阆中大像山石窟的形制、题材与时代

位于四川省阆中市的大像山石窟,主要开凿于中晚唐和宋代,明清时期也有少量开凿。现有37龛,以方形龛、外方内圆拱形龛及圆拱形龛为主,方形龛最为多见。龛楣大多无装饰,雕刻简单。题材主要有弥勒佛、七佛、千佛、观音、天王、力士、经幢及舍利塔等。造像组合较少,以单身造像为多。阆中独特的地理位置,使得大像山石窟兼具广元、巴中两地石窟的特点,其丰富的内容为巴蜀佛教石窟寺的深入研究提供了重要的实物资料。     

SO2与水分综合影响下的云冈石窟砂岩劣化研究

气体污染物SO₂是造成云冈石窟文物本体劣化的重要因素之一。为厘清SO₂与水分耦合作用下的云冈砂岩劣化规律，开展不同SO₂浓度、相对湿度以及降水条件下的室内模拟风化试验，测定试样质量、表面特征和化学成分变化。结果表明：SO₂易与砂岩中的碳酸盐矿物(如方解石)和长石发生化学反应，产物包括CaSO₄·2H₂O、MgSO₄·7H₂O和高岭石等，且随着相对湿度增加，反应程度增大，造成试样的质量、色差值、可溶盐含量上升及硅铝比下降；液态水的参与能显著加快SO₂与砂岩的相互作用过程，不但增加了各项指标的变化幅度，还加大了SO₂入侵深度。研究成果可为砂岩质文物的科学认知和预防性保护提供参考。     

云冈石窟佛衣类型

云冈石窟主要雕凿于北魏中后期,分为三期。第一期及第二期造像为太和改制以前流行的佛衣,多沿袭印度传统,其中勾联纹覆肩袒右佛衣可能是在云冈形成的样式。第二期太和改制以后及第三期盛行的佛衣,偏重汉地传统,大概多与南朝的影响有关。甘肃天水麦积山石窟与敦煌莫高窟早期洞窟中流行勾联纹覆肩袒右佛衣,推测两地早期洞窟中佛像始凿的时间不早于云冈第一期。北魏迁都洛阳后,云冈的佛衣在龙门石窟继续发展。     

馆藏壁画保护理论探索与实践——以甘肃省博物馆藏武威天梯山石窟壁画的保护修复为例

馆藏壁画是具有重要历史、科学和艺术价值的博物馆藏品之一,大部分为来自考古发掘现场的墓葬壁画,其次为揭取搬迁的石窟壁画和殿堂壁画。因其制作材料(主要为泥质或石灰层地仗)脆弱,保存年代久远,各种病害多发且严重。已有研究结果表明,石窟壁画保护的难点是水—盐运移引起的壁画酥碱等病害问题,而当石窟壁画转移到博物馆作为藏品保存后,其赋存环境条件发生了根本变化,博物馆可控的、稳定的温度、湿度使其保护难度大大降低,保护现存实物原状与历史信息必然成为馆藏壁画保护的重要内容。本研究以甘肃省博物馆藏武威天梯山石窟壁画的保护修复为例,结合多年石窟壁画保护实践,探讨了馆藏石窟壁画保护理论与保护程序,重点阐述了壁画附加支撑体的去除、新支撑体的选择以及安装等方面的技术要点。提出通过举办专题展览,利用多媒体等高新技术,可以生动、形象、准确地反映和展示馆藏壁画的价值及保护修复过程,弥补传统陈列展览模式的不足。研究成果对同类文物的保护具有重要的借鉴价值。     

Khmer sandstone quarries of Kulen Mountain and Koh Ker: a petrographic and geochemical study

Sandstone from several ancient quarries and natural outcrops located at the eastern foothill of Kulen Mountain and in Koh Ker, northern Cambodia, has been characterized by means of petrographic analysis, scanning electron microscopy, and geochemical analysis. The samples have been collected during a series of field surveys organized jointly by The Metropolitan Museum of Art and the Authority for the Protection and Management of Angkor and the Region of Siem Reap (APSARA). The data show how the sandstone quarried from these sites is characterized by an overall petrographic and geochemical homogeneity, and is consistent with the upper terms of the Lower–Middle Jurassic Terrain Rouge Formation.     

麦积山第100窟调查与年代研究

麦积山第100窟为麦积山石窟早期很重要的一个洞窟,该窟由于有过数次的重修,对之做系统的调查进而分析其始建年代与重修年代,有利于麦积山石窟成组洞窟及年代学的研究。本文在详细调查的基础上,认为该窟与第128窟等为北魏太和时期开凿,北魏晚期对该窟进行了重修,宋代再次重修。     

Joint controlled fluid flow patterns and iron mass transfer in Jurassic Navajo Sandstone,Southern Utah,USA

The Jurassic Navajo Sandstone of Grand Staircase Escalante National Monument (GSENM), Utah, exhibits a broad range of iron oxide/oxyhydroxide concretionary geometries that record a complex paragenetic history of the reservoir. The concretionary geometries are as follows: (i) common macroconcretions (>5 mm in diameter), (ii) ubiquitous microconcretions (<5 mm in diameter), (iii) localized iron oxide/oxyhydroxide‐lined northeast‐striking joints, and (iv) loopy asymmetrical mineralization and banded precipitation patterns (Liesegang bands) associated with the joints. Spheroidal concretion geometries typically indicate diffusive mass transfer, whereas asymmetrical mineralization represents advective directional flow. Liesegang bands parallel to asymmetrical mineralization denote a diffusive mass transfer component perpendicular to the principal flow direction. Careful study of concretionary geometries and their cross‐cutting relationships establishes a relative timing of precipitation and mobilization events. Macroconcretions formed post‐Laramide (<55 Ma), prior to and independent of the Miocene joints. The joints provided conduits for later oxidizing fluids that precipitated iron oxide/oxyhydroxide lining on the joint faces. Advective mass transfer overprinted the area with preferentially cemented flow lines (asymmetrical mineralization) less than 10 Ma, coincident with development of a hydraulic low to the southeast of the region (Colorado River downcutting). Certain trace elements are genetically tied to concretion formation, and evaluation of trace elements establishes precursor mineral phases. Enriched uranium concentrations in concretions (relative to the host rock) and low/undetectable sulfur concentrations in both host rock and concretions suggest that iron oxyhydroxide was a primary precipitate rather than a reduced iron mineral (i.e., pyrite or siderite) that later oxidized. Enrichment of Ni and As in concretions functions as fingerprints for diagenetic concretion formation when determining genesis of ambiguous iron oxide/oxyhydroxide spherules such as the remotely sensed ‘blueberries’ on Mars. Similarities between Mars and Utah spherules such as geometry, in situ spacing and volumetric density suggest that Mars spherules precipitated via a geochemically self‐organized nucleation pattern in diffusive chemical reaction fronts.     

典型石窟砂岩的毛细吸水与变形响应特征

针对云冈石窟、乐山大佛和大足石刻,选择当地新鲜砂岩开展蒸馏水一维毛细上升试验,获取吸水质量和浸润前锋演变趋势,同时利用三向应变花测定试样不同高度处表面局部微应变的发展规律,并结合微观结构特征对宏观性质进行分析。研究结果表明:整个毛细吸水过程可划分为3个阶段,吸水率以及毛细高度随时间变化最快和最慢的分别是乐山砂岩和大足砂岩;云冈、大足和乐山砂岩局部微应变的最终值依次增加,且存在数量级上的差异,其变化趋势与浸润前锋运移密切相关,竖直和斜45°应变表现为先收缩后膨胀;砂岩毛细吸水和水化变形能力的关键影响因素分别是孔径分布和黏土矿物成分,其与文物真实产生的粉化、崩解、开裂和片状剥落等表面风化病害的形成密切相关。研究成果可为毛细水相关的劣化机理揭示提供丰富的参考数据,并向类似文物的病害评估与科学保护提供可靠的理论依据。     

八硼酸钠抑制砂石质文物硫酸盐结晶研究

针对砂石质文物的可溶盐病害治理,本研究提出了一种采用八硼酸钠抑制硫酸钠结晶的方法。通过偏光显微镜、扫描电镜、X射线衍射等分析,以陕北砂岩为例,研究了梯度浓度的八硼酸钠对硫酸钠结晶的抑制效果,初步探讨了八硼酸钠对硫酸钠的微观作用机理。研究表明,八硼酸钠浓度越大,硫酸钠结晶析出量越少,考虑到“文物保护最低限度干预”的原则,当八硼酸钠的质量分数为15%,抑盐效果最佳。同时本研究对可溶盐病害治理与砂石质文物保护具有重要的理论和实践意义。     

A Reconsideration of the Construction Period of the Cruciform Terraces and the Elevated Causeways in the Angkor Monuments,Based on the Magnetic Susceptibility of the Sandstone Blocks*

In this paper, the construction period of the cruciform terraces with columns and the elevated causeways in the Angkor monuments of Cambodia is reconsidered, based on the results of our investigation of magnetic susceptibility and other characteristics of sandstone blocks. From an art‐historical point of view, they are generally considered as modifications in the post‐Bayon style period—the period during the reign of Jayavarman VIII (1243–95 ce ) or later. However, from a lithological point of view, the average magnetic susceptibilities of the sandstone blocks in the cruciform terraces with columns and the elevated causeways are consistent with the rest of the monument. In addition, the characteristics of the sandstone blocks in the cruciform terraces, such as their shape, the orientation of the bedding plane and the stacking method, suggest that they were constructed in the same period as the rest of the monument.