Geochemical Characterization of Bolivian Formative Earthen Architecture by Wavelength‐Dispersive X‐ray Fluorescence

In this study, we employ wavelength‐dispersive X‐ray fluorescence (WDXRF) to characterize construction materials from Formative civic architecture (1000 B.C.E.–C.E. 400), ethnographic mudbricks, and off‐site controls from the Taraco Peninsula, Bolivia. The preparation of earthen construction materials for civic buildings can shed light on aspects of community development such as labor organization, resource management, and architectural technologies. We apply geochemical results to reconstructing how public buildings were made as communities moved toward socio‐political complexity in this region. However, there are few geochemical studies in the Andes, and little prior scientific analysis of earthen architecture. We therefore tested the efficacy of WDXRF for this region, and developed control materials. Our archaeological samples were selected from two Formative villages, Chiripa and Kala Uyuni. In this study, we performed WDXRF analyses on 63 archaeological and control samples including archaeological floors, walling, plasters, and mortars, as well as contemporary ethnographic walling and topsoils. Elemental signatures for 28 elements clearly distinguished the archaeological flooring, walling, plaster, and mortars from ethnographic and off‐site controls. More subtle variations were detected that distinguish study sites and the different material types. Laboratory‐calibrated multi‐element XRF effectively supports efforts to reconstruct the pathways to social complexity in the Titicaca Basin.     

Organic matter heterogeneities in 2.72 Ga stromatolites: Alteration versus preservation by sulfur incorporation

The stromatolites of the weakly metamorphosed 2.72 Ga Tumbiana Formation present abundant organic globules that resemble in size, shape and distribution the microorganisms observed in modern stromatolites. In order to evaluate the significance of these cell-like organic materials, we characterized organic matter in-situ down to the nanoscale using a combination of Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Raman microspectroscopy, scanning transmission X-ray microscopy (STXM) and transmission electron microscopy (TEM).These analyses revealed the occurrence of two distinct types of organic matter forming μm-scale textural and chemical heterogeneities distributed in distinct mineralogical laminae of the stromatolites. Type A organic matter, which is by far the most abundant, consists of sulfur-poor organic matter that is located in mud-type laminae at grain boundaries, mostly in association with silicate minerals. In contrast, Type B organic matter is rare and preserved as inclusions in the core of calcite grains forming laminates. It occurs as micrometer-sized cell-like globules containing variable amounts of organic sulfur likely in the form of thiophenes.Different scenarios may account for these compositional heterogeneities in the kerogen. Based on textural and compositional analogies with modern stromatolites, it is argued that Type B sulfur-rich globules may represent microbial cells protected by mineral encapsulation and selectively preserved through polymerization by early diagenetic sulfurization. In modern sediments, this reaction is fuelled by bacterial sulfate reduction (BSR). This metabolism has been widely considered as a major driver in modern stromatolites calcification and could thus have played an important role in the formation of the Tumbiana Formation stromatolites. In contrast, Type A sulfur-poor organic matter corresponds to either fossil extracellular polymer substances (EPS) or recondensed kerogen. This pool was likely not sulfurized due to either local and/or timely variations in the concentrations of H₂S or adverse pyritization driven by the availability of iron. Our observations thus show the need to use spatially-resolved techniques to complement organic geochemistry analyses and provide a detailed analysis of the organic carbon pools composing Archean stromatolites.     

阿尔泰可可托海3号伟晶岩脉中的铪质锆石

利用电子探针技术研究了阿尔泰可可托海3号伟晶岩脉中铪质锆石的成分特征。结果表明：细粒花岗岩和正岩浆阶段结构带(Ⅳ带)的锆石相对贫Hf，(HfO2)=3．06％-13．33％，主要属于普通锆石；岩浆-热液过渡阶段结构带(V带和Ⅶ带)锆石相对富}Hf，w(HfO2)=9．06％-35．21％，主要属于铪质锆石，少量具有普通锆石特征；同时本区发现的铪质锆石中HfO2最高含量是目前伟晶岩已报道铪质锆石中HfO2的最高含量。成分特征还显示，边部细粒花岗岩和正岩浆阶段锆石成分变化非常局限，岩浆-热液过渡阶段锆石成分变化巨大。认为锆石中HfO2含量从正岩浆阶段结构带到岩浆-热液过渡结构带的高度富集是挥发份从岩浆中分离出来独立成相的结果，而岩浆-热液过渡结构带锆石中HfO2含量在带内的巨大变化可能与热液流体的富集有关。     

我国首次发现原生—自然硅

本文对自然硅进行了矿相学，矿物学研究，该矿物产于福建某地矽卡岩型硫，多金属矿床中，自然硅呈亮灰银白色、强金属光泽。性脆。镜下呈浑圆粒状、乳滴状，均质。实测比重ｄ＝２．３６８。硬度ＨＭ＝６．７６。反射率Ｒ：４７０ｎｍ３７０８；５４６ｎｍ３１．２７；６５０ｎｍ２９．９６。经扫描电镜能谱分析、电子探针分析，Ｓｉ９９．８７％～９９．９４％。含少许Ａｌ，Ｃａ，Ｆｅ机械混入物，Ｘ射线粉晶分析，主要Ｘ射线粉晶谱     

微纳米Ca(OH)2加固遗址土室内试验研究

无机材料以兼容性强、耐久性好等特点被广泛应用于土遗址加固,特别疏松结构土遗址加固一直是学界关注的焦点,微纳米Ca(OH)₂具有分子结构小、加固效果显著和耐久性好等特点。以世界文化遗产锁阳城为代表,制备密度为1.5g/cm³的疏松土样,采用浓度为5%、7.5%和10%微纳米Ca(OH)₂的悬浊液滴渗加固,通过透气性、色差、无侧限抗压强度和抗剪强度测试发现,透气性下降值均在2%以内,5%和7.5%微纳米Ca(OH)₂加固后色差ΔE_ab*均小于4,在一定范围内可接受;其中用浓度为7.5%微纳米Ca(OH)₂加固3次后抗压强度和抗剪强度均有提高,无侧限抗压强度增长率为9.8%,土的黏聚力增加了34%,内摩擦角提高了9°;土-水特征曲线表明,微纳米Ca(OH)₂对土的体积收缩率具有较好的抑制作用。扫描电镜、X射线衍射和热重分析发现,微纳米Ca(OH)₂渗透加固后,在碱性环境下发生了的物理化学反应,在物理层面主要通过填充、包...     

大洋锰结核氨浸渣脱硫产物处理含镉废水的研究

研究了大洋锰结核氨浸渣脱硫产物去除废水中镉离子的多种影响因素,如接触时间、脱硫产物粒径、溶液pH值、初始镉离子浓度和吸附剂量。并利用X射线粉末衍射(XRD)、场扫描电镜(SEM)、X射线光电子能谱(XPS)对材料和产物进行了表征。结果表明减小脱硫产物粒径、增大吸附剂量等有利于提高去除效果;大洋锰结核氨浸渣脱硫产物去除水中镉离子是基于离子交换反应的原理:MnS+Cd2+→CdS+Mn2+。     

燕山震旦系碳酸岩分类

碳酸岩占沉积岩体积的五分之一。全世界将近一半的石油、天然气产于其中。许多沉积矿床和热液交代矿床,如铁、锰、磷、镁、铜、铅、锌、汞以及放射性元素等矿床多产于碳酸岩中。碳酸岩本身也是建筑、化工、纺织等工业部门的重要原料,因而碳酸岩的研究愈来愈被重视。碳酸岩的合理分类是研究碳酸岩的必要途径。     

罗子沟盆地有机质热演化对砂岩物性的改造作用

基于岩石薄片观察、压汞分析、扫描电镜和X衍射分析等方法对罗子沟盆地大砬子组砂岩物性特征进行了定性-定量研究。结果表明：罗子沟盆地大砬子组砂岩成分成熟度和结构成熟度低,以岩屑长石砂岩和长石砂岩为主;岩石孔隙度高,孔隙度主要为16.2%~26.4%,次生孔隙占总孔隙度面孔率的88%,但总体渗透率极低,渗透率主要分布在（0.13~1.68）×10^-3 μm²,为高孔特低渗的物性特征。有机元素分析、色谱分析、岩石热解及显微组分镜检分析表明,罗子沟盆地大砬子组泥页岩中有机质在热演化过程中产生大量有机酸,有机酸对砂岩中长石等矿物的溶蚀作用是次生孔隙发育的主要原因,但有机酸溶蚀产生的次生矿物在一定程度上堵塞了孔隙喉道。因此,研究区砂岩形成高孔特低渗的物性特征。     

成岩作用对储层孔隙的影响--以辽河盆地荣37块气田下第三系为例

通过对岩芯、铸体薄片、阴极发光薄片观察及X－衍射分析,认为辽河盆地下第三系砂岩储层成岩作用中的压实作用和胶结作用减小和破坏储层孔隙,溶蚀作用则增加储层孔隙,且后者仅在一定深度范围内作用,并从沉积相、砂岩的成因及岩屑成份等方面探讨了成岩作用对储层孔隙度的影响。     

东营凹陷永北地区砂砾岩体储集层特征及影响因素

东营凹陷位于济阳坳陷的东南部。通过岩心观察、薄片鉴定、物性分析、扫描电镜观察等技术手段, 研究了东营凹陷永北地区砂砾岩体储集层的主要岩石类型、储集空间类型、物性特征和影响因素。研究结果表明, 砂砾岩体岩石学特征具有成分成熟度和结构成熟度低的特点; 主要储集空间类型为粒间溶孔和粒内溶孔, 铸膜孔和胶结物溶蚀孔也具有一定的储集意义。影响本区储集物性的因素主要有埋藏深度、成岩作用以及沉积相带, 其中埋藏深度是控制储集层物性的主要因素。      

Masters of mudbrick: Geoarchaeological analysis of Iron Age earthen public buildings at Ashdod-Yam (Israel)

Excavations at Ashdod-Yam exposed a fortification system that features a massive mudbrick wall with large earthen ramparts laid on either side. This fortified horseshoe-shaped enclosure once surrounded what was likely a human-made harbor and an adjacent acropolis with complex earthen architecture, constructed and active during Iron Age IIB–C (eighth–seventh centuries B.C.E.). These Iron Age public structures are at the center of the current research. In this paper, we present the geoarchaeological analyses of Ashdod-Yam's earthen architecture. We applied a multidisciplinary methodology to new evidence for mudbrick manufacture with the goal of understanding the relationship between governing bodies and craftsmen. The analyses combine X-ray fluorescence, loss on ignition, environmental scanning electron microscopy, and thin-section petrography to investigate raw material procurement, manufacturing choices, and labor organization at Ashdod-Yam during Iron IIB–C. Construction techniques and the standardization of the mudbrick recipe point to a local enterprise regarding the site's public earthen architecture. Furthermore, the degree of labor organization must have been closely observed and supervised by a central political power. Thus, it is argued here that construction and maintenance of the site was carried out by the kingdom of Ashdod, either as a part of its own local initiative or on behalf of the Neo-Assyrian empire.     

Compositional and Isotopic Analytical Methods in Archaeological Micromorphology

Resin‐impregnated sediment blocks are a by‐product of micromorphological sample processing. These blocks can be further studied using a variety of destructive, nondestructive, and minimally destructive geochemical techniques. X‐ray fluorescence microanalyses conducted on sediment blocks yield semiquantitative major and trace elemental abundances that can be used to generate compositional maps, and to illustrate compositional change within or between archaeological strata and features. Sediment blocks can also be drilled to obtain small sediment samples for stable oxygen and carbon isotopic analyses. Both elemental and isotopic analyses can be conducted in conjunction with micromorphological analyses to yield a holistic picture of archaeological sediment composition, source, and depositional processes. The integration of micromorphological, compositional, and isotopic analyses is used here to aid in the differentiation of calcareous ash and lime plasters from the Neolithic site of Asıklı Höyük, Turkey.     

Iron oxyhydroxide mineralization on microbial extracellular polysaccharides

Iron biominerals can form in neutral pH microaerophilic environments where microbes both catalyze iron oxidation and create polymers that localize mineral precipitation. In order to classify the microbial polymers that influence FeOOH mineralogy, we studied the organic and mineral components of biominerals using scanning transmission X-ray microscopy (STXM), micro X-ray fluorescence (μXRF) microscopy, and high-resolution transmission electron microscopy (HRTEM). We focused on iron microbial mat samples from a creek and abandoned mine; these samples are dominated by iron oxyhydroxide-coated structures with sheath, stalk, and filament morphologies. In addition, we characterized the mineralized products of an iron-oxidizing, stalk-forming bacterial culture isolated from the mine. In both natural and cultured samples, microbial polymers were found to be acidic polysaccharides with carboxyl functional groups, strongly spatially correlated with iron oxyhydroxide distribution patterns. Organic fibrils collect FeOOH and control its recrystallization, in some cases resulting in oriented crystals with high aspect ratios. The impact of polymers is particularly pronounced as the materials age. Synthesis experiments designed to mimic the biomineralization processes show that the polysaccharide carboxyl groups bind dissolved iron strongly but release it as mineralization proceeds. Our results suggest that carboxyl groups of acidic polysaccharides are produced by different microorganisms to create a wide range of iron oxyhydroxide biomineral structures. The intimate and potentially long-term association controls the crystal growth, phase, and reactivity of iron oxyhydroxide nanoparticles in natural systems.     

Evolution of 2:1 layered silicates in low-grade metamorphosed Liassic shales of Central Switzerland

White mica from the Liassic black shales and slates in Central Switzerland was analysed by transmission electron microscopy (TEM) and electron microprobe to determine its textural and compositional evolution during very low-grade prograde metamorphism. Samples were studied from the diagenetic zone, anchizone and epizone (T ≈100°–450 °C). Phyllosilicate minerals analysed include illite/smectite (I/S), phengite, muscovite, brammallite, paragonite, margarite and glauconite. Textural evolution primarily is towards larger, more defect-free grains with compositions that approach those of their respective end-members. The smectite-to-illite transformation reduced the amounts of the exchange components SiK_?1Al_?1, MgSiAl_?2, and Fe³⁺Al_?1. These trends continue to a lesser degree in the anchizone and epizone. Correlations between the proportion of smectite in I/S and the composition of I/S indicate that smectite layers may contain a high layer charge. Illite in I/S bears a compositional resemblance to macrocrystalline phengite in some samples, but is different in others. Paragonite first appears in the upper diagenetic zone or lower anchizone as an interlayer-deficient brammallite, and it may be mixed with muscovite on the nanometre scale. Owing to the small calculated structure factor for paragonite-muscovite superstructures, conventional X-ray powder diffraction cannot distinguish between mixed-layer structures and a homogeneous compositionally intermediate solid solutions. However, indirect TEM evidence shows that irregularly shaped domains of Na- and K-rich mica exist below 10 nm. Subsequent coarsening of domains at higher grades produced discrete paragonite grains at the margins of muscovite crystals or in laths parallel to the basal plane of the host muscovite. Margarite appears in the epizone and follows a textural evolution similar to paragonite in that mixtures of margarite, paragonite, and muscovite may initially occur on the nanometre scale. However, no evidence of interlayer-poor margarite has been found.     

Asbestiform and non-asbestiform morphologies in a talc and vermiculite mine from the province of Córdoba (Argentina): a case study

In this work, a talc and vermiculite mine from the province of Córdoba (Argentina) was investigated with special emphasis on the occurrence of asbestiform and non-asbestiform phases. The meta-ultramafic rock was studied by a multimethodological approach, complementing field studies with petrographic-mineralogical, compositional and morphological analyses. Samples were examined by stereomicroscopy, polarizing light microscopy, SEM–EDS, XRD, DSC-TGA and FTIR. Complementary, compositional and textural analyses were performed with FE-SEM–EDS and EPMA. Talc-rich veins with a laminar and fibrous appearance were at first recognized. However, the fibrous morphology observed both in the field and by microscopy is due to an apparent habit because of the sample orientation. To avoid erroneous interpretations, studies by secondary electron images (SEM) are fundamental to carrying out this type of analysis. Tremolite was identified in different zones of the outcrop; however, only ~40% of the crystals located in the vermiculite zone have dimensions to be considered as asbestiform fibres in the range of respirable particles. In these types of complex deposits affected by superimposed metamorphic, igneous and deformational events, multimethodological approaches are necessary to develop models of occurrence of asbestiform morphologies that may be applicable to other with similar characteristics.     

Macrostructural changes in compacted earthen construction materials under loading

There is increasing interest in the use of earthen materials for modern construction. The mechanical behaviour of these materials is strongly controlled by their internal macrostructures. Rammed earth (RE) is one example of these materials, created by in situ compaction of a wet soil mixture. Changes to the material structure occur on loading and during compaction; therefore, the nature of these changes needs to be understood if the effect on the material behaviour can be predicted. Here, the change in the macrostructure of RE on the application of compressive loading is investigated by using X-ray computed tomography and fractal analysis to monitor the changes in loaded RE specimens. The macrostructures of specimens comprising different layer thicknesses are also investigated in order to determine how layer thickness affects the compaction of the material. Results are used to recommend procedures for manufacturing specimens that are representative of the material found in full-scale RE structures.     

Sedimentary characteristics of suspensions in London Stormwater

The paper reports the results of an investigation into the size and compositional variations of suspended solids during storm-runoff events in an urban catchment. Particle-size analysis indicates that the mass-size distribution for suspended sediments is typically bimodal, although the relative size, breadth and location of the peaks varies through the cycle and from one storm to another. The importance of particle aggregation on the size distributions is discussed and the role of organic particulates in this relation examined. The elemental composition is dominated by silicon and aluminium with the mineralogy being dominated by impure mixtures of quartzo-feldspathic material.The observed textural, compositional and mineralogical variations have been used as diagnostic properties in the identification of source materials and their transport history through the catchment.     

鹅湖岩体岩石谱系单位的建立及其就位机制分析

鹅湖岩体为S型花岗岩 ,具有结构和成分演化序列。运用岩石结构序列法 ,将其划分为 5个单元 ,归并为 1个超单元。按侵入体空间展布形式、岩体地质学、岩石学、构造等资料 ,探讨了岩体就位机制     

Three-dimensional quantitative textural analysis of metamorphic rocks using high-resolution computed X-ray tomography: Part II. Application to natural samples

Three-dimensional quantitative textural analysis coupled with numerical modelling has been used to assess the dominant mechanisms governing crystallization of garnet porphyroblasts in rocks from diverse regional metamorphic environments. In every case, spatial dispositions, crystal size distributions, and compositional zoning patterns of porphyroblasts indicate the dominance of diffusion-controlled nucleation and growth mechanisms.
Nine samples from three geological areas were studied: a suite of semi-pelitic rocks from the Picuris Mountains, New Mexico (USA); a suite of mafic samples from the Llano Uplift, Texas (USA); and a kyanite schist from Mica Dam, British Columbia (Canada). The semi-pelitic suite exhibits post-deformational garnet growth, whereas garnet in the mafic suite and in the kyanite schist grew synkinematically in rocks displaying weak and strong penetrative fabrics, respectively.
For each sample, the centres and radii of thousands of garnet crystals were located and measured in three dimensions, using images produced by high-resolution computed X-ray tomography. Statistical measures of the degree of ordering and clustering of nucleation sites, and estimates of crystal isolation for each porphyroblast, were then computed from the measured spatial dispositions. These measures can be reproduced in simple numerical models only by diffusion-controlled nucleation and growth mechanisms. Normalized radius-rate relations computed from compositional zoning patterns in the garnets require thermally accelerated diffusion-controlled growth, providing independent confirmation of the conclusions based on textural analysis. The unexpected similarity of results from all samples indicates that diffusion-controlled nucleation and growth mechanisms may govern porphyroblast crystallization in many metamorphic regimes.