970 resultados para Gd@C82
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In the title compound, C12H10ClN7S, the dihedral angles made by the plane of the thione-substituted triazole ring with the planes of the other triazole ring and the benzene ring are 73.57 (3) and 46.65 (2)degrees, respectively. Inter-and intramolcular hydrogen bonds and pi-pi stacking interactions stabilize the structure.
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The title compound, N'-(4-methoxybenzylidene)-2-(1H-1,2,4-triazol-1-yl)acetohydrazide, was synthesized and its structure was confirmed by means of IR, MS,H-1 NMR and elemental analysis. The single crystal structure of the title compound was determined by X-ray diffraction. The preliminary biological test shows that the synthesized compound has a low antifungal activity.
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用APAGE技术检测了43个春小麦品种在醇溶蛋白水平上的遗传变异,在计算Jaccard相似系数的基础上用UPGMA方法进行聚类分析。共得到42种不同的带型,电泳共分离出37条带,其中33条具有多态性。品种间在醇溶蛋白水平上的遗传距离变异范围很大(0.0000~0.8148),平均遗传距离GD=0.5073。说明43个品种在醇溶蛋白编码位点上存在较大变异。聚类结果显示,除佛手麦自成一类外(GS=0.28),地方品种和引进品种与大多数育成品种(GS=0.46)分属不同的亚类,说明育成品种同地方品种和引进品种在醇溶蛋白编码基因上存在较大变异。育成品种间在醇溶蛋白水平上的遗传多样性程度不高,这一结果提示在这一地区进行与醇溶蛋白相关的品质育种很难在现在的育成品种间杂交的基础上取得成功。从遗传多样性的演变趋势来看,历史上以地方品种间醇溶蛋白的遗传变异程度最大(GD=0.5455),50年代引进品种变异程度最小(GD=0.3310)。从60~90年代,育成品种醇溶蛋白水平上的遗传多样性有一先增后减的过程,但总体上变异程度要低于地方品种,其原因与亲本单一和育种目标由高产到优质变化条件下人工选择压由弱到强有关。
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利用22对SSR引物的扩增结果计算品种间的Jaccard相似系数,在此基础上用UPGMA方法进行了聚类分析,检测了43个春小麦品种间在DNA水平上的遗传变异。22对引物共扩增出102条多态性带,平均每对引物可扩增出4.64条多态性带,具有较好的多态性。SSR水平上43个品种间遗传距离变异范围为0.2222~0.8393,平均遗传距离GD%=0.6054。43个品种聚为两大类,除佛手麦自成一类外,其余42个品种聚为第二大类。聚类结果真实地反映了品种间基因型差异。历史上地方品种间SSR水平上的遗传变异最大,育成品种遗传多样性水平总体上呈下降趋势,且低于地方品种和引进品种。1BL/1RS易位片段特异性引物Rye检测结果显示,共有7个品种含朋1RS片段,结果需进一步证实和深入研究。
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在数量性状水平上,调查了43个春小麦品种的19个数量性状,利用主成分分析法计算品种间的欧氏平方遗传距离,并在此基础上用最小方差法做了聚类分析。发现43个品种间在数量性状水平上的遗传距离变异范围很大(0.926~67.942),平均遗传距离为18.000,说明供试品种的19个考察性状上存在较大的表型变异。从聚类结果来看,地方品种基本上被聚在一起,说明地方品种同引进品种和育成品种至少在表型上存在较大差异。从20世纪40年代以来,在数量水平上甘、青两省春小麦地方品种间的遗传多样性水平最高(GD=31.389),其次是20世纪50年代引进品种(GD=26.308),而育成品种间的遗传多样性水平最低,总体上呈下降趋势。说明随着育种进程的深入,作为育种目标追求的经济性状趋于一致,其变异集中在一个狭小的范围之内,品种间的遗传多样性下降。
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The Dabie Mountains is a collisional orogenic belt between the North China and Yantze Continental plates. It is the eastern elongation of the Tongbai and Qingling orogen, and is truncated at its east end by the Tan-Lu fault. Jadeite-quartzite belt occurs in the eastern margin of UHPMB from the Dabie Mountains. Geochemical features indicate that the protoliths of the jadeite-quartzite and associated eclogite to be supracrustal rocks. The occurrence of micro-inclusions of coesite in jadeite and garnet confirmed that the continental crust can be subducted to great depth (8 0-100km) and then exhumed rapidly with its UHP mineral signature fairly preserved. Therefore, study of UHP jadeite-quartzite provides important information on subduction of continental crustal rocks and their exhumation histories, as well as the dynamics of plate tectonic processes at convergent margins. The purpose of this paper is to investigate the presence of hydrous component in the jadeite-quartzite belt, significant natural variations in the hydrous component content of UHP minerals and to discuss the role of water in petrology, geochemistry and micro-tectonic. On the basis of our previous studies, some new geological evidences have been found in the jadeite-quartzite belt by researches on petrography, mineralogy, micro-tectonic, hydrous component content of UHP minerals and combined with the study on rheology of materials using microprob, ER, TEM. By research and analysis of these phenomenona, the results obtained are as follows: 1. The existence of fluid during ultra-high pressure metamorphic process. Jadeites, omphacite, garnet, rutile, coesite and quartz from the jadeite-quartzite belt have been investigated by Fourier transform infrared spectrometer and TEM. Results show that all of these minerals contain trace amount of water which occur as hydroxyl and free-water in these minerals. The two-type hydrous components in UHP minerals are indicated stable in the mantle-depth. The results demonstrated that these ultra-high pressure metamorphic minerals, which were derived from continental crust protoliths, they could bring water into the mantle depth during the ultra-high pressure metamorphism. The clusters of water molecules within garnet are very important evidence of the existence of fluid during ultra-high pressure metamorphic process. It indicated that the metamorphic system was not "dry"during the ultra-high pressure stage. 2.The distribution of hydrous component in UHP minerals of jadeite-quartzite. The systematic distribution of hydrous components in UHP minerals are a strong indication that water in these minerals, are controlled by some factors and that the observed variations are not of a random nature. The distribution and concentration of hydrous component is not only correlated with composition of minerals, but also a function of geological environment. Therefore, the hydrous component in the minerals can not only take important part in the UHP metamorphic fluid during subduction of continental crustal rocks, but also their hydroxyl transported water molecules with decreasing pressure during their exhumation. And these water molecules can not only promote the deformation of jadeite through hydrolytic weakening, but also may be the part of the retrograde metamorphic fluid. 3.The role of water in the deformed UHP minerals. The jadeite, omphacite, garnet are strong elongated deformation in the jadeite-quartzite from the Dabie Mountains. They are (1) they are developed strong plastic deformation; (2) developed dislocation loop, dislocation wall; (3) the existence of clusters of water molecular in the garnet; and (4) the evolution of micero-tectonic from clusters of water molecular-dislocation loop in omphacite. That indicated that the water weakening controlled the mechanism of deformed minerals. Because the data presented here are not only the existence of clusters of water molecular in the garnet, but also developed strong elongation, high density of dislocation and high aspect ratios, adding microprobe data demonstrate the studied garnet crystals no compositional zoning. Therefore, this indicates that the diffusion process of the grain boundary mobility did not take place in these garnets. On the basis of above features, we consider that it can only be explained by plastic deformation of the garnets. The clusters of water molecules present in garnet was directly associated with mechanical weakening and inducing in plastic deformation of garnet by glissile dislocations. Investigate of LPO, strain analysis, TEM indicated that these clinopyroxenes developed strong elongation, high aspect ratios, and developed dislocation loop, dislocation wall and free dislocations. These indicated that the deformation mechanism of the clinopyroxenes plastically from the Dabie Mountains is dominant dislocation creep under the condition of the UHP metamorphic conditions. There are some bubbles with dislocation loops attached to them in the omphacite crystal. The bubbles attached to the dislocation loops sometimes form a string of bubble beads and some loops are often connected to one another via a common bubble. The water present in omphacite was directly associated with hydrolitic weakening and inducing in plastic deformation of omphacite by dislocations. The role of water in brittle deformation. Using microscopy, deformation has been identified as plastic deformation and brittle deformation in UHP minerals from the Dabie Mountains. The study of micro-tectonic on these minerals shows that the brittle deformation within UHP minerals was related to local stresses. The brittle deformation is interpreted as being caused by an interaction of high fluid pressure, volume changes. The hydroxyl within UHP minerals transported water molecules with decreasing pressure due to their exhumation. However, under eclogite facies conditions, the litho-static pressure is extreme, but a high fluid pressure will reduce the effective stress and make brittle deformation possible. The role of water in prograde metamorphism. Geochemical research on jadeite-quartzite and associated eclogite show that the protoliths of these rocks are supracrustal rocks. With increasing of temperature and pressure, the chlorite, biotite, muscovite was dehydrous reaction and released hydrous component during the subduction of continental lithosphere. The supracrustal rocks were transformed UHP rocks and formed UHP facies assemblage promotely by water introduction, and was retained in UHP minerals as hydrous component. The water within UHP minerals may be one of the retrograde metamorphic fluids. Petrological research on UHP rocks of jadeite-quartzite belt shows that there was existence of local fluids during early retrograde metamorphism. That are: (1) coronal textures and symplectite around relict UHP minerls crystals formed from UHP minerls by hydration reactions; (2) coronal textures of albite around ruitle; and (3) micro-fractures in jadeite or garnet were filled symplectite of Amp + PI + Mt. That indicated that the reactions of early retrograde metamorphism dependent on fluid introduction. These fluids not only promoted retrograde reaction of UHP minerals, but also were facilitate to diffuse intergranular and promote growth in minerals. Therefore, the hydrous component in the UHP minerals can not only take important part in the UHP metamorphic fluid during subduction of continental crustal rocks, but also their hydroxyl transport water molecules with decreasing pressure and may take part in the retrograde metamorphic fluid during their exhumation. 7. The role of water in geochemistry of UHP jadeite-quartzite. Geochemical research show that there are major, trace and rare earth element geochemical variations in the jadeite-quartzite from the Changpu district of Dabie Mountains, during retrograde metamorphic processes from the jadeite-quartzite--gneiss. The elements such as SiO_2、FeO、Ba、Zr、Ga、La、Ce、PTN Nd% Sm and Eu increase gradually from the jadeite-quartzite to retrograded jadeite-quartzite and to gneiss, whilst TiO_2. Na_2CK Fe2O_3、Rb、Y、Nb、Gd、Tb、Dy、Ho、Er、Tm、Yb decrease gradually. And its fO_2 keep nearly unchanged during early retrograde metamorphism, but decreased obviously during later retrograde metamorphism. These indicate that such changes are not only controlled by element transformation between mineralogical phases, but also closely relative to fluid-rock interaction in the decompression retrograde metamorphic processes.
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普朗斑岩铜矿是一个典型的与洋壳俯冲相关的大型乃至超大型矿床,通过对矿区代表性含矿斑岩与无/弱矿化斑岩的稀土元素特征对比、硫同位素示踪等方面的研究,表明矿石随Cu品位的增高,稀土总量(∑REE)和稀土分馏参数[(LREE/HREE)、(La/Yb)N及(La/Yb)N、(Gd/Yb)N]呈连续降低趋势,负铕异常一般显示为逐渐增强的趋势,但在发育有强烈的晚期钾长石脉的情况下,出现反弹减弱特征。硫化物(黄铜矿、黄铁矿和辉钼矿)的δ^34SCDT变化范围为一2.23‰-3.75‰,基本呈塔式分布特征,主要为深源岩浆硫。
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湘中地区的锑(金)成矿多与脉岩相伴生,对其成因及对矿床成矿作用的贡献至今仍不清楚。本文通过对板溪石英斑岩脉的研究表明,全岩K,Ar年龄为200Ma±,至少比板溪锑矿成矿晚200Ma,因此脉岩与成矿不存在成因联系。板溪脉岩显示过铝质特征,其A/CNK为1.08~2.61,A/NK为1.08~2.71,K20为0.9%~3.66%,K20±Na2O为4.28%~7.5%,大多数样品的K2O/Na2O小于1。稀土元素以相对富集LREE,LREE分馏不明显、HREE分馏明显,配分曲线右倾为特点,其(LJYb)n为14.47~28.11,(Gd/Yb)n为9.8~14.3,并且具强负Eu异常,δEu为0.05~0.14,这表明岩石在成岩演化过程中,经历了强的分异结晶作用。在原始地幔标准化蛛网图上,脉体相对富集LILE,并具Ti和P负异常。(^87Sr/^86Sr)i变化范围较大,为0.6653~0.7149,其中B-3样品的(^87Sr/^86Sr)i为0.7149,与来自地壳上部的花岗岩的^87Sr/^86Sr初始比值相当。在构造环境判别图中,样品显示岛弧/同碰撞花岗岩的特点。结合前人的研究成果,笔者推测板溪脉岩为地壳上部岩石部分熔融的产物,并经历了混染和高度的分异演化。其动力来源为200Ma左右,地壳叠置加厚作用后幔源岩浆的底侵作用.
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从矿物学、地球化学两个方面对钾质斑脱岩的研究进展进行综合评述.矿物学研究表明,钾质斑脱岩为岩浆成因,由粘土矿物与非粘土矿物组成,粘土矿物以伊-蒙混层矿物和伊利石为主,非粘土矿物包括原生斑晶矿物和次生矿物.钾质斑脱岩的矿物学研究有助于地层对比难题的解决,亦将促进古大陆再造研究.钾质斑脱岩及斑脱岩的主量元素数据统计结果显示,钾质斑脱岩以相对富钾为特征,K2O含量一般大于3.5%.微量元素数据统计表明,钾质斑脱岩的微量元素以Th、U的明显富集为特征,同时均具有负Eu异常并缺乏负Ce异常.通过对早寒武世、奥陶纪及志留纪的钾质斑脱岩的微量元素特征进行对比研究,认为不同时期钾质斑脱岩的微量元素与REE的配分模式表现出不同的特征,尤其是Nb/Y、Th/U等微量元素比值及(La/Yb)N、(La/Sm)N、(Gd/Yb)N、δEu和δCe等稀土元素参数的差异明显.经对比,初步判定滇东石岩头组底部钾质斑脱岩与遵义石岩头组钾质斑脱岩可能不属于同一期火山活动的产物.
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广泛分布于大洋海山上的富钴结壳被认为是目前最具潜在经济价值的海底矿产资源;同时富钴结壳的形成受控于古海洋和古沉积环境,保存了古海洋和古气候的重要信息,记录了其生长时期的海洋和气候的演化历史,因此,富钴结壳又是一种潜在的古海洋学记录。富钴结壳的元素和同位素组成特征包含了这些重要信息,因此,国内外学者对富钴结壳的地球化学特征进行了较为深入的研究。然而,前人对富钴结壳的研究通常是以结壳表层或整块作为研究对象,掩盖了结壳所记录的几十个百万年不断变化的海洋循环和大陆风化的信息,这严重制约着对结壳形成过程和演化历史的认识。目前,系统的富钴结壳地层剖面研究工作国内外涉及非常少,因此,通过开展富钴结壳完整剖面的地球化学研究才能更好的揭示其所蕴含的古海洋学意义。海洋环境中Os同位素能够提供一些其它同位素如Pb、Nd、Sr所无法给出的重要信息,在示踪物源、古海洋环境、古气候及古陆地风化等方面,具有明显的优势。但目前富钴结壳的Os同位素研究非常薄弱,属于国际前缘研究。富钴结壳的定年方法种类繁多,各具优势,但没有任何一种方法能够以较高的精确度和简捷性给出富钴结壳的真实生长年龄,具有较大潜力的Os同位素年代学研究,国内外基本处于空白。因此,开展系统的富钴结壳剖面的地球化学特征和Os同位素地层年代学研究,对于了解富钴结壳形成过程中元素的地球化学行为,示踪不同时期结壳的成矿物质来源,标定富钴结壳的形成时间,揭示古海洋环境及其演化和进一步揭示富钴结壳成矿过程和成矿机制,均具有极其重要的理论和实际意义。 本文以中太平洋莱恩海山的富钴结壳为研究对象,在对其进行系统宏观观察和显微研究的基础上,进行了系统的、高精度分层取样分析,系统揭示了各壳层的结构构造、矿物学、元素地球化学、Sr同位素和Os同位素地球化学特征,并利用Os同位素地层学方法对富钴结壳进行了年代学研究。论文主要获得了以下几个方面的认识: 本文研究所用的两块富钴结壳均为典型的三层构造结壳,从底部到顶部依次为致密层、疏松层、较致密层。结壳中矿物结晶程度差,结构单一,主要为胶状结构。结壳内部的显微构造复杂多样。壳层中的显微构造呈现有规律的变化:下部致密层构造较为单一,以纹层状构造为主;中部疏松层构造杂乱,以斑杂状构造多见;上部较致密层介于其中,以柱状、树枝状构造为主。结壳的垂直剖面结构构造的变化特征可以反映结壳生长过程中古海洋环境的演变过程,并与其地球化学特征相关联。富钴结壳MP5D17和MP2D06主要由锰相矿物(水羟锰矿为主)和铁相矿物组成,含少量石英、长石、粘土矿物、方解石和磷灰石等次要矿物。 富钴结壳剖面的元素地球化学研究表明,莱恩海山区不同区域的结壳MP5D17和MP2D06,元素富集特征相似。在海水中的滞留时间较短、具有高分配系数的元素,在结壳中相对富集。富钴结壳中,多数元素的含量在剖面上变化较大,不同构造层组化学组分含量相差明显,这反映了结壳生长过程中海水化学及海洋环境随时间发生了明显的改变。不同结壳剖面中元素的变化既有共性,也有差异,由于其所处的海山位置不同,不同的古海洋环境条件决定了它们元素分布的差异。富钴结壳剖面中稀土元素具有极为明显富集的特征,结壳生长过程中各种稀土元素的丰度在剖面中的变化趋势相似,各壳层稀土元素配分模式基本一致,显示轻微的轻稀土富集、强正Ce异常和负Y异常、弱正Eu异常和负Gd异常。 富钴结壳的锶同位素地球化学研究表明, 87Sr/86Sr值在结壳剖面上具有明显的变化规律,且与结构构造的变化相对应。结壳中87Sr/86Sr变化主要受大陆古老硅铝质岩风化经河流输入和海底年轻的火山岩蚀变输入的影响。结壳的Sr同位素演化与海水的Sr同位素演化趋势差异较大,磷酸盐化作用以及Sr的扩散作用使得富钴结壳不能完好的保存其生长时期周围海水的Sr同位素组成,因此,被广泛使用的Sr同位素地层学不适合作为富钴结壳的定年工具。 通过对富钴结壳MP5D17剖面上各壳层样品进行锇同位素分析。结果表明,结壳中187Os/188Os比值变化较大,范围在0.4262~1.0155之间。上部较致密层187Os/188Os较大,中部疏松层较小,下部致密层介于二者之间。结壳中Os同位素组成变化是陆源物质、幔源物质和地外物质输入共同作用的结果。结壳剖面的锇同位素曲线具有与80 Ma以来海水锇同位素演化曲线相似的演化趋势。使用Os同位素地层学方法,初步推测富钴结壳MP5D17的生长起始时间约为72 Ma,四个构造层组的生长速率分别为:1.2 mm/Ma、1.0 mm/Ma、5.1 mm/Ma和4.0 mm/Ma。研究证实了结壳的Os同位素是一种有效的定年手段,Os同位素地层年代学方法是目前除古生物化石法以外,解决年龄超过15 Ma的富钴结壳年代学的最有效途径。 综合研究表明,中太平洋莱恩海山的厚层富钴结壳为氧化环境下形成的水成成因结壳,是物理化学成矿作用的结果。
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华南早寒武世黑色岩系赋存Ni-Mo-PGE、V-U、Se、磷块岩、重晶石(毒重石)、石煤等多种矿产,富含As、Se、Hg、Gd、Pb等多种对生态环境有害的元素,产出小壳、海绵骨针、大型双壳节肢动物等多种古生物化石,因而它在矿产勘查、环境保护、地史古生物等方面具有重要的研究意义。然而,目前这些方面的研究还处于积累阶段,许多科学问题还没有得到很好地解决,一方面是因为华南早寒武世地层划分不统一,缺乏精确的年代学数据;另一方面是因为沉积地球化学研究程度不高。为了深入认识早寒武世古海洋的环境特征和演化历史,促进统一的早寒武世地层的建立,本论文选择了扬子地台上的贵州遵义早寒武世中南村黑色岩系剖面为对象,进行了系统的沉积地质学和地球化学研究,取得了如下几个方面的重要认识: (1)中南村黑色岩系剖面从下到上由磷块岩层、富黄铁矿粘土岩层、“破碎层”、硅质(页)岩层、钒矿层、含粉砂黑色页岩层、镍钼矿层、含化石黑色页岩层、黑色页岩层和粉砂质页岩层10个岩层组成,具有两个明显的特征,一是沉积环境发生了变化,从剖面底部远岸的、砂质输入较少的远海环境逐渐过渡到剖面顶部近岸的、砂质输入较多的近海环境;二是剖面下部的地质活动相对较丰富,除了火山成因“破碎层”和热水成因硅质岩外,还含有三个重要的硫化物矿化层:富黄铁矿粘土岩层、钒矿层和镍钼矿层。 (2)磷块岩主要由碳氟磷灰石和自生石英组成,含少量自生重晶石和含钒伊利石;磷灰石具有“老磷块岩”型REE配分曲线:∑REE高,Ce明显负异常,MREE富集,HREE亏损;磷灰石的硫酸盐硫同位素较大,平均为38.1‰。由此可推测,磷块岩是在分层海洋的上升洋流区的氧含量最小带的沉积物-水界面上形成的,沉积、成岩过程中吸收了海水中的硫酸盐和REE;磷块岩中磷灰石所记录的早寒武世海水硫酸盐的硫同位素组成为36.6±1.6‰。 (3)黑色硅、泥质岩中,微量元素Ba、Ni、U、V和Mo含量总体上较高,元素/Sc值与有机碳/Sc值之间的相关性明显;有机碳同位素组成较低,为-34.3‰~-31.2‰,表明早寒武世海洋可能为具有分层结构、古生产力水平较高、静海缺氧环境等特点的古海洋。剖面上,元素/Sc值向上逐渐降低,13Corg向上变大,有机质中的REE组成向上变为海水型,表明从早期到晚期古生产力水平和缺氧程度在不断减弱。 (4)微量元素U/Sc值、Mo/Sc值,有机碳同位素组成,有机质中的REE特征等参数在硅质岩、“破碎层”、钒矿层、镍钼矿层中均显示明显的异常,暗示它们的形成与热水/热液活动有关。镍钼矿层处的地球化学异常与古海洋历史性调整有关,可作为“前三叶虫统”分阶的标志,其它层位的异常特征可以作为区域地层对比的标志。
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富磷过铝质岩浆是过铝质岩浆体系中的一个重要类型,它通常以富P,高ASI[铝饱和指数,Al2O3/(Na2O+K2O+CaO)摩尔比值],贫Fe、Mg、Ca,强烈亏损REE、Th、Y,与稀有金属(W、Sn、Be、Nb、Ta)矿化具有成因联系为特征。富磷过铝质岩浆体系的性状及其演化的地球化学特征、岩浆液态分离、磷酸盐-硅酸盐矿物对平衡对熔体相中磷的制约以及富磷过铝质岩浆-热液体系中微量元素(包括REE)地球化学行为等科学问题尚未得到系统解决,目前更缺乏实验地球化学的直接证据。对上述科学问题的研究、探索,将有助于了解富磷过铝质岩浆体系形成和演化的地球化学特征,有助于揭示磷对微量元素(包括稀有、稀土元素)地球化学行为的影响,这对于理解过铝质岩浆体系成岩、成矿作用过程具有重要的理论和实际意义。 本文以天然钠长花岗岩为初始物,针对上述内容,开展了不同PTX条件下高温高压下实验研究,获得了如下重要认识: 1) 确定了100 MPa条件下磷对过铝质岩浆液相线温度的影响。随着体系中P2O5的含量增大,液相线温度由1.91 wt%P2O5的780 C降至4.83 wt%P2O5的760C、7.71 wt%P2O5的740 C,即体系中每增加1 wt%P2O5,液相线温度降低约7~10 C; 2) 不同PTX条件下的实验产物中均未见不混溶球粒结构、乳滴结构或流动构造,初步推断富磷过铝质岩浆体系中可能不存在单纯由磷引起的岩浆液态分离现象; 3) 锰铝榴石-磷灰石矿物平衡反应制约着形成过铝质初始岩浆中P2O5含量,熔体相中P2O5含量在750 C的0.47~0.80 wt%、830 C的0.35~2.26 wt%范围内。熔体相中的P2O5含量与ASI之间存在二次函数关系(P2O5 wt%=3.5×ASI2-11.3×ASI+9.5 )。锰铝榴石溶解,促使体系中Al2O3活度增大,含锰氟磷灰石的溶解及其端元磷灰石结晶之间的化学平衡,导致熔体相中P2O5的降低,很可能是熔体中P2O5随体系ASI增大而降低的机制。 4) 不同PTX条件下稀有金属元素(W、Sn、Be、Nb、Ta)在流体/熔体相间的分配系数(Dif/m)<<0.1,预示着W、Sn、Be、Nb、Ta强烈富集在富磷过铝质熔体相中。由此,可推测富P过铝质岩浆体系的演化晚期,不太可能分异出富含上述成矿元素的成矿流体。随着岩浆分异演化的进行,残余熔体相中最终导致绿柱石、锆石、锡石、铌钽矿物等矿物饱和结晶,形成有经济意义的花岗岩型或伟晶岩型稀有金属矿床。 5) 不同PTX条件下REE在流体/熔体间的分配系数(DREE)随REE的原子序数增大而逐渐降低,构成右倾的平滑曲线,不存在在Nd-Pm、Gd、Ho-Er处的拐点;Y与Ho在流体/熔体相间分配系数的比值(DY/DHo)约为1,不受体系温度、压力和P2O5含量变化的影响。上述实验结果揭示,富磷过铝质量岩浆演化至岩浆-热液过渡阶段,熔体-流体作用不会导致Y-Ho间的分异,不会引起REE间的分异,因此,富磷过铝质岩浆演化晚期的熔体-流体作用过程不可能是产生稀土“四分组”效应的根本机理。
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由于缺乏相应的沉积地层,贵州新生代地质、环境演化恢复一直是学术界的难点问题。夷平面研究的兴起,为陆地地壳抬升、地貌演变等反演提供了理论基础,而风化壳正是夷平面研究的重要替代对象,尤其是对各类沉积地层不发育的地区。因而,贵州高原各级台地上发育有较为广泛的红色风化壳自然地、就成了主要研究载体。然而一与其它岩类不同,碳酸盐岩风化成土作用过程研究并没有得到同等重视,其研究范围和程度均很不充分。显然,要想利用碳酸盐岩风化壳进行夷平面等地质、地貌意义研究,就必需详细了解贵州或中国南方碳酸盐岩风化成土的基本过程。也只有如此,才能明确各种对比指标的使用条件和范围,才能明确各种测年结果的具体意义,才能真正地通过贵州碳酸盐岩风化壳获取全省地质、环境演化信息。本论文通过对贵州省岩溶台地碳酸盐岩石灰土、红色风化壳剖面形成地球化学过程的剖析,开展石灰土与红色风化壳之间的关联和差异性综合对比、红色风化壳之间发育程度的比较,以及风化壳剖面尝试性的侧年等方面研究,取得了以下儿点认识:1、石灰土形成地球化学过程及对比通过矿物组成、粒度分布特征、地球化学方法判别,确定了本文所选石灰土剖面物质来源于下伏碳酸盐岩中的酸不溶物,是碳酸盐岩风化后酸不溶物原地残余堆积的结果。石灰土形成的地球化学过程都遵循碳酸盐岩风化成土之两阶段模式:母岩-酸不溶物,大量可溶性物质Ca、Mg、Mn、P、Na淋失,而Si、K·Fe、Al、Ti则相对富集。该过程的矿物组成变化表现为,伴随碳酸盐矿物(方解石、白云石等)的溶解、迁移,硅酸盐相矿物(长石、2:1型粘土矿物等)残余、累积。酸不溶物,土层或土层的演化,K、Si(长石、伊利石)不断淋失,而Al(伊利石、高岭石、三水铝石)、Fe(针铁矿、赤铁矿等)逐渐富集,体现出脱硅、富铝(铁)过程。我们强调碳酸盐岩风化成土分为两个阶段,但也认识到风化作用是综合的、复杂的:在碳酸盐矿物大量淋失过程中,同时也进行着酸不溶物的风化。石灰土分为原生和次生两种成因类型。原生石灰土的风化程度总体较低,剖面中还残留一定量的CaCO3,剖面从下到上矿物组成、地球化学各种指标具有逐渐演化的过渡特征。原生石灰上土层演化过程显示出正风化序列,从下到上风化程度逐渐增大、可溶性物质逐渐减少、稳定和相对稳定组分(Al、Fe.、REE)含量不断增大。另外,主量元素的质量迁移系数在剖面中的变化与风化程度呈明显的相关性。而次生石灰土不但具有很高的风化程度,而且剖面无过渡特征,显示可能是由遭受强烈风化作用的物质直接转变形成的。剖面中也含有一定量后期加入的碳酸盐,但与高CIA值特征不相匹配;SiO2、Al2O3、Fe2O3组分具有不同的变化特征,与)成化程度无明显关联;REE在剖面岩一上界面出现富集层。2、碳酸盐岩红色风化壳形成地球化学过程及其与石灰土的对比红色风化壳形成的地球化学过程也遵循碳酸盐岩风化成土之两阶段模式:母岩一酸不溶物,大量可溶性物质Ca、Mg、Mn、P、Na淋失,而Si、K、Fe、Al、Ti则相对富集。该过程的矿物组成变化表现为,伴随碳酸盐矿物(方解石、白云石等)的溶解、迁移,硅酸盆相矿物(长石、2:1型粘土矿物等)残余、累积。酸不济物一土层或上层的演化,K、Si(长石、伊利石)不断淋失,而Al(伊利石、高岭石、三水铝石)、Fe(针铁矿、赤铁矿等)逐渐富集,体现出脱硅、富铝(铁)过程。石灰土与红色风化壳之间既存在共性,又有一定的差异性。红色风化壳与原生石灰土一样都具有过渡特征,但后者仅在剖面下部出现一定的过渡层位;原生石灰士的城化程度远低于红色风化壳,仅与后者底部土层相当;原生石灰土不具有红色风化壳之岩-土REE(超常)富集层。总体上,原生石灰土可以作为红色风化壳的前身。次生石灰土与红色风化壳在矿物组成、风化程度等各种地球化学指标等都十分接近(略低),显示与红色风化壳之间存在某种关联:由红色风化壳物质直接转变,或由酸不溶物已强烈风化的(白云岩)岩粉、碎裂岩风化形成。3、碳酸盐岩风化成土母岩差异性碳酸盐岩风化成土存在母岩差异性,石灰土母岩差异性较为明显,而红色风化壳的母岩差异性较弱,体现出红色风化壳的均一化特征。石灰土母岩差异性体现为:母岩为灰岩的石灰土剖面主量元素含量变化特征较为一致,而白云岩则具有不同的变化;灰岩石灰土Fe3+、Al具有不同的富集、亏损特征,且具有富集层的补偿亏损层,而白云岩石灰上两组分都呈现无补偿层位的相同富集态势;灰岩石灰土剖面出现负Eu异常和具以Gd为中心的倒“V”型MREE稀土富集特征(母岩标准化),而白云岩石灰土无明显Eu异常和具L既E或HREE稀士.富集特征;灰岩和白云岩石灰土的微量元素富集、亏损特征也有所不同,前者从上到下逐渐富集,而后者无明显变化趋势。红色风化壳形成的基本过程、主量元素地球化学行为无明显的母岩相关性,没有如石灰土剖面灰岩和白云岩之间存在的差异性,显示出红土化作用的均一化过程;微量元素中受重矿物影响的元素与母岩类型有一定的关联,但大多数元素的亏损、富集等与具体剖面的微环境关系密切。4、碳酸盐岩红色风化壳发育程度的对比及意义多利指标对比显示所选红色风化壳的风化程度有一定的强弱差别:平坝剖面>湖潮剖面>天龙剖面、大兴剖面>花溪剖面、新蒲剖面,但这种差异性不足以否定各剖面隶属于贵州山盆期广泛夷平面的基本推测。各剖面之间的微弱差异是红色风化壳形成时纬度分带和垂向分带的体现。低纬度的平坝、湖潮、天龙剖面经历的风化作用强于高纬度的新蒲、大兴剖面;高海拔的新蒲剖面风化程度低于海拔低的大兴剖面。5、红色风化壳次生石英裂变径迹测年红色风化壳次生石英裂变径迹方法测年尝试,得到一定的结果和认识:晶形相对较好的石英,是次生的,与母岩中碎屑及成岩阶段没有关联;各剖面上部与中、下部次生石英的诱发裂变径迹的密度有着明显的区别,可能暗示它们的形成环境不同;名一剖面石英的形成或退火年龄分布较为分散,1.2-25.2Ma,同一剖面的石英年龄也不均一,变化较大;从下到上,年龄值呈现出逐渐减小的规律性,与风化作用的正常序列相反。如果能确切其成因,次生石英裂变径迹年代学研究将是确定风化壳形成时代及揭示主要风化作用信,却钩有利武器。
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The p16 tumor suppressor gene is inactivated by promoter region hypermethylation in many types of tumor. Recent studies showed that aberrant methylation of the p16 gene is an early event in many tumors, especially in lung cancer, and may constitute a new biomarker for early detection and monitoring of prevention trials. We detected tumor-associated aberrant hypermethylation of the p16 gene in plasma and tissue DNA from 153 specimens using a modified semi-nested methylation-specific PCR (MSP) combining plastic microchip electrophoresis or slab gel electrophoresis, respectively. Specimens were from 79 lung cancer patients, 15 abdominal tumor patients, 30 positive controls and 30 negative controls. The results showed that the positive rate obtained by microchip electrophoresis was more than 26.6% higher and the same speciticity was kept when compared with slab gel electrophoresis. The microchip electrophoresis can rapidly and accurately analyze the PCR products of methylated DNA and obviously improve the positive rate of diagnosis of cancer patients when compared with gel electrophoresis. This method with the high assay sensitivity might be used for detection of methylation of p16 gene and even to facilitate early diagnosis of cancer patients. (C) 2004 Elsevier B.V. All rights reserved.