进化序列系统学——以二叠纪瓦岗珊瑚类为例

进化序列系统学是古生物学中研究物种间和类别间的系统发育关系为目的的学科, 包括研究物种或类别间的亲缘关系, 并确定它们形成的先后序列.表型-分支系统学是该系统学的基础.分支系统学的许多重要概念在该系统学中加入了时间的含义, 例如, 认为最亲近的姐妹种之间的时间间隔不会超过它们母种的生存期.姐妹群和性状镶嵌分析是进化序列研究的主要方法, 而理解性状镶嵌分布是关键.这些分析可由计算机程序实现.以二叠纪瓦岗珊瑚类作为研究进化序列系统学的实例, 该类在特提斯地区广泛分布.通过对瓦岗珊瑚类的特征分析确定了17个性状用于研究, 并且每一性状确定了几个变化状态.根据最广布的性状状态、化石记录和个体发生等原则分辨出近祖性状状态, 并根据性状在系统发育中的重要性确定性状分级.然后, 确定了姐妹群间的关系和物种间的进化序列.在姐妹群与进化序列分析相互检验中可发现性状退化、平行演化和多向分支等古生物学重要现象, 并分辨出物种的异常顺序.在检验生物地层学首次出现事件讨论中推测了一些化石首次出现的可能层位.      

过氧化钙在处理厌氧底泥中的应用初探

为改善河道厌氧底质及内源氮、磷等营养盐释放问题,考察对沉水植被恢复的影响,研发可同步解决沉积物供氧和削减内源氮、磷释放的氧缓释材料.实验通过向沉积物-水界面处散点注射不同剂量的过氧化钙(Ca O2),研究界面处溶解氧的动态变化特征及表层沉积物与底层水体之间溶解态氮、磷的交换过程.结果表明:添加Ca O2显著提高了界面处底层上覆水溶解氧浓度,随着Ca O2浓度的增加溶解氧浓度增加,不同处理组之间具有显著差异;Ca O2对沉积物中PO3-4-P释放具有明显的抑制作用,且随Ca O2浓度的增加抑制效果愈加明显,上覆水中可溶性活性磷浓度最大可削减98%.实验开始时,磷释放速率可降至-241.916±22.501 mg/(m2·d),降幅最高可达到144%;Ca O2对沉积物NH+4-N释放的抑制效果不佳,上覆水中NH+4-N浓度随着时间的变化波动性较大,且有逐渐增大的趋势.另外,添加Ca O2会显著提高底层上覆水p H值,不同处理组之间差异显著,但当Ca O2投加量小于0.529 kg/m2时,不会对苦草种子的萌发生长有显著影响,p H值波动在可接受范围内(7.62~10.87).因此,结合污染沉积物的状况,适当地投加Ca O2有望同步解决底质厌氧、内源磷释放及后期沉水植被定植底质生境改善的问题,可推荐为一种黑臭污染底泥治理技术在实际的河道生态工程中应用,其适宜浓度为0.176 kg/m2左右.     

多重分形滤波方法和地球化学信息提取技术研究与进展

圈定地球化学异常是勘查地球化学和环境地球化学研究中的一项基础性工作。笔者通过详细分析近30年来与地球科学密切相关的分形和多重分形等现代非线性理论和新方法的迅速发展和应用,特别是以解决地球化学复杂背景与叠加异常分解难题为例,介绍了广义自相似理论与分形滤波技术的发展和应用,相信在资源、环境、灾害的其他应用领域也将发挥重要影响。文中阐明了多重分形是更具普适性的地球化学元素分布模式,"密度-面积"分形模型是刻画地球化学异常的基础模型,并为多个空间开展分形滤波和分解地球化学复杂背景与叠加异常的理论基础。该方法的显著优势在于将地球化学场的各向异性、尺度不变性、广义自相似性等特征集于一体,具有压制变化性背景干扰,突出局部异常的能力,其中C-A和S-A业已广泛应用于矿产勘查靶区圈定和环境污染模式识别,形成了分解地球化学复杂背景和叠加异常的常用技术,在国内外多个成矿区带取得了显著的找矿效果。     

Fractal and Multifractal Properties of Geochemical Fields

A fractal model, introduced by De Wijs to study the distribution, redistribution, or enrichment/depletion of element concentrations in a region, has become widely accepted. This paper uses it to simulate various geochemical fields for element concentration values. The frequency distribution and spatial pattern of the simulated values or concentrations are analyzed by the method of moments and the concentration–area (C–A) model. The spatial pattern of the original De Wijs model is shown to be intrinsically characterized by -shaped and symmetrical multifractal spectrum curves, whose center and width change systematically with the enrichment factors set in the simulation. The corresponding frequency distribution pattern on the log–log plot of frequency versus concentrations is called simple continuous multifractal (SCM) by the authors. In other experiments, when a De Wijs model is locally superimposed by another De Wijs model of different enrichment factors, the symmetry of the multifractal spectrum graph is broken and a different pattern of frequency distribution is found. It is referred to as highly accumulated continuous multifractals (HACM). Concentrations of 12 elements in 1448 rock samples from Shaoguan district, North Guangdong Province, South China, and 12 oil/gas indexes in surface soils from Sangtamu region, Tarim Basin, Northwest China, have been applied. The real geochemical fields, both metallic and oil/gas, are found to be remarkably compatible to those simulated patterns of De Wijs models with backgrounds of various enrichment and different degrees of superimposition, indicating that the frequency and spatial distribution patterns revealed by the authors are most possibly universal features of geochemical fields. It is particularly interesting to note that the major geochemical indicators of oil/gas geochemical fields are closer to the results of De Wijs models with a small enrichment factor, either with or without local superimposition, whereas those of the metallic geochemical field correspond more closely to De Wijs models with a background field of larger enrichment factors. The results obtained herein potentially have important implications in mineral and oil/gas resource assessment.     

High Temperature Strain Structures and Quartz C-Axis Fabrics from Mylonitic Rocks in the Ailaoshan-Red River Shear Zone, Yunnan, and Their Tectonic Implication

<正>The Ailaoshan-Red River(ASRR) shear zone is one of the major Southeast Asian tectonic discontinuities that have figured the present tectonic framework of the eastern Tibet.Several metamorphic massifs are distributed linearly along the shear zone,e.g.Xuelongshan,Diancangshan, Ailaoshan and Day Nui Con Voi from north to south.They bear a lot of lines of evidence for the tectonic evolution of the eastern Tibetan at different crustal levels in different tectonic stages.Controversy still exists on the deformation structures,microstructures and their relationship with metamorphisms along the ASRR.In this paper detailed microstructural and EBSD(Electron Backscattered Diffraction) fabric analysis of some highly sheared granitic rocks from different massifs along the ASRR are conducted.High temperature structures and microstructures are preserved in unsheared gneisses,in weakly sheared xenoliths or in some parts of the highly sheared rocks(mylonites).Several types of high temperature quartz c-axis fabrics show symmetrical patterns or transitions from symmetrical to asymmetrical patterns.The former are attributed to coaxial deformation during regional shortening in an early stage of the Indian-Eurasian tectonic interaction and the latter are related to the transitions from coaxial compression to noncoaxial shearing during the post-collisional ASRR left lateral shearing.     

New Zircon U-Pb Geochronology of the Post-kinematic Granitic Plutons in the Diancang Shan Metamorphic Massif along the Ailao Shan-Red River Shear Zone and Its Geological Implications

<正>The Ailao Shan-Red River fault zone is the boundary between the Yangtze block to the northeast and the Indochina block to the southwest.It is an important tectonic zone due to its role in the southeastward extrusion of the Indochina block during and subsequent to the Indian-Eurasian collision.Diancang Shan(DCS) high-grade metamorphic complex,located at the northwest extension along the Ailao Shan-Red River(ASRR) shear zone,is a representative metamorphic complex of the ASRR tectonic belt.Structural and microstructural analysis of sheared rocks in the high-grade metamorphic rocks reveals that they are coherent with solid-state high-temperature ductile deformation,which is attributed to left-lateral shearing along the ASRR shear zone.New LA-ICP-MS zircon U-Pb geochronological and microstructural studies of the post-kinematic granitic plutons provide a straightforward time constraint on the termination ductile left-lateral shearing and exhumation of the metamorphic massif in the ASRR shear zone.It is suggested that the left-lateral shearing along the ASRR shear zone ended at ca.21 Ma at relative lower-temperature or decreasing temperature conditions.During or after the emplacement of the young dikes at ca.21 Ma,rapid brittle deformation event occurred,which makes the DCS massif start fast uplift/exhumation and cooling to a shallow crustal level.     

Wave velocity and stress/strain in rock brittle failure

This paper reports the relationship between wave velocity and stress/strain during rock brittle failure under compression. It is assumed that the rock is a strain-softening medium whose strength can be described by Weibull’s distribution. Based on renormalization group theory, it is found that the stress ratio λ _c (the ratio of the stress at the critical point to the peak stress) depends mainly on the homogeneity index or shape parameter m in the Weibull’s distribution for the rock. Measured stress–strain curves and corresponding wave velocity–strain curves in four case studies suggest that the changes caused by internal cracking are correlated to variations of rock wave velocity, and the stress at the critical point on the stress–strain curve is considered to correspond to the rapid decreasing point on the wave velocity–strain curve. For uniaxial compression, the critical stress ratio λ _c is derived to be about 75.4 %, which is very close to the measured value.     

断层带中假玄武玻璃成因机制及非稳态流变意义

假玄武玻璃呈玻璃质或隐晶质特性,常常与断层带相伴出现,其形成能有效地降低断层摩擦强度,被认为是古地震快速滑动的化石纪录。因此,对假玄武玻璃的研究对深入了解深部就位的断层变形和地震成因机制等具有重要意义。尽管国内外学者对假玄武玻璃开展了长期的研究,也积累了丰富的资料,然而,由于天然假玄武玻璃非常少见或零星地被报道,再加上其形成环境和过程的复杂性,对假玄武玻璃的构造特征、形成环境和成因机制仍然存在诸多争议及亟待解决的关键科学问题。研究表明,假玄武玻璃可以发育在大陆岩石圈不同深度范围内,即中下地壳乃至上地幔以糜棱岩为主的韧性变形领域（>60 km）,或中上地壳层次以碎裂岩为主的脆性变形域（<12 km）。越来越多证据也显示出在断层带的脆—韧性转换域中形成的假玄武玻璃跟浅源地震活动直接关联,也意味着中上地壳脆性变形和中下地壳塑性变形之间存在着更为复杂的耦合关联,同时对不同深部岩石强度和力学行为提出了挑战。对假玄武玻璃形成机制存在由断层面上的摩擦热导致的摩擦熔融体或仅仅是断层面岩石超碎裂粉碎作用认识的争议。而有研究认为干的环境有利于假玄武玻璃形成,因为流体的存在会降低断层面的有效正应力,不利于热量的积累以及摩擦熔融的进行;然而,另外一种观点认为流体的存在可以降低矿物熔融温度有利于断层摩擦熔融及形成假玄武玻璃。本文从假玄武玻璃的形成机制、形成深度、流体影响、形成后对断层强度的影响、以及保存与破坏机制几方面进行了最新总结,并对假玄武玻璃中非晶态物质的成因、脆—韧性转换带之下岩石的变形机制以及对陆壳强度的影响和非稳态流变意义进行探讨。     

基于AOD数据的秸秆焚烧监测

秸秆焚烧会增加可吸入颗粒物(particulate matter with particle size less than or equal to 10 microns,PM10)的浓度。首先,分别从秸秆焚烧火点、10 m风场、气溶胶光学厚度(aerosol optical depth,AOD)3个方面对发生在安徽及周边省市的2009年6月1—9日PM10污染事件进行机理分析;其次,利用拉格朗日混合单粒子轨迹(hybrid single particle lagrangian integrated trajectory,HYSPLIT)模式对2009年6月5日阜阳市出现的PM10污染事件进行后向轨迹分析;最后,对火点密度与AOD值进行相关分析。结果表明:秸秆焚烧火点、10 m风场及AOD之间存在一致性,这表明使用AOD数据对秸秆焚烧进行监测是可行的;2009年6月5日阜阳市出现的PM10污染事件中有外来污染物的输入,污染物来自阜阳西部、河南中部、东南部和湖北北部、东部,因此很有必要加强区域秸秆焚烧的联防联控;火点密度与AOD值之间有正相关性,这表明秸秆焚烧可显著提高区域的AOD值。     

The relationship between the deformation mechanism and permeability on brittle rock

In order to study the relationship between the deformation mechanism and permeability on brittle rock, the curves of stress–strain and permeability–strain of brittle rock were analyzed, the results indicated that the permeability of brittle rock increased rapidly at the critical failure point due to the microstructure changed seriously during the compaction, elastic deformation, and progressive failure process. When the rock bridges or asperities on the internal structural plane were ruptured partly or completely after the peak stress, a sudden decrease in rock strength occurred and the peak permeability could be the maximum. The strain at the critical point and turning point on the stress–strain curve corresponded to that at the rapid increase point and the peak point on the permeability–strain curve according to the renormalization theory and curves of stress–strain and permeability–strain. In addition, the ratios could be described by mathematical expressions. The conclusions could be proved reasonably by the experimental studies and examples of statistical analysis.