地球内部高温超高压流体的水热金刚石压砧原位观测

地球内部极端条件下流体原位观测实验研究有了巨大进展。使用金刚石压砧结合各种谱学方法及同步辐射光源技术,在高温超高压条件下原位直接测量水和水合物结构性质,已经获得关于地球内部流体的分子-原子尺度信息的新实验数据。本次研究通过金刚石压砧对高压(10GPa)和高温高压(800℃/3GPa)NaCl-H_2O和NaCl-D_2O-H_2O的红外谱原位直测,研究了高压和高温高压下水分子结构。发现高压高温水分子OH振动频率随温度升高向高波数变化,而且,在临界态区域时水分子间的氢键网络破坏。水分子OH振动频率随盐度升高向高波数变化。水分子的其它方式运动的频率也随温度改变。实验说明了水分子在极端条件下的结构和运动方式。地球内部由深到浅,不同深度上的流体性质不断变化,如水的密度、介电常数等物理参数随温度压力改变,水的性质在临界态会出现突变。这些变化可以用高压高温的水的各种谱学特征来表征。水的性质取决于水的分子结构(键态)、分子振动方式。在跨越临界区时的水性质异常涨落与水分子结构变化、分子振动形式变化和氢键网络破坏有关。高温超高压流体原位红外谱观测实验是从分子尺度认识地球内部流体性质。水分子尺度的信息有利于我们深入理解地球深部流体性质、活动及物质相互作用,有利于理解岩石圈和地球深内部过程。     

临界区流体与矿物和岩石在地球内部极端条件下的反应

极端条件下水热化学反应是一个新的科学问题。借助于高温超高压原位直接测量方法、各种谱学方法和同步辐射光源技术研究地球内部流体物质相互作用,可以获得反应过程的产物的分子-原子尺度信息,这些信息可以提供认识极端条件下水和矿物(岩石)反应动力学的新实验途径。地球内部的流体性质随所处高温高压条件发生变化。水的密度、介电常数等物理参数随温度压力变化而改变,在临界态会出现突变。水的性质的剧变会影响水与岩石(矿物)相互作用。文中报道了在极端条件下(20～435℃和23～35MPa)实验测量矿物(钠长石、辉石、石英和阳起石等)和岩石(玄武岩、正长岩)在水溶液里的溶解反应速率的研究结果,发现矿物里各种不同类型金属离子与水反应的速率不同,随温度变化而改变。在升温过程中,进入临界态时,矿物(岩石)与水反应出现一次反应速率的涨落。在恒压升温过程中(临界压力,或略高于临界压力),硅酸盐矿物溶解速率会逐步升高,如硅近临界区(300℃)抵达最大值,然后随升温溶解反应速率减低。地球内部的流体由深处上升到浅处,会从超临界区域进入近临界的气与液的两相不混溶区域。含金属流体里的金属会在气相与液相分离时出现再分配。实验表明:金属Au、Cu、Sn、W、Zn会进入气相,气体可以迁移金属。事实说明:地球内部流体结构和性质从深到浅在不断变化,在跨越临界区时的水的性质异常变化会导致水与矿物(岩石)反应动力学涨落,并且促使金属在临界区出现沉淀和在气液相分离过程中进行再分配及迁移。     

地球深部流体临界区和水岩相互作用化学动力学

通常,国际一些科学家把地球深部(压力为临界压力以上)300～500 ℃范围称为水溶液的近临界和临界区.     

用金刚石压砧实验研究极端条件下水热系统

极端条件下的物质,通过使用金刚石压砧与各种谱学仪器(红外、激光拉曼、X光等),尤其是配合同步辐射光源的实验技术,在高温超高压下原位实验研究取得了突破性成果.     

地球内部流体研究评介

地球内部流体研究评介王小龙（中国地质大学《地学前缘》编辑部北京１０００８３）关键词地球内部流体，宏观构造，圈层流体，变质流体ＣＯ２长期以来，地球科学仅仅限于用地壳固体物质的研究来建立和发展其知识和概念。然而愈来愈多的事实表明，流体在地球内部广泛存在，...     

地球深部流体演化与矿石成因

文中重点讨论含矿NaClH2 O溶液在从高温、高压向低温、低压条件改变时性质变化对矿石形成过程的影响。通过对含矿NaClH2 O溶液的实验观测获得对地球深部流体性质的新认识。地球深部的NaClH2 O流体大多处于超临界态流体 ,在上升过程中经减压降温后 ,通过临界态 ,进入低于临界态的热液状态。流体在这一跨越临界态的转变过程中造成了大多数矿石的沉淀。自然界里的许多矿石是在开放流动体系和在非平衡的化学动力学过程中形成的。开放流动体系矿物与水的反应动力学实验 ,证明一些矿石可能形成于流动热液。跨越临界态这一转变过程中的矿物水反应动力学实验结果表明了反应速率的大涨落。地球深部流体在上升过程中的性质演化、流动体系和非均相反应动力学是现代矿石成因研究的 3个关键问题     

地球内部流体系统科学统一理论

从当前人类面临的重大而紧迫的全球性资源、环境、减灾问题的挑战出发，论述了地球内部流体研究在三大领域中的地位和作用。地球内部流体系统科学统一理论从科学系统观出发，在研究思路上坚持多门学科间大跨度交叉，立足于层次性、全球性和统一性的整体观，并以地球系统科学为理论基础，从而具有在更高层次上进行综合学科研究的特点和时空有序多层结构的研究领域。最后，阐述了从定性到定量的系统学、非线性科学的方法学和方法论。同时，地球内部流体与成矿作用，与环境、灾害及全球变化，地球内部流体的实验研究和动力学研究以及地球内部流体的探测，是统一理论研究的主题。     

地球内部水与无机成烃

地球内部水是广泛存在的,由于高温高压作用使其具有独特的物理和化学性质,它对于烃类物质生成和运移都具有重要的意义。在地球内部,水与无机矿物作用产生H2或者O2,对C-O-H流体平衡存在影响,这是烃类物质形成和稳定的重要因素。地球内部高温高压水热流体一方面为有机反应提供高效的介质,另一方面它直接作为反应物与碳酸盐和金属碳化物反应生成烃类物质。对于地球早期有机物形成和水热条件下有机物的主要合成反应——费托反应,其重要的成烃物质H2主要由水与矿物作用产生,这是目前较为认同的地球内部无机成烃的重要方式。     

金刚石压腔（DAC）技术及其在地球科学中的应用

近几十年来金刚石压腔（DAC）技术被广泛应用于高温高压实验研究领域,它可以达到550 GPa的压力和6 000 K的温度。与其他静高压实验技术（大压力机、高压釜等）相比,金刚石压腔具有独特的优势,它不仅可以进行极端温压条件下物质的结构性质、相变及状态方程等研究,而且可以原位观测整个实验过程。文中简述了金刚石压腔装置的结构及温压测量方法,然后分别从物质相变、矿物溶解度、流体性质和组成、油气成因、稳定同位素分馏系数和布里渊声学测量等方面简要介绍了金刚石压腔技术在地球科学中的研究进展。随着实验技术的不断发展和更新,金刚石压腔技术将具有更广阔的应用前景。     

碳酸岩型稀土矿床成矿流体演化机制研究现状及展望

与碱性岩有关的碳酸岩型内生稀土矿床在中国乃至世界上轻稀土资源储量中占有极为重要的地位,诸如我国内蒙古的白云鄂博稀土矿床、川西冕宁—德昌稀土成矿带中的牦牛坪、大陆槽等稀土矿床、山东微山县郗山稀土矿床以及美国的Mountain Pass稀土矿床等都属于这种类型的稀土矿床.当前,对于这类稀土矿床的成矿流体演化机制,学界主要存...     

Phlogopite and quartz lamellae in diamond‐bearing diopside from marbles of the Kokchetav massif,Kazakhstan: exsolution or replacement reaction?

Exsolution lamellae of pyroxene in garnet (grt), coesite in titanite and omphacite from UHPM terranes are widely accepted as products of decompression. However, interpretation of oriented lamellae of phyllosilicates, framework silicates and oxides as a product of decompression of pyroxene is very often under debate. Results are presented here of FIB‐TEM, FEG‐EMP and synchrotron‐assisted infrared (IR) spectroscopy studies of phlogopite (Phlog) and phlogopite + quartz (Qtz) lamellae in diamond‐bearing clinopyroxene (Cpx) from ultra‐high pressure (UHP) marble. These techniques allowed collection of three‐dimensional information from the grain boundaries of both the single (phlogopite), two‐phase lamellae (phlogopite + quartz), and fluid inclusions inside of diamond included in K‐rich Cpx and understanding their relationships and mechanisms of formation. The Cpx grains contain in their cores lamellae‐I, which are represented by topotactically oriented extremely thin lamellae of phlogopite (that generally are two units cell wide but locally can be seen to be somewhat broader) and microdiamond. The core composition is: (Ca_0.94K_0.04Na_0.02) (Al_0.06Fe_0.08Mg_0.88) (Si_1.98Al_0.02)O_6.00. Fluid inclusions rich in K and Si are recognized in the core of the Cpx, having no visible connections to the lamellae‐I. Lamellar‐II inclusions consist of micron‐size single laths of phlogopite and lens‐like quartz or slightly elongated phlogopite + quartz intergrowths; all are situated in the rim zone of the Cpx. The composition of the rim is (Ca_0.95Fe_0.03Na_0.02) (Al_0.05Fe_0.05Mg_0.90)Si₂O₆, and the rim contains more Ca, Mg then the core, with no K there. Such chemical tests support our microstructural observations and conclusion that the phlogopite lamellae‐I are exsolved from the K‐rich Cpx‐precursor during decompression. It is assumed that Cpx‐precursor was also enriched in H₂O, because diamond included in the core of this Cpx contains fluid inclusions. The synchrotron IR spectra of such diamond record the presence of OH^? stretching and H₂O bending motion regions. Lamellar‐II inclusions are interpreted as forming partly because of modification of the lamellae‐I in the presence of fluid enriched in K, Fe and Si during deformation of the host diopside; the latter is probably related to the shallower stage of exhumation of the UHP marble. This study emphasizes that in each case to understand the mechanism of lamellar inclusion formation more detailed studies are needed combining both compositional, structural and three‐dimensional textural features of lamellar inclusions and their host.     

In situ X-ray observations of the decomposition of brucite and the graphite–diamond conversion in aqueous fluid at high pressure and temperature

 An experimental technique to make real-time observations at high pressure and temperature of the diamond-forming process in candidate material of mantle fluids as a catalyst has been established for the first time. In situ X-ray diffraction experiments using synchrotron radiation have been performed upon a mixture of brucite [Mg(OH)₂] and graphite as starting material. Brucite decomposes into periclase (MgO) and H₂O at 3.6 GPa and 1050 °C while no periclase is formed after the decomposition of brucite at 6.2 GPa and 1150 °C, indicating that the solubility of the MgO component in H₂O greatly increases with increasing pressure. The conversion of graphite to diamond in aqueous fluid has been observed at 7.7 GPa and 1835 °C. Time-dependent X-ray diffraction profiles for this transformation have been successfully obtained. Received: 17 July 2001 / Accepted: 18 February 2002     

莺歌海盆地泥底辟成因、展布特征及其与天然气运聚成藏关系

泥底辟是南海北部边缘西区莺歌海盆地颇具特色的地震地质异常体，具有欠压实异常、高温高压特点及低密低速的地球物理特征，其展布则具有明显分带性且沿盆地北西走向呈近南北向雁行式排列。泥底辟成因及分布，主要受控于盆地快速沉降及高速沉积充填压实与排出流体不均衡所产生的巨大异常高温高压潜能．和区域控盆断裂晚期右旋走滑伸展活动。而晚期泥底辟热流体上侵活动及其他成藏条件的有效配置，则有效地控制了天然气及CO2运聚成藏规律。     

Fluid inclusions in high pressure/low temperature rocks from the Calabrian Arc (Southern Italy): the burial and exhumation history of the subduction-related Diamante-Terranova unit

The Diamante-Terranova Unit (DIATU), in the Calabrian Arc of southern Italy, is part of an ophiolitic sequence involved in a high pressure/low temperature event (P=8 kbar; T =400 °C) followed by re-equilibration at greenschist facies conditions (P=3 kbar; T =300 °C). The rocks contain two types of quartz–calcite veins – an earlier generation of deformed, folded and faulted veins formed during or before subduction, and a later set of planar, undeformed veins formed during exhumation of the DIATU. The earlier folded quartz–calcite veins contain regularly shaped aqueous inclusions as well as inclusions with a highly irregular dendritic texture. The later planar veins contain only regularly shaped aqueous inclusions similar to those in the earlier veins. In both vein types, all inclusions are demonstrably secondary in origin. Regularly shaped inclusions from both vein types are low salinity (0–5 wt% NaCl). Most contain liquid and vapour and homogenize to the liquid (Th 135–180 °C), whereas others contain only liquid at room temperature. Both the two-phase and monophase inclusions occur in the same fractures and are thought to record the same trapping event, with the monophase inclusions remaining metastable liquid at room temperature. No microthermometric data could be obtained from the dendritic inclusions in the earlier folded veins. Inclusions with the highly irregular dendritic texture found in the earlier veins are similar to those produced experimentally during laboratory-induced deformation of synthetic inclusions in quartz under conditions of internal underpressure, simulating either isobaric cooling or isothermal compression. The occurrence of inclusions with the dendritic texture in the earlier folded veins, and their absence from the later planar veins, suggests that the earlier veins formed before or during subduction and were folded and faulted in a compressional environment and their contained fluid inclusions were modified to produce the dendritic texture. During later uplift of the DIATU, planar veins containing regularly shaped aqueous inclusions formed and some of the fluids forming these veins were also trapped as secondary inclusions in the earlier folded veins. The results of this study provide convincing evidence that inclusions with a highly irregular dendritic morphology represent early inclusions that have survived prograde conditions in a high pressure/low temperature metamorphic environment (but have been texturally modified). The high pressure/low temperature ‘implosion’ texture is preserved over geological time, even after being overprinted by internal overpressure conditions generated during retrograde decompression. We suggest that inclusions that have survived prograde metamorphism are common in high pressure/low temperature rocks, but are often not identified as such due to their morphology which makes their recognition difficult.     

大陆下地壳麻粒岩的流变学研究进展

大险下地壳麻粒岩的流变学研究可以解释地壳变形、壳幔物质交换以及岩石圈深部动力学过程等科学问题.前人通过研究各矿物的显微构造变形特征与变形机制,运用广义混合流变律探讨多矿物复合岩石的流变性质,结合水与流体对岩石变形强度的弱化作用,阐明在大陆下地壳变形环境下复矿麻粒岩的塑性变形和韧性流变性质.目前人们致力于对天然变形岩石和...