多维分形奇异功率谱分析与应用          下载免费PDF全文

李庆谋;  ;  刘少华; 《地球物理学进展》2005,20(4)

地球物理信号中普遍含有噪声，消除噪声是地球物理信号处理中的关键技术之一.奇异功率谱分析（SSA）是在状态空间（又称相空间）中研究（系统）动力学、非线性科学与混沌现象的方法.本文在状态空间中通过SSA分解，研究、应用地球物理序列的尺度不变性进行多维分形滤波：通过在状态空间的SSA分解，构造了经验正交函数系（EOF）；在EOF子空间中定义了两种尺度与测度后，发现了两种测度与尺度皆在多个尺度范围内存在尺度不变性；利用这种尺度~测度的尺度不变性，设计、实现了多维分形奇异功率谱(MSSA)滤波模型；处理解释了大洋钻探（ODP）1143A孔岩芯自然反射性（NGR）资料；Fourier功率谱分析结果证明，MSSA能有效地压制噪声，提取有用信号.研究得出，嵌入维数对MSSA基本无影响（小于1/1000），多维分形滤波器（MSSA）能有效压制噪声或提取有用信号.  相似文献   

Petrology and Geochemistry of West Philippine Basin Basalts and Early Palau-Kyushu Arc Volcanic Clasts from ODP Leg 195, Site 1201D: Implications for the Early History of the Izu-Bonin-Mariana Arc   总被引：3，自引：0，他引：3  

SAVOV  IVAN P.; HICKEY-VARGAS  ROSEMARY; D'ANTONIO  MASSIMO; RYAN  JEFFREY G.; SPADEA  PIERA 《Journal of Petrology》2006,47(2):277-299

Site 1201D of Ocean Drilling Program Leg 195 recovered basalticand volcaniclastic units from the West Philippine Basin thatdocument the earliest history of the Izu–Bonin–Marianaconvergent margin. The stratigraphic section recovered at Site1201D includes 90 m of pillow basalts, representing the WestPhilippine Basin basement, overlain by 459 m of volcaniclasticturbidites that formed from detritus shed from the Eocene–Oligoceneproto-Izu–Bonin–Mariana island arc. Basement basaltsare normal mid-ocean ridge basalt (N-MORB), based on their abundancesof immobile trace elements, although fluid-mobile elements areenriched, similar to back-arc basin basalts (BABB). Sr, Nd,Pb and Hf isotopic compositions of the basement basalts aresimilar to those of basalts from other West Philippine Basinlocations, and show an overall Indian Ocean MORB signature,marked by high ²⁰⁸Pb/²⁰⁴Pb for a given ²⁰⁶Pb/²⁰⁴Pb and high¹⁷⁶Hf/¹⁷⁷Hf for a given ¹⁴³Nd/¹⁴⁴Nd. Trace element and isotopicdifferences between the basement and overlying arc-derived volcaniclasticsare best explained by the addition of subducted sediment orsediment melt, together with hydrous fluids from subducted oceaniccrust, into the mantle source of the arc lavas. In contrastto tectonic models suggesting that a mantle hotspot was a sourceof heat for the early Izu–Bonin–Mariana arc magmatism,the geochemical data do not support an enriched, ocean islandbasalt (OIB)-like source for either the basement basalts orthe arc volcanic section. KEY WORDS: back-arc basalts; Izu–Bonin–Marianas; Philippine Sea; subduction initiation; Ocean Drilling Program Leg 195  相似文献   

Inversion of titanomaghemite in oceanic basalt during heating     

David Krása  Jürgen Matzka 《Physics of the Earth and Planetary Interiors》2007,160(2):169-179

We studied the change of magnetic behaviour upon laboratory heating of altered mid-ocean ridge basalt (MORB) samples in the age range of 16-35 Ma to determine the influence of titanomaghemite inversion on the thermal demagnetisation of natural remanent magnetisation (NRM) of these basalts. MORB samples were heated to successively higher temperatures and at the same time the temperature dependence of either saturation magnetisation or NRM was monitored continuously. After each heating step, hysteresis loops and remanent magnetisation curves between 10 K and room temperature were measured. With this procedure, it is shown that the dominant magnetic remanence carrier in our MORB samples is cation deficient titanomaghemite. Moreover, it is demonstrated that the titanomaghemite is gradually changing to a Ti-poor titanomagnetite as the final inversion product. During inversion, both the Curie temperature as well as the maximum unblocking temperature of the NRM are gradually increasing. We show that the paradox of unblocking temperatures above the Curie temperatures often observed for altered MORBs is an artefact of this gradual, heating induced inversion process.  相似文献