ENSO--热带海洋和大气中和谐的海气相互作用现象   总被引：10，自引：1，他引：10  

巢纪平 《海洋科学进展》2002,20(3):1-8

简要评述了ENSO的发展过程.着重指出,厄尔尼诺和拉尼娜海温距平信号一般都在温跃层曲面传播和发展,海温距平信号在暖池次表层生成和发展后,沿赤道温跃层向东、向上传播,到赤道东太平洋后,信号一般向北传播,在10°N附近向西传播并南下到暖池的赤道纬度形成一个循环,这一循环的时间一般是3～4 a.这些观测事实的揭示是对ENSO循环的新认识.  相似文献   

分段式造波机生成波浪内外部结构的一致性分析     

张宁川  俞聿修  柳长青 《海洋工程》2000,18(2):51-57

用60个波高仪组成2m×2m的方阵,同步测量波面过程,用Doppler声学流速仪获得了二维正向和斜向规则波、二维正向和斜向随机波以及三维随机波浪场中不同水深处的同步Euler水质点速度各方向分量的高精度的时间过程资料.以此为出发点,讨论了分段式造波机生成波浪的周期分布特征,发现三维随机波浪周期分布的μ值与二维随机波浪比较有明显增大的趋势.分别从速度合矢量方向与波向的吻合程度(对二维波浪)、"多点波面"组合与"波面-水质点速度"组合两种方式得到方向谱的吻合程度(对三维随机波浪)等不同角度,论证了分段式造波机产生的波浪的内外部结构的一致性.  相似文献   

El Niño/Southern Oscillation (ENSO) Related Variations in Particulate Export Fluxes in the Western and Central Equatorial Pacific     

Hodaka Kawahata  Lallan Prasad Gupta 《Journal of Oceanography》2003,59(5):663-670

Time-series data from sediment trap moorings intermittently deployed during 1991–1999 show that the fluxes of biogenic material (carbonate, opal and organic matter, including amino acids) and other related parameters are temporally and spatially distinct across the Western Pacific Warm Pool (WPWP). These variations resulted from the El Niño and La Niña conditions, which alternately prevailed over the equatorial Pacific Ocean during the mooring deployments. The westernmost WPWP (a hemipelagic region) recorded relatively high average total mass and amino acid fluxes during the El Niño event. This was in sharp contrast to the eastern part of the WPWP (oligotrophic and weak upwelling regions) which recorded higher flux values during the La Niña event. Settling particulate organic matter was rich in labile components (amino acids) during La Niña throughout the study area. Relative molar ratios of aspartic acid to β-alanine together with relative molar content of non-protein amino acids β-alanine and γ-aminobutyric acid) suggested that organic matter degradation was more intense during La Niña relative to that during El Niño in the WPWP. This study clearly shows that during an El Niño event the well documented decrease in export flux in the easternmost equatorial Pacific is accompanied by a significant increase in export flux in the westernmost equatorial Pacific Ocean.  相似文献   

Three monthly coral Sr/Ca records from the Chagos Archipelago covering the period of 1950–1995 A.D.: reproducibility and implications for quantitative reconstructions of sea surface temperature variations     

Miriam Pfeiffer  Wolf-Christian Dullo  Jens Zinke  Dieter Garbe-Schönberg 《International Journal of Earth Sciences》2009,98(1):53-66

In order to assess the fidelity of coral Sr/Ca for quantitative reconstructions of sea surface temperature variations, we have generated three monthly Sr/Ca time series from Porites corals from the lagoon of Peros Banhos (71°E, 5°S, Chagos Archipelago). We find that all three coral Sr/Ca time series are well correlated with instrumental records of sea surface temperature (SST) and air temperature. However, the intrinsic variance of the single-core Sr/Ca time series differs from core to core, limiting their use for quantitative estimates of past temperature variations. Averaging the single-core data improves the correlation with instrumental temperature (r > 0.7) and allows accurate estimates of interannual temperature variations (~0.35°C or better). All Sr/Ca time series indicate a shift towards warmer temperatures in the mid-1970s, which coincides with the most recent regime shift in the Pacific Ocean. However, the magnitude of the warming inferred from coral Sr/Ca differs from core to core and ranges from 0.26 to 0.75°C. The composite Sr/Ca record from Peros Banhos clearly captures the major climatic signals in the Indo-Pacific Ocean, i.e. the El Niño–southern oscillation and the Pacific decadal oscillation. Moreover, composite Sr/Ca is highly correlated with tropical mean temperatures (r = 0.7), suggesting that coral Sr/Ca time series from the tropical Indian Ocean will contribute to multi-proxy reconstructions of tropical mean temperatures.  相似文献   

Phase Equilibria Constraints on Relations of Ore‐bearing Intrusions with Flood Basalts in the Panxi Region,Southwestern China     

ZHANG Zhaochong  HAO Yanli  AI Yu  LI Ying  ZHAO Li 《《地质学报》英文版》2009,83(2):295-309

There are two types of temporally and spatially associated intrusions within the Emeishan large igneous province (LIP); namely, small ultramafic subvolcanic sills that host magmatic Cu-Ni-Platinum Group Element (PGE)-bearing sulfide deposits and large mafic layered intrusions that host giant Ti-V magnetite deposits in the Panxi region. However, except for their coeval ages, the genetic relations between the ore-bearing intrusions and extrusive rocks are poorly understood. Phase equilibria analysis (Q-Pl-Ol-Opx-Cpx system) has been carried out to elucidate whether ore-bearing Panzhihua, Xinjie and Limahe intrusions are co-magmatic with the picrites and flood basalts (including high-Ti, low-Ti and alkali basalts), respectively. In this system, the parental magma can be classified as silica-undersaturated olivine basalt and silica-saturated tholeiite. The equivalents of the parental magma of the Xinjie and Limahe peridotites and picrites and low-Ti basalts are silica-undersaturated, whereas the Limahe gabbro-diorites and high-Ti basalts are silica-saturated. In contrast, the Panzhihua intrusion appears to be alkali character. Phase equilibria relations clearly show that the magmas that formed the Panzhihua intrusion and high-Ti basalts cannot be co-magmatic as there is no way to derive one liquid from another by fractional crystallization. On the other hand, the Panzhihua intrusion appears to be related to Permian alkali intrusions in the region, but does not appear to be related to the alkali basalts recognized in the Longzhoushan lava stratigraphy. Comparably, the Limahe intrusion appears to be a genetic relation to the picrites, whereas the Xinjie intrusion may be genetically related to be low-Ti basalts. Additionally, the gabbro-diorites and peridotites of the Limahe intrusion are not co-magmatic, and the former appears to be derived liquid from high-Ti basalts.  相似文献   

缅甸达贡山风化壳型硅酸镍矿床   总被引：2，自引：0，他引：2  

程迁群  罗太旭 《云南地质》2009,28(4):420-424

矿床产于超基性岩顶部的风化壳硅镁镍矿层中,超基性岩方辉橄榄岩是成矿母岩和矿体直接载体。矿石为硅酸镍氧化矿石,镍以类质同象存在于硅酸盐矿物中。具有典型的风化壳型硅酸镍矿床特点。  相似文献   

ENSO循环与黄河上游径流的丰枯   总被引：6，自引：0，他引：6  

蓝永超  马全杰  康尔泗  张济世  张智慧 《中国沙漠》2002,22(3):262-266

分析了黄河上游径流主要形成区——唐乃亥以上流域的气象和水文特性,在此基础上,根据 El Nino 现象及 La Nina 现象与黄河上游径流的丰枯的对应关系,探讨了 ENSO 事件对黄河上游径流的影响。统计结果表明,ENSO 现象与黄河上游唐乃亥以上流域的径流丰枯有着密切的关系。总体而言,伴随着 El Nino 事件的发生,黄河上游出现枯水的概率较大,而黄河上游的洪水常伴随着 La Nina 事件发生。  相似文献   

The Horto-Baratinha itabirite-hosted iron ore: A basal fragment of the Espinhaço basin in the eastern São Francisco Craton     

《Journal of South American Earth Sciences》2019

The Horto-Baratinha (HBD) iron ore deposit is located at the eastern border of São Francisco Craton, comprising BIF-hosted high-grade bodies (>60 wt.% Fe) associated with polydeformed quartz-mica-schists, amphibole-schist of Statherian maximum deposition age, enclosed by Statherian granitoids of the Borrachudos Suite and Neoarchean gneiss. All the sequence is crosscut by undeformed dikes and sills of pegmatitic bodies probably formed during Late Ediacaran-Cambrian. The metasedimentary sequence is stratigraphically correlatable with the Orosirian-Statherian Serra da Serpentina and Serra de São José Groups that comprise the basal units of the Espinhaço Supergroup and was intensively segmented into distinct tectonic blocks. The sedimentary/diagenetic bedding of the metamorphosed BIF (itabirite) is generally transposed by an axial planar schistosity. The lamellar hematite from itabirite is the oldest iron oxide generation, which was formed during the syn-deformational stage, parallel-oriented to the rock foliation. The (keno)magnetite grains from itabirite, iron ore and pegmatite bodies developed as idioblasts that grew over the foliation formed during late and post-deformational stages. Magnetite oxidizes subsequently to martite and granular hematite. Coarse lamellar hematite crystals randomly oriented in the border of the pegmatitic bodies also formed during the post-deformational stage due to hydrothermal reaction with itabirite. The country rocks have undergone at least three stages of deformation developed during the syn-collisional and late-collisional (Ediacaran to early-Cambrian) phases of the Brasiliano Orogeny: stage 1 with the development of a pervasive foliation (S₁), parallel to axial plane to tight folds and transposition of all sedimentary structures; stage 2 with folding of S₁; stage 3 with refolding of S₁. Both fold systems interfere with each other making up a dome and basin refolding shape. During the late-collisional (Ediacaran to early-Cambrian) and post-collisional/gravitational collapse (Cambrian) the sequence was intruded by anatectic pegmatitic bodies, which are part of the Eastern Brazilian Pegmatite Province, one of the most significant pegmatitic regions worldwide. The fluid related with these intrusions could be related with the Si leaching, crystallization of magnetite and granular hematite, and consequent formation of high-grade iron bodies.  相似文献   

黄河源秋季洪峰对西风指数的响应     

孙立群  李铁键  李晴岚  吴一平 《冰川冻土》2019,41(6):1475-1482

分析了1961—2010年黄河源的水文气象要素的演变过程。由于丰水期（7月、 8月、 9月）降水减少而温度升高, 导致黄河源年径流及降水总体上呈非显著减少趋势, 且1990年代以来9月份秋季洪峰消失。以30年为一个时间窗口, 使用偏相关方法, 分别计算了黄河源丰水期的降水、 径流与WCI（西风指数）、 ENSO（厄尔尼诺-南方涛动）和IOD（印度洋偶极子）的偏相关关系并排除了ENSO、 IOD与WCI之间的共同作用, 发现WCI对黄河源丰水期径流影响要高于ENSO与IOD, WCI的增强可能是黄河源8月降水减少及9月洪峰消减的主要因素。  相似文献   

Large geographic and temporal extensions of the Río de la Plata Craton,South America,and its metacratonic eastern margin   总被引：1，自引：0，他引：1  

João O.S. Santos  Carlos J. Chernicoff  Eduardo O. Zappettini  Neal J. McNaughton  Léo A. Hartmann 《International Geology Review》2019,61(1):56-85

Integration of existing isotopic and geological data allows a reconsideration of the distribution and age of the Río de la Plata Craton within South America. The reinterpretation increases the area of the craton to about 2,400,000 km² with implications for the tectonic map of South America and for global reconstruction of palaeocontinents. Four areas previously considered as separate cratons (Luís Alves, Curitiba, Tebicuary, and Paranapanema) are interpreted as part of the same Río de la Plata Craton. The craton is organized into six provinces and domains: Buenos Aires–Piedra Alta, Taquarembó, Tebicuary, Luís Alves, Encantadas, and Nico Pérez. The term ‘Transplatense’ is proposed to replace ‘Trans-Amazonian’ for Rhyacian events that occurred within the Río de la Plata Craton. The craton is formed not only by dominant Rhyacian rocks and local Archaean rocks, but also by Statherian and Mesoproterozoic rocks. The domains are all partially to totally covered by Phanerozoic basins (Paraná, Chacoparanense, Claromecó, Salado, Balcarce, and Colorado) which makes their investigation difficult. The Ediacaran–Cambrian collisions of the Brasilian orogen generated tectonic mixtures of orogenic and cratonic zones. This is more evident in the eastern margin of the craton, which behaved as a metacraton.  相似文献