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41.
In rehydroxylation (RHX) dating, the activation energy of the rehydroxylation reaction is required first in the estimate of a material's effective lifetime temperature (ELT), and second to correct the RHX rate constant obtained at a given measurement temperature to that at the ELT. Measurement of the activation energy is thus integral to the RHX methodology. In this paper, we report a temperature‐step method for the measurement of activation energy and develop fully the underlying theoretical basis. In contrast to obtaining the activation energy from a series of separate experiments (each of which requires the sample to be dehydroxylated prior to measuring the RHX rate constant), the temperature‐step method not only requires a single dehydroxylation at 500°C but also eliminates repeated acquisition of Stage I data, which are not required for dating purposes. Since the first temperature step is set to correspond to the temperature at which a dating determination is carried out, the measurement of rate constants at higher temperatures simply becomes an extension of dating. Consequently, the logistics of obtaining the activation energy of rehydroxylation are greatly simplified. 相似文献
42.
The Monte Perdido thrust fault (southern Pyrenees) consists of a 6‐m‐thick interval of intensely deformed clay‐bearing rocks. The fault zone is affected by a pervasive pressure solution seam and numerous shear surfaces. Calcite extensional‐shear veins are present along the shear surfaces. The angular relationships between the two structures indicate that shear surfaces developed at a high angle (70°) to the local principal maximum stress axis σ1. Two main stages of deformation are present. The first stage corresponds to the development of calcite shear veins by a combination of shear surface reactivation and extensional mode I rupture. The second stage of deformation corresponds to chlorite precipitation along the previously reactivated shear surfaces. The pore fluid factor λ computed for the two deformation episodes indicates high fluid pressures during the Monte Perdido thrust activity. During the first stage of deformation, the reactivation of the shear surface was facilitated by a suprahydrostatic fluid pressure with a pore fluid factor λ equal to 0.89. For the second stage, the fluid pressure remained still high (with a λ value ranging between 0.77 and 0.84) even with the presence of weak chlorite along the shear surfaces. Furthermore, evidence of hydrostatic fluid pressure during calcite cement precipitation supports that incremental shear surface reactivations are correlated with cyclic fluid pressure fluctuations consistent with a fault‐valve model. 相似文献
43.
1995年 ,在徐州市东郊东甸子西汉一号墓中出土一枚封泥 ,上有阳文隶书“府”。本文对这枚封泥的封缄方法及相关问题进行了研究。 相似文献
44.
The purpose of this study was to identify changes in firing practices that occurred during a timeframe that saw the introduction of European kiln technology to the Andes (AD 900–1800). Pottery from an excavated context at the archaeological site of Aqnapampa in the southern highlands of Peru was examined for changes in paste recipes that adapted local materials to increased firing temperatures indicative of evolving firing technologies. Sherds (60) and fragments refired to 890 °C from 12 stratigraphic levels were compared by style, surface treatment, paste color, and vitrification structures (ESEM). Four technological phases of the Cuzco pottery sequence emerged and were used to evaluate the trajectory of a single decorative style (Killke). Previously thought to have been produced in pre-Inca times and curated into later periods, the Killke sherds presented evidence that the style was produced using technologies introduced in the Inca and Spanish Colonial Period. 相似文献
45.
黄龙 《文物保护与考古科学》1996,8(2):37-44
金属成形加工技术是人类文明的杰出贡献,在中国,传统金属加工技术门类繁多,其中发展最深、应用最广的首推铸造技术。考古发掘与文物研究证明：中国悠远灿烂的青铜文化其基础为铸造技术,而泥质铸型处理技术又是中国传统铸造技术的关键之一。本文拟通过现存传统泥质铸型处理技术的研究、古代文献资料的分析、出土泥质铸型（陶范）的科学测试,对中国传统泥质铸型处理技术的形成作初步探源工作。 相似文献
46.
赵凡 《文物保护与考古科学》2021,33(1):110-117
为了解广汉龙居寺中殿建筑热湿环境特征,采用基于物联网技术的环境温湿度监测系统对建筑空间温度和相对湿度进行监测,分析建筑空间温湿度时空变化规律,评估建筑热湿环境特征,探讨热湿环境对文物保存的影响。结果表明,该建筑对外界环境温湿度变化具有较好的缓冲和隔离作用,建筑内部热湿环境对文物保存不利,主要体现在相对湿度高、波动大,湿度调控将是文物预防性保护的关键。建筑热湿环境为壁画酥碱和霉斑病害主要成因,同时促进了编竹夹泥墙体结构安全问题的发生。研究成果不仅丰富了对四川地区明代编竹夹泥墙木结构古建筑热湿环境特征的认识,而且为该建筑壁画病害和墙体结构安全问题的成因分析提供了依据。 相似文献
47.
为探讨我国北方著名窑场之一的耀州窑唐、五代时期青瓷胎釉化妆土与北宋时期之间白色中间层的区别,利用具有电子探针微区分析功能的能量色散X射线光谱仪测试。结果表明,北宋时期青瓷的中间层和唐、五代的化妆土在化学组成上存在着一些差异。白色中间层中不仅铁的含量比胎釉都低,CaO和K_2O的含量则高于胎,而靠近釉;而化妆土的化学组成除了Fe_2O_3含量较低外,其它化学组成十分接近瓷胎;中间层和化妆土相比,Fe_2O_3的含量更低一些。 相似文献
48.
Fired bricks are a hard and durable masonry material that has played a major role in the emergence of early human urban civilization. In China, fired clay bricks have been widely used as a building and flooring material since the Qin Dynasty (476?206 bc ), although a few lines of evidence show that fired clay bricks might have been invented as early as 5500 years ago in eastern central China. However, these burnt clumps of clay appear not to be bricks in the strict sense, and our knowledge about the origin of fired clay bricks in China still remains fragmentary. Archaeological excavations at a Middle Neolithic cultural site in northwestern China reveal that the making of fired clay bricks began some 5000 years ago. Our findings also open a window into the process of prehistoric brickmaking in East Asia. 相似文献
49.
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 (kv) and horizontal (kh) 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 kh/kv ratio of 2.03 but an upscaled kh/kv ratio is 39, using the arithmetic mean of kh and the harmonic mean of kv. 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. 相似文献
50.
本文采用中子活化分析技术对陶寺遗址出土的74件泥质陶器样品进行了分析研究,结果显示出土于遗址不同功能区的泥质陶器在原材料的使用或制作工艺上存在差异性,这或许表明了不同阶层的人所使用的泥质陶器也是有差别的,已经有了贫富贵贱之分。 相似文献