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盐风化是干旱区一种重要的岩石风化过程。本文初步研究了盐风化作用的性质、机制和强度及其在地貌塑造和生产实践上的意义。盐风化包括盐结晶风化作用和盐水化风化作用两种类型。盐风化的强度在很大程度上取决于盐类矿物性质和气候条件。高温和干旱相结合的气候最有利于盐风化过程。通过对未风化岩石和风化岩石的对比,证明盐风化发展的速率很高。Tafoni是盐风化发展阶段的一种重要标志。 相似文献
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将南极生长的南极石萝（ＵｓｎｅａａｎｔａｒｃｔｉｃａＤｕＲｉｅｔｚ）、蔟花石萝（Ｕｓｎｅａａｕｒａｎｔｉａｃｏ－ａｔｒａ（Ｊａｃｑ．）Ｂｏｒｙ．）和石蕊（Ｃｌａｄｏｎｉａｓｐ．）三种地衣分别对上部、中部和基部三部分作横切,用扫描电镜和能谱仪观察和测定各部位的表、间、中央各层的元素组成和相对含量,结果发现三种地衣体的组成元素基本相同;各部位的Ａｌ、Ｓｉ、Ｋ、Ｃａ四种元素的相对含量较高,Ｐ的相对含量相近;三种地衣体不同的部位、不同层的元素相对含量均不相同。研究结果对进一步探讨地衣体的结构和生理特点以及分析南极的地质环境均有重要意义 相似文献
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福建长乐屏山风化坑与河流壶穴的成因及其证据 总被引：1，自引：0，他引：1
风化坑和壶穴是一种常见的岩石坑穴地形,其形成原因和形态完全不同,但容易被误解和混淆.结合对福建长乐三溪河地区这两种坑穴地形的实地考察,本文从地貌学,沉积学,岩石化学和矿物学等各个方面对两者的形成过程、影响因素进行了论证和对比.研究表明：风化坑形成于岩石面积水的风化作用,壶穴则是由河流的旋转水流对河床产生的侵蚀作用形成;山顶风化坑的发育与河流流水作用没有关系,河流壶穴的形成与河谷的发育过程有关,河谷中的风化坑只能在河流深切后,流水不再作用到的河床部位发育;只要条件合适,风化坑或壶穴随时可以生成;风化坑与河流壶穴的形态,坑内沉积物的磨圆度、粒度特征等反映出各自不同的形成过程.风化坑内碎屑与周边岩石的化学蚀变指数CIA 值的差异反映了风化坑的化学风化成因;风化坑内碎屑与周边岩石石英长石比例的差异说明风化坑是矿物差异风化的结果;用CIA 值和英长比均无法区分河流壶穴和风化坑中的碎屑颗粒,但两者化学元素迁移特征的差别反映了风化坑的风化作用和河流壶穴的流水搬运作用的成因差别;风化坑的风化程度达不到当地风化壳的风化程度,但不同气候带风化坑碎屑的CIA 值能反映不同气候带风化作用的强度差异. 相似文献
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地衣喀斯特侵蚀作用的初步研究 总被引：13，自引：1，他引：13
地衣喀斯特侵蚀作用是生物喀斯特的一个重要研究内容。本文通过对多种气候环境下的地衣喀斯特侵蚀作用及其形态的野外观察及室内镜下（光学显微镜及扫描电镜）微形态观察分析,讨论了岩表及石内地衣侵蚀形态类型的性质及其与地衣的特殊生物组织的联系。文中还讨论了地衣侵蚀的化学机制、物理机制和生物机制。 相似文献
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为了研究南极的植物与环境间的关系 ,探讨植物在南极环境监测中的作用 ,在无标样条件下 ,利用微束 X荧光分析法对南极菲尔德斯半岛的 6种藻类和地衣植物进行了元素分析。其中藻类植物有孔石莼 (Ulva pertusa)、海膜 (H alymenia sp.)和大型鞘丝藻 (Lyngbya major) ,地衣植物有筛石蕊 (Cladonia borealis)、喇叭石蕊 (C.fimbriata)和松萝 (Usnea sp.)。研究结果发现 ,不同的藻类植物对各种元素的吸收能力不同 ,在 XRF(X射线荧光 )谱中 ,孔石莼比海膜含有更多的元素 ,象 As、Br和 Rb,Cu和 Zn的含量也较高。在大型鞘丝藻中 ,K比 Ca少 ,Zn的含量较高。在 3种地衣植物中 ,其 XRF谱中的元素种类组成非常相似 ,只是 Mn、Fe、Cu和 Zn等元素的相对含量有些差异 相似文献
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流域化学风化与河流水化学研究综述与展望 总被引：8，自引：0，他引：8
工业革命以来大气CO2浓度不断上升,其源汇机制和时空变化成为学界关注的焦点。岩石特别是硅酸盐类岩石的化学风化是全球生物地球化学循环的重要碳汇。控制化学风化速率的因素较为复杂,各因素作用的机理和重要性还不完全明确。源于人类排放的H2SO4普遍参与到化学风化过程中,这加快了流域化学风化的速率,但这一过程对碳汇效应的影响机理尚缺乏足够的研究。当前河流水化学研究中用来判断河水化学类型及离子来源的方法可分为定性和定量两类,前者有Gibbs图法、三角图法和端元图法等;后者包括质量平衡法和同位素示踪法等。目前对影响流域化学风化速率因素的研究多侧重于对单一环境要素与风化速率之间响应关系的分析,在今后的研究中有必要介入更为严谨的数理统计方法;有关硫酸参与流域化学风化过程的研究成果还较少,随着酸雨现象日趋严重,这一课题的重要性日渐突出;在短时间尺度上碳酸盐岩化学风化的碳汇效应不可忽视,今后应加强对其研究。 相似文献
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对采集自南极乔治王岛和北极新奥尔松地区的32份地衣标本中共生藻rDNA ITS序列进行测定,发现均为Trebouxia jamesii;结合Genbank中来自不同地区地衣中该藻的序列信息,发现T. jamesii的基因型与地衣物种及采集地都没有明确的对应关系。广布于全球范围的T. jamesii作为地衣优势共生藻,存在多种基因型,并且可以被多种地衣共生菌选择;其中优势基因型A在采集自南极洲、欧洲、北美洲和北极地区的地衣中均有发现,而其它基因型则在一定程度上出现地区特有性。本研究为地衣中的藻交换提供了证据,并提出地衣体碎片是实现地衣共生藻长距离传播的载体。 相似文献
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阿尔泰山风化作用的初步研究 总被引：1，自引：0，他引：1
阿尔泰山的风化作用分为两类,即以化学风化作用为主的古风化阶段和风化作用随山体高度变化发生分异的现代风化阶段。占风化作用深入而持久,成了广泛分布而具有不同色彩的古风化壳和氧化带,是寻找原生矿的重要标志。现代风化作用类型复杂而多样,它们对找矿具有指导意义。 相似文献
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Saxicolous species of lichens are able to induce and accelerate weathering of their rock substrate, and effects of lichens
on substrate can be attributed to both physical and chemical causes. This paper is focused on biotic weathering actions of
epilithic and endolithic species on the different rock types (sandstones and volcanogenic rocks) in Antarctica. The patterns,
mechanisms, processes and neoformations of rock-weathering resulting from lichen colonization are expounded in detail. Furthermore,
it is pointed out that, for a better understanding of the impacts of lichens on environments, the studies on the rate of biotic
weathering and the comprehensive involvement of the lichen effects on weathering of natural rocks remain to be carried out
in Antarctica. 相似文献
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Saxicolous species of lichens are able to induce and accelerate weathering of their rock substrate, and effects of lichens on substrate can be attributed to both physical and chemical causes. This paper is focused on biotic weathering actions of epilithic and endolithic species on the different rock types (sandstones and volcanogenic rocks) in Antarctica. The patterns, mechanisms, processes and neoformations of rock-weathering resulting from lichen colonization are expounded in detail. Furthermore, it is pointed out that, for a better understanding of the impacts of lichens on environments, the studies on the rate of biotic weathering and the comprehensive involvement of the lichen effects on weathering of natural rocks remain to be carried out in Antarctica. 相似文献
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１ＩｎｔｒｏｄｕｃｔｉｏｎＡｓｔｈｅｅａｒｌｉｅｓｔｃｏｌｏｎｉｚｅｒｓｏｆｔｅｒｅｓｔｒｉａｌｈａｂｉｔａｔｓｏｎｔｈｅｅａｒｔｈ,ｔｈｅｏｃｕｒｅｎｃｅｏｆｌｉｃｈｅｎｓｍａｙｂｅｄａｔｅｄｆｒｏｍｔｈｅＥａｒｌｙＤｅｖｏｎｉａｎ（Ｔａｙｌｏｒｅ... 相似文献
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The endolithic lichen Lecidea auriculata is known to enhance rock surface weathering on the Little Ice Age moraines of the glacier Storbreen in Jotunheimen, central southern Norway. This study demonstrates the reduction in Schmidt hammer Rvalues that followed the rapid colonization by this lichen of pyroxene‐granulite boulders on terrain deglaciated over the last 88 years. In the absence of this lichen, the characteristic mean R‐value of boulder surfaces is 61.0 ± 0.3; where this lichen is present, R‐values are lower by at least 20 units on surfaces exposed for 30–40 years. A similar reduction in rock hardness on rock surfaces without a lichen cover requires about 10 ka. The rapid initial weakening of the rock surfaces is indicative of rates of biological weathering by endolithic lichens that may be two orders of magnitude (200–300 times) faster than rates of physico‐chemical weathering alone. If not avoided, the effects of this type of lichen are likely to negate the effectiveness of the Schmidt hammer and other methods for exposure‐age dating, including cosmogenic‐nuclide dating, in severe alpine and polar periglacial environments. The results also suggest a new method for dating rock surfaces exposed for <50 years. 相似文献
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In situ quantification of localized weathering processes on basalt flows in New Mexico and Hawaii demonstrates that small‐area factors can be more important than other more readily observable factors. Further, it demonstrates that the factorial concept of the Pope Boundary‐Layer weathering model is partially solvable, that organic weathering can accentuate glass weathering (with implications for climate models and storage of nuclear waste), and that silica coatings are not a simple solution for the preservation of stone monuments. Enhancement of glass weathering by lichens on the McCartys flow, El Malpais National Monument, New Mexico, remains restricted to a half‐millimeter directly underneath the lichen‐covered surface. In contrast, although the inorganic rock coating of silica glaze reduces weathering directly underneath the coating by up to nine times rates found in uncoated locales, silica glaze can almost double variability in weathering along its margins. 相似文献
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The reliability of lichenometric dating is dependent on a good understanding of lichen growth rates. The growth rate of lichens can be determined from direct measurement of growing lichens or indirect methods by measuring lichens growing on surfaces of known age, although there are limitations to both approaches. Radiocarbon (14 C) analysis has previously been used in only a handful of studies to determine lichen growth rates of two species from a small area of North America. These studies have produced mixed results; a small amount of carbon turnover appears to occur in one of the species ( Caloplaca spp.) previously investigated introducing uncertainty in the growth rate, while much higher carbon cycling occurred in another ( Rhizocarpon geographicum ), making the 14 C approach unsuitable for estimating growth rates in the species most commonly used in lichenometric dating. We investigated the use of bomb-14 C analysis to determine the growth rate of a different crustose species ( Pertusaria pseudocorallina ) common to Northern Europe. 14 C-based growth rates were considerably higher than growth rates of morphologically similar species based on direct measurement made at locations nearby and elsewhere in the UK. This observation strongly suggests that a degree of carbon turnover probably occurs in Pertusaria pseudocorallina , and that bomb-14 C analysis alone cannot be used to determine lichen age or absolute growth rates in this lichen species. 相似文献
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丹霞山顺层洞穴风化特征的试验研究 总被引：1，自引：1，他引：0
以丹霞盆地丹霞组2段顺层洞穴为研究对象,探讨不同岩性红层抗风化能力的差异,重点关注软岩夹层的风化特征及其对顺层洞穴发育的影响。在野外考察的基础上,选择3个典型顺层洞穴为案例,采集了洞穴剖面不同岩性红层的岩样及夹层水样品,进行一系列的岩矿理化测试和水样分析实验。结果表明：洞穴剖面岩性的不均一性及软岩夹层的风化凹进是形成丹霞山顺层洞穴的主要原因。顺层洞穴发育的软岩夹层一般是粉砂质泥岩,粘土矿物含量高,以泥质胶结为主,吸水性较强,开型空隙率较大,抗压强度小,易于风化破碎;上下岩层主要是砂岩和砂砾岩,以钙质和铁质胶结为主,吸水性较弱,开型孔隙率较小,抗压强度较大,风化速度较慢。在洞穴岩层风化过程中,粘土矿物的胀缩、钙质胶结物的溶解, 及铁质胶结物的水化作用等是导致岩体结构破坏的重要因素,但促使不同岩性红层风化的主导因素有所差别。粉砂质泥岩的风化以粘土矿物的胀缩作用为主,砂岩和砂砾岩的风化则以钙质胶结物的溶解作用为主。此外,酸性雨水渗入岩体后与各种矿物进行的一系列离子交换作用也促进了顺层洞穴岩层的风化。 相似文献