Nanoscale Chemical Imaging by Photo‐Induced Force Microscopy: Technical Aspects and Application to the Geosciences

Photo‐induced force microscopy (PiFM) is a new‐frontier technique that combines the advantages of atomic force microscopy with infrared spectroscopy and allows for the simultaneous acquisition of 3D topographic data with molecular chemical information at high spatial (~ 5 nm) and spectral (~ 1 cm^?1) resolution at the nanoscale. This non‐destructive technique is time efficient as it requires only conventional mirror‐polishing and has fast mapping rates on the order of a few minutes that allow the study of dynamic processes via time series. Here, we review the method’s historical development, working principle, data acquisition, and evaluation, and provide a comparison with traditional geochemical methods. We review PiFM studies in the areas of materials science, chemistry and biology. In addition, we provide the first applications for geochemical samples including the visualization of faint growth zonation in zircons, the identification of fluid speciation in high‐pressure experimental samples, and of nanoscale organic phases in biominerals. We demonstrate that PiFM analysis is a time‐ and cost‐efficient technique combining high‐resolution surface imaging with molecular chemical information at the nanoscale and, thus, complements and expands traditional geochemical methods.     

原子探针层析技术及其在矿床研究中的应用

原子探针层析技术（APT）是一种能够以亚纳米分辨率提供定量的三维元素和同位素分析的测试分析技术,具有极高的空间分辨率和低的检出限。虽然原子探针主要用于材料科学和半导体领域,但随着近年来在矿床研究中应用的不断增加,正逐渐成为矿床研究的有用手段。与传统的地质分析技术相比,原子探针具有独特的技术优势,可以测量体积＜0.0007μm3的矿物的元素组成,能够在纳米尺度上揭示矿物成分的复杂性,为理解地质演化过程提供全新的认识。本文在简述原子探针层析技术的基本原理、样品的选择和处理以及针尖样品制备的基础上,重点从成矿元素赋存状态、纳米尺度包裹体和稳定同位素组成三个方面阐述了原子探针在矿床研究中的代表性应用成果。迄今为止,原子探针在矿床学中的应用主要集中在成矿元素赋存状态的分析上,尤其是与金矿相关的黄铁矿或其他化学组成相对简单的矿物。而在纳米尺度包裹体和稳定同位素组成方面,原子探针应用成果虽不如前者丰富,但也取得了一些重要的全新认识,表现出良好的应用前景。原子探针在矿床学领域迅速发展的同时,也存在一些亟需解决的问题,如复杂质谱峰的标定、三维重建失真等。尽管如此,相信随着技术的不断进步,原子探针将逐渐成为矿床研究的重要工具。     

Nanoscale chemical characterisation of phase separation,solid state transformation,and recrystallization in feldspar and maskelynite using atom probe tomography

The feldspar minerals occur in a wide variety of lithologies throughout the Solar System, often containing a variety of chemical and structural features indicative of the crystallization conditions, cooling history and deformational state of the crystal. Such phenomena are often poorly resolved in micrometre-scale analyses. Here, atom probe tomography (APT) is conducted on Ca-rich (bytownite) and Na-rich (albite) plagioclase reference materials, experimentally exsolved K-feldspar (sanidine), shock-induced plagioclase glass (labradorite-composition), and shocked and recrystallized plagioclase to directly test the application of APT to feldspar and yield new insights into crystallographic features such as amorphisation and exsolution. Undeformed plagioclase reference materials (Amelia albite and Stillwater bytownite) appear chemically homogenous, and yield compositions largely within uncertainty of published data. Within microstructurally complex materials, APT can resolve chemical variations across a ~?20 nm wide exsolution lamella and define major element (Na, K) diffusion profiles across the lamella boundaries, which appear gradational over a ~?10 nm length scale in experimentally exsolved K-feldspar NNPP-04b. The plagioclase glass within the Zagami shergottite shows no heterogeneity in the distribution of major elements, although the enrichment of Fe, Mg and Sr in the bulk microtip points to at least minor incorporation of surrounding phases (pyroxene), and with that supports a shock-melt origin for the glass (maskelynite). The recrystallization of feldspar during post-shock annealing, such as in poikilitic shergottite NWA 6342, appears to induce a range of chemical nanostructures that locally effect the composition of the material. These findings demonstrate the ability of APT to yield new insights into nanoscale composition and chemical structures of alumniosilicate phases, highlighting an exciting new avenue with which to analyse these key rock-forming minerals.     

NanoSIMS: Technical Aspects and Applications in Cosmochemistry and Biological Geochemistry

The NanoSIMS ion probe is a new‐generation SIMS instrument, characterised by superior spatial resolution, high sensitivity and multi‐collection capability. Isotope studies of certain elements can be conducted with 50–100 nm resolution, making the NanoSIMS an indispensable tool in many research fields. We review technical aspects of the NanoSIMS ion probe and present examples of applications in cosmochemistry and biological geochemistry. This includes isotope studies of presolar (stardust) grains from primitive meteorites and of extraterrestrial organics, the search for extinct radioactive nuclides in meteoritic materials, the study of lunar samples, as well as applications in environmental microbiology, cell biology, plant and soil science, and biomineralisation.     

Re-Os同位素体系在矿床地球化学中的应用

简述了Re-Os同位素地球化学体系的原理与方法,在此基础上重点介绍了国内外目前在矿床地球化学研究中,应用Re-Os同位素体系进行成矿作用年代学及矿质来源等方面研究的一些最新成果.认为Re-Os同位素体系是对矿床进行定年和示踪研究的有力工具,为成矿作用机制等的深入研究提供了新的思路.尽管Re-Os同位素定年研究中存在矿物适应性等问题,但本世纪初期Re-Os同位素体系的研究将会深刻地推动矿床地球化学的进步和发展.     

Defining the Potential of Nanoscale Re‐Os Isotope Systematics Using Atom Probe Microscopy

Atom probe microscopy (APM) is a relatively new in situ tool for measuring isotope fractions from nanoscale volumes (< 0.01 μm³). We calculate the theoretical detectable difference of an isotope ratio measurement result from APM using counting statistics of a hypothetical data set to be ± 4δ or 0.4% (2s). However, challenges associated with APM measurements (e.g., peak ranging, hydride formation and isobaric interferences), result in larger uncertainties if not properly accounted for. We evaluate these factors for Re‐Os isotope ratio measurements by comparing APM and negative thermal ionisation mass spectrometry (N‐TIMS) measurement results of pure Os, pure Re, and two synthetic Re‐Os‐bearing alloys from Schwander et al. (2015, Meteoritics and Planetary Science, 50, 893) [the original metal alloy (HSE) and alloys produced by heating HSE within silicate liquid (SYN)]. From this, we propose a current best practice for APM Re‐Os isotope ratio measurements. Using this refined approach, mean APM and N‐TIMS ¹⁸⁷Os/¹⁸⁹Os measurement results agree within 0.05% and 2s (pure Os), 0.6–2% and 2s (SYN) and 5–10% (HSE). The good agreement of N‐TIMS and APM ¹⁸⁷Os/¹⁸⁹Os measurements confirms that APM can extract robust isotope ratios. Therefore, this approach permits nanoscale isotope measurements of Os‐bearing alloys using the Re‐Os geochronometer that could not be measured by conventional measurement principles.     

GGR Biennial Critical Review: Analytical Developments Since 2014

This GGR biennial critical review covers developments and innovations in key analytical methods published since January 2014, relevant to the chemical, isotopic and crystallographic characterisation of geological and environmental materials. In nine selected analytical fields, publications considered to be of wide significance are summarised, background information is provided and their importance evaluated. In addition to instrumental technologies, this review also presents a summary of new developments in the preparation and characterisation of rock, microanalytical and isotopic reference materials, including a précis of recent changes and revisions to ISO guidelines for reference material characterisation and reporting. Selected reports are provided of isotope ratio determinations by both solution nebulisation MC‐ICP‐MS and laser ablation‐ICP‐MS, as well as of radioactive isotope geochronology by LA‐ICP‐MS. Most of the analytical techniques elaborated continue to provide new applications for geochemical analysis; however, it is noted that instrumental neutron activation analysis has become less popular in recent years, mostly due to the reduced availability of nuclear reactors to act as a neutron source. Many of the newer applications reported here provide analysis at increasingly finer resolution. Examples include atom probe tomography, a very sensitive method providing atomic scale information, nanoscale SIMS, for isotopic imaging of geological and biological samples, and micro‐XRF, which has a spatial resolution many orders of magnitude smaller than conventional XRF.     

纳米尺度下的生物矿物和生物矿化:基于介晶的视角

纳米地质学的兴起和发展,促使地质工作者从纳米尺度重新认识固体地球物质,将对地球科学的各个领域产生广泛而深刻的影响.作为纳米地质学的重要分支,纳米矿物学也将走出传统矿物学只把矿物看成理想晶体点阵的局限,从纳米尺度深入探究矿物包括生物矿物在内的矿物结构与性质,突破口之一是介晶.介晶是一种特殊的结晶纳米结构,近年来得到了物理学家和化学家尤其是材料化学家越来越多的关注.介晶是非经典结晶过程产物,以纳米颗粒为基本构筑单元,具备纳米颗粒的性质和宏观尺寸.现已发现,许多生物矿物如脊椎动物骨骼和牙齿、贝壳珍珠层、蛋壳、海胆骨针、有孔虫和珊瑚等都具有介晶结构.因此,从纳米尺度和介晶角度重新理解生物矿化,有助于揭示生物矿物中纳米多级结构的成因机制,拓展纳米矿物学的科学内涵.首先介绍生物矿化和生物矿物的基本概念,之后对介晶的概念和结构特征进行阐述,最后介绍生物矿物中的介晶结构及介晶形成的典型机制,涉及有机基质辅助、物理场驱动、矿物桥或有机桥连接、空间限域、取向附集和晶面选择性分子作用等多种物理化学过程,有望进一步推动纳米矿物学的发展.      

纳米地球化学:穿透覆盖层的地球化学勘查

盖层下方隐伏矿成矿及伴生元素如何穿透覆盖层到达地表,是深穿透地球化学迁移机理研究的热点。笔者以隐伏铜镍矿和金矿为例,同时采集地气、土壤、矿石样品,使用透射电子显微镜(TEM),对样品中微粒物质的粒径、形貌、成分、结构进行了观测,发现微粒具有下列特点:(1)广泛观测到的微粒成分是铜及铜合金,金只在金矿上方土壤孔隙气体中能被观测到;(2)单个金属微粒粒径主体为几十nm,也有个别小到几个nm,大到上百个nm,微粒大多呈团聚体;(3)微粒晶形完整,内部原子呈有序晶体排列;(4)迁移柱实验表明纳米微粒具有快速迁移能力。在地气、土壤和矿石中同时观测到纳米级金属微粒,粒径大小、微粒形态、元素组合都非常相同或相近,表明两者具有来源一致性并具有序晶体结构,表明形成于内生作用。这是首次同时观测到矿石、土壤、气体介质中具有继承性关系的纳米金属微粒。矿石中纳米级金属微粒通过与微气泡表面相结合,以地气流为载体,或纳米微粒本身具有类气体性质,可以克服重力影响,穿透厚覆盖层迁移至地表,到达地表后一部分纳米颗粒仍然滞留在气体里,另一部分被土壤地球化学障(粘土、胶体、氧化物等)所捕获。这为深穿透地球化学从描述性或推测性模型走向实证性科学迈出了重要一步,为利用土壤作为采样介质、精确分离含矿信息用于寻找外来盖层下的隐伏矿提供了纳米地球化学技术。     

Nanoscale resetting of the Th/Pb system in an isotopically-closed monazite grain: A combined atom probe and transmission electron microscopy study

Understanding the mechanisms of parent-daughter isotopic mobility at the nanoscale is key to rigorous interpretation of Ue The Pb data and associated dating. Until now, all nanoscale geochronological studies on geological samples have relied on either Transmission Electron Microscope(TEM) or Atom Probe Microscopy(APM) characterizations alone, thus suffering from the respective weaknesses of each technique. Here we focus on monazite crystals from a ~1 Ga, ultrahigh temperature granulite from Rogaland(Norway). This sample has recorded concordant UeP b dates(measured by LA-ICP-MS) that range over 100 My, with the three domains yielding distinct isotopic Ue Pb ages of 1034 ± 6 Ma(D1; Srich core), 1005 ± 7 Ma(D2), and 935 ± 7 Ma(D3), respectively. Combined APM and TEM characterization of these monazite crystals reveal phase separation that led to the isolation of two different radiogenic Pb(Pb*) reservoirs at the nanoscale. The S-rich core of these monazite crystals contains Cae Srich clusters, 5 -10 nm in size, homogenously distributed within the monazite matrix with a mean interparticle distance of 40 -60 nm. The clusters acted as a sink for radiogenic Pb(Pb*) produced in the monazite matrix, which was reset at the nanoscale via Pb diffusion while the grain remained closed at the micro-scale. Compared to the concordant ages given by conventional micro-scale dating of the grain,the apparent nano-scale age of the monazite matrix in between clusters is about 100 Myr younger, which compares remarkably well to the duration of the metamorphic event. This study highlights the capabilities of combined APM-TEM nano-structural and nano-isotopic characterizations in dating and timing of geological events, allowing the detection of processes untraceable with conventional dating methods.     

基于预分类策略的激光诱导击穿光谱技术用于岩石样品定量分析

岩石样品中复杂的基质效应严重影响激光诱导击穿光谱（LIBS）定量分析的准确性,其原因是目标元素的发射特性会受到基质的影响,导致其发射强度偏离理想的规律。为提高定量分析准确性,本文提出一种基于岩性基质特性的预分类定量分析方法。该方法首先构建基于k近邻（kNN）与支持向量机（SVM）算法的多层分类模型识别样品的岩性进行分类,通过kNN算法将样品分成碳酸盐和硅酸盐两大类,再利用SVM算法将大类细分成6类,而后针对不同岩性样品分别构建元素定量模型。通过采用预分类方法,可以确保分析的样品具有相似的化学成分,更好地确定分析时的基准线和校准曲线,从而减少分析中的不确定度,提高定量准确性。kNN算法通过交叉验证选取最优的k值,同时使用网格寻优方法确定了SVM算法中关键惩罚参数C和RBF宽度参数γ,利用该分类模型对来自6类岩性的39个国标岩石样品和国标岩石混合样品中的Si、Ca、Mg和K元素进行分析,岩性识别的准确率达100%,保证了后续定量分析的准确性,并针对不同岩性中的不同元素采用了合适的预处理方式提升光谱数据的稳定性。相比于传统标准曲线定量方法,采用预分类方法可以减少不同岩性基质之间的相互影响,从而减小样品基质非均匀性带来的误差。对比两种方法进行数据分析,测试集样品的预测值与参考值相关性分析系数从0.231～0.664提高至0.994～0.999,平均相对标准偏差从38.2%降低至8.6%。与传统定量分析方法相比较,采用预分类定量分析方法所构建模型对上述4种元素定量分析结果准确性有着明显的提高,为提高岩石元素定量分析准确性提供新的思路,拓宽了LIBS技术的实际应用范围。     

自然资源时期:大数据与地球系统科学——再论全面发展时期的勘查地球化学

中国勘查地球化学全面发展的重要标志和本质特征是大数据信息与地球系统科学。勘查地球化学的全面发展坚持资源与环境并重方针,真实生动地反映国家经济社会发展的历史轨迹,在科学技术领域具有典型意义。自然资源时期地质工作关于资源内涵从矿产资源、国土资源到一切自然资源,关于环境内涵从地质环境、国土环境到包括山水林田湖草生命共同体在内的一切自然环境。本文继2008年对此有所评述后,在国家自然资源部成立之际,地质工作面临深刻转型之时,从大数据信息科学与自然资源地球化学调查、建立地球系统科学指导的自然资源地球化学理论体系与自然资源地球化学评价体系,以及针对自然资源领域重大科学问题,深化地球化学应用研究与理论研究,构建完善的科学体系等若干值得注意的方面再次就此议题加以评论。勘查地球化学的长期目标是通过大数据信息与地球系统科学研究揭示自然资源与自然环境状况,实现对地球资源的科学开发、合理利用和整体保护,创造人类与地球和谐共处的生存环境。由此,转型和升级贯穿中国勘查地球化学发展的全过程。地球化学将以形态和内涵的系统性、综合性、整体性作用,以及应用实践的多目标全方位面貌出现在国家行业部门与科技领域,极大地拓展和深入经济社会发展各个方面。勘查地球化学以方法技术优势实行大调查、大数据、大应用战略,建立大环境、大生态、大地球观,向大地质、大资源、大科学转变,为解决自然资源与生态环境问题提供地球化学方案,将全面发展时期的勘查地球化学从大数据信息应用优势和地球系统科学理论高度提升到"大地球化学"境界。     

天然放射性碳同位素在海洋有机地球化学中的应用

天然放射性碳（¹⁴C）是年代测定的有效手段，它在考古学和地质学的应用已有几十年的历史。过去10年中，伴随着加速器质谱仪（AMS）技术和检测灵敏度的提高，AMS已经能够检测少于mg C量级样品中自然丰度水平的¹⁴C，这大大扩展了¹⁴ C在自然科学，特别是地球科学研究中的应用范畴。简要评述了利用天然¹⁴ C进行海洋地球化学研究的应用，重点介绍了前景广阔、并已取得显著成果的应用领域。     

Comparison of modern and ancient barite‐bearing acid‐sulphate soils using micromorphology,geochemistry and field relationships

Although pedogenic barite has been documented in many modern soils and palaeosols, no actualistic studies on its formation have been reported. Because barite is stable over the entire range of pressure and temperature of the Earth's crust, it preserves reliable data about the original environment in which it formed. Pedogenic barite and barite‐bearing soils have been used as indicators of landscape stability, environmental conditions, climate and microbial acti‐vity. This study compares field data, micromorphology and stable isotope geochemistry of a barite‐bearing palaeosol from the Morrison Formation (Jurassic) and a modern analogue soil in south‐central Texas, USA. Morrison barite‐bearing palaeosols are over‐thickened cumulic palaeosols that developed in subaerially exposed lacustrine sediments during an extended lake contraction event. Lateral facies relationships document changes in hydrology and duration of episaturated conditions (perched water table above the Btg horizons) that correspond to differences in barite nodule morphology and abundance. Barite precipitation occurred at a redox boundary higher on the landscape after organic matter was completely oxidized. Sulphur isotope data indicate that the initial source of sulphur was soil organic matter. Meteoric water is the likely source of oxygen for the sulphate. Barium sourced from weathering feldspars and clays. The modern analogue displays similar catenary relationships, redox features and micromorphological characteristics compared to the Morrison palaeosols, suggesting that similar pedogenic processes led to barite precipitation. Synthesized data suggest that conditions favourable to barite‐bearing soil formation are low‐gradient basins that have received feldspar‐rich sediments (i.e. volcanically influenced basins), soils that developed near salt domes, soils that developed in exposed wetland or lacustrine sediments and coastal plain deposits. When studied in a well‐documented palaeogeographic context, barite‐bearing soils are valuable to palaeoclimate, palaeoenvironmental and palaeohydrological studies. Combined with regional interfluve palaeosols, barite‐bearing palaeosols may document temporal changes in drainage, surface stability, and accommodation consistent with sequence boundaries/maximum flooding surfaces and climate changes.     

Comprehensive Chemical and Isotopic Analyses of Basalt and Sediment Reference Materials

Geochemical studies of geological samples require the precise determination of their major and trace element contents and, when measured, of their isotopic compositions. It is now commonly accepted that the accuracy and precision of geochemical analyses are best estimated by the concomitant analysis of international reference materials run as unknown samples. Although the composition of a wide selection of basalts is relatively well constrained, this is far from being the case for sedimentary materials. We present here a comprehensive set of major and trace element data as well as Nd, Hf, Sr and Pb isotopic compositions for thirteen commonly used international reference materials – eight magmatic rocks (BHVO‐2, BR, BE‐N, BR 24, AGV‐1, BIR‐1, UB‐N, RGM‐1) and five sediments (JLk‐1, JSd‐1, JSd‐2, JSd‐3, LKSD‐1). We determined the concentrations of over forty elements in the magmatic rocks together with Sr, Nd, Hf and Pb isotopic compositions. Our trace element results were both accurate (difference ≤ 3%) and precise (reproducibility at 1s ≤ 3%) and the isotopic results were very similar to other published values. In contrast, we observed a significant chemical and isotopic variability in the sedimentary materials, which we attribute to mineral heterogeneities in the powders. Despite the limitation imposed by this heterogeneity, our work presents a complete set of data determined with a precision not yet achieved in the literature for sedimentary material. We also provide the first Nd, Hf and Pb isotopic measurements for the five sediments, which are commonly used by the geochemical community. Our study of both basalt and sediment reference materials represents a comprehensive and self‐consistent set of geochemical data and can therefore be considered as a reference database for the community.     

地球深部物质科学在地球深部研究中的作用和意义

为解决地球深部探测过程中地球物理和地球化学两大系列研究成果无法联系和统一的难题，地球深部物质科学应运而生。该学科既要研究组成地球深部的一切物质实体的物理和化学的属性，又要从物质的角度去研究地球深部的结构和动力学过程。随着该学科的发展，将会为地球深部的观测结果和计算模拟结果赋予物质内容，从而促进对地球深部的物质组成、结构分层以及动力学形成统一认识，建立适合于各学科的地球深部模型。     

大数据科学从信息化、模式化到智能化:现代地球化学应用研究的新范式

地球科学领域处在信息科学与信息化社会时代,基于大数据战略驱动的现代地球科学正在蓬勃兴起.诞生于近代的地球化学具有天然的结构化信息科学属性.提出建立从信息化、模式化到智能化的地球化学大数据信息科学应用研究总体思路,即基于地球化学大数据首先建立信息化系统,运用地球系统科学方法理论建立成矿地球化学分带富集模式与生态地球化学累...     

Natural Obsidian Glass as an External Accuracy Reference Material in Laser Ablation‐Inductively Coupled Plasma‐Mass Spectrometry

Compared with solution ICP‐MS, LA‐ICP‐MS studies have thus far reported comparatively few external reference data for accuracy estimates of experiments. This is largely the result of a paucity of available reference materials of natural composition. Here, we report an evaluation of natural glass (obsidian) as an inexpensive and widely available external reference material. The homogeneity of over forty elements in six different obsidian samples was assessed by LA‐ICP‐MS. Accuracy was tested with two obsidian samples that were fully characterised by electron probe microanalysis and solution ICP‐MS. Laser ablation experiments were performed with a variety of ablation parameters (fluence, spot sizes, ablation repetition rates) and calibration approaches (natural vs. synthetic reference materials, and different internal standard elements) to determine the best practice for obsidian analysis. Furthermore, the samples were analysed using two different laser wavelengths (193 nm and 213 nm) to compare the effect of potential ablation‐related phenomena (e.g., fractionation). Our data indicate that ablation with fluences larger than 6 J cm^?2 and repetition rates of 5 or 10 Hz resulted in the most accurate results. Furthermore, synthetic NIST SRM 611 and 612 glasses worked better as reference materials compared with lower SiO₂ content reference materials (e.g., BHVO‐2G or GOR128‐G). The very similar SiO₂ content of the NIST SRM glasses and obsidian (i.e., matrix and compositional match) seems to be the first‐order control on the ablation behaviour and, hence, the accuracy of the data. The use of different internal standard elements for the quantification of the obsidian data showed that Si and Na yielded accurate results for most elements. Nevertheless, for the analysis of samples with high SiO₂ concentrations, it is recommended to use Si as the internal standard because it can be more precisely determined by electron probe microanalysis. At the scale of typical LA analyses, the six obsidian samples proved to be surprisingly homogenous. Analyses with a spot size of 80 μm resulted in relative standard deviations (% RSD) better than 8% for all but the most depleted elements (e.g., Sc, V, Ni, Cr, Cu, Cd) in these evolved glasses. The combined characteristics render obsidian a suitable, inexpensive and widely available, external quality‐control material in LA‐ICP‐MS analysis for many applications. Moreover, obsidian glass is suited for tuning purposes, and well‐characterised obsidian could even be used as a matrix‐matched reference material for a considerable number of elements in studies of samples with high SiO₂ contents.     

可持续发展进程中的资源、环境地球化学研究——以广东省为例

可持续发展进程中的资源、环境地球化学研究——以广东省为例乔玉楼匡耀求谭建军郭国章（中国科学院广州地球化学研究所，广州５１０６４０）关键词持续发展资源环境地球化学资源环境是维持人类生态系统的物质基础，资源环境的持续发展则是人类的生存和可持续发展的基础［...     

济南-济阳地区土壤地球化学特征

通过对济南—济阳研究区内土壤地球化学特征的对比分析,探讨了元素的丰缺、土壤质量及对农业环境的影响。