TEMPORAL ORDERING OF SURFACE-COLLECTED OBSIDIAN ARTIFACTS BY HYDRATION MEASUREMENT

Two samples of obsidian projectile points from northwestern Nevada, one surface collected and the other excavated, were subjected to obsidian hydration measurement. The temporal ordering of the three projectile-point types in each of the two samples was demonstrated to be the same on the basis of their hydration measurements. The validity of this temporal ordering of the projectile-point types in the two samples was confirmed by the stratigraphic sequence of the types in the excavated sample. We have found that surface-collected obsidian artifacts can be relatively dated by hydration measurement. In northwestern Nevada they hydrate at a rate almost double that of their excavated typological counterparts, but their relative ordering remains the same.     

Polychromic structures and pigments in Guangyuan Thousand-Buddha Grotto of the Tang Dynasty (China)

This paper presents a multi-analytical study of the polychromy in the Guangyuan Thousand-Buddha Grotto. Samples taken from 15 locations in No. 512 and No. 689 caves are prepared as cross-sections for the analysis by optical microscopy (OM) and scanning electron microscopy coupled with backscattered electron imaging (SEM-BSE). The cross section analysis indicates that some paintings were repainted in the past. The chemical composition of each painting layer is obtained by scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDX). The main pigments for 15 samples including green, red, blue, white and black paint layers, are identified by the combination of polarized light microscopy (PLM), Fourier Transform infrared spectrum (FT-IR), Raman spectroscopy (RS) and X-ray diffraction (XRD) analysis. The integrated analytical results reveal that the green pigments are malachite and atacamite; the red color is attributed to minium, hematite and cinnabar; the blue pigments are lazurite and organic blue materials; the white color is ascribed to anglesite and gypsum; and the black surface of polychrome is the accumulation of longtime smudging by folk burning incense in the devotional practice or the soot deposition resulting from burning bonfires in the caves. Some arsenic-containing pigment is detected in the green samples. This case study also demonstrates the advantages and the limitations of every analytical technique for the pigment identification, confirming the necessity of the integrated analytical techniques approach. The present results are not only useful to assist in the authenticity of the used pigment materials and history of the polychromic in the past, but also aimed at guiding the conservation scientists in taking into account materials and methods utilized in the past.     

URANIUM‐SERIES AND LUMINESCENCE DATING OF VOLCANIC LITHIC ARTEFACTS*

U‐series dating was used to determine the growth rate of a feldspar‐to‐clay weathering rind in a mid‐Holocene Cascade–Olcott tradition andesite core, and luminescence dating (last exposure to sunlight) was used to date fine‐grained feldspars scraped from the surfaces of similar buried artefacts from a ¹⁴C‐sediment‐dated archaeological site (45KI464) on the wet western slope of the Cascade Mountains of Washington. For U‐series dating, we measured ²²⁶Ra excess (²²⁶Ra excess =²²⁶Ra –²³⁰Th) in five stratigraphic depth controlled rind scrapings. ²³⁸U, ²³²Th and ²³⁰Th were counted by alpha spectrometry, and ²²⁶Ra and ²¹⁰Pb were counted by gamma spectrometry on each sub‐sample.     

美国大都市区尺度上的工业区位研究

工业化和城市化之间的互动关系体现在都市区尺度上的工业区位上。本文在新经济地理学和城市地理学所揭示的产品差异化和城市集聚效应相互关系的基础上,通过区位熵分析、赫芬达尔-赫希曼指数,对美国工业区位与大都市区间的耦合关系进行实证研究。结果显示:集聚于大都市区核心区的往往是产品个性化和定制化程度较高的行业;位于大都市区外围区的大都是产品依赖于城市市场,但标准化程度较高的行业;传统制造业则往往位于非大都市区。多数都市工业的市场集中度较低,而大部分传统工业的市场集中度较高。这不仅印证了新经济地理学的理论推演和城市地理学的行业分析,而且对包括中国在内的转型国家城市及其产业发展具有重要的参考意义。     

敦煌石窟艺术应用颜料的产地之谜

论述了敦煌石窟彩绘艺术颜料的研究背景、科学分析方法和结果。并根据史料所载以及现代科学的实际勘探考察,结合颜料的科学分析,对敦煌石窟艺术所用的朱砂、铅丹、赭石、绛矾、雄黄、雌黄、密陀僧、金粉、金箔、石绿、铜绿、石青、青金石、群青、铅粉、石膏、白垩、云母、二氧化铅等主要矿物质颜料的化学成分、应用及其产地进行了探索。     

析康熙釉上彩花卉草虫纹盘

6月4日北京某拍卖公司春拍的预展现场,展出一件清康熙釉上彩绘折沿盘。此盘为敞口,浅腹,圈足,通体施白釉,胎质细腻,釉水肥润,盘底中心用青花绘双圈,内书＂大清康熙年制＂楷书款。根据盘沿上书写的＂万寿无     

面向城市基调管控的建筑群色彩感知和意义理解分析——以北京故宫建筑群为例

北京新一轮总体规划提出保护城市色彩基调。本研究认为该任务的目的是保护色彩基调对于人的文化意义，因此从新文化地理学的角度提出问题，人们对城市色彩的感知和意义理解之间是否有联系?研究以北京故宫建筑群为研究区域，运用眼动实验调查人们对色彩的感知，以结构性访谈法了解人们的色彩意义理解，目的是探究文化在感知和认知中的作用，以及眼动实验方法在反映色彩意义理解结果的可行性。结果显示色彩感知与意义理解间两者无统计上的相关性，眼动指标无法解释被试对色彩意义的理解。研究结论是被试对色彩的理解具有“整体依赖”的特点，实践性建议是具有文化认同的城市色彩可以保留，同时允许主体对城市色彩有多角度的感知和积极理解。     

Polarized Light Microscopy: An Old Technique Casts New Light on Māori Textile Plants

Understanding the composition of an artefact has ramifications for advancing human history and behaviour knowledge, providing cultural information about trade, agricultural practices and adaptation to new environments. However, accurate plant identification from artefacts is problematic, since textile production, age, dirt and/or conservation treatments obscure morphological features, and specimen size and/or ethical considerations hamper modern analytical methods. This study tested the efficacy of polarized light microscopy (PLM) in the identification of New Zealand plant species commonly used in Māori textiles, and demonstrates that morphological and birefringent features observed using PLM have the potential to distinguish between‐ and within‐plant genera.     

Diffusion and kinetic control of weathering layer development

The formation of porous weathering rinds (layers of chemical alteration) on the exterior of rocks is a consequence of dissolution and precipitation of minerals occurring at the mineral–fluid interface within the pores. The speed at which the developed rind advances is controlled by both kinetic reaction rates and the transport of reaction products away from the pore spaces into the outside fluid. We show, using both reaction‐diffusion theory and numerics, that under diffusion limitations, the weathering rate depends on the size and curvature of the sample. This leads to a relationship between rind thickness, δ, and age, t. As the rind thickens, the result in three dimensions differs substantially from the one‐dimensional result of . We describe the conditions under which the one‐dimensional and diffusion‐limited approximations apply and how they evolve as the rock weathers. Under chemical kinetic limitations, the rind advances at a constant rate, dδ/dt = v. We defend the application of a spherical approximation to irregular non‐spherical rocks and apply our results to field observations reported in the literature to show consistency with established methods. Finally, we argue that the variability in size, as well as in mineralogy, over ensembles of grains contributes to heterogeneous weathering rates. We demonstrate that this heterogeneity can contribute to the aging, or gradual decrease with time, of weathering rates previously observed in laboratory and field measurements.     

博物馆照明对苏木染色丝绸的影响研究

苏木是古代常见的一种红色植物染料,为了从保护角度探讨苏木染色丝绸的照明需求,研究了博物馆照明常用的LED灯、卤素灯、荧光灯对它的褪色影响,从光照与其他环境因素入手,尝试构建了针对苏木染色丝绸的"变色因子"指标。研究结果显示,LED的"变色因子"大于传统的卤素灯与荧光灯的,低色温照明的"变色因子"略小于高色温照明的;照度越高,"变色因子"越大;其他环境因素对"变色因子"也有很大影响。因此针对苏木染色丝绸文物的展陈照明,建议选用卤素灯或低色温的荧光灯和LED灯,并应控制展陈照明的照度。同时展陈环境中的其他环境因素也不容忽视。研究结果为指导博物馆在对苏木染丝绸文物的照明选择方面提供了依据,同时为客观评价各种环境因素对染色丝绸的影响提供一种可借鉴的方法。     

STUDY ON THE PIGMENTS IN THE CRUCIFORM GALLERY OF ANGKOR WAT,CAMBODIA

In the cruciform gallery of Angkor Wat in Cambodia, red, orange, white and black pigments were widely painted on the surfaces of pillars, walls and friezes. The application sequence of the pigments is different from area to area. The following substances were confirmed from the pigments: hematite (laterite), minium, calcium oxalate hydrates (whewellite and weddellite), Pb–Cl compounds (cotunnite, laurionite and blixite), calcium phosphates (whitlockite), gypsum, hydrocerussite, calcite, anglesite, lead dioxide, azurite and carbon black. The orange pigment (minium) underlies the red pigment (hematite). The former may have been applied at the time of the foundation (the Angkor Wat style period), and the latter in the Bayon style period or later, but mainly before the early 17th century of the current era.     

STUDY OF ROMAN ANCHOR FROM THE DEAD SEA SHORE*

A wooden Roman anchor was discovered at the retreating shore of the Dead Sea, north of Ein Gedi. The anchor's wood material was coated by a thick veneer of aragonite and gypsum crusts. The wood was dated by radiocarbon to the early Roman time in the Levant. Lead isotope analyses carried out on the Pb–Fe–Cu anchor material (remains of the anchor's metal parts) yielded ratios that indicate origin of the metal in Italian ores (maybe Tuscan). For the wooden part of the anchor a local tree was used.     

On The Grounds Of Post‐Byzantine Greek Icons

The grounds of 51 post‐Byzantine icons (Eastern Orthodox panel paintings) were studied by means of analytical techniques. The artefacts cover the period from the mid‐15th to the mid‐19th century and originate mainly from western (Epirus and the Ionian Islands) and southern Greece (Crete). The findings are examined in the light of technical recipes from related areas and eras, while special insights are gained from the exploration of a gypsum processing recipe by Dionysius of Fourna. A spectrum of ground fabrication practices that is richer than that reported so far or can be deduced from surviving Greek recipes is documented; three instances of ‘grosso‐sottile’ type grounds and a case of ‘inverse grosso‐sottile’ ground are among the reported novel, for post‐Byzantine icons, findings. Moreover, a case of an early icon restoration intervention is documented.     

Induced hydration of obsidian: a simulation study of accuracy requirements

Determination of the hydration rate constant of obsidian is basic to the use of obsidian for establishing chronologies. The constant can, in principle, be determined in either of two ways: by correlations with archaeological sequences, or by laboratory experiments using induced hydration. Induced hydration holds promise of great accuracy, but results reported to date have been disappointing. This paper is based on the hypothesis that the outcomes are the result of error build-up in the induced hydration protocol, and describes an analysis based on a Monte Carlo simulation of the measurement and analysis process. Data are presented which show that the poor results are due to errors inherent in optical measurement of hydration rim thickness. It is concluded that successful use of induced hydration requires an order of magnitude improvement in accuracy of hydration rim measurement over the accuracies currently claimed for optical microscopy. The results do not affect the validity of hydration dating based on archaeological correlations.     

Uses of Gypsum in Spanish architectural heritage: Typologies and some unique construction techniques

ABSTRACT

In Spain, gypsum and its many typologies play an important role as a construction material in Spanish architectural heritage. Its historical use is mainly a direct consequence of the abundance of gypsum deposits and a constructive tradition which began in ancient times. In addition to being a sign of constructive identity, gypsum is a clear example of the strong link between traditional architecture and the natural resources of the territory. The aim of this article is after to identify gypsum deposits and gypsum architectural heritage found in different parts of Spain and to explain the different gypsum typologies—other than powdered gypsum—used. Finally, the most unique construction techniques are described, differentiating between structural elements, partitions, and enclosures, as well as architectural elements and surface finishes.     

A fluid inclusion record of magmatic/hydrothermal pulses in acid Salar Ignorado gypsum,northern Chile

Salar Ignorado is a shallow acid saline lake hosted by a small intervolcanic basin high in the Andes Mountains of northern Chile. Modern surface waters have 3.3–4.1 pH, 0.5–3% total dissolved solids (TDS) and are actively precipitating gypsum crystals. The gypsum crystals trap the acid saline water as fluid inclusions, providing a record of recent surface water characteristics. Salar Ignorado gypsum contains three distinct types of primary fluid inclusions, which result from growth of the gypsum from surface waters. Petrography and microthermometry were performed on 27 gypsum crystals from Salar Ignorado to gain an understanding of recent water chemistry of the salar. One 18.3‐cm‐long gypsum crystal, hosting primary fluid inclusions along 28 successive growth bands, was the focus for fluid inclusion studies and allowed a record of high‐resolution chemical trends. This crystal showed a change in parent fluids during growth, from low salinity, to high salinity, back to low salinity. At the bottom of the crystal, the lowest six fluid inclusion assemblages have salinities of 1.7–5.1 eq. wt. % NaCl. The next nine fluid inclusion assemblages have significantly higher salinity (18.6–27.4 eq. wt. % NaCl) inclusions. The twelve fluid inclusion assemblages near the top of the crystal have low salinity (0.9–8.3 eq. wt. % NaCl) like those at the bottom of the crystal. The high‐salinity fluid inclusions in the middle of this gypsum crystal are interpreted to have formed during a pulse of magmatic/hydrothermal fluids to the surface, perhaps during local active volcanism. Secondary evidence of a magmatic influence on surface waters includes hydrogen sulfide and high molecular weight solid hydrocarbons within some fluid inclusions. This study is among the first detailed fluid inclusion studies of gypsum and suggests that fluid inclusions in gypsum can be paleo‐hydrogeologic proxies.     

Permeability of the Mercia Mudstone: suitability as caprock to carbon capture and storage sites

The Upper Triassic Mercia Mudstone is the caprock to potential carbon capture and storage (CCS) sites in porous and permeable Lower Triassic Sherwood Sandstone reservoirs and aquifers in the UK (primarily offshore). This study presents direct measurements of vertical (k_v) and horizontal (k_h) permeability of core samples from the Mercia Mudstone across a range of effective stress conditions to test their caprock quality and to assess how they will respond to changing effective stress conditions that may occur during CO₂ injection and storage. The Mercia samples analysed were either clay‐rich (muddy) siltstones or relatively clean siltstones cemented by carbonate and gypsum. Porosity is fairly uniform (between 7.4 and 10.7%). Porosity is low either due to abundant depositional illite or abundant diagenetic carbonate and gypsum cements. Permeability values are as low as 10^?20 m² (10nD), and therefore, the Mercia has high sealing capacity. These rocks have similar horizontal and vertical permeabilities with the highest k_h/k_v ratio of 2.03 but an upscaled k_h/k_v ratio is 39, using the arithmetic mean of k_h and the harmonic mean of k_v. Permeability is inversely related to the illite clay content; the most clay‐rich (illite‐rich) samples represent very good caprock quality; the cleaner Mercia Mudstone samples, with pore‐filling carbonate and gypsum cements, represent fair to good caprock quality. Pressure sensitivity of permeability increases with increasing clay mineral content. As pore pressure increases during CO₂ injection, the permeability of the most clay‐rich rocks will increase more than carbonate‐ and gypsum‐rich rocks, thus decreasing permeability heterogeneity. The best quality Mercia Mudstone caprock is probably not geochemically sensitive to CO₂ injection as illite, the cause of the lowest permeability, is relatively stable in the presence of CO₂–water mixtures.     

THE MOSES-PREDOHL PULL AND THE LOCATION DECISION OF THE FIRM*

ABSTRACT This paper exploits the two-stage approach and the envelope theorem to examine the role of the Moses-Predhol pull in the cost-minimizing location theory of the firm. It shows that the two-stage approach introduces the Moses-Predohl pull into the first-order conditions. The Moses-Predohl pull is shown to be equal to zero through the envelope theorem. These results show why the assertions of Bossert and Buhl (1986) concerning Kusumoto (1984,1985) are incorrect.     

受阻胺H-622改性B72及光稳定机理研究

为了提高B72文物保护材料的耐光性能,采用高分子量受阻胺H622对B72进行物理共混改性。监测了改性材料老化前后的颜色、失重等参数的变化,并探讨了受阻胺的稳定机理。实验结果表明,经受阻胺H622改性后,材料的耐光老化性大大提高,红外光谱、接触角、失重、硬度等指标的变化明显较改性前降低。同时观察到老化近500h时,改性材料的颜色基本不变。受阻胺H622对B72的稳定作用是由于受阻胺吸收光能后转变为可以再生的氮氧自由基,能捕获B72老化降解产生的自由基,从而阻止B72降解反应的不断进行。由此可见,采用受阻胺H622改性B72是可行的,提供了一种延长B72寿命的新方法。     

Effective hydration temperature of obsidian: a diffusion theory analysis of time-dependent hydration rates

An estimate of effective hydration temperature (EHT) is needed for chronological use of obsidian hydration data. This paper describes a method for calculating EHT by the practicing archaeologist, replacing three techniques that are in general use today: estimates based on mean temperature, numerical integration of models of diurnal and annual temperature variations, and use of temperature cells. The hydration (or diffusion) coefficient of obsidian is a function of temperature and thus is time varying, while the classic quadratic law of hydration is not valid for time-varying diffusion coefficients. This paper presents a mathematical solution to the case of a time-varying hydration coefficient, based on diffusion theory, with a concise definition of EHT. It is shown that the results are not affected by concentration dependence in the diffusion coefficient. A computer program to compute the rigorous solution is described, and data are presented to explore the resulting range of variation. That use of the Lee equation to compute EHT is not appropriate for obsidian hydration studies is evident from the data presented. The effects of paleoclimatic variation are estimated, and an algebraic best fit equation and worksheet are provided as practical aids to the archaeologist.