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在出露地表的中、高压相麻粒岩地体代表下陆壳的认识基础上,建成全球麻粒岩相地体地球化学成分数据库（共１６８５套分析数据）。利用ＩＢＭ４３８１大型计算机对全部数据进行了多元变量统计分析,成功地建立了迄今为止精度最高的太古代、后太古代和全球大陆下地壳化学成分模型。 相似文献
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Xiaolin Xiong Zhenhua Zhao Zhenghua Bai Houjun Mei Yixian Wang Qiang Wang Jifeng Xu Hecai Niu Zhiwei Bao 《科学通报(英文版)》2001,46(10):811-817
The sodium-rich dacites and albite porphyries of Permian in the Awulale Mountain of west Tianshan have unique chemical and trace element signatures identical to adakite. These intermediate-acidic igneous rocks are characterized by high Na2O, Al2O3 and Sr contents and high Sr/Y and La/Y ratios (＞40 and ＞20, respectively), and low Y and Yb contents, and strong depletion in HREE, and positive Eu anomaly. The (143Nd/144Nd)i is in the range from 0.51236 to 0.51248 and the eNd(t) is positive value (+0.79—+3.11); the (87Sr/86Sr)i is in the range from 0.7052 to 0.7054. These Nd and Sr isotopic composition features indicate that the source rocks of these adakite-type rocks are from a weakly depleted mantle, or a depleted mantle, but was contaminated by the crustal materials. These adakite-type rocks were most likely derived from the partial melting of new underplated basaltic rocks under the conditions of amphibolite to eclogite transition in the postcollisional environment of North Xinjiang during the Permian Period. They are not only the Phanerozoic juvenile crust materials, but also are probably animportant symbol of the underplating of mantle- derived basaltic magmas and the vertical growth of continental crust in the west Tianshan area during the postcollision of Late Paleozoic. 相似文献
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LIU Rui ZHOU HanWen ZHANG Li ZHONG ZengQiu ZENG Wen XIANG Hua JIN Song LU XinQian & LI ChunZhong State Key Laboratory of Geological Processes Mineral Resources Faculty of Earth Sciences China University of Geosciences Wuhan China State Key Laboratory of Continental Dynamics Northwest University Xi’an The th Geological Team of Zhejiang Province Lishui 《科学通报(英文版)》2009,54(9):1543-1554
A combined study of zircon LA-ICP-MS U-Pb dating, trace elements and Hf isotope was carried out for gneissic granite from the Sanzhishu area in Jingning, SW Zhejiang Province. Nearly all the zircons separated from the granite exhibited oscillatory zoning and high Th/U ratios (>0.1). The REE profile showed a pronounced positive Ce anomaly, negative Eu anomaly and an enrichment of HREE, which are typical characteristics of magmatic zircon. Thirteen concordant or nearly concordant analytical data yielded a weighted mean 207Pb/206Pb age of 1860±13 Ma (MSWD=0.084), representing the formation age of the granite. The magmatic zircons had negative εHf(t) values of −15.6 to −10.0 and two-stage Hf model ages of 3.1 to 3.4 Ga, indicating that the granites were formed by reworking of ancient crust. The major- and trace-element data indicate that the gneissic granites are metaluminous high-K calc-alkaline rocks and exhibit the same geochemical characteristics as aluminous A-type granites, implying the emplacement of the granite in a post-orogenic extensional tectonic setting. We conclude that the Paleoproterozoic crustal reworking event in the Cathaysia Block of South China marked the transition from assembly to break-up of the Columbia supercontinent. Supported by National Natural Science Foundation of China (Grant No. 40873004), Special Funds for National Scientific Research of Commonweal Industries, the Ministry of Land and Resources of China (Grant No. 2008110015), Opening Foundation of State Key Laboratory of Continental Dynamics, Northwest University (Grant No. 06LCD12) and the Project of Land and Resources Bureau of Zhejiang Province (Grant No. 2004005) 相似文献
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YU JinHai 《科学通报(英文版)》2007,52(1):13-22
U-Pb dating for fifty-six detrltsl zircons from a paragneiss in Nanxiong area, northern Guangdong Province, Indicates that the latest Neoproterozoic sediments in Cathaysia hinterland are composed of numerous Grenvillian and Necerchaean clasUc materials, as well as some Mesoproterozolc detritus. Minor Paleoarchaean （3.76 Ga） and Mesoarchaean （3.0-3.2 Ga） zircons, which are the oldest zircons In South China, also are firstly found in the sediments, suggesting that the Cathaysia Block may contsln very old materials. The Hf isotope compositions of thirty-seven zircons reveal that these clastlc materials have different origins. Minor zircons crystslllzed from magma generated from relatively juvenile crust, while the parental magma of most zircons was derived from ancient crust. Integration of U-Pb dating and Hf Isotope analysis of these zircons suggests that the generation of juvenile crust in the Cathaysia block mainly occurred at 2.5-2.6 Ga. Mesoarchaean （3.0-3.3 Ga）, late Paleoproterozolc （-1.8 Ga） and Paleoarchaean （-3.7 Ga） may also be important episodes of crustal growth. Grenvllllan magmatism is extremely Intense, but it mainly involved recycling of ancient crustal components with little formation of Juvenile crust. The marked presence of -2.1 Ga Hf model ages and the absence of the zircons with crystsllizatlon ages at -2.1 Ga suggest that the parental magma of many zircons was probably derived from the mixed source consisting of Neoarchaean and late Paleoproterozoic materlals. 相似文献
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长英质的大陆地壳是地球区别于其他星球的重要特征之一。传统观点认为大陆地壳的生长主要发生于俯冲增生型造山带,经典的陆陆碰撞造山带大陆地壳的生长并不显著,主要以地壳的重熔改造为主。青藏高原是全球最经典的陆陆碰撞造山带之一,然而近年来的研究揭示青藏高原南部的冈底斯带发育大量具有亏损同位素组成的与碰撞造山过程有关的岩浆岩,说明碰撞造山过程中也可以发生显著的地壳生长作用。文中聚焦冈底斯带岩浆岩,以冈底斯岩基和林子宗火山岩为研究对象,综述了相关岩石地球化学研究进展,探讨了碰撞造山过程相关的岩浆作用与地壳生长的关系,并分析了可能的地壳生长机制。 相似文献
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南秦岭前寒武纪岩浆构造事件与地壳生长 总被引：6，自引：0，他引：6
前寒武纪构造体制与地球动力学机制是当前南秦岭构造带研究的薄弱环节 ,利用南秦岭广泛分布的前寒武纪岩石地层、岩浆 -构造事件 ,尤其是记录前寒武纪地壳生长、演化及其地幔动力学机制的岩浆构造事件 ,对南秦岭前寒武纪地质体、岩浆活动、构造事件的组成、特征与年代学进行了综合研究。结果表明 :南秦岭太古代类似于华北太古代地幔的特征 ;元古代地幔则发生了先亏损后富集的演化 ;其中 ,8～ 9亿年南秦岭发生了急剧的地壳生长事件 ,并以垂向加积增生为主要机制。 相似文献
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南海北部大陆架海洋生态系统Ecopath模型的应用与分析 总被引：8，自引：1，他引：8
过度捕捞和环境恶化导致渔业资源和海洋生态系统逆向发展。采用EwE5.1软件,对南海北部大陆架建立Ecopath(生态通道模型)模型。通过各级流量、生物量、生产量、捕捞量、系统总流量以及生态位和混和营养效应等方面的分析,得出营养流通主要有2种途径,肉食鱼类间饵料竞争非常激烈,低值鱼类间具相似的捕食压力,顶级捕食者对大部分鱼类负效应不明显。系统受过度捕捞渔业影响很大,并存在营养级I利用效率低和渔业资源小型化、低值化等不稳定的幼态特征。 相似文献
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O’REILLY S Y 《科学通报(英文版)》2009,54(9):1555-1563
This paper presents geochemical analyses of a lamprophyre intruding the Caledonian Doushui granite body in Shangyou County, southern Jiangxi Province. U-Pb dating and Hf-isotope analyses are espe-cially carried out for zircons from it. Petrological and geochemical features show that the lamprophyre belongs to a high-K, weakly alkaline pyroxene-biotite lamprophyre. It is characterized by high Mg# (0.74), Ni (253 μg/g) and Cr (893 μg/g) contents, and also enriched in incompatible elements, such as REE, Rb, Sr... 相似文献
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南海北部大陆架海洋生态系统Ecosim模型的动态模拟 总被引：2，自引：0，他引：2
为了确定最佳的渔业政策,采用EwE 5.1软件,对南海北部大陆架海洋生态系统构建了1987-1998年Ecosim(时间动态)模型。Ecosim模型包含了32个功能组,初始参数来源于20世纪80年代末期静态平衡的Ecopath模型。通过营养关系,分析了渔业捕捞对主要经济鱼类的动态影响。结果显示1998年系统总输出、总生物量都有不同程度的增加,而总捕捞量则有所降低;强化的捕捞压力导致了低值小型鱼类被捕食压力的间接缓解,大中型高价值鱼类的生物量发生明显下降;说明了生态系统呈现出逆向发育的主要原因在于过度捕捞所产生的从上而下(top-down)的控制作用。 相似文献
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The South China Sea (SCS) is one of the largest marginal seas in the western Pacific. Its northern part has the features of a passive continental margin. The studies of deep crustal structure in this area are very important for understanding the tectonic nature, evolution history, basin formation of the northern margin, and the origin of the SCS. In the past decades, the deep seismic experiments of crustal studies in the northern SCS have gone through three stages, namely the sonobuoy, two-ship Expanding Spread Profile (ESP), and Ocean Bottom Hydrophone/Seismometer (OBH/OBS). Along the continental slope, the sonobuoy experiments provided useful information about the velocity structure of the upper crust, while the ESP data recorded for the first time the seismic signals from deep crustal structure and Moho interface. And the OBH/OBS profiles revealed the crustal structure in much greater detail. This paper first gives a brief historical review of these deep seismic experiments and studies, then a summary of the latest progress and important research results. The remaining problems and suggestions for further research work are presented as conclusive remarks. 相似文献
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Crustal growth at ～2.5 Ga in the North China Craton：evidence from whole-rock Nd and zircon Hf isotopes in the Huai＇an gneiss terrane 总被引：5，自引：0，他引：5
The Huai’an gneiss terrane mainly consists of TTG gneisses and dioritic gneisses. Laser in situ U-Pb dating of magmatic zircon cores indicates that protolith of these gneisses was formed at ~2.5 Ga. The TTG gneisses have positive εNd（t） values of 2.7 to 4.3, and most of the magmatic zircons have positive εHf（t） values of 2.0 to 8.3. These positive εNd（t） and εHf（t） values are both similar to those of the contemporaneous depleted mantle at 2.5 Ga. Moreover, the young Hf model ages of 2.44 to 2.73 Ga for the magmatic zircons are close to the timing of the zircons growth. The whole-rock εNd（t） values are lower in the dioritic gneisses （0.8 to 1.7） than in the TTG gneisses due to the involvement of ancient crust in its source. However, many magmatic zircons from the dioritic gneisses have similar εHf（t） values （2.0 to 7.9） to that of the coeval depleted mantle; their Hf model ages of 2.49 to 2.75 Ga are close to the U-Pb ages of zircons. The highest εHf（t） values are close to the value of the depleted mantle, and the relatively high εHf（t） values corresponds to the relatively young Hf model age. These Nd and Hf isotope features suggest that these two types of gneisses of the Huai’an gneiss terrane originated from the juvenile crust at ca. 2.5 Ga. 相似文献
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Integrated study on the tectonic, basin filling and thermal evolution of the Tertiary basins on the northern margin of the South China Sea has indicated that the rift continental margin on the northern South China Sea is not a passive margin and that the western margin is characteristic of the transform-extension. Episodic rifting and the thermal events since 10 Ma in the area have been documented by the integrated analysis of dynamic process. It has been clarified that the tectono-thermal events have exerted a significant influence on basin features and hydrocarbon accumulation, and particularly, the westward collision of the Lusong Island Arc, the generation of densely spaced faults in the Pearl River Mouth Basin, the rapid subsidence, high heat flow and large-scale over pressure and thermal-fluid breakthrough in the Yinggehai and the Qiongdongnan basins have proved to be the important factors determining the formation of oil and gas in these basins. 相似文献
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南海深部计划与国际大洋钻探航次取得了一系列创新进展与重大突破:1)发现南海陆缘岩石圈减薄之初未出现地幔蛇纹岩出露,且岩浆迅速出现;2)新提出南海不是\"小大西洋\",而是\"板缘张裂\"盆地,与经典的大西洋型\"板内张裂\"陆缘模式不同;3)揭示南海受到俯冲带的强烈控制,提出俯冲诱发地幔上涌并影响南海岩浆活动。 相似文献
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To study the thinning of cratonic lithosphere in North China has been the hot subject of basic research in the fields of solid earth science in China. This paper presents an overview on the formation and evolution of continental crust, and outlines the mechanisms of forming the lithospheric mantle. It is suggested that the thinning of cratonic lithosphere principally proceeds in two ways, one by subduction erosion （e.g., North China）, and the other by a combination of subduction erosion and underplating degistion （e.g., Yangtze）. 相似文献
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南海中部存在巨大的中南断裂将南海海盆分割为东-西两部分,至少自1亿年以来,在沉积环境与沉积厚度、洋陆边界的属性与特征、大陆破裂的时代、岩浆活动的来源与程度、减薄大陆架和大陆坡的宽度、洋壳年龄与磁性层结构、磁异常条带特征、岩石化学等诸多方面都存在巨大差异,它们主要受控于早期地质构造背景的差异、东西部大陆减薄伸展速率的变化以及海底扩张的构造环境的不同,并深刻影响了之后的区域沉积分区和沉降特征。 相似文献
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GAO Tianshan TANG Jiafu SANG Haiqing HU Shiling QIAN Cunchao 《科学通报(英文版)》2006,51(12):1494-1500
Greenschist-facies metasedimentary and metaigne- ous rocks are frequently found to occur continuously along convergent plate margins where high pressure (HP) or ultrahigh pressure (UHP) metamorphic rocks also crop out[1-7]. Geological investigations of co… 相似文献
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The authors analyze the coral growth band from a colony in the northwestern South China Sea. The coral growth band can provide comprehensive environmental information on climate. The trend from the two-century-long annual density of the coral is in a good agreement with that of the global CO2 concentration. Both trends were small prior to the end of the 19th century; after that, trends became clear, more so from the 1960s to the 1990s (the end of the coral record). The overall coral density shows a steady d... 相似文献
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As an important part of the global continents, China continent has long been situated in the peculiar tectonic position and experienced extremely complicated activities, which resulted in the regional unique characteristics for China continent on the global common geological background. These characteristics contain abundant information regarding scientific key issues of modern geological frontier. Thus, China continent can be a natural laboratory and excellent arena for the modern geosciences. The modern earth sciences have started entering the era featured with earth systematic science and beyond plate tectonics. How to take the regional advantage and exploit the treasure resource to participate the new theoretical and methodological creation is a historic opportunity and great challenge we are facing. This paper generalizes research priorities in four fields on China continental geology and tectonics for discussion. They are: China continental tectonics and dynamics; Mesozoic-Cenozoic crustal deformation and deep-seated processes in China continent and the adjacent regions; deep-seated dynamic background and evolutionary trend of crustal tectonic activities on the time scale of human existence; deep-seated background and processes of conjunction and transformation of different tectonic systems. 相似文献