The last glaciation in the Western Mourne Mountains,Northern Ireland

During the late‐Midlandian (25–13 ¹⁴C ka BP), the last Irish Ice Sheet was thicker in the Western Mourne Mountains than previously argued. Geomorphological and sedimento‐logical analysis shows that regional ice from the Irish Ice Sheet spilled over the mountains, reaching a major limit 5 km along Pigeon Rock Valley. These findings differ from the previous view that a local valley glacier occupied the valley during this period. The pattern of deglaciation was reconstructed using glacial and periglacial evidence. A complex topographic environment in the upper reaches of the valley suggests that regional ice stagnated as it wasted away. During the Nahanagan Stadial (Younger Dryas, ca. 11–10 ka ¹⁴C BP) an arcuate ridge was formed on the western flank of the valley. Calculations suggest that the Equilibrium Line Altitude, influenced by topographic conditions favourable for snow accumulation, was approximately between 1736 m and 1386 m lower during the Nahanagan Stadial than at present.     

土遗址病害的评估体系研究

土遗址病害评估是对土遗址进行科学保护、管理、利用的一项基础性工作,但土遗址病害评估的体系还没有建立。为此,通过对土遗址病害的分析,借鉴地质工程、岩土工程的相关理论和方法,采用逐次分析的方法评估土遗址的载体和本体病害,探讨了土遗址病害评估体系。通过研究认为,可以从地质灾害、稳定性、表面风化三方面对土遗址病害程度进行评估。地质灾害和稳定性有其它学科相对成熟的理论和方法可以借鉴和采用。表面风化评估应考虑到风化剥蚀速率、遗址保存程度和文物价值三个方面,引进风化度和文物价值权重系数的概念,利用模糊数学原理对表面风化的危险程度进行综合评估是一种新思路。     

Preservation of bird bones: erosion versus digestion by owls

Surface damage to bird bones from pellets of three species of owls (S. aluco, A. otus and B. bubo) was compared with that of bird bones exposed to weathering and soil corrosion (Záskogo Cave in the Western Balkan Mountains, Bulgaria and Ciemna Cave, southern Poland). Scanning electron microscopy and light microscope examinations indicate that the effects of weathering of bird bones (extensive pitting and flaking away on whole bones, holes with sharp edges, depressions with rough bottoms and sharp edges of breakage) are distinguishable from those of digestion (rounding of hole edges on articular ends and sometimes on shafts, rounding of breakage). However, soil corrosion may produce similar rounding to that of digestion, which may hamper taphonomic interpretations of fossil assemblages. Two stages of weathering in bird bone are distinguished. Generally, the kind of damage done to bird bones is similar to that done to mammalian remains. Taphonomic studies of fossil bird remains should take into account a combination of features, including surface damage, fragmentation and possible chemical alterations of bone tissues. © 1997 John Wiley & Sons, Ltd.     

非水分散体加固剂固结砂土能力的研究

有机树脂非水分散体是一种新的土体防风化加固材料,对黄土样品和考古遗址都有好的加固效果。为检验这种加固剂对不同土体的加固能力,选择砂土作为被加固材料,用1．5％TD和2％21J加固剂进行加固试验。结果表明这种材料以低的浓度就有好的加固效果,经过加固的砂土样颜色和孔隙率变化小,土样的力学强度得到提高,具有好的耐水耐冻融能力及较好的耐盐能力,证明这种材料可用于砂土质遗址的加固保护。     

Environmental Conditions During the Early Human Settlement of Chagyrskaya Cave (Altai)

The article presents the results of a palynological study conducted at the Middle Paleolithic site of Chagyrskaya Cave (Altai). Sediments containing the technocomplex of the Sibiryachikha facies of the Altai Middle Paleolithic accumulated at the end of MIS 4 which corresponds with the final stage of the Ermakovo glaciation. The results of the palynological analysis indicate that during the period in question, predominantly steppe landscapes existed in dry, cold climate conditions.     

Salt weathering of sandstone at the Angkor monuments,Cambodia: identification of the origins of salts using sulfur and strontium isotopes

The Angkor monuments in northwestern Cambodia, which are primarily made of sandstone, are suffering from deterioration due to salt weathering. In order to elucidate the sources of the salts and salt weathering process, this paper analyzed bulk chemical compositions and S (sulfur) and Sr (strontium) isotopic ratios for the salts and surrounding environmental materials. At places where bats inhabit the structures, various kinds of sulfate and phosphate salts are formed on the surface of the sandstone. The results of the analysis demonstrate that the S and P (phosphorus) components in the salts are primarily derived from bat guano. Moreover, Ca (calcium), which is the major element in the salts, is suggested to be derived from both bat guano and the sandstone. The isotopic data strongly suggests that bat guano is related to salt weathering. Removal of these animal excrements is essential for future conservation of these monuments. On the other hand, exfoliation of sandstone commonly occurs due to crystallization of calcite (CaCO₃) on platform surfaces of pyramid-type monuments. A large amount of Ca in calcite is suggested to be derived from calcite cement of the building sandstone.     

Strontium isotopic characterization of the Palmottu hydrosystem (Finland): water–rock interaction and geochemistry of groundwaters

The Palmottu hydrosystem is located in a granitic host rock in southern Finland. Along well‐defined pathways in the fractured crystalline rock, strontium isotopes are used to trace the degree of water–rock interaction (WRI) and mixing processes in groundwaters. The ⁸⁷Sr/⁸⁶Sr ratios range between 0.716910 and 0.735606 in the surface waters and between 0.719991 and 0.750787 in the groundwaters, but are between 0.720 and 0.735 in most of the samples. Moreover, the results show a lack of correlation between the water chemistries determining the classification into different water‐types (Na–Cl, Na–SO₄, etc.) and the results of the strontium (Sr) contents and Sr isotopic ratios. From a WRI standpoint, this implies that the Sr behaviour is independent of the water chemistry; the occurrence of large ⁸⁷Sr/⁸⁶Sr variations is site specific and mainly dependent on the lithology. A model to determine the ⁸⁷Sr/⁸⁶Sr ratio of water after interaction with granite was developed. This model is based on the assumption that Sr was derived from three minerals: plagioclase, K‐feldspar and biotite. The results of the calculation indicate that around half of the water analysed within the Palmottu hydrosystem can be explained by the weathering of the granites. However, clearly lower ⁸⁷Sr/⁸⁶Sr are observed in waters when compared to the calculated ⁸⁷Sr/⁸⁶Sr and other sources of Sr, with low ⁸⁷Sr/⁸⁶Sr, rather than the calculated granite–water interaction, which may be suspected. When comparing the ⁸⁷Sr/⁸⁶Sr and ion ratios (Ca/Na, Mg/Na, Sr/Na, Cl/Na), the scattering of the data can be explained by the presence of four end‐members: a brine component (low ⁸⁷Sr/⁸⁶Sr and Ca/Na ratios…), a deep granitic component (high ⁸⁷Sr/⁸⁶Sr ratios and low Ca/Na ratios…), a subsurface component (intermediate ⁸⁷Sr/⁸⁶Sr ratios associated with high Ca/Na ratios…) and a surface end‐member:snow and river drainage (low ⁸⁷Sr/⁸⁶Sr and low Ca/Na ratios…). These extreme end‐members define a series of WRI‐mixing line within a rather complex hydrosystem.     

重庆大足石刻舒成岩砂岩本体表面风化产物研究

针对重庆大足舒成岩摩崖造像和岩体富集灰尘部位出现的粉化伴随着层状剥落现象,采用X-射线衍射仪(XRD)、X-射线荧光光谱仪(XRF)、傅里叶变换红外光谱仪(FTIR)、环境扫描电子显微镜(SEM)和X-射线光电子谱(XPS)对岩石、岩体风化产物与灰尘样品进行了组成结构表征研究。研究发现灰尘和有害气体干沉降过程中酸性物质能够导致砂岩中钙质胶结物发生溶解,伴随着各种盐类结晶应力,导致岩石表层发生风化。研究成果为西南地区石窟寺保护提供了重要参考数据。     

Changes in sub‐water table fluid flow at the end of the Proterozoic and its implications for gas pulsars and MVT lead–zinc deposits

A fundamental change in the nature of sub‐water table fluid flow occurred at roughly the Proterozoic–Phanerozoic boundary when organic matter began to be buried in sufficient quantities that nonaqueous fluids could occupy a significant fraction of the pore space. This allowed the formation of remarkably durable capillary seals that could trap gas in large portions (hundreds of kilometers) of a basin for hundreds of millions of years. Gas loss from these gas zones can be highly dynamic, especially during gas generation. Under the right circumstances, hundreds of cubic kilometers of gas can be rapidly discharged into adjacent permeable aquifers. In Pennsylvanian/Permian time, the Arkoma Basin may have repeatedly discharged such volumes of gas into the very permeable Cambrian sandstone and karstic carbonate aquifers of the mid‐continent of the United States. This could have displaced brines rapidly enough to form the Mississippi Valley‐type (MVT) lead–zinc deposits of this age that are associated with the Arkoma Basin, heating them only briefly as required by maturity indicators. Sea level rise accompanying the melting of Permian continental glaciers may have triggered the gas expulsion events. This radically new mechanism for the formation of MVT deposits is just one example of the nonlinear dynamics of gas accumulations that are possible since Late Proterozoic time.     

Moisture content measurement and surface water absorption test in the inner gallery of Bayon for the conservation of the bas-relief

The bas-relief carved on the sandstone wall in the central part of the inner gallery of Bayon in the Angkor monuments, Cambodia, has been severely damaged mainly due to calcite crystallization. In order to confirm the mechanism of salt weathering and help determine conservation measures for the bas-relief, measurements of the annual change in the moisture content in the bas-relief were conducted. We found that water supplied from the platform behind the bas-relief is the cause of calcite crystallization. It is therefore indispensable for the conservation of the bas-relief to prevent the water permeating from the inside of the platform behind it. As precipitated calcite from the water block pores near the surface of the sandstone, the surface water absorption test is a useful method to evaluate the degree of the salt weathering.     

有机-无机复合疏水型二氧化硅涂层制备及性能

为研究制作保护石质文物的加固材料,采用溶胶-凝胶法,以两种有机硅材料(正硅酸乙酯(TEOS)和甲基三乙氧基硅烷(MTES))为共同前驱体,少量正辛胺为催化剂,聚二甲基硅氧烷(PDMS)(方法 1)或硅烷偶联剂KH-570(方法 2)为有机改性剂,制备了有机-无机复合疏水型Si O2涂层。通过红外光谱(FT-IR)、扫描电镜(SEM)和水接触角(WCA)来表征在砖块表面形成的SiO_2膜层化学组成、表面形貌以及疏水性能,然后再通过测试砖块加固前后外观、吸水性能和孔隙率的变化来验证实际加固效果。结果表明,两种方法均可以制备骨架带-CH3基团的SiO_2溶胶。采用方法 1(添加前驱体质量10%的PDMS)或者方法 2(MTES/TEOS质量比为2),加固后的砖块对水接触角均超过140°,毛细吸水率降低到未处理时的1%~2%,并且砖块的色差和光泽度改变较小。通过耐候性能测试表明,方法 2的保护效果相对较好,说明用此种方法合成的疏水性二氧化硅涂层可以作为砖块加固材料。