorological Agency),many hypocenters of earthquakes have been located.However,due to the small number of observation stations and narrow configuration of the array,the hypocenters lo-cated contain some systematic errors.Numerical experiments on the extent of the errors and the reliabilityof the JMA seismic observation network showed that the obtained hypocenters deeper than 100 km werereliable,but that for the obtained hypocenters shallower than 100 km,only the epicenters were reliable. 展开更多
关键词 EXAMINATION numerical experiment HYPOCENTER depth JMA southern OKINAWA trough
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Petroleum Potentials of the Nigerian Benue Trough and Anambra Basin: A Regional Synthesis 被引量:3
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作者 M. B. Abubakar 《Natural Resources》 2014年第1期25-58,共34页
A review on the geology and petroleum potentials of the Nigerian Benue Trough and Anambra Basin is done to identify potential petroleum systems in the basins. The tectonic, stratigraphic and organic geochemical evalua... A review on the geology and petroleum potentials of the Nigerian Benue Trough and Anambra Basin is done to identify potential petroleum systems in the basins. The tectonic, stratigraphic and organic geochemical evaluations of these basins suggest the similarity with the contiguous basins of Chad and Niger Republics and Sudan, where commercial oil discovery have been made. At least two potential petroleum systems may be presented in the basins: the Lower Cretaceous petroleum system likely capable of both oil and gas generation and the Upper Cretaceous petroleum system that could be mainly gas-generating. These systems are closely correlative in temporal disposition, structures, source and reservoir rocks and perhaps generation mechanism to what obtains in the Muglad Basin of Sudan and Termit Basin of Niger and Chad Republics. They are very effective in planning future exploration campaigns in the basins. 展开更多
关键词 Benue trough Anambra BASIN Petroleum POTENTIALS southern Benue trough Central Benue trough NORTHERN Benue trough
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Role of the Subtropical Westerly Jet Waveguide in a Southern China Heavy Rainstorm in December 2013 被引量:16
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作者 LI Chun SUN Jilin 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2015年第5期601-612,共12页
An extreme rainstorm hit southern China during 13–17 December 2013, with a record-breaking daily rainfall rate, large spatial extent, and unusually long persistence. We examined what induced this heavy rainfall proce... An extreme rainstorm hit southern China during 13–17 December 2013, with a record-breaking daily rainfall rate, large spatial extent, and unusually long persistence. We examined what induced this heavy rainfall process, based on observed rainfall data and NCEP–NCAR reanalysis data through composite and diagnostic methods. The results showed that a Rossby waveguide within the subtropical westerly jet caused the event. The Rossby wave originated from strong cold air intrusion into the subtropical westerly jet over the eastern Mediterranean. With the enhancement and northward shift of the Middle East westerly jet, the Rossby wave propagated slowly eastward and deepened the India–Burma trough, which transported a large amount of moisture from the Bay of Bengal and South China Sea to southern China. Strong divergence in the upper troposphere, caused by the enhancement of the East Asian westerly jet, also favored the heavy rainfall process over Southeast China. In addition, the Rossby wave was associated with a negative-to-positive phase shift and enhancement of the North Atlantic Oscillation, but convergence in the eastern Mediterranean played the key role in the eastward propagation of the Rossby wave within the subtropical westerly jet. 展开更多
关键词 subtropical westerly jet waveguide southern China rainstorm Rossby wave India–Burma trough North At-lantic Oscillation
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我国南方西南和中东部区域两次持续性低温雨雪过程与关键环流系统的关系研究
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作者 孙晓娟 陈跞 +1 位作者 卢楚翰 秦育婧 《气象科学》 2024年第2期267-279,共13页
利用NCEP再分析资料和国家气象信息中心提供的753站逐日气温和降水资料,对比分析了我国南方西南和中东部区域两次持续10 d以上的低温雨雪过程,结果表明:(1)两次过程中欧亚大陆中高纬东亚大槽均加深,但环流形势有差异。西南过程呈现"... 利用NCEP再分析资料和国家气象信息中心提供的753站逐日气温和降水资料,对比分析了我国南方西南和中东部区域两次持续10 d以上的低温雨雪过程,结果表明:(1)两次过程中欧亚大陆中高纬东亚大槽均加深,但环流形势有差异。西南过程呈现"北高南低"形势,关键脊区在贝加尔湖,而中东部区域过程"北高南低"和"西高东低"形势共存,关键脊区从乌拉尔山延伸至贝加尔湖。两次过程异常的环流与北大西洋向东传播的波列有关。(2)西南过程关键脊区提前过程3 d发展并东移至贝加尔湖,形成稳定形势;而中东部区域过程关键脊区提前过程一周发展,在开始日达最强。两次过程均伴随蒙古高压东移南压使地面降温,500 hPa关键脊区超前蒙古高压2 d变化。西南过程降温主要受到冷平流和绝热冷却影响,而中东部区域过程主要受到冷平流的影响。(3)西南过程水汽来自孟加拉湾,只受南支槽支配。中东部区域过程水汽来自孟加拉湾、南海和西太平洋,由南支槽和西太平副热带高压的共同影响。两次过程水汽正收支主要来自南边界。 展开更多
关键词 南方西南与中东部区域 持续性低温雨雪过程 环流特征 蒙古高压 南支槽
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南沙海槽—西北巴拉望构造特征及其意义
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作者 李学杰 汪俊 +2 位作者 王哲 姚永坚 祝嵩 《吉林大学学报(地球科学版)》 CAS CSCD 北大核心 2024年第4期1081-1094,共14页
南沙海槽-西北巴拉望构造对认识南海成因与演化至关重要。综合南海南缘地质地球物理资料分析认为:南沙海槽极薄地壳可能不是古南海的残余,是夭折的扩张中心;南沙海槽存在挤压逆冲作用,形成时间很晚,与南海扩张无关,是南海形成后挤压的... 南沙海槽-西北巴拉望构造对认识南海成因与演化至关重要。综合南海南缘地质地球物理资料分析认为:南沙海槽极薄地壳可能不是古南海的残余,是夭折的扩张中心;南沙海槽存在挤压逆冲作用,形成时间很晚,与南海扩张无关,是南海形成后挤压的结果。南沙海槽挤压作用与西北巴拉望Pagasa楔变形对比表明,南海南缘的挤压作用停止时间东部早于西部;中、南巴拉望蛇绿岩来自其南部往北逆冲的产物,可能表明古南海由南往北俯冲。综上认为南巴拉望蛇绿岩可能来自新特提斯洋壳,中巴拉望蛇绿岩来自古南海洋壳;不同时期洋壳俯冲残余最终被逆冲至岛弧系之上;巴拉望蛇绿岩是长期由南往北逆冲的结果,最后就位时间可能是中晚中新世。 展开更多
关键词 南海南缘 南沙海槽逆冲构造 古南海 巴拉望蛇绿岩
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冲绳海槽中部和南部玄武岩的区域性差异及其成因研究 被引量:17
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作者 马维林 王先兰 +3 位作者 金翔龙 陈建林 韩喜球 章伟艳 《地质学报》 EI CAS CSCD 北大核心 2004年第6期758-769,共12页
本文从岩石学和岩石化学角度出发 ,对冲绳海槽中部和南部玄武岩样品进行了对比研究。结果表明中部和南部玄武岩均系亚碱性玄武岩 ,其中前者兼具钙碱性系列和拉斑玄武岩系列两种性质 ,后者则主要属拉斑玄武岩系列。根据岩石化学特征命名 ... 本文从岩石学和岩石化学角度出发 ,对冲绳海槽中部和南部玄武岩样品进行了对比研究。结果表明中部和南部玄武岩均系亚碱性玄武岩 ,其中前者兼具钙碱性系列和拉斑玄武岩系列两种性质 ,后者则主要属拉斑玄武岩系列。根据岩石化学特征命名 ,中部样品主体为石英拉斑玄武岩 ,南部样品则为橄榄拉斑玄武岩。两区海槽玄武岩岩浆均由下伏地幔岩部分熔融而成 ,但源区地幔性质不均一 ,岩浆演化程度各异。中部样品源区地幔性质为过渡型 ,结晶分异程度较高 ;南部样品源于近亏损或富集型的地幔 ,结晶分异程度较弱 ;另外两区玄武岩样品均受到了不同程度的陆壳物质混染。中、南部海槽玄武岩在岩石学、岩石化学方面的差异与源区地幔性质不均一和岩浆演化程度各异有直接关系。海槽玄武岩构造环境属于过渡洋中脊玄武岩 (张性 )与岛弧玄武岩 (压性 )之间 ,代表的仍是海槽早期的岩浆活动。 展开更多
关键词 玄武岩 地幔 冲绳海槽 源区 岩浆演化 岩石化学 岩石学 结晶 样品 研究
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基于Cloudsat探测的一次非典型东北冷涡结构及其降水 被引量:10
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作者 施春华 李慧 +1 位作者 郑彬 郭栋 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2013年第8期2594-2602,共9页
采用ERA-Interim气象分析资料、云顶亮温TBB资料、Cloudsat云雷达资料、降雨量资料等,对2009年6月10日至12日我国东北地区的一次冷涡天气过程进行研究,重现了该冷涡的精细三维结构和演变过程.分析表明冷涡发生前,东北亚地区处于南北双... 采用ERA-Interim气象分析资料、云顶亮温TBB资料、Cloudsat云雷达资料、降雨量资料等,对2009年6月10日至12日我国东北地区的一次冷涡天气过程进行研究,重现了该冷涡的精细三维结构和演变过程.分析表明冷涡发生前,东北亚地区处于南北双槽结构之间,随后北槽向赤道发展切断后形成东北冷涡.南槽背景的冷涡热力结构特殊,强冷空气集中在涡内西北象限,暖湿空气在东北象限,南部为相对中性空气,该配置导致北部暖锋强盛,西部冷锋仅在发展初期较强,冷涡过程没有经典挪威学派的气旋锢囚锋出现.冷涡发展初期,狭长冷舌快速入侵南下,冷舌前冷锋对流降水较强,冷舌后部左侧还有暖锋降水;冷涡发展后期,冷锋减弱,冷锋上的高层云停止降水,系统内主要为冷涡北部的暖锋雨层云降水;冷涡成熟后,中心辐合加强,有较强的对流性降水. 展开更多
关键词 东北冷涡 切断低压 对流降水 锋面降水 南槽
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冲绳海槽南部柱状沉积物地球化学特征及其古环境意义 被引量:21
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作者 蒋富清 李安春 李铁刚 《海洋地质与第四纪地质》 CAS CSCD 北大核心 2002年第3期11-17,共7页
对冲绳海槽南部 E0 17柱状沉积物进行了地球化学分析 ,结果表明 ,该柱状沉积物主要的化学组成为Si O2 、Al2 O3、Ca O和 TFe2 O3(全铁 ) ,K2 O、Na2 O、Mg O和 Mn O次之 ,具有明显的东海陆架沉积特征 ,但微量元素明显富集。 R型因子分... 对冲绳海槽南部 E0 17柱状沉积物进行了地球化学分析 ,结果表明 ,该柱状沉积物主要的化学组成为Si O2 、Al2 O3、Ca O和 TFe2 O3(全铁 ) ,K2 O、Na2 O、Mg O和 Mn O次之 ,具有明显的东海陆架沉积特征 ,但微量元素明显富集。 R型因子分析可将该柱状沉积物的化学组成划分为 5种组合类型 :(1) Si O2 、Na2 O、Zr、Al2 O3、K2 O、TFe2 O3、Mg O、Co和 Cr;(2 ) Ca O和 Sr;(3) Si O2 、Na2 O和 Zr;(4) Cu、Pb、Zn和 Ni;(5 ) Mn O和 Ba。根据元素在垂向上的协同变化关系 ,前 3个元素组合分别对应于陆源碎屑沉积、生源沉积和火山沉积 ,后两个元素组合主要与早期成岩过程中元素的再分配和自生沉积作用有关。氧同位素和 AMS1 4C的测年结果表明 ,该柱状沉积物属于末次冰消期 (约 15 ka BP)以来的沉积 ,全新世和末次冰消期的界线在 175 cm左右。与全新世相比 ,末次冰消期沉积速率较高 ,沉积物的粒度相对较粗 ,陆源碎屑组分 Si O2 、Al2 O3、K2 O等相对较高 ,生源组分 Ca O和 展开更多
关键词 地球化学特征 古环境 柱状沉积物 冲绳海槽 化学组成 自生沉积作用
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春季南支槽的年代际变化及其与降水、大气环流的关系 被引量:11
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作者 张永莉 范广洲 +3 位作者 朱克云 袁东升 华维 王炳赟 《高原气象》 CSCD 北大核心 2016年第4期934-945,共12页
由于春季青藏高原动力作用在其南侧形成南支槽,南支槽年代际变化的异常,可能与中国降水异常有密切的关系。利用NCEP/NCAR月平均再分析资料和中国596个测站月降水资料,采用突变检验、合成分析等方法,分析了1950 2014年春季南支槽的强度... 由于春季青藏高原动力作用在其南侧形成南支槽,南支槽年代际变化的异常,可能与中国降水异常有密切的关系。利用NCEP/NCAR月平均再分析资料和中国596个测站月降水资料,采用突变检验、合成分析等方法,分析了1950 2014年春季南支槽的强度和东、西位置的年代际变化特征,探讨了两者与同期中国降水年代际异常及环流背景场的关系。结果表明:春季南支槽的强度和位置都具有显著的年代际变化特征,南支槽强度在20世纪70年代末期有一次强弱突变过程,位置在90年代初期发生了明显的由东向西移动的转折,分别选取强度和位置突变前后的时间段进行分析,得到春季南支槽强度突变前(后),南支槽越强(弱),位置突变前(后),南支槽越偏东(西),会出现黄河流域、长江中下游及其以北和以南的大部分地区降水偏多(少),而青藏高原及其周围地区降水偏少(多)的现象,从两者突变前后与大气环流、垂直运动和水汽条件的显著关系能够合理地解释突变前后降水差异的原因。在此基础上,总结了春季南支槽年代际尺度与中国降水、大气环流的概念模型,可为中国春季的气候变化和气候预测提供更多的科学依据。 展开更多
关键词 春季南支槽 年代际变化 突变 降水 大气环流
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春季南支槽变化特征及其与降水和大气环流的关系 被引量:14
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作者 张永莉 范广洲 +4 位作者 周定文 向卫国 谢清霞 王霄 赖欣 《高原气象》 CSCD 北大核心 2014年第1期97-105,共9页
利用NCEP/NCAR月平均再分析资料,结合国家气象信息中心提供的1961-2007年4月中国596个测站月降水量资料,采用小波分析、相关分析和合成分析等方法,定义了春季南支槽强度指数和东、西位置指数,讨论了近60年两个指数的变化特征及其与中国... 利用NCEP/NCAR月平均再分析资料,结合国家气象信息中心提供的1961-2007年4月中国596个测站月降水量资料,采用小波分析、相关分析和合成分析等方法,定义了春季南支槽强度指数和东、西位置指数,讨论了近60年两个指数的变化特征及其与中国同期降水和大气环流的关系。结果表明,春季南支槽总体呈强度减弱、位置逐渐西移的趋势。春季南支槽强度指数值越小(大),则南支槽越强(弱);春季南支槽位置指数值越大(小),则南支槽位置越偏东(西),出现长江中游及其以南部分地区降水越多(少),而西南的部分地区降水越少(多)的现象。另外,对两个指数与大气环流的关系分析表明,强度指数和位置指数与环流的关系比较显著,能够合理地给出中国降水差异的原因。 展开更多
关键词 春季南支槽 强度指数 位置指数 降水 大气环流
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低纬高原两次冬季南支槽强降水的对比分析 被引量:26
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作者 郭荣芬 高安生 杨素雨 《大气科学学报》 CSCD 北大核心 2010年第1期82-88,共7页
利用常规高空观测资料,对发生在云南低纬高原2007年1月31日—2月1日和2008年1月26—27日的两次南支槽强降水过程进行对比分析。结果表明,两次南支槽降水的环流形势及影响系统均不同,前者为高原南支槽前西南暖湿气流与低层切变、冷锋共... 利用常规高空观测资料,对发生在云南低纬高原2007年1月31日—2月1日和2008年1月26—27日的两次南支槽强降水过程进行对比分析。结果表明,两次南支槽降水的环流形势及影响系统均不同,前者为高原南支槽前西南暖湿气流与低层切变、冷锋共同影响,属典型的"槽潮"天气;后者无明显强冷空气配合,因中低层西南急流的建立并长时间维持,新生南支槽东移补充、西南涡及静止锋的共同影响造成。物理机制上,湿位涡的CSI机制分析表明,两次过程均属于对称不稳定降水;在2007年的强降水过程中,θse密集带在地面锋区附近形成,冷暖气流形成次级垂直环流圈,导致强降水强降温并伴有大范围降雪的寒潮天气出现。后者无次级垂直环流圈形成,但有两个θse密集带锋区长久维持,滇中以西持续的上升气流不断增强且深厚,滇中以东中低层形成有弱的气流辐合带,故强降水以液体降水为主,降温不明显;两次强降水过程均有锋生,前者锋生是由切变增强西移,低层冷高压促使冷锋增强,后者锋生为东移西南涡与稳定持续的强劲西南风低空急流触发而成。 展开更多
关键词 冬季 南支槽 强降水 对比分析
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南冲绳海槽岩石圈构造动力作用机制探讨 被引量:11
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作者 高金耀 李家彪 林长松 《海洋与湖沼》 CAS CSCD 北大核心 2002年第4期349-355,T003,T004,共9页
由最新获得的重磁、地震和多波束地形数据 ,结合多尺度的地幔流动力分析 ,展示了南冲绳海槽岩石圈构造动力的多样性特征和其内在的联系。从上新世开始的三幕张性断陷活动是在以前的压性断裂构造的基础上发展起来的 ,向岛弧侧迁移 ,岩浆... 由最新获得的重磁、地震和多波束地形数据 ,结合多尺度的地幔流动力分析 ,展示了南冲绳海槽岩石圈构造动力的多样性特征和其内在的联系。从上新世开始的三幕张性断陷活动是在以前的压性断裂构造的基础上发展起来的 ,向岛弧侧迁移 ,岩浆、火山活动主要集中在正断层与平移断层的交汇处。深部动力源可归结为上地幔对流产生的菲律宾海板块俯冲 ,引起岛弧岩石圈挤压褶皱而向海沟旋张掀斜 ,产生弧后岩石圈的张性构造 ;进一步引起弧后软流圈挤压隆起 ,岩石圈与软流圈耦合作用导致海槽断陷张裂、岩浆活动。冲绳海槽仍是一个软流圈在汇聚的弧后盆地。全球性左旋压扭滑移背景 ,琉球海沟南段俯冲受阻小、强度大 ,台湾—吕宋的北向挤压 ,使海槽表现为剪张性 ,由平移断层调控使张性断裂左旋雁行排列 ,整个海槽张性构造由北往南推进 ,张应力方向由NW过渡到NNW。 展开更多
关键词 构造动力作用机制 南冲绳海槽 张性断陷 岩石圈 软流圈 地幔流
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2009/2010年冬季云南严重干旱原因的进一步分析 被引量:57
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作者 宋洁 杨辉 李崇银 《大气科学》 CSCD 北大核心 2011年第6期1009-1019,共11页
为了揭示2009/2010年冬季云南出现严重干旱灾害的原因,本文利用NCEP/NCAR再分析资料以及云南省台站降水资料计算得到的云南冬季降水指数,讨论了在北半球冬季(12~2月)北大西洋涛动(North Atlantic Oscillation,简称NAO)和云南省降水(旱... 为了揭示2009/2010年冬季云南出现严重干旱灾害的原因,本文利用NCEP/NCAR再分析资料以及云南省台站降水资料计算得到的云南冬季降水指数,讨论了在北半球冬季(12~2月)北大西洋涛动(North Atlantic Oscillation,简称NAO)和云南省降水(旱涝)之间的联系。分析结果表明,在1961/1962~2009/2010年间的49个冬季,冬季平均的云南降水指数和NAO指数的相关系数为0.373(超过95%信度),表明NAO和云南省冬季降水之间存在着一定的联系。云南省冬季降水指数和北半球300hPa位势高度异常场之间的回归结果表明,和云南冬季降水联系紧密的环流系统可分为南北两个主要部分:南支槽波列和贝加尔湖高压脊系统。研究表明,NAO可以通过在亚—非副热带急流中传播的准定常波列以及波的反射分别影响这两个系统。因此,NAO和云南冬季降水之间存在一定的联系。同时,我们的结果还表明NAO和云南冬季降水之间的关系还受ENSO事件的调制。在ENSO为暖位相的冬季,NAO和云南降水关系更为紧密,而在ENSO为冷位相的冬季,NAO和云南冬季降水的联系则不太显著。 展开更多
关键词 云南 冬季干旱 北大西洋涛动 南支槽波列 贝加尔湖高压脊
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南沙海槽南部表层重砂矿物及其成矿远景 被引量:6
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作者 陈忠 颜文 +2 位作者 古森昌 陈木宏 汤贤赞 《海洋地质与第四纪地质》 CAS CSCD 北大核心 2003年第1期13-18,共6页
南沙海槽南部海区80余个站位重砂矿物研究表明,重矿物主要受古巽他河、湄公河及加里曼丹岛的短源河流影响,具有多期、多来源沉积特点。重砂矿物为钛铁矿、金红石、锆石、独居石等,主要分布于北康暗沙和南康暗沙一带、曾母暗沙浅滩海域... 南沙海槽南部海区80余个站位重砂矿物研究表明,重矿物主要受古巽他河、湄公河及加里曼丹岛的短源河流影响,具有多期、多来源沉积特点。重砂矿物为钛铁矿、金红石、锆石、独居石等,主要分布于北康暗沙和南康暗沙一带、曾母暗沙浅滩海域的钙质生物砂中。砂矿品位和成矿元素Fe、Ti、Zr含量分布表明,南沙海槽南部海域砂矿可划分为3个成矿远景区:(1)北康暗沙锆石、独居石远景区;(2)南康暗沙锆石、钛铁矿远景区;(3)曾母暗沙锆石、钛铁矿、金红石远景区。 展开更多
关键词 重砂矿物 成矿元素 南沙海槽 成矿元素 沉积物 沉积作用 成矿远景
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