△T球体异常的三元解释法

在△Ｔ异常解释课题中，一个新的角度参量─—视磁化特征角的拟定，最大限度地简化了球体磁场表达式。从而才有可能通过特殊解法，给出了球体磁场的极值与拐点公式。作者据此建立了四种不受正常场制约、仅需异常的局部持征曲线即可全面解释三度异常的解释方法。屏障分解、叠加判别、三元迭代的设计，为解释三度体叠加异常给出了简单而易行的途径。     

The importance of oxygen isotope provenance in relation to solute content of bulk meltwaters at Imersuaq Glacier,West Greenland

Stable oxygen isotope analysis and measurement of several dissolved cations and anions of bulk meltwater samples have provided information about the hydrochemical environment of the glacial hydrological system at Imersuaq Glacier, an outlet tongue from the Greenland ice‐sheet, West Greenland. The samples were collected at frequent intervals during the period 20–28 July 2000 in a small (<20 L s^?1) englacial meltwater outlet at the glacier margin. The results document the following findings: (i) a marked diurnal variation of δ¹⁸O is related to the composition of oxygen isotope provenances, mainly near‐marginal local superimposed ice and basal up‐sheared ice further up‐glacier; (ii) a relationship is seen between all base cations (Na⁺, K⁺, Ca²⁺, Mg²⁺), SO₄^2? and δ¹⁸O, indicating that solute acquisition is provided by solid–solution contact with the up‐sheared ice—as the relationship with Cl^? is weak the influence of seasalt‐derived solutes is small in the area; (iii) when the melt rate is high, two diurnal maxima of δ¹⁸O values and solute concentrations are measured, and it is suggested that a snow meltwater component is responsible for the second maximum of δ¹⁸O—a short residence time leads to a delayed decrease in ion concentrations. Copyright © 2003 John Wiley & Sons, Ltd.     

History of crustal growth and recycling at the Pacific convergent margin of South America at latitudes 29°–36° S revealed by a U–Pb and Lu–Hf isotope study of detrital zircon from late Paleozoic accretionary systems

Detrital zircon provides a powerful archive of continental growth and recycling processes. We have tested this by a combined laser ablation ICP-MS U–Pb and Lu–Hf analysis of homogeneous growth domains in detrital zircon from late Paleozoic coastal accretionary systems in central Chile and the collisional Guarguaráz Complex in W Argentina. Because detritus from a large part of W Gondwana is present here, the data delineate the crustal evolution of southern South America at its Paleopacific margin, consistent with known data in the source regions.Zircon in the Guarguaráz Complex mainly displays an U–Pb age cluster at 0.93–1.46 Ga, similar to zircon in sediments of the adjacent allochthonous Cuyania Terrane. By contrast, zircon from the coastal accretionary systems shows a mixed provenance: Age clusters at 363–722 Ma are typical for zircon grown during the Braziliano, Pampean, Famatinian and post-Famatinian orogenic episodes east of Cuyania. An age spectrum at 1.00–1.39 Ga is interpreted as a mixture of zircon from Cuyania and several sources further east. Minor age clusters between 1.46 and 3.20 Ga suggest recycling of material from cratons within W Gondwana.The youngest age cluster (294–346 Ma) in the coastal accretionary prisms reflects a so far unknown local magmatic event, also represented by rhyolite and leucogranite pebbles. It sets time marks for the accretion history: Maximum depositional ages of most accreted metasediments are Middle to Upper Carboniferous. A change of the accretion mode occurred before 308 Ma, when also a concomitant retrowedge basin formed.Initial Hf-isotope compositions reveal at least three juvenile crust-forming periods in southern South America characterised by three major periods of juvenile magma production at 2.7–3.4 Ga, 1.9–2.3 Ga and 0.8–1.5 Ga. The ¹⁷⁶Hf/¹⁷⁷Hf of Mesoproterozoic zircon from the coastal accretionary systems is consistent with extensive crustal recycling and addition of some juvenile, mantle-derived magma, while that of zircon from the Guarguaráz Complex has a largely juvenile crustal signature. Zircon with Pampean, Famatinian and Braziliano ages (< 660 Ma) originated from recycled crust of variable age, which is, however, mainly Mesoproterozoic. By contrast, the Carboniferous magmatic event shows less variable and more radiogenic ¹⁷⁶Hf/¹⁷⁷Hf, pointing to a mean early Neoproterozoic crustal residence. This zircon is unlikely to have crystallized from melts of metasediments of the accretionary systems, but probably derived from a more juvenile crust in their backstop system.     

伊通盆地梁家地区奢岭组混源扇三角洲内幕结构

伊通盆地梁家地区(二号断层上盘)钻井揭示奢岭组是该区主要的油气富集层,目前研究结果认为奢岭组储集层是由两个方向的扇三角洲混合沉积形成,但由于资料有限,应用常规方法无法清楚地认识两个不同方向的物源混合沉积的扇三角洲的内幕特征以及这两个物源如何动态地控制着砂体的分布,影响了对该区油气储集层的深入认识.应用地震和地质资料,在波阻抗反演结果二次解释的基础,解析了这两个混合物源扇三角洲的内幕特征和演化特征,得出3个结论:(1)伊通盆地梁家地区奢岭组至少有4期扇三角洲沉积,每期扇三角洲的沉积范围由下向上逐渐扩大,反映了基准面逐渐下降的过程;(2)奢岭组的4期扇三角洲是由两个物源混合沉积形成,这4期扇三角洲逐渐由受从二号断层来的物源控制为主,变为由受从北东方向来的物源控制为主;(3)基于波阻抗体进行的砂层组解释和分析,能够清楚地分析扇三角洲沉积体的内幕结构,是应用波阻抗进行高分辨率地震分析和应用的一种新的分析方法.     

基于子波分析的悬浮物散射信号特征提取实验研究

概述了应用子波分析对悬浮物测量中的声散射信号进行特征提取的方法 ,并对声散射信号识别的研究进行了探讨。对实测数据的实验取得了较好的结果     

Mineral provinces and matter provenance of the surficial sediments in the western Philippine Sea: implication for modern sedimentation in West Pacific marginal basin

The characteristics and distribution patterns of detrital minerals (0.063~0.125 mm) in marine sediments provide a significant indicator for the identification of the origin of sediment.The detrital mineral composition of 219 surface sediment samples was analysed to identify the distribution of sediments within the western Philippine Sea. The area can be divided into three mineral provinces: (I) province east of the Philippine Trench, the detrital minerals in this province are mainly composed of calcareous or siliceous organisms, with the addition of volcanogenic minerals from an adjacent island arc; (II) middle mineral province, clastic minerals including feldspar, quartz and colorless volcanic glass, sourced from seamounts with intermediate-acid volcanic rock, or erupting intermediate-acid volcano; (III) province west of the Palau—Kyūshū Ridge, the matter provenance within this province is complex; the small quantity of feldspar and quartz may be sourced from seamounts or erupting volcano with intermediate-acid composition, with a component of volcanic scoria sourced from a volcano erupting on the Palau—Kyūshū Ridge. it is suggested that, (1) Biogenic debris of the study area is closely related to water depth, with the amount of biogenic debris controlled by carbonate lysocline. (2) Volcaniclastic matter derived from the adjacent island arc can be entrained by oceanic currents and transported towards the abyssal basin over a short distance. The weathering products of volcanic rocks of the submarine plateau (e.g.,Benham Plateau) and adjacent ridges provide an important source of detrital sedimentation, and the influence scope of them is constrained by the intensity of submarine weathering. (3) Terrigenous sediments from the continent of Asia and the adjacent Philippine island arc have little influence on the sedimentation of this study area, and the felsic mineral component is probably sourced from volcanic seamounts of intermediate-acid composition.     

南极中山站大气气溶胶的化学组成及其来源的判别

从1998年3月7日至1999年11月23日历时21个月，在南极中山站连续采集89个海洋气溶胶样品，本文提供全部样品的13种化学元素Cu、Pb、Zn、Cd、Fe、Al、Mn、Cr、V、K、Na、Ca、Mg含量的实测值．研究表明中山站气溶胶化学成份的含量具有季节性变化的特征．通过相关分析、因子分析、富集因子等方法判别不同时间段中山站气溶胶化学成份的来源。     

天然气水合物的形成与识别

探讨了天然气水合物矿藏的形成条件和机理、水合物矿藏的聚集方式。天然气水合物的形成除了必要的气体和水,还需要一定的温压和地质条件;其形成机理可用高渗漏系统和弱渗漏系统来解释;天然气水合物在沉积物中主要以构造聚集和地层聚集的方式存在。综述了天然气水合物矿藏的识别方法。     

南海北部海区水团的判别分析

将判别分析应用于南海北部海区的水团分析。划分为八个水团:沿岸冲淡水团(F),近岸混合水团(M),暖表层水团(WS),表层水团(S),表—次层混合水团(SU),次层水团(U),次—中层混合水团(UI)和中层水团(I)。给出了各水团在四季代表月的Bayes多组判别的系数和参数。用资料检验判别的成效.冬季和春季可达95.90％以上,夏季为94.80％,秋季是全年最低值,为92.72％。讨论了造成错判的原因,并与Fisher判别作了比较。当测值维数较低时,建议选用Bayes判别。对八个水团以及各水团两两之间差异的显著性进行了检验,证实在每个季节中各水团之间的差异,都在高度置信水平(α=0.01)上具有显著性。因而,划分为八个水团是有实际意义的,其判别式的系数和参数,可用于实际的判别和预报。     

形变,应变短临前兆标志体系

建立各手段的前兆异常标志,从而组合各类前兆标志体系是“八五”地震短临预报攻关研究项目的重要目标之一。本文以形变,应变手段的主要研究对象,初步建立了一个形变应变短临前兆标志体系,并总结出了各种异常的判别标志,为利用系统优化理论和专家系统理论进一步研究形变应前兆系统和地震之间的关系,从而为提高中短期地震预报的水平打下了一定的基础。