龙门石窟潜溪寺凝结水病害形成机理及防治对策研究

文中阐述了龙门石窟凝结水病害的影响因素,初步分析了凝结水的形成机理.以龙门石窟潜溪寺作为监测点,通过对比分析总结潜溪寺凝结水变化的现场、发展直至消失的规律,并提出了龙门石窟凝结水病害的防治对策.     

A study of limestone from the Longmen Grottoes of Henan province,China by neutron activation analysis

The Longmen Grottoes, also known as the Longmen Caves or Dragon's Gate Grottoes, are located near the city of Luoyang, Henan province, China. The grottoes were carved into the limestone cliffs during the period from 493 AD to 1130 AD. Limestone samples from different areas within the grottoes were analyzed by neutron activation analysis (NAA) to determine the concentrations of major, trace and rare-earth elements (REEs). Three compositional groups were identified corresponding to different areas within Longmen Grottoes. X-ray diffraction (XRD) was performed on a few samples to obtain information about the mineral structure. The results indicate that rocks in the northern area are comprised of dolomite, while rocks in the middle and southern areas are comprised of limestone. The NAA results provide information useful for identifying and relocating fragments from the grottoes that may have lost their identity. The compositional data also provides important clues regarding the geologic history of the limestone formation at Longmen.     

Black limestone used in antiquity: recognizing the limestone of Teos

This paper documents the petrographic and isotopic characteristics of some black limestones that were exploited in antiquity near the ancient site of Teos in Ionia (south‐western Anatolia, Turkey). The best‐quality black limestone of Teos is represented by a series of step‐cut‐shaped blocks situated north of the Seferihisar–S??ac?k road, destined to be exported and used for architectural elements. The techniques used to study these blocks allow possible identification of the origin of Teos in ancient black stone artefacts. Nevertheless, petrographic and geochemical investigation on some black limestones that outcrop in the area near Teos has not firmly identified the quarry fronts from which these blocks were quarried away, but it supports the known hypothesis that Teian black limestones were found and quarried in conjunction with the Africano marble.     

龙门石窟小型坍塌窟龛的修复

龙门石窟小型窟龛坍塌、缺失的现象比较普遍,对坍塌、缺失窟龛进行适当修补和复原,可使雕刻品免受日晒雨淋的侵蚀。为此,以龙门石窟683号洞窟坍塌窟顶的保护性修复为例,选用石材在坍塌洞窟恢复小体量窟顶的修复方法。试验证明,这种方法对石窟外观的改变不大,又可以解决雕刻品直接受到的日晒雨淋问题。试验表明,本方法有可能应用于其它露天摩崖石刻的保护。     

Preparation of a new calcite layer from calcium glycolate for the conservation of sulfated limestone artifacts

A novel preparation method of calcite layer was explored for the conservation purpose of the surface sulfation limestone artifacts. In this method, the alcoholic solution of calcium glycolate was used as a precursor of calcite layer. After application on the surface of gypsum crust on limestone by spraying, calcium glycolate can combine with the carbon dioxide spontaneously and form a compact calcite layer. The obtained calcite layer can act as a shelter and can prevent the gypsum crust from the dissolution damage of the natural precipitation. The protective properties of the calcite layer were investigated by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS), X-ray diffraction (XRD), infrared spectroscopy (FTIR), water erosion resistance, water absorption, colour difference, surface strength, and hardness test. The results revealed that the water erosion resistance, surface strength, and hardness of the treated sample were increased remarkably. Meanwhile, the intrinsic physical properties such as porosity, capillary absorption, and appearance were not affected obviously, indicating a good compatibility of the proposed protection method.     

3D打印技术在龙门石窟金刚经洞修复中的应用

为了缓解龙门石窟金刚经洞因局部坍塌引起的水害、微生物等病害发育问题,利用3D打印技术对坍塌部位进行修复:修复部件以光敏树脂为打印材料,修复部件为空心结构以减轻荷载；对修复部件进行光场、温度场仿真设计,使洞窟内日光辐射强度降低至日光直射的50%~56%,窟内温度分布差值由6.6℃降低到1.9℃；修复部件采用S8801涂覆内外表面,S8801老化实验后主要性能保持率均大于90%,并采用玄武岩纤维与玻璃纤维增强修复部件内表面。经多次降雨后观察,龙门石窟金刚经洞由缺失导致的雨水倒勾等问题得到有效缓解。该工作为3D打印技术与不可移动石质文物修复工作结合奠定基础。     

Determining the provenance of black limestone artifacts using petrography,isotopes and EPR techniques: the case of the monument of Bocco

This paper investigates the provenance of the black limestone of the monument known as Bocco, named after the king of Mauretania who presented Silla with this work as a sign of his submission to the power of Rome. A multi-method approach, comprising petrographic observations, carbon and oxygen isotope composition and electron paramagnetic resonance (EPR) spectra characteristics, was used for this purpose. The monument is part of a reconstruction of a rectangular base (approx. 8 × 2 m) which is likely to have served as the base for a bronze statuary group and is currently composed of six blocks of limestone whose exterior is engraved with a fine frieze. The results of the different analyses were compared with the data of a published database of the most important black limestone quarries exploited during Roman times in the Mediterranean area. The petrographic and physico-chemical parameters did not prove to be very effective in determining the provenance of the black limestone of Bocco; the isotopes result even raised some uncertainty as to whether all six blocks came from the same quarry, though this doubt was dispelled by the EPR data and, above all, by the evident petrographic similarity between them. Differences in the isotopic composition of the various blocks may be due to an in situ rock alteration process caused by interaction with an aqueous fluid. It was, however, impossible to determine with certainty the origin of the material of the stone artifact using the database available; it is possible that the black limestone of Bocco came from an ancient quarry that is likely to be located in north western Africa but has not yet been uncovered. An alternative hypothesis, according to which the limestone used for the monument of Bocco came from the ancient quarry of Ain el Ksir, one of the Tunisian quarries present in the database, is also discussed.     

Stability of phytoliths in the archaeological record: a dissolution study of modern and fossil phytoliths

Opaline phytoliths are important microfossils used in archaeological and ecological research. Relatively little is known about the stability of phytoliths after burial. Under alkaline pH conditions they can dissolve, and mechanical disturbances can cause a loss of their more delicate appendages. Here we present an experimental study of phytolith stability (combination of solubility and abrasion). Modern and fossil phytoliths were extracted from wheat using new methods to minimize dissolution, and by burning in an oven. These assemblages were placed in a solution buffered to pH 10 and maintained under constant temperature and shaking conditions. The silicon concentrations in the solution were monitored once a week for 5 weeks. The phytolith morphologies in each assemblage were determined at the outset of the experiment and after 5 weeks. The results show that there are differences in stability between various assemblages. Modern inflorescence wheat phytolith assemblages are more unstable than those from leaves/stems. Burnt assemblages are less stable than unburnt assemblages, and a fossil phytolith assemblage about 3000 years old is more stable than the modern wheat assemblages. The results also show that individual phytolith morphotypes have different stabilities, and as a result of dissolution and abrasion, some morphotypes may resemble others. This study further shows that archaeological and/or paleo-environmental interpretation of phytolith assemblages may change with the assemblage’s state of preservation.     

用羧甲基纤维素封护法加固龙门石窟擂鼓台南洞一尊宝冠佛像的研究

龙门石窟擂鼓台南洞部分佛像风化开裂严重,为了有效地保护这些佛像,探讨微裂隙造像加固封护的方法,采用羧甲基纤维素封护法对其中一尊开裂严重的宝冠佛像进行了试验性加固。结果表明,用这种材料进行封护不仅能够满足微裂隙造像加固的需要,而且操作简便,安全性好,是一种可行的加固封护方法。     

Permian bivalve molluscs from the Gai-As Formation,northern Namibia: systematics,taphonomy and biostratigraphy

Fossil bivalves from two horizons in the Gai-As Formation of NW Namibia are tentatively correlated with mid-Permian taxa of the Passa Dois Group of Brazil, supporting the concept that the Paraná Basin extended into Africa. The Namibian fauna includes a new genus and species, Huabiella compressa, which was previously confused with Brazilian taxa. The taphonomy of the bivalve-rich strata indicates deposition under the influence of episodic events, such as storms. The Gai-As Formation directly overlies the mesosaurid-bearing deposits of the Huab Formation, indicating a significant unconformity when compared with the more complete succession of the Passa Dois Group, Paraná Basin, Brazil. The studied bivalve assemblages are no younger than 265±2.5 Ma (mid-Permian), based on U/Pb radiometric dating of zircons from tuffs.