岩石风化与岩石化学成分的变化研究

研究岩石风化过程中岩石化学成分的变化规律,对于进一步研究岩石的风化机理以及岩石的物理力学性质变化过程有着十分重要的意义.本文通过对湘西地区陡山沱组黑色岩石不同风化程度的化学成分分析研究表明,岩石中的化学成分将随风化的进行而不断发生变化,在一定程度上反映了陡山沱组黑色岩石风化过程中其化学成分的变化趋势.     

崂山山顶风化坑化学风化过程的岩石化学与矿物学证据

2011年5月对崂山山顶风化坑进行考察和采样,通过对风化坑内碎屑和坑外岩石的粉晶X射线衍射矿物分析、X射线荧光光谱化学全量分析,研究了风化坑内外的矿物风化及各元素迁移特征,对风化坑的成因过程进行探讨.研究结果表明:1)崂山山顶风化坑碎屑的英长比总是大于其周边岩石的英长比,说明风化坑的形成是花岗岩造岩矿物差异风化的结果;...     

关于岩石风化过程中化学组分迁移的定量研究方法

岩石化学分析结果的定和效应给定量研究风化体系中化学组分的迁移规律带来困难。一般岩石风化体系可以有母岩-滤液和母岩-风化产物两个子体系。本文即探讨该二子体系中化学组分迁移的定量计算问题。对比分析表明,母岩-滤液子体系方法较适用于风化程度高的体系,而母岩-风化产物子体系方法较适用于风化程度低的体系。对于风化程度中等的体系,宜采用两种子体系方法所得结果的加权平均,其中权重按风化程度取值。     

绵阳地区白垩系岩石风化过程的生态效应

论述了四川绵阳地区白垩系七曲寺组砂岩、泥岩风化过程的信息动态及其对森林植被的生态效应，为长江上游水土保持防护林提供开发信息。     

鄱阳湖流域岩石化学风化特征及CO2消耗量估算

岩石风化过程中所产生的碳汇是全球碳循环的重要组成部分,该领域受到研究全球变化科学家们的普遍关注。文中通过对鄱阳湖流域河水系统的样品采集和化学成分分析,研究了河水化学成分来源及流域岩石风化所产生的碳汇效应。以大气降水、蒸发岩、硅酸岩和碳酸盐岩为4个端员,计算出它们对河水中溶解质的贡献率分别为10．4％、21．9％、30．...     

遵义附近岩石及其风化成壤过程中元素地球化学特征初探

本文利用一比五万遵义市幅、遵义县幅区域地质调查工作中岩石和土壤测量成果,较系统地论述全区各时代地层岩石元素背景含量、元素共生组合和富集成矿的特征,以及土壤剖面上元素含量变化规律等方面入手,对遵义地层岩石及其风化土壤中元素地球化学特征作一初步探讨,可供该区进行地质找矿、研究环境地球化学、探讨化探工作方法时参考。     

白水黄土-红粘土化学风化强度的剖面特征与粒度效应

白水剖面黄土-红粘土全样化学分析表明,以CIA指数为代表的化学风化强度从剖面下部往上逐步变弱,波动增大,总体趋势与深海氧同位素代表的全球冰量变化可以很好对比。分粒级组分化学分析则显示,黄土-红粘土主要元素迁移及化学风化强度与粒度强烈相关,CIA指数表征的化学风化强度变化在相当程度上受到粒度变化的控制。总体上,黄土-红粘土各粒级颗粒的风化程度都不高,而且沉积之后的成土风化作用对其主要元素含量的影响有限,黄土-红粘土化学成分的长期变化趋势主要受到物源的新加入和混合过程的影响。从剖面变化看,粗粒级部分(5～20μm和20～63μm)的风化指数的变化特征与细粒级部分(2O/Al2O3,Na2O/Al2O3,CaO/Al2O3和MgO/Al2O3比率的变化依次出现转折,这很可能与晚新生代黄土-红粘土物源区构造抬升、冰川剥蚀能力不断加大,使得新鲜基岩不断被剥蚀、去顶,由此造成主要造岩矿物顺序剥蚀、接受风化,成为粉尘新物源有关。     

Effect of Aspergillus niger on weathering of phosphorite rock

Weathering mechanism of phosphorite rock by Aspergillus niger has been studied. Ten strains of phosphate-solubilizing fungi were isolated from rhizosphere soils by using dilute plate method in solid inorganic phosphorus culture. According to the size of soluble phosphate circle in the medium, a strain of stronger phosphate-solubilizing fungus was acquired, which was identified as, Aspergillus niger using identification methods of morphology and ITS sequences comparison in Genbank. In liquid culture, incubation in static state, the weathering of apatite rock with the fungus by contrast method： putting apatite powder （200 mesh） in liquid culture medium of flask, inoculation fungus after autoclave （setting sterile control） for studying direct weathering process; putting dialysis bag with apatite powder （200 mesh） in liquid culture medium of flask, inoculation fungus after autoclave （setting sterile control） for studying indirect weathering process.     

洛阳龙门石窟围岩风化特征研究

对洛阳龙门石窟围岩风化特征及风化作用影响因素进行调查研究,指出目前围岩风化作用主要为生物风化和物理风化作用,并进一步对其风化机理进行了探讨。以往研究结果认为风化作用主要类型为物理风化作用,本文研究表明,目前由于西山山顶植被的不断发育,随着植被根须机械破坏作用及植被腐殖质分解的产物引起岩体解离的生物化学破坏作用日益加剧,生物风化作用亦已成为风化破坏主要影响因素,应引起有关部门注意。     

Sandstone weathering processes damaging prehistoric rock paintings at the Albarracin Cultural Park, NE Spain

The rock paintings in cliff-foot caves of the Albarracin Cultural Park are known as some of the most important evidences of the Levantine prehistoric art of Spain (8000–3000 BP). The paintings are on sandstone (Buntsandstein facies) of Triasic age, which may develop intense weathering. The analysis of the variables controlling the weathering indicate that salt and wetting-drying weathering are responsible for granular disintegration and flaking, which lead to rock painting deterioration.     

硫化物风化产酸对流域岩石风化和碳循环的影响——以黄河支流三川河流域为例

硫化物风化产酸可加速岩溶作用但抑制大气二氧化碳参与流域碳循环,其复杂的地球化学机制和过程待阐明。本文以黄河二级支流三川河流域为例,通过采集20个三川河及其支流地表水点样和30个柳林泉地下水点样,经实验测试获得了流域比较系统的水化学资料和δ¹³C、δ³⁴ S数据,运用碳、硫同位素分析与水化学平衡计量方法,量化了流域硫化物风化产酸对岩石风化作用的贡献以及对碳循环的影响。计算结果表明：煤系地层硫化物和矿床硫化物的氧化及大气酸沉降所形成的硫酸明显促进了流域碳酸盐岩的溶蚀,对碳酸盐岩溶蚀的贡献约占64.59%;柳林泉水石膏溶解来源的SO₄^2-占69%,河水中石膏溶解来源的SO₄^2-占30%,但这些部分SO₄^2-没有参与溶蚀作用,应当扣除;三川河流域平均岩石风化速率为10.02 mm/ka,其中碳酸盐岩、硅酸盐岩的风化速率分别为9.14 mm/ka和0.88 mm/ka,低于国内外很多流域;由于硫酸抵消了碳酸盐岩石风化作用对大气二氧化碳的吸收,流域岩石风化消耗大气/土壤CO₂通量为116.58 mmol/（km² ·a）,不足珠江流域的1/5,且硅酸盐岩风化的贡献占63.3%。

     

Contribution of carbonate rock weathering to the atmospheric CO2 sink

To accurately predict future CO₂ levels in the atmosphere, which is crucial in predicting global climate change, the sources and sinks of the atmospheric CO₂ and their change over time must be determined. In this paper, some typical cases are examined using published and unpublished data. Firstly, the sensitivity of carbonate rock weathering (including the effects by both dissolution and reprecipitation of carbonate) to the change of soil CO₂ and runoff will be discussed, and then the net amount of CO₂ removed from the atmosphere in the carbonate rock areas of mainland China and the world will be determined by the hydrochem-discharge and carbonate-rock-tablet methods, to obtain an estimate of the contribution of carbonate rock weathering to the atmospheric CO₂ sink. These contributions are about 0.018 billion metric tons of carbon/a and 0.11 billion metric tons of carbon/a for China and the world, respectively. Further, by the DBL (Diffusion Boundary Layer)-model calculation, the potential CO₂ sink by carbonate rock dissolution is estimated to be 0.41 billion metric tons of carbon/a for the world. Therefore, the potential CO₂ source by carbonate reprecipitation is 0.3 billion metric tons of carbon/a. Received: 12 May 1999 · Accepted: 16 August 1999     

差异风化型危岩力学模型及破坏机制研究

差异风化型危岩多形成于由砂岩和泥岩等软、硬岩性组成的互层陡倾岩质边坡中,其崩塌破坏属地质灾害中的常见形态。以普洱渡危岩高边坡为例,推导出差异风化型危岩岩腔后壁泥岩压应力随岩腔深度增加而增大的计算公式。据普洱渡危岩高边坡地形地貌和地质构造特征建立了两类4种差异风化型危岩力学模型：第1类为主控结构面贯通率等于1时的泥岩基座压裂破坏型和转动破坏型危岩;第2类为主控结构面贯通率小于1时的坠落型和倾倒型危岩。利用岩石强度理论推导出研究区砂岩的二次抛物线型摩尔强度包络方程,以极限平衡理论和摩尔强度理论推导了4种危岩体在自重、地震力和裂隙水压力共同作用下的崩塌破坏判别表达式,并由此反演出危岩体的临界崩塌边界方程,得出危岩体崩塌边界（岩腔深度、危岩体厚度和高度、主控裂隙深度）之间的关系,为现场预测和判别危岩体的稳定性和崩落时序提供简便可靠的依据。     

单轴压缩下岩石材料尺寸效应的数值模拟

考虑到岩石材料的非均质性,应用岩石破裂过程分析系统RFPA^2D,对端面有摩擦和无摩擦两种条件下同直径不同长度的岩样,进行了单轴压缩下的数值模拟研究,并对模拟结果寻求了试验验证。结果表明,岩石强度的长度效应是由于岩样端面摩擦效应所致,而并非根源于材料本身的非均质性。     

微生物对碳酸盐岩的风化作用

微生物-矿物相互作用可以促进许多表生生物地球化学反应过程,是表生地球化学研究的重要内容。通过综合岩石表面的微生物类群及其地质作用,分析碳酸盐岩微生物风化的各种现象,特别是微观尺度上的各种形态,阐述碳酸盐岩的微生物风化机制与风化产物,笔者提出微生物对碳酸盐岩风化的4种途径:(1)通过微生物在岩石表面和缝隙中生长,导致岩石表层发生生物溶蚀、生物磨蚀和生物钻孔作用,加速岩石风化进程;(2)微生物群体形成的钻孔网络可以增强岩石化学溶蚀的有效表面积并导致其表面强度减弱而促进机械侵蚀作用,微生物对周围岩石颗粒胶结结构的破坏、疏松作用也会导致岩石矿物颗粒的分解;(3)微生物的持水作用,微生物分泌的有机酸以及微生物呼吸所释放的CO2对岩表水分的酸化过程亦加速岩石矿物的分解;(4)微生物生长过程中从岩石内摄取营养元素和产生复杂的有机配体,能促进矿物元素的释放。文中提出在开展微生物对碳酸盐岩风化过程和机理研究的基础上,有必要引入微生物生物技术来综合开发本地低品位含钾磷矿产资源,加速岩溶地区山地土壤的形成与演化。     

Recycling and chemical weathering in tectonically controlled Mesozoic–Cenozoic basins of New Zealand

Sedimentation in molasse basins is controlled by tectonics, however, recycling and chemical weathering play a critical role in the compositional evolution of a sedimentary succession. The Cretaceous to Pliocene molasse deposits of Central Otago, New Zealand are excellent examples of tectonically related deposits that were governed by the effects of chemical weathering and recycling. Preserved in fault-controlled basins floored by flysch deposits of the Otago Schist, the clastic successions contain ubiquitous unconformities and lithofacies consistent with alluvial, fluvial and lacustrine depositional settings. Textural analysis of Central Otago sandstones establishes a general quartz enrichment and increased mixing of angular and well-rounded quartz varieties up-section, consistent with a history of sediment recycling. Rare earth element (REE) patterns, which reflect upper crustal compositions, are similar for the flysch-type Otago Schist (Permian–Early Cretaceous), a palaeo-weathering profile, and the overlying molasse deposits. The development of quartz arenites is also consistent with high degrees of chemical weathering, and erosion of the schist basement, which contains numerous quartz veins. Although recycling has occurred, SiO₂ and TiO₂ do not consistently show a negative correlation over time. This reflects erosion of previously deposited quartz-rich sediment and the Otago weathering profile, which produced an inverse stratigraphy. CIA values range from 52 for lithic-rich, coarse-grained sandstones and polymictic conglomerate matrices, to 93 for coarse-grained to pebble-rich quartz arenites. Individual samples were split into finer- and coarser-grained pairs (<2·5φ and 2·5 to −1φ) and were analysed separately. The results show that finer-grained samples contain higher REE abundances and less SiO₂, but the coarser-grained Miocene–Pliocene samples have higher CIA values than their finer-grained counterparts. These coarse-grained deposits are quartz-rich and plot erratically on tectonic discrimination diagrams, implying that using SiO₂-poor samples is more reliable for geochemical analysis. Overall, the petrographic and geochemical results indicate that the main factors controlling the composition of the Central Otago molasse deposits were source composition, chemical weathering and recycling. Studies of this nature can be conducted in Archaean tectonically controlled molasse basins that are affected by similar allocyclic factors.