石榴子石反应边及其地质意义——以大兴安岭第四纪火山岩为例

大兴安岭第四纪火山岩(包括诺敏河火山区和哈拉哈河-绰尔河火山区)地幔包体中含有少量石榴子石,普遍发育矿物反应边.根据显微照片和BSE图像特征,石榴子石反应边可分为3类:①冠冕状石榴子石反应边,包裹在石榴子石矿物外部,具有一期或者多期反应的特征,厚度通常为0.1～1 mm,反应边矿物组合为Opx+Glass、Cpx+Gl...     

化学反应优化(CRO)图像分割的研究与分析

应用化学反应优化技术(chemical reaction optimization,CRO)作了图像分割的尝试。介绍了CRO图像分割的原理与方法,同时对新分割方法的特点作了具体的分析和说明,并说明了新分割方法的具体作业过程。通过对3幅航空影像的分割实验,验证了对新方法特点分析的正确性,得到了一些有益的结论。     

针铁矿/水界面反应性的实验研究

选择针铁矿对Pb2+、Cu2+、Cd2+等3种重金属离子的吸附实验,开展矿物/水界面反应性研究.金属离子(M2+)在矿物-水溶液间分配有多种表面反应机制,这些表面反应发生作用的条件主要取决于吸附质水化学性质和矿物表面荷电性,因此,溶液pH值是影响矿物/水界面反应性的关键因素.在不同pH值条件下, 表面羟基可通过发生质子化或去质子化反应而使得矿物表面产生荷电性并发生改变,而金属离子的水解则可显著加快金属羟基配合物的形成,从而进一步增强了矿物/水界面反应.本实验条件下针铁矿表面对重金属离子的吸着量随pH值升高而升高,在一个较窄的pH值范围内吸附率急剧升高,呈S形分布.针铁矿对3种不同的重金属离子的吸附能力的强弱顺序是Cu2+＞Pb2+＞Cd2+.无论是Langmuir方程还是Freundlich方程,都能较好拟合针铁矿对重金属离子的等温吸附过程.Freundlich方程的n值均在0.1～0.5之间,说明重金属离子在针铁矿表面的吸附并不能简单地归结为单配位或双配位模式,可能存在着多种吸附结合形态.表观吸附常数KM值的变化规律,说明重金属离子与针铁矿表面反应模式及其表面吸附形态发生了变化,具体的吸附形态还有待谱学研究进一步证实.     

Compositional variation of phlogopite in a marble sample: implications for geological thermobarometry

Abstract The textural and compositional features of phlogopites in a contact-metamorphic dolomite marble inclusion in the Bergell intrusion (central Alps) and in a metasomatic reaction vein cutting through this marble suggest different origins for vein phlogopites:
(a) High-Al vein phlogopite represents former marble phlogopite which has been compositionally modified by reaction with the vein forming fluid.
(b) Low-Al vein phlogopite represents phlogopite precipitated from the vein forming fluid.
As both types of vein phlogopite were in contact with the same vein forming fluid at the same time, low-Al phlogopite most likely represents an equilibrium phlogopite composition, whereas high-Al phlogopite does not. High-Al vein phlogopite retained its Al-content from the contact-metamorphic marble parent phlogopite and only underwent Fe-Mg exchange with the metasomatic fluid.
All the vein phlogopites studied are strongly enriched in Fe relative to marble phlogopite. The data may suggest in general that phlogopite Al/Si ratios may be retained from the conditions under which the phlogopites first formed, whereas the Mg/Fe-ratios may be substantially modified by exchange with other ferromagnesian solid phases and/or a metamorphic fluid at later stages in their metamorphic history. This may have significant effects on calculated pressures and temperatures from thermobarometers involving biotite.     

Orthopyroxene–sillimanite–quartz assemblages: distribution, petrology, quantitative P–T–X constraints and P–T paths

Granulite facies magnesian metapelites commonly preserve a wide array of mineral assemblages and reaction textures that are useful for deciphering the metamorphic evolution of a terrane. Quantitative pressure, temperature and bulk composition constraints on the development and preservation of characteristic peak granulite facies mineral assemblages such as orthopyroxene + sillimanite + quartz are assessed with reference to calculated phase diagrams. In NCKFMASH and its chemical subsystems, peak assemblages form mainly in high‐variance fields, and most mineral assemblage changes reflect multivariant equilibria. The rarity of orthopyroxene–sillimanite–quartz‐bearing assemblages in granulite facies rocks reflects the need for bulk rock X_Mg of greater than approximately 0.60–0.65, with pressures and temperatures exceeding c. 8 kbar and 850 °C, respectively. Cordierite coronas mantling peak minerals such as orthopyroxene, sillimanite and quartz have historically been used to infer isothermal decompression P–T paths in ultrahigh‐temperature granulite facies terranes. However, a potentially wide range of P–T paths from a given peak metamorphic condition facilitate retrograde cordierite growth after orthopyroxene + sillimanite + quartz, indicating that an individual mineral reaction texture is unable to uniquely define a P–T vector. Therefore, the interpretation of P–T paths in high‐grade rocks as isothermal decompression or isobaric cooling may be overly simplistic. Integration of quantitative data from different mineral reaction textures in rocks with varying bulk composition will provide the strongest constraints on a P–T path, and in turn on tectonic models derived from these paths.     

大石桥地区辽河岩群变泥质岩石中几种重要的变质反应及其地质意义

在大石桥地区进行１：５００００地质填图过程中，经过大量的岩石薄片观察，在江河岩群变泥质岩石中，首次发现了红柱石转变为蓝晶石和十字石转变为蓝青石的变质反应．详细的岩相学、岩石化学及矿物化学的研究表明，变泥质岩中先后发生的这两种变质反应，代表了本区变质作用演化的两个重要阶段．揭示了本区在伸展体制下地壳拉伸、减薄和收缩体制下的褶叠、推覆及之后的抗返、抬升的地球动力学过程．     

Experimental study of gold activation-transportation in the process of potash metasomatism-alteration——North China platform gold deposit taken as an example

Chemical reactions of plagioclase, biotite and their singleminerals, as well as a mineral mixture of (plagioclase +biotite+quartz), with KCl and (KCl+KHCO3) solutions were carried out at 150400℃ and 5080 MPa. Experiments show that alkaline fluid promotes plagioclase’s changing into potash feldspar, while acid fluid helps plagioclase, potash feldspar and biotite alteration form chlorite and sericite. After chemical reaction the acidity-alkalinity of solutions often changes reversely. It was observed that gold dissolved from the tube wall and recrystallized on the surfaces of biotite and pyrite. Therefore the transportation and enrichment of gold are related to the elementary effect of the fluid-mineral interfaces. Fe3+-Fe2+, as an oxidition-reduction agent, and volatile components Cl? and CO2 play important roles in the reaction process.     

剪切应力作用下晶质矿物的化学行为及其地质意义

地壳中晶质矿物的化学行为主要为溶解、固相－固相反应和表面化学行为３类，剪切应力作用可以加速和促进这３类行为。其原因主要在于剪切应力作用可以改变矿物的晶格结构，增加其内部和表面缺陷。     

煤岩有机质成油、成气热模拟动力学模型及其标定

借助热解实验技术和PY-GC分析技术分别建立了有机质成油和成气的动力学模型,并在数学优化求解上作了比较深入的工作。所得模型的理论计算值与实验结果在不同条件下均有良好的吻合关系,初步显示了该模型的可行性及其应用前景。     

Characteristics of Corona Textures in the Huangtuling Granulite in the Dabie Comples,China and Their Implications for Tectonic Settings

Widely developed in the Dabie complex are various disequilibrium textures which provide direct evidence for the evolution of metamorphism and late-stage uplifting history.The typical mineral assemblasge in the Opx-Gt-Pl-Bi gneiss in Huangtuling,Luotian County,Hubei Province,Is Opx(I) Gt Pl(I) Bi(I) Q.The corona composed of cordierite and orthopyroxene(Ⅱ）growing around garnets in the granulite makes it clear that there occurres the following metamorphic reaction:Gt Q→Cd Opx(Ⅱ）.It is estimated that the gran ulite-forming temperature(T)and pressure(P)are 857-998℃ and 1.18-1.23Gpa,respectively,and the corona was formed under the following conditions:T=829-911℃ and P=0.52-0.59GPa.The above results indicate that There occurred a rapid and nearly adiabatic uplifting event and a decompressional metamorphism in the Dabie complex after the formation of granulite.As compared with the granulites worldwidely distributed in 90 locations(Harley 1989),the Huangtuling granulite should belong to the high-pressure type,which represents the composition of the crust at a depth of more than 40 kilometers.