Simultaneous determinations of U–Pb age,Hf isotopes and trace element compositions of zircon by excimer laser-ablation quadrupole and multiple-collector ICP-MS

We describe an in situ method for simultaneous measurement of U–Pb–Hf isotopes and trace element compositions of zircons using a quadrupole and multiple-collector inductively-coupled-plasma mass spectrometer (Q-ICP-MS and MC-ICP-MS, respectively) connected to a single excimer laser-ablation system. A laser-generated zircon aerosol was split behind the ablation cell into two transport tubes via a Y-shaped connector and simultaneously introduced into the two mass spectrometers. Hafnium isotopes were measured on the MC-ICP-MS instrument, while U–Pb ages and trace element compositions were determined using the Q-ICP-MS. The precision and accuracy of this method was evaluated using six well-known and widely used zircon standards (91500, Temora-2, GJ-1, Mud Tank, BR266 and Monastery). Analyses were carried out using spot sizes of 32, 44 and 60 μm. For the 44 and 60 μm spot, the resulting U–Pb ages, Hf isotopic and rare earth element (REE) compositions of these six zircons agree with recommended/reported values within 2σ error. The difference in relative standard deviations (RSD) of ²⁰⁶Pb/²³⁸U ages between split-flow measurements and those obtained separately on the Q-ICP-MS is within ～ 20% for 91500, Temora-2 and GJ-1, and ～ 60% for Mud Tank (due to its lower U and Pb concentrations). Our method provides a precise approach for determining the U–Pb age and the Hf isotopic and trace element compositions of zircon within a single ablation event. This is in particular important for analysis of zircons that are small or contain complicated zoning patterns. Finally, the REE composition of zircon BR266 is more homogeneous than other zircons and could be a suitable standard by which to benchmark new standards for microprobe analyses of zircons.     

Upper crustal abundances of trace elements: A revision and update

We report new estimates of abundances of rarely analyzed elements (As, B, Be, Bi, Cd, Ge, In, Mo, Sb, Sn, Te, Tl, W) in the upper continental crust based on precise ICP-MS analyses of well-characterized upper crustal samples (shales, pelites, loess, graywackes, granitoids and their composites) from Australia, China, Europe, New Zealand and North American. Obtaining a better understanding of the upper crustal abundance and associated uncertainties of these elements is important in placing better constraints on bulk crust composition and, from that, whole Earth models of element cycling and crust generation. We also present revised abundance estimates of some more commonly analyzed trace elements (Li, Cr, Ni, and Tm) that vary by > 20% compared to previous estimates. The new estimates are mainly based on significant (r² > 0.6) inter-element correlations observed in clastic sediments and sedimentary rocks, which yield upper continental crust elemental ratios that are used in conjunction with well-determined abundances for certain key elements to place constraints on the concentrations of the rarely analyzed elements. Using the well-established upper crustal abundances of La (31 ppm), Th (10.5 ppm), Al₂O₃ (15.40%), K₂O (2.80%) and Fe₂O₃ (5.92%), these ratios lead to revised upper crustal abundances of B = 47 ppm, Bi = 0.23 ppm, Cr = 73 ppm, Li = 41 ppm, Ni = 34 ppm, Sb = 0.075, Te = 0.027 ppm, Tl = 0.53 ppm and W = 1.4 ppm. No significant correlations exist between Mo and Cd and other elements in the clastic sediments and sedimentary rocks, probably due to their enrichment in organic carbon. We thus calculate abundances of these elements by assuming the upper continental crust consists of 65% granitoid rocks plus 35% clastic sedimentary rocks. The validity of this approach is supported by the similarity of SiO₂, Al₂O₃, La and Th abundances calculated in this way with their upper crustal abundances given in Rudnick and Gao [Rudnick, R., Gao, S., 2003. Composition of the continental crust. In: Rudnick, R.L. (Ed.), The Crust. In: Holland, H.D., Turekian, K.K. (Eds.), Treatise on Geochemistry, vol. 3. Elsevier–Pergamon, Oxford, pp. 1–64.]. The upper crustal abundances thus obtained are Mo = 0.6 ppm and Cd = 0.06 ppm. Our data also suggest a  20% increase of the Tm, Yb and Lu abundances reported in Rudnick and Gao [Rudnick, R., Gao, S., 2003. Composition of the continental crust. In: Rudnick, R.L. (Ed.), The Crust. In: Holland, H.D., Turekian, K.K. (Eds.), Treatise on Geochemistry, vol. 3. Elsevier–Pergamon, Oxford, pp. 1–64.].     

An Approach to Single Image Automatic Orientation and Point Determination by Using Ortho-Images and a Dtm

This paper describes an approach to single image automatic orientation and point determination by using current ortho-images and a DTM, and the experience gained in its implementation. The procedure proposed automatically extracts and matches feature points in evenly distributed patches on aerial images and ortho-images. A large number of image measurements (up to several thousand) are obtained in this process and are included in a robust space resection to determine the orientation parameters of the aerial image. For point determination with a single image, a method is formalised which integrates the DTM interpolation into the space resection so that the 3D ground coordinates of the image points can be determined in a unified mathematical model. Tests and analyses of this method show that the large number of automatic image measurements relieves the requirement for complicated and precise feature extraction and matching methods. The ground points obtained from single image intersection have an accuracy of approximately 1 pixel in planimetry, which fulfils the requirement for ortho-image updating. The elevation accuracy is mainly dependent on the quality of the current DTM and the interpolation method applied to it.     

唐山7.8级地震前后地下流体动态异常演化特征

以30口水动态及油井动态观测井1973年至1978年的观测资料为基础，对唐山7．8级地震前后水动态和油井动态异常的演化过程进行了分析研究，认为该次地震前后水动态演化过程可分为4个阶段。异常首先在震中区附近出现，然后异常区向外围区扩展，并呈现多点集中的特点。在中短期阶段异常明显向震中区收缩、迁移。在临震阶段在震中区附近形成高异常集中区。     

The Source System of Mesozoic Magmatism in Middle and Lower Yangtze Valleys and Adjacent Areas—A Geochemical Tracer Study

The mechanism that controls regional mineralization must be governed by a series of geochemical reactions in relation to the source system of magmatism.In this respect,the geological bodies must have been overprinted by various kinds of tracers in terms of either chemical elements or isotopes.For this reason,the problem may be better approached by treating the lithosphere as a whole with due considerations given to the various tracer elements and isotopes and the various media of the magmatism(magmatic as well as sedimentary rocks).Presented in this paper are the results of this attempt based on a great wealth of available data concerning the source system of Mesozoic magmatism in the Middle and Lower Yangtze Valleys and adjacent areas.     

非均质空间动态随机扩散的一般方程及其应用

通过非均质空间条件下革新随机游动模式的理论推导，结合实证研究成果，建立了非均质空间动态随机扩散方程。同时，将此方程应用于城市基准地价评估，予以实例验证。     

Research on the time changes of transfer functions at Heze observatory before and after Heze earthquake of magnitude 5.9 A discussion with Qi Wang

In this paper, the coefficients of Parkinson vectora, b and the in-phase partA _r, B_r and quadrature-phase partA _i, B_i of transter functions are calculated by using two kinds of data processing methods, respectively. The results of both methods are close to each other. All these six parameters above are low in value, showing that the electric structure in Heze area is rather uniform. It seems that the anomalous changes appeared in both results, and the values of parameters decrease before and after Heze earthquake. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 113–120, 1991.     

高温高压下元素配分的原位实验与计算模拟研究进展

地球内部元素的配分行为具有重要意义,有助于揭示地球内部物质循环、元素成矿、超临界流体性质等基础地质问题。同步辐射微聚焦X射线荧光光谱(SR-μXRF)结合金刚石压腔(DAC)技术,可以在高温高压条件下实现高准确度和高分辨率的原位(in situ)测试元素在不同物相间的浓度,并获取配分系数。而基于地球化学热力学的理论计算模拟,可以获得元素在不同物相间的赋存形式,有助于揭示元素配分机制。本文综述了SR-μXRF结合DAC技术和地球化学热力学计算模拟原位测定高温高压下元素配分的研究方法,及其在地球内部元素迁移、成矿作用和地球早期形成过程等领域中的应用进展,认为利用该套方法研究高温高压下元素配分行为的体系将变得更加复杂,对温度、压力条件则要求更高。本文旨在更新和丰富高温高压下元素配分系数数据,深化对地球内部物质循环等问题的认知。     

渤海湾盆地西部保定凹陷构造-地层层序与盆地演化

保定凹陷位于渤海湾盆地内冀中坳陷的西部, 西侧以太行山山前断层为界与太行山隆起相隔.凹陷内构造-地层层序的划分, 对研究其构造演化和油气勘探有着重要的意义, 对探讨太行山山前断层的发育特征也有一定的帮助.按照井、震结合的思路, 利用最新的钻井和地震资料, 并结合周缘的地质填图成果, 建立了保定凹陷的地层系统; 根据区域性不整合面的发育特征, 对保定凹陷构造-地层层序进行了划分; 利用平衡剖面技术, 分析了保定凹陷的构造演化.研究发现, 保定凹陷内发育了古近系孔店组底部和新近系馆陶组底部两个区域性角度不整合面, 据此将保定凹陷在纵向上划分为3个构造层: 基底构造层、断陷期构造层和拗陷期构造层.保定凹陷的形成演化经历了基底形成、古近纪断陷、渐新世末反转和新近纪-第四纪拗陷4个阶段, 其中, 古近纪断陷期又可以分为强烈断陷期、持续断陷期和断陷末期.     

甘肃中部降水性层状云微物理结构特征个例分析

利用机载PMS粒子探测系统对2006年8月27日甘肃省中部一次降水性天气过程进行空中观测,对云中微物理特征进行了分析。研究发现云层中小粒子对含水量的贡献较大,云层主要以平均直径小于20μm的小云滴为主。在低层云滴浓度和含水量大于上层,而平均直径小于上层,符合"播撒-供给"降水机理,云上部主要增长方式有凝华增长、淞附增长,在云下部主要增长机制是碰并增长。