碳酸盐岩红色风化壳中的氧化铁矿物

氧化铁矿物是碳酸盐岩红色风化壳的主要矿物成分和重要结构单元。运用X射线衍射、透射电镜、扫描电镜、穆斯堡尔谱和电子探针等方法对碳酸盐岩红色风化壳中的氧化铁矿物进行了系统研究。碳酸盐岩红色风化壳中的氧化铁矿物主要有针铁矿、赤铁矿和磁赤铁矿。氧化铁矿物组合、含量和化学成分随成土环境和风化强度在剖面中呈明显的规律性变化,这为碳酸盐岩风化成土作用、红色风化壳成因与环境问题的深入研究提供了重要的矿物学依据。     

内陆湖泊流域的化学风化及气候变化—以内蒙古岱海为例

利用湖泊沉积物中Rb/Sr值来反映受古气候制约的流域陆地化学风化率的变化，并恢复了岱海近400a以来以小冰期为特征的、具有100a准周期（经谱分析）的气候波动历史。通过磁化率、粘土矿物含量和种类的综合分析，确证了湖泊沉积物Rb/Sr值的变化可以用来重建流域内化学风化率与其相应的古气候演化过程，是湖泊沉积记录中具有比磁化率更明显气候意义的有效代用指标。     

Investigations regarding Alpine talus slopes using ground‐penetrating radar (GPR) in the Bavarian Alps,Germany

The applicability of ground‐penetrating radar (GPR) for the investigation of loose debris was tested at two sites (Viererkar and Zugspitzplatt). A pulseEKKO 100 GPR system equipped with 25 MHz antennae was utilized. The aim of the investigation was to record the base of the debris layer, and thereby acquire an estimation of the backweathering rates of the adjacent rockwalls. The study areas are situated in the Northern Alps near the German–Austrian border. The sites are characterized by steep limestone rockwalls and extensive talus accumulations. A total of six profiles was surveyed. The method is suitable and effective for a quick survey in this dry, high‐ohmic substrate. The GPR system was able to deliver information about the subsurface stratigraphy to c. 70 m depth. The boundary line to the bedrock was discovered – depending upon the profile surveyed ?5 to 25 m below the surface. The base of the debris material sometimes shows no distinct reflection. Buried features (V‐shaped furrows, zones overdeepened by ice action, geological structures) could be detected. Arched structures well below the talus–bedrock interface can be interpreted as drainage systems in the karstic bedrock. A thick scree layer of Late Glacial age was separated from a thinner layer on the talus surface, which was related to the Holocene. The backweathering rates were fixed by a calculation of talus volume to c. 100 mm/10³ a during the Holocene (Viererkar) and 150–300 mm/10³ a (Zugspitzplatt). The detrital formation in north‐exposed sites is twice as intense as in south‐exposed sites. These results match the rates of recent rockfall in the same area of investigation. The calculated backweathering for the late glacial period is 150–730 mm/10³ a. The magnitude of the calculated rockwall retreat lies well within the range of previous measurements. The discrepancy between some weathering rates highlights the fact that recent and past relief formation must be differentiated. Otherwise recent removal rates may be overestimated. Copyright © 2001 John Wiley & Sons, Ltd.     

Twenty‐year weathering remeasurements at St Paul's Cathedral,London

Microerosion meter (MEM) measurements of the surface height of the balustrade of St Paul's Cathedral, London, have been repeated in the year 2000 following earlier measurements in 1980, 1981, 1985 and 1990. Methodological sources of error mean that while the measurements were made to 0·0001 mm, the data are reliable to two decimal places. There was a reduction in the mean erosion rate on horizontal sites from 0·045 mm a^?1 in the period 1980–1990 to 0·025 mm a^?1 in 1990–2000. Decreases in atmospheric SO₂ levels from 20–25 ppb in 1980–1982 to around 10 ppb in 1990–2000, offer a causal explanation. The surface topography evolved more erratically in 1990–2000 than before, with much, but not all, of the more microelevated areas showing greater, and often more variable erosion. There are also indications of less erosion and more surface rises in low‐lying microareas on horizontal sites which is interpreted as possible deposition and/or microfloral growth in wetter depressions, the pattern being largely absent on a well drained vertical site. Copyright © 2001 John Wiley & Sons, Ltd.     

石质文物风化病害防治的环境地质问题

石质文物的风化病害防治必须重视对地质环境的研究 ,地质环境的研究是彻底根治风化病害的前提。论述了风化病害的类型和机理 ,讨论了影响风化的主要环境因素和环境地质问题 ,提出了风化病害防治的原则与对策。     

微量元素记录的化学风化和气候变化：以巴丹吉林沙漠查格勒布鲁剖面为例

查格勒布鲁剖面包含7种类型的沉积相，地层中微量元素的总质量分数大致按照“风成砂→湖相层→黄土→古土壤”的顺序递增。多数微量元素的质量分数在剖面中的演化趋势与沉积物的中值粒烃和硅酸系数的大小呈负相关。与洛川剖面的马兰黄土相比，查格勒布鲁剖面上更新统地层处于相对微弱的化学风化环境，表明，晚更新世期间，巴丹吉林沙漠一带的干湿变化取决于东亚夏季风的盛衰，西风气流带来的降水到达不了巴丹吉林沙漠附近地区。     

Spatial variation of early season surface water chemistry in Kärkevagge, Swedish Lapland

This study examines the spatial variability of early season water chemistry in the arctic-alpine valley of Kärkevagge, Sweden. The data demonstrate the spatially heterogeneous nature of water chemistry and the general patterns of chemical weathering in the valley. Water chemistry in this valley is dominated by two anions, bicarbonate and sulfate. Bicarbonate is derived from the dissolution of atmospheric CO₂ and the weathering of carbonate units in the local metamorphic rocks, while the sulfate is derived from the oxidation of pyrite in the Seve-Koli tectonic nappe. Spatial patterns of chemical constituents reflect the broad effects of local geology on surface water chemistry. In particular, they demonstrate the effects that mineral species present in minor amounts have on basin-wide water chemistry. However, solute flux rates derived from water chemistry and discharge demonstrate less variability.     

Little ice age alluvial fan development in Langedalen, western Norway

This paper reports a preliminary investigation of the sedimentary succession in two alluvial fans in western Norway. Sedimentological information is supplemented by palaeoecological data from pollen analysis and the age of the sequence is constrained by six radiocarbon age estimates on woody fragments and peat. These data suggest that significant accumulation of fan sediments took place after AD 1637–1685. Before this, the fluvial landscape and the adjacent slopes may have been more stable with the development of Betula , Salix and Alnus woodland on the valley floor and sides. Although there is no indication of gradual climatic deterioration in the vegetation record from these sites, the radiocarbon chronology suggests that enhanced fan development was coincident with the climatic change associated with the 'Little Ice Age'. This was probably a response to glacier expansion and increased discharge and sediment supply to the alluvial fans from outlets of the Jostedalsbreen ice cap on the southern side of Langedalen. Initial response to climate change in this setting was therefore enhanced geomorphic activity and instability of the valley-side slopes.     

Using gravestones to assess changing rates of weathering in the United Kingdom

Weathering rates were calculated using the height difference between lead lettering and marble on gravestones at three sites in the UK. Comparison of their regression lines and residuals suggested that two of the sites, Portsmouth and Wolverhampton, had similar amounts and rates of weathering over the last 100-150 years. Gravestones in Swansea appear to have weathered much more and much faster than gravestones at the other two sites. These differences may be the result of the differing pollution and rainfall histories of the three sites.     

Rapid formation of rock varnish and other rock coatings on slag deposits near Fontana,California

Manganiferous rock varnish, silica glaze and iron skins have formed on 20- to 40-year-old slag piles near Fontana, southern California. Rapid rock-varnish formation is associated with an unidentified cocci bacterium that grows rapidly in culturing experiments, combined with the likelihood that Mn-rich solutions flow over slag surfaces. A new model is proposed for the formation of silica glaze, involving soluble Al-Si complexes and the nature of wetting films. Iron skins occur where runoff is concentrated, and where iron bacteria grow. Observations indicate: (i) substrate can be important in supplying Mn, as well as maintaining a stable surface and channelling runoff to microspots where varnish grows; (ii) ignorance of boundary layer pH/Eh conditions makes chemical-physical models of varnish formation speculative; (iii) the balance between cementation of recently nucleated varnishes and erosional shear stresses is poorly understood, but is probably an important limiting factor on varnish growth rates; and (iv) there must be at least two steps in biotic varnishing-accretion of Mn-Fe in casts, followed by cementation of clays by either in situ cast residue or Mn-Fe remobilized from casts. Varnish accretion may be limited by the rate at which both steps occur. Rapid development of readily distinguishable manganiferous rock varnishes at this post-1952 site highlights the danger of speculation on the ages of landforms based solely on the appearance of rock-varnish coatings.