Modified frequency-wavenumber algorithm for regional seismograms using Filon's quadrature: modelling of L_g waves in eastern North America     

Chandan K. Saikia 《Geophysical Journal International》1994,118(1):142-158

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新疆康古尔断裂带东段的地球化学特征   总被引：2，自引：0，他引：2  

白云来 《新疆地质》1991,(3)

新疆康古尔断裂带东段(土墩—黄山)的地球化学异常规模大,元素组合为铜、钴、镍铁、钒、钛、铬、钇、锆、铌、金、银等.从聚类分析、因子分析结果及镍、铬、钴、钛、钒累乘等值线图表明,康古尔断裂两侧地球化学系统明显不同,是性质不同的两个壳块.断裂带存在有“榴辉岩化地壳”.康古尔断裂可能是哈萨克斯坦—准噶尔古板块与塔里木古板块间的分界线.  相似文献   

Two-step interface and velocity inversion—— Study o e of the Tangshan seismic region     

XIAO LING LAI XIAN KANG ZHANG XU YAO ZHENG Research Center of Exploration Geophysics  China Seismological Bureau  Zhengzhou  China 《地震学报(英文版)》1998,(6)

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3-D seismic tomography for velocity and interface structure of the crust and upper mantle (theoretical part)     

郑需要  张先康 《地震学报(英文版)》1998,11(5):547-555

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塔里木盆地轮南奥陶系风化壳SYT法物性探测试验研究   总被引：3，自引：0，他引：3  

王文祥  汤寒松 《地球物理学进展》1998,13(3):63-68

ＳＹＴ型物性探测仪自从１９９２年石油系统使用之后,先后在陕北,华北,吉林,大庆油田取得了一定的试验效果,在仪器硬件和方法软件不断改进的基础上,在塔里木盆地轮南地区又进行了深为５７００余米的探测试验,其界面探测精度误差为０．５％～１．２％,在地面上直接解译奥灰顶界面深度,奥灰风化壳裂隙性岩溶发育程度,判译地下油气有等方面,无疑这将会大大降低对油气勘探投资的风险系数,塔里木盆地轮南奥灰风化壳ＳＹＴ法试  相似文献   

Nature and growth rate of the Northern Izu–Bonin (Ogasawara) arc crust and their implications for continental crust formation     

ASAHIKO  TAIRA  SANEATSU  SAITO  KAN  AOIKE  SUMITO  MORITA  HIDEKAZU  TOKUYAMA  KIYOSHI  SUYEHIRO  NARUMI  TAKAHASHI  MASANAO  SHINOHARA  SCHOICHI  KIYOKAWA  JIRO  NAKA & ADAM  KLAUS 《Island Arc》1998,7(3):395-407

The bulk composition of the continental crust throughout geological history is thought by most previous workers to be andesitic. This assumption of an andesitic bulk composition led to an early hypothesis by 72 ) that the continental crust was created by arc magmatism. This hypothesis for the origin of continental crust was challenged by several authors because: (i) the mean rate of arc crust addition obtained by 50 ) is too small to account for some certain phases of rapid crustal growth; and (ii) the bulk composition of ocean island arcs, the main contributor to the Archean and early Proterozoic crust, is basaltic rather than andesitic ( 4 ; 49 ). New data from the Northern Izu–Bonin arc are presented here which support the 72 ) hypothesis for the origin of the continental crust by andesitic arc magma. A geological interpretation of P wave crustal structure obtained from the Northern Izu–Bonin arc by 66 ) indicates that the arc crust has four distinctive lithologic layers: from top to bottom: (i) a 0.5–2-km-thick layer of basic to intermediate volcaniclastic, lava and hemipelagite (layer A); (ii) a 2–5-km-thick basic to intermediate volcaniclastics, lavas and intrusive layer (layer B); (iii) a 2–7-km-thick layer of felsic (tonalitic) rocks (layer C); and (iv) a 4–7-km-thick layer of mafic igneous rocks (layer D). The chemical composition of the upper and middle part of the northern Izu–Bonin arc is estimated to be similar to the average continental crust by 73 ). The rate of igneous addition of the Northern Izu–Bonin arc since its initial 45-Ma magmatism was calculated as 80 km³/km per million years. This rate of addition is considered to be a reasonable estimate for all arcs in the western Pacific. Using this rate, the global rate of crustal growth is estimated to be 2.96 km³/year which exceeds the average rate of crustal growth since the formation of the Earth (1.76 km³/year). Based on this estimate of continental growth and the previously documented sediment subduction and tectonic erosion rate (1.8 km³/year, 24 ), several examples of growth curves of the continental crust are presented here. These growth curves suggest that at least 50% of the present volume of the continental crust can be explained by arc magmatism. This conclusion indicates that arc magmatism is the most important contributor to the formation of continental crust, especially at the upper crustal level.  相似文献   

Velocities of a natural mid-ocean ridge basalt glass   总被引：2，自引：0，他引：2  

Yucheng Pan  Nikolas I. Christensen  Rodey Batiza  Teresa L. Coleman 《Tectonophysics》1998,290(3-4):171-180

We report, for the first time, ultrasonic velocity values for a pure (>95%), natural, submarine basalt glass of mid-ocean ridge basalt composition, from 10 to 1000 MPa at room temperature. These new data show that basalt glass, abundant in the upper oceanic crust, has the lowest velocity of any primary solid component of the oceanic crust. In addition, natural basalt glass has a steeper pressure-dependence of velocity than previously measured in more crystalline samples, indicating that cracks in natural basalt glass are weaker than in more crystalline rocks. To obtain values for the pure glass phase, we correct the natural glass data for the low-pressure closure of cracks, and the presence of minor mineralogic components and vesicles. These new data provide a baseline for evaluating the effect of abundant basalt glass and glassy mesostasis in oceanic upper crust on in situ seismic velocities. In addition, data on the elastic and seismic properties of natural glasses are useful for a better understanding of glass structure, and glass relaxation, with potential applications to submarine volcanology.  相似文献   

中国大陆地壳密度差异多尺度反演   总被引：29，自引：4，他引：25       下载免费PDF全文

侯遵泽  杨文采 《地球物理学报》1998,41(5):642-651

利用小波分析方法原理,在对中国布格重力异常多尺度分解的基础上,反演了各种尺度意义下中国大陆地壳的密度差异,给出了中国大陆地壳中相对密度差异的空间分布,为研究中国大陆地壳构造、进行深部地质研究提供了新结果．  相似文献   

早前寒武纪地壳增生、再造作用与基底变质建造分析──以华北为例   总被引：1，自引：0，他引：1       下载免费PDF全文

张福勤 《地球物理学报》1998,41(Z1):88-98

早前寒武纪地壳演化的具体表现可以从增生作用和陆壳再造作用这两个方面进行描述按照增生表壳岩系类型可以将早前寒武纪大陆地壳划分为绿岩型和沉积型陆壳增生区;按陆壳再造作用的类型可以将早期大陆地壳划分为变质改造型和重熔分异型陆壳再造区对区域上绿岩型表壳岩系、沉积型表壳岩系;TTG岩系、钾质花岗岩系等与地壳演化进程的关系作了概括．不同类型陆壳区反映了地壳增生进程是不一样的,增生地壳受再造作用的程度以及遭受的陆壳再造作用类型也可以是不同的,而一个完整的地壳演化旋回应包含活动增生、陆壳再造与克拉通化作用,一个地壳区地壳演化往往是这些作用交替发展并形成与邻区地壳演化进程的差异．进而提出了早前寒武纪克拉通基底建造分析的思路、原则和模式  相似文献   

富钴锰结壳分析技术评介   总被引：3，自引：1，他引：2  

王毅民  王晓红  张学华 《岩矿测试》1998,17(4)

简要评介了用于富钴锰结壳成分分析的现代分析技术,包括船上现场分析、陆上实验室的多元素分析、矿物微区分析和元素微区分布特征研究的微探针方法及相关标准物质的研制。讨论了结壳品位分析时的取样问题及干基温度的确定和对“绿色”分析技术的需求。  相似文献