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西藏当雄错盐湖卤水冬季日晒蒸发实验研究 总被引：7，自引：0，他引：7
西藏当雄错盐湖位于藏北高原腹地西南侧,其水化学类型属典型的中度碳酸盐型,具有很好的工业开发前景和价值.自然蒸发是盐田日晒工艺的应用基础工作,本文基于室内卤水等温蒸发实验的相关结果,在当雄错湖区现场开展了盐湖卤水冬季日晒蒸发实验,通过考察碳酸盐型盐湖卤水在现场低温条件下自然蒸发过程中液相各元素的富集规律以及矿物的结晶析盐规律,分析了锂、硼、钾等元素的集散行为,并根据卤水蒸发过程中的元素富集、蒸失水量、盐类析出顺序、矿物组合以及物化性质的变化探索了盐类分离的控制条件.以Na+,K+/CO2-3,SO2-4,Cl--H2O五元体系(25℃)介稳相图为参考依据,绘制了当雄错盐湖卤水冬季日晒蒸发的结晶析盐路线.实验结果表明,当雄错盐湖卤水在冬季日晒蒸发过程中依次析出石盐、泡碱、天然碱、硼砂、钾石盐和扎布耶石,另有少量芒硝和泡碱等低温产物会提前析出或被母液夹带析出,利用冬季低温蒸发可制取富锂卤水,蒸发后期的母卤还可用于提取硼砂和钾石盐等矿物资源.实验结果为下一步开展盐田工程设计及制卤工艺操作提供了必要的基础数据,同时也为碳酸盐型盐湖卤水的综合利用和开发提供了理论支持. 相似文献
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随着国内钾锂盐需求不断增大,浅层盐湖卤水勘探开发技术趋于成熟,深层卤水资源已成为经济矿产目标。四川盆地在三叠系发育了面积广泛且巨厚的蒸发岩层,并赋存了优质且丰富的富钾锂卤水储层。针对以往岩相古地理“盐味”不足的特点,文章通过分析四川盆地蒸发岩分布规律、岩相古地理特征以及沉积演化,明确了膏盐盆的形成具有“多期多区”特征,揭示了三叠系嘉四段—雷三段重点成盐期的膏盐盆规模、分布、迁移规律;同时基于地质、测井资料,明确了四川盆地富钾锂卤水储层的地质和测井响应特征,认为四川盆地富钾锂卤水储层质量受层位、相带、孔隙类型的控制,表现出中-高伽马、低电阻率、高声波时差、低密度的耦合特征。研究成果将对国内外深层海相层系的富钾锂卤水储层勘探起到一定的指导意义。 相似文献
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西藏扎布耶碳酸盐型盐湖卤水相化学研究 总被引：12，自引：0，他引：12
中国盐湖资源丰富,且水化学类型齐全。西藏扎布耶盐湖位于西藏高原腹地,该湖卤水水化学类型为碳酸盐型,已处于盐湖演化晚期,是一个固液共存的盐湖矿床,具有很好的工业开发价值。笔者分别在15℃、25℃下对该卤水进行了等温蒸发实验,研究了在此两个温度下卤水中各元素富集行为和盐类矿物析出规律。并通过讨论其与国内外碳酸盐型和硫酸盐型锂盐湖的卤水蒸发路径和矿物析出异同,指出扎布耶盐湖具有其独特的卤水蒸发析盐路径。在本实验中低温有利于卤水中锂的富集,而高温有利于硼的富集,碳酸锂和钾盐交叉析出,低温时钾的矿物主要为钾石盐,高温时主要为钾芒硝,高温有利于获得高品位的碳酸锂混盐。 相似文献
4.
评判盐湖卤水蒸发浓缩阶段对指示成钾具有重要的意义,由于库车盆地始新统含盐系地层岩盐溴氯比值很低,导致这种传统的找钾地球化学指标方法受限.然而,得益于近年来稳定同位素的快速发展,氯同位素组成可以很好地指示含盐系的蒸发阶段.本文以库车盆地DZK01钻孔13个原生石盐岩为研究对象,分析结果显示,δ37Cl值均为负值,介于-1.20‰～-0.51‰之间;KCl含量介于0.13％～0.29％之间.在剖面上从下往上,δ37Cl值有升高的趋势,KCl含量有降低趋势,指示了库车盐盆中始新世古卤水经历了一个逐渐淡化的演化过程.早期卤水蒸发浓缩程度较高,并析出钾盐或含钾矿物;晚期卤水蒸发浓缩程度较低,较少发现甚至未发现钾盐或含钾矿物.此外,库车盐盆中始新统蒸发岩系的成盐物质主要为海相来源,且蒸发浓缩程度较高,具有较好的成钾前景. 相似文献
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基于相化学研究老挝万象钾镁盐矿床形成的机制 总被引：2，自引：0，他引：2
老挝万象钾镁盐矿床是一个典型的海相碎屑盐缺硫酸盐型钾盐矿床, 该矿床形成于古近纪, 是古海水蒸发浓缩沉积形成。老挝万象钾镁盐矿床中缺乏硫酸盐和碳酸盐沉积物, 因此深入研究该矿床的形成机制很重要。本文研究探讨了该矿床形成时的古海水特点, 根据相化学, 分析成钾原始卤水的物理化学特性, 从矿体形成的化学基础来研究老挝钾镁盐矿床形成的机制。结果表明: 显生宙以来海水组分发生变化, 经海相非骨骼灰岩和钾盐蒸发岩矿物学研究, 发现这两种沉积岩长期以来连续变化, 在“文石海”是MgSO4型蒸发盐, 在“方解石海”是KCl型蒸发盐, 从白垩纪晚期、第三纪早期的底部石盐溴含量及矿物学特征表明, 此时处于“方解石海”, 古海水组分的特点是造成缺硫酸盐型钾盐矿床形成的物化基础; 通过NaCl-KCl-MgCl2-H2O和NaCl-KCl-MgCl2-CaCl2-H2O两个体系相图的分析认为, 当时所形成的成钾原始体系母液是高镁、低钾氯化物型的卤水, 在母液蒸发过程中, 由于原始海侵母液与残余高镁母液的掺杂作用, 致使结晶路线直接从氯化钠区到E点母液或光卤石与氯化钠共饱线上, 而没有通过氯化钠和氯化钾的共饱线, 因而在矿体中氯化钾相很少或几乎不存在, 由于外界CaCl2型水体的掺杂, 使成钾母液进入光卤石相区, 随着蒸发的进行, 最终形成溢晶石矿物。 相似文献
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罗布泊盐湖富钾卤水成因再探讨——碎屑层卤水蒸发实验分析 总被引：1，自引：0，他引：1
罗布泊盐湖钙芒硝岩孔隙中蕴藏有超大型规模的卤水钾矿,富钾卤水成因一直备受关注。罗北凹地从统一的罗布泊大湖区中分隔出来后,成盐过程中其湖水仍以南部大湖的补给为主,罗北凹地卤水化学演化与"大耳朵"湖水密切相关。"大耳朵"湖区含石膏碎屑层普遍储藏有卤水,应该是罗北凹地盐湖的"源卤水",钾离子(ρ(K~+)为3.12 g/L左右)已初步富集,平均矿化度为198.83 g/L。为了查明该卤水的化学演化趋势及析盐序列,笔者于2009年、2010年两次采集了大量卤水样品,分别进行室内等温蒸发和自然蒸发实验。蒸发实验结果表明:随着卤水浓缩首先析出(硬)石膏,随后析出大量石盐,最后出现少量钾石盐和光卤石,与EQL/EVP卤水蒸发模型模拟结果相似。将碎屑层卤水蒸发过程中化学组成变化与罗北凹地卤水进行对比,结果显示罗布泊古湖水蒸发至石膏沉积之后,在罗北凹地水化学组成明显发生变化,没有大量石盐沉积,而以钙芒硝沉积为主。推测应是受到深部"富钙水"的持续补给,而"大耳朵"湖起到"预备盆地"的作用,罗布泊古湖水经"大耳朵"湖蒸发浓缩后,钾离子得到初步富集,在流入罗北凹地后与深部"富钙"水混合,强烈蒸发浓缩,大量钙芒硝矿物析出,最后形成富钾卤水。 相似文献
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位于我国东部的许多新生代盆地,在地质历史时期发育了巨厚的岩盐沉积。尽管这些盆地的成盐模式研究已经历了40多年,但由于缺乏“深水成盐”的现代沉积模式,到底是“深盆-深水”还是“深盆-浅水”成盐,一直难以定论。为了理解“深水成盐”的控制因素,很多现代盐湖开展了水文学和水化学调查,然而这些湖盆的矿物组合各不相同,“深水成盐”的形成条件和控制因素尚不清楚。本文对死海、佛瑞湖等“深水成盐”的现代盐湖以及我国东濮凹陷沙三段的成盐特征进行了解剖,从盐度、水深、湖平面波动以及卤水分层等角度探讨了“深水成盐”的形成条件,对比分析了“深水成盐”的相对位置以及沉积物特征,总结了“深水成盐”的识别标志。研究表明,盐岩层系在岩心和测井资料上显示出多尺度的旋回性。“深水成盐”为水深较大的洼陷中心成盐,与盆缘的“浅水成盐”同盆共存。沉积相对岩盐层系的结构和组成有明显的控制作用,其中洼陷带的“深水成盐”,主要在洼陷带的卤水-湖底沉积物界面附近,析出和增生粗晶的盐类矿物,常与富含有机质和黄铁矿的暗色泥岩共存;而湖滨附近的“浅水成盐”,单层厚度薄,结晶粒度细小,通常含有较多的陆源碎屑。死海为代表的现代盐湖以及东濮凹陷等古代成盐盆地的沉积特征表明,“深水成盐”发生于湖平面的下降期,而且卤水剖面的厚度对蒸发岩的形成分布有明显的控制作用,同时具有“深水”和“深盆”特征的内陆盐湖更容易形成单层厚度大、横向稳定的岩盐沉积。本研究有助于改变人们以往对内陆湖盆成盐机理的认知,尤其是现代盐湖的卤水分层析盐特征,对解读地质历史中的其他成盐事件具有重要启示。基于现代沉积实例的“深水成盐”识别标志,可以为古代岩盐沉积模式的建立提供限定条件。 相似文献
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思茅盆地江城含盐带勐野井地区在“二层楼”钾盐成矿理论的指导下,逐步在侏罗系钾盐资源调查中取得重要成果,但盆地内其他含盐带研究程度薄弱。本文以整董含盐带的磨黑L2井勐野井组(K1m)盐岩样品为研究对象,通过显微镜观察、扫描电镜能谱分析、石盐矿物元素含量电子探针微区原位测试方法的建立,精细研究了样品岩相学、石盐矿物学及元素含量特征。同时,测试了江城含盐带勐野井地区MK-1井花开左组(J2h)石盐样品。对比研究两个井样品中石盐矿物微量元素K和Br含量及103Br/Cl值(质量分数比)特征,结合研究区地质演化,取得以下认识。L2井K1m(含)泥砾盐岩中石盐矿物发育两类产状:一类是胶结碎屑颗粒的主体石盐,具塑性流变特征;另一类是析出在碎屑中被盐类或黏土矿物碎屑包裹的石盐,两类包裹体特征指示均属次生成因。电子探针测得L2井K1m的主体石盐、碎屑包裹和勐野井MK-1井J2h含钾盐层石盐的K含量分别为≤0.09%、≤0.18%和≤0.13%,Br含量分别为≤60×10-6、70×10-6~410×10-6和70×10-6~500×10-6,103Br/Cl值分别为≤0.10、0.12~0.71和0.12~0.85,主体石盐显著低于后二者,处于陆源或海陆混合源石盐阶段或重结晶石盐阶段,而后二者数值接近,大多处在海源石盐阶段,小部分处在海源母液结晶钾石盐阶段和光卤石阶段。推断磨黑L2井碎屑包裹的石盐属深部古盐体刺穿贯入的证据,可能的成矿模式为深部中侏罗统海相古盐体受盐底辟作用迁移到浅层下白垩统勐野井组后,部分被盆地内侧向迁移来的中侏罗世残留海水、盆地周缘汇入的陆源水以及深部热液的共同溶蚀淋滤和混染改造形成新的卤水,部分以固体古石盐砾保留下来,在早白垩世晚期新母液卤水蒸发成盐过程中被形成的盐类和陆源碎屑矿物包裹,后期在母液结晶的主体石盐胶结下沉积成岩和成矿。以上认识完善了“二层楼”成矿理论在整董含盐带的勘探实践。 相似文献
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四川盆地中三叠统雷口坡组中发育多种类型的钾盐矿藏,是我国找钾的重点目标层系。磨溪气田雷口坡组地层卤水富含K、Li、Br、B元素,定性为中低矿化度KCl、LiCl、Br-、B2O3等超标的优质化工原料水,显示出较好的钾盐勘探前景。地震资料解释结果表明,磨溪气田雷口坡组一段的第一亚段(雷一1)顶面表现为一个完整的长轴背斜形态,断层不发育。富钾卤水发育在背斜的翼部,而天然气则占据了背斜的核部,二者共同贮存在雷一1亚段溶蚀孔洞发育的滩相白云岩中,构成了典型的同层型气钾复合矿藏。借鉴含油气系统的概念,将富钾卤水的形成、聚集及后期保存等影响卤水型钾矿形成全过程的各种因素总结归纳为6大关键要素,即钾的物质来源,储层物性、封盖条件、圈闭条件、运移方式和保存条件。在乐山—龙女寺古隆起形成和演化的背景下,确定构造圈闭形成时间,分析优质储层发育有利因素以及后期保存条件,并按照各要素在时空上的搭配关系,动态地分析雷口坡组同层型气钾复合矿藏的形成过程。烃类物质和卤化物都是地下水所含的特殊物质,在地下水动力场的作用下,地层水在雷口坡组内部向着川中地区的继承性发育的古构造高点——磨溪背斜持续运移。被运移而来的由蒸发浓缩的古海水和石膏脱水形成的初始富钾地层水不断捕获下伏绿豆岩释放的钾离子,使得钾离子二次富集成藏。在地层水运移和气藏压力的共同作用下,形成气在上、富钾卤水在下的复合矿藏。长期继承性发育的古隆起不仅是油气聚集的有利部位,亦是二次运移、聚集的富钾卤水矿藏发育部位。本次研究成果为四川盆地及其他类似盆地的“气钾兼探”工作提供了一种新的方法和思路。 相似文献
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Oliver J. Schatz David Dolej John Stix Anthony E. Williams-Jones Graham D. Layne 《Chemical Geology》2004,210(1-4):135-147
Fluid-saturated experiments were conducted to investigate the partitioning of boron among haplogranitic melt, aqueous vapor and brine at 800 °C and 100 MPa. Experiments were carried out in cold-seal pressure vessels for 1 to 21 days, and utilized powdered synthetic subaluminous haplogranite glass doped with 1000 ppm B (crystalline H3BO3) and variable amounts of NaCl and H2O at a fluid/haplogranite mass RATIO=1:1. Run-product glasses were analyzed for boron concentration by secondary ion mass spectrometry (SIMS) and for major elements and chlorine by electron microprobe. The composition of the coexisting fluid was calculated by mass balance. Boron partition coefficients between aqueous vapor and hydrous granitic melt range from 3.1 to 6.3, and demonstrate a clear preference of boron for the vapor over the hydrous melt. Partition coefficients between brine and hydrous granitic melt vary from 0.45 to 1.1, suggesting that boron has no preference for the brine or the melt. The bulk fluid–melt partition coefficients for low-salinity and high-salinity experiments are DB(vapor/melt)=4.6±1.3 and DB(brine/melt)=0.91±0.49, respectively. The corresponding vapor–brine partition coefficient is 5.0±3.1, demonstrating that boron partitions preferentially into the vapor over the brine at the conditions of this study. The preferential incorporation of boron in the aqueous vapor is controlled by borate speciation and solution mechanism. The dominant borate species in aqueous fluids, H3BO3o, is highly soluble in aqueous vapor (XB2O3=0.187); however, B2O3 is immiscible in NaCl liquid. Consequently, concentrations of boron in aqueous vapor are significantly higher than in the coexisting brine. Furthermore, Na–B complexing in the melt at high chlorine fluid contents stabilizes boron in the melt thereby contributing to the non-preferential partitioning of boron between brine and melt. The commonly observed association of tourmalinization (boron metasomatism), brecciation and ore deposition in nature is consistent with the preferential partitioning of boron into aqueous vapor of magmatic-hydrothermal systems predicted by this study. 相似文献
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Alexandra Guedes Fernando Noronha Marie-Christine Boiron David A. Banks 《Chemical Geology》2002,190(1-4):273-289
In order to identify and characterise fluids associated with metamorphic rocks from the Chaves region (North Portugal), fluid inclusions were studied in quartz veinlets, concordant with the main foliation, in graphitic-rich and nongraphitic-rich lithologies from areas with distinct metamorphic grade. The study indicates multiple fluid circulation events with a variety of compositions, broadly within the C–H–O–N–salt system. Primary fluid inclusions in quartz contain low salinity aqueous–carbonic, H2O–CH4–N2–NaCl fluids that were trapped near the peak of regional metamorphism, which occurred during or immediately after D2. The calculated P–T conditions for the western area of Chaves (CW) is P=300–350 MPa and T500 °C, and for the eastern area (CE), P=200–250 MPa and T=400–450 °C. A first generation of secondary fluid inclusions is restricted to discrete cracks at the grain boundaries of quartz and consists of low salinity aqueous–carbonic, H2O–CO2–CH4–N2–NaCl fluids. P–T conditions from the fluid inclusions indicate that they were trapped during a thermal event, probably related with the emplacement of the two-mica granites.
A second generation of secondary inclusions occurs in intergranular fractures and is characterised by two types of aqueous inclusions. One type is a low salinity, H2O–NaCl fluid and the second consists of a high salinity, H2O–NaCl–CaCl2 fluid. These fluid inclusions are not related to the metamorphic process and have been trapped after D3 at relatively low P (hydrostatic)–T conditions (P<100 MPa and T<300 °C).
Both the early H2O–CH4–N2–NaCl fluids in quartz from the graphitic-rich lithologies and the later H2O–CO2–CH4–N2–NaCl carbonic fluid in quartz from graphitic-rich and nongraphitic-rich lithologies seem to have a common origin and evolution. They have low salinity, probably resulting from connate waters that were diluted by the water released from mineral dehydration during metamorphism. Their main component is water, but the early H2O–CH4–N2–NaCl fluids are enriched in CH4 due to interaction with the C-rich host rocks.
From the early H2O–CH4–N2–NaCl to the later aqueous–carbonic H2O–CO2–CH4–N2–NaCl fluids, there is an enrichment in CO2 that is more significant for the fluids associated with nongraphitic-rich lithologies.
The aqueous–carbonic fluids, enriched in H2O and CH4, are primarily associated with graphitic-rich lithologies. However, the aqueous–carbonic CO2-rich fluids were found in both graphitic and nongraphitic-rich units from both the CW and CE studied areas, which are of medium and low metamorphic grade, respectively. 相似文献
13.
Igor S. Peretyazhko Victor Ye. Zagorsky Sergey Z. Smirnov Mikhail Y. Mikhailov 《Chemical Geology》2004,210(1-4):91-111
Coexisting melt (MI), fluid-melt (FMI) and fluid (FI) inclusions in quartz from the Oktaybrskaya pegmatite, central Transbaikalia, have been studied and the thermodynamic modeling of PVTX-properties of aqueous orthoboric-acid fluids has been carried out to define the conditions of pocket formation. At room temperature, FMI in early pocket quartz and in quartz from the coarse-grained quartz–oligoclase host pegmatite contain crystalline aggregates and an orthoboric-acid fluid. The portion of FMI in inclusion assemblages decreases and the volume of fluid in inclusions increases from the early to the late growth zones in the pocket quartz. No FMI have been found in the late growth zones. Significant variations of solid/fluid ratios in the neighboring FMI result from heterogeneous entrapment of coexisting melts and fluids by a host mineral. Raman spectroscopy, SEM EDS and EMPA indicate that the crystalline aggregates in FMI are dominated by mica minerals of the boron-rich muscovite–nanpingite CsAl2[AlSi3O10](OH,F)2 series as well as lepidolite. Topaz, quartz, potassium feldspar and several unidentified minerals occur in much lower amounts. Fluid isolations in FMI and FI have similar total salinity (4–8 wt.% NaCl eq.) and H3BO3 contents (12–16 wt.%). The melt inclusions in host-pegmatite quartz homogenize at 570–600 °C. The silicate crystalline aggregates in large inclusions in pocket quartz completely melt at 615 °C. However, even after those inclusions were significantly overheated at 650±10 °C and 2.5 kbar during 24 h they remained non-homogeneous and displayed two types: (i) glass+unmelted crystals and (ii) fluid+glass. The FMI glasses contain 1.94–2.73 wt.% F, 2.51 wt.% B2O3, 3.64–5.20 wt.% Cs2O, 0.54 wt.% Li2O, 0.57 wt.% Ta2O5, 0.10 wt.% Nb2O5, 0.12 wt.% BeO. The H2O content of the glass could exceed 12 wt.%. Such compositions suggest that the residual melts of the latest magmatic stage were strongly enriched in H2O, B, F, Cs and contained elevated concentrations of Li, Be, Ta, and Nb. FMI microthermometry showed that those melts could have crystallized at 615–550 °C.
Crystallization of quartz–feldspar pegmatite matrix leads to the formation of H2O-, B- and F-enriched residual melts and associated fluids (prototypes of pockets). Fluids of different compositions and residual melts of different liquidus–solidus P–T-conditions would form pockets with various internal fluid pressures. During crystallization, those melts release more aqueous fluids resulting in a further increase of the fluid pressure in pockets. A significant overpressure and a possible pressure gradient between the neighboring pockets would induce fracturing of pockets and “fluid explosions”. The fracturing commonly results in the crushing of pocket walls, formation of new fractures connecting adjacent pockets, heterogenization and mixing of pocket fluids. Such newly formed fluids would interact with a primary pegmatite matrix along the fractures and cause autometasomatic alteration, recrystallization, leaching and formation of “primary–secondary” pockets. 相似文献
14.
石膏是矿山开采及冶炼等工业过程产生的大宗固体废弃物。工业活动产生的废液普遍有高含量的砷等有毒元素,这导致所产生的石膏也含有较高浓度的砷等有毒元素。研究砷在石膏中地球化学行为和归趋对含砷石膏的砷污染控制具有重要的理论和实际意义。然而目前对含砷石膏中不同形态的砷的定量测定和分析尚存在问题。本文在不同pH值的条件下共沉淀砷和石膏,利用电感耦合等离子体质谱(ICP-MS)、同步辐射X-射线吸收近边光谱(XANES)和电子顺磁共振(EPR)对石膏中掺杂态和表面吸附沉淀态的砷进行定量分析。ICP-MS的结果表明随着pH从2升高到12 和14,石膏中砷的含量由57×10-6 增加到 67 470×10-6和63 980×10-6。同步辐射X-射线吸收近边光谱和电子顺磁共振光谱分析表明石膏样品中主要含有五价砷。在2≤pH≤7.5时,固体样品中同步辐射吸收边后的峰形状和掺杂态砷的形状类似,而在pH≥8时,其边后峰的形状发生明显的变化;粉末电子顺磁共振(EPR)定量分析表明在2≤pH≤7.5时砷在石膏中的含量和ICP-MS的分析结果一致,而在pH≥8时其含量明显小于ICP-MS的分析结果。这些结果揭示了在2≤pH≤7.5时,砷在石膏中主要以掺杂态的形式存在,而在pH≥8时大部分砷是以吸附态或表面沉淀的形式存在。五价砷在石膏中的含量和固定机制随着pH值的变化而变化,其研究对了解尾矿中石膏对砷污染的控制作用具有重要作用。此外,研究石膏中由辐射导致的g约为2.33的[AsO3]2-自由基电子顺磁共振特征峰,有助于补充和完善石膏的电子顺磁共振特征谱在地质测年及辐射剂量学中的应用。 相似文献
15.
Maria Luce Frezzotti Tom Andersen Else-Ragnhild Neumann Siri Lene Simonsen 《Lithos》2002,64(3-4):77-96
Three types of fluid inclusions have been identified in olivine porphyroclasts in the spinel harzburgite and lherzolite xenoliths from Tenerife: pure CO2 (Type A); carbonate-rich CO2–SO2 mixtures (Type B); and polyphase inclusions dominated by silicate glass±fluid±sp±silicate±sulfide±carbonate (Type C). Type A inclusions commonly exhibit a “coating” (a few microns thick) consisting of an aggregate of a platy, hydrous Mg–Fe–Si phase, most likely talc, together with very small amounts of halite, dolomite and other phases. Larger crystals (e.g. (Na,K)Cl, dolomite, spinel, sulfide and phlogopite) may be found on either side of the “coating”, towards the wall of the host mineral or towards the inclusion center. These different fluids were formed through the immiscible separations and fluid–wall-rock reactions from a common, volatile-rich, siliceous, alkaline carbonatite melt infiltrating the upper mantle beneath the Tenerife. First, the original siliceous carbonatite melt is separated from a mixed CO2–H2O–NaCl fluid and a silicate/silicocarbonatite melt (preserved in Type A inclusions). The reaction of the carbonaceous silicate melt with the wall-rock minerals gave rise to large poikilitic orthopyroxene and clinopyroxene grains, and smaller neoblasts. During the metasomatic processes, the consumption of the silicate part of the melt produced carbonate-enriched Type B CO2–SO2 fluids which were trapped in exsolved orthopyroxene porphyroclasts. At the later stages, the interstitial silicate/silicocarbonatite fluids were trapped as Type C inclusions. At a temperature above 650 °C, the mixed CO2–H2O–NaCl fluid inside the Type A inclusions were separated into CO2-rich fluid and H2O–NaCl brine. At T<650 °C, the residual silicate melt reacted with the host olivine, forming a reaction rim or “coating” along the inclusion walls consisting of talc (or possibly serpentine) together with minute crystals of NaCl, KCl, carbonates and sulfides, leaving a residual CO2 fluid. The homogenization temperatures of +2 to +25 °C obtained from the Type A CO2 inclusions reflect the densities of the residual CO2 after its reactions with the olivine host, and are unrelated to the initial fluid density or the external pressure at the time of trapping. The latter are restricted by the estimated crystallization temperatures of 1000–1200 °C, and the spinel lherzolite phase assemblage of the xenolith, which is 0.7–1.7 GPa. 相似文献
16.
Kenneth M. Voglesonger John R. Holloway Eileen E. Dunn Peter J. Dalla-Betta Peggy A. O''Day 《Chemical Geology》2001,180(1-4):129-139
The abiotic synthesis of organic compounds in seafloor hydrothermal systems is one mechanism through which the subsurface environment could be supplied with reduced carbon. A flow-through, fixed-bed laboratory reactor vessel, the Catalytic Reactor Vessel (CRV) system, has been developed to investigate mineral–surface promoted organic synthesis at temperatures up to 400°C and pressures up to 30 MPa, conditions relevant to seafloor hydrothermal systems. Here we present evidence that metastable methanol can be directly synthesized from a gas-rich CO2–H2–H2O mixture in the presence of a mineral substrate. Experiments have been performed without a substrate, with quartz, and with a mixture of quartz and magnetite. Temperatures and pressures in the experiments ranged from 200°C to 350°C and from 15 to 18 MPa, respectively. Maximum conversion of 5.8×10−4% CO2 to CH3OH per hour was measured using a mixture of magnetite and quartz in the reactor. After passivation of the stainless steel reactor vessel, experiments demonstrate that methanol is formed at temperatures up to 350°C in the presence of magnetite, and that the formation rate decreases over time. The experiments also show a loss of surface reactivity at 310°C and a regeneration of surface reactivity with increased temperature up to 350°C. Concentrations of CO2 and H2 used in the experiments simulate periodic, localized and dynamic conditions occurring within the seafloor during and immediately following magmatic diking events. High concentrations of CO2 and H2 may be generated by dike injection accompanied by exsolution of CO2 and reaction of dissolved H2O with FeO in the magma to form H2. The experiments described here examine how the ephemeral formation of an H2–CO2-rich vapor phase within seafloor hydrothermal systems may supply reactants for abiotic organic synthesis reactions. These experiments show that the presence of specific minerals can promote the abiotic synthesis of simple organic molecules from common inorganic reactants such H2O, CO2 and H2 under geologically realistic conditions. 相似文献
17.
Daniel Harlov Peter Tropper Wolfgang Seifert Timo Nijland Hans-Jürgen Frster 《Lithos》2006,88(1-4):72-84
Reaction rims of titanite on ilmenite are described in samples from four terranes of amphibolite-facies metapelites and amphibolites namely the Tamil Nadu area, southern India; the Val Strona area of the Ivrea-Verbano Zone, northern Italy, the Bamble Sector, southern Norway, and the northwestern Austroalpine Ötztal Complex. The titanite rims, and hence the stability of titanite (CaTiSiO4O) and Al–OH titanite, i.e. vuaganatite (hypothetical end-member CaAlSiO4OH), are discussed in the light of fH2O- and fO2-buffered equilibria involving clinopyroxene, amphibole, biotite, ilmenite, magnetite, and quartz in the systems CaO–FeO/Fe2O3–TiO2–SiO2–H2O–O2 (CFTSH) and CaO–FeO/Fe2O3–Al2O3–SiO2–H2O–O2 (CFASH) present in each of the examples. Textural evidence suggests that titanite reaction rims on ilmenite in rocks from Tamil Nadu, Val Strona, and the Bamble Sector originated most likely due to hydration reactions such as clinopyroxene + ilmenite + quartz + H2O = amphibole + titanite and oxidation reactions such as amphibole + ilmenite + O2 = titanite + magnetite + quartz + H2O during amphibolite-facies metamorphism, or, as in the case of the Ötztal Complex, during a subsequent greenschist-facies overprint. Overstepping of these reactions requires fH2O and fO2 to be high for titanite formation, which is also in accordance with equilibria involving Al–OH titanite. This study shows that, in addition to P, T, bulk–rock composition and composition of the coexisting fluid, fO2 and fH2O also play an important role in the formation of Al-bearing titanite during amphibolite- and greenschist-facies metamorphism. 相似文献
18.
低密度的水热蒸气和超临界似气流体广泛存在于中地壳至地球表面的各种地质环境中, 是成矿金属搬运和富集的重要介质。火山喷气凝结水、火山结壳和升华物、矿床的流体包裹体气相中均存在具有地质意义的W含量或含钨矿物, 表明W同样可在含水气相中溶解和迁移。本文在350 ℃~400 ℃和压力为60~200 bar的实验条件下, 测定了WO3-H2O体系中W在水蒸气和似气流体中的溶解度, 考察了水蒸气压力对W溶解度的影响。结果显示, W在水蒸气中的逸度(或含量)远高于依据无水体系中固体WO3挥发性数据计算的蒸气压力, 证明气态溶质W与溶剂水蒸气之间存在促进W溶解的水合作用。经热力学方法分析, 认为可能形成了WO3·nH2O(g)形式的水合气体物种, 其水合数n在350 ℃、370 ℃和400 ℃时分别为1.4、1.6和2.9。因此WO3·3H2O(g)或H2WO4·2H2O(g)及H6WO6(g)在温压较高的岩浆-热液或气成-热液成矿环境中(如斑岩系统)对W的气态迁移和浓集可能具有重要作用, 而在温压较低的水热蒸气条件下, W的迁移形式可能以水合数较小的WO3·H2O(g)(或H2WO4)和WO3·2H2O(g)(或H2WO4·H2O)物种为主, 其含量或比例随水蒸气的压力而改变。某些斑岩型和脉型钨(钼)矿床常存在富气体包裹体, 伴随酸性岩浆结晶出溶的以低盐度含水蒸气占优势的岩浆流体对斑岩系统中W、Mo在高温阶段的气态迁移和矿质在花岗岩体顶部和上覆岩层的聚集具有重要意义, 之后蒸气冷凝可产生高盐度的含矿卤水或与渗流地下水混合形成低-中等盐度的成矿流体, 流体的减压沸腾(相分离)和对围岩的交代蚀变导致W、Mo等金属在不同阶段和构造-岩性部位沉淀富集。 相似文献
19.
20.
天然水体系的体积性质与压力、温度、组成的相关性(PVTx性质)研究在地球化学、盐湖化工等领域有广泛的应用。密度是卤水最基本的体积性质,不仅可以通过实验测定,还可以用理论模型进行预测。建立富钾卤水密度与组成、温度的关联模型有助于认识钾在复杂卤水中的富集、迁移规律。为了构建基于Pitzer离子相互作用模型的卤水密度预测方法,本文用高精度振荡管密度计测定了常压下KCl、CaCl2纯盐溶液以及最高离子强度为11.8 mol·kg-1的混合溶液在283~323 K下的密度,用所测得的密度通过Pitzer离子相互作用模型拟合得到多温下Pitzer单电解质参数和Pitzer混合参数。用Pitzer模型参数计算了Na-K-Ca-Mg-Cl-H2O体系293~313 K的密度,计算密度值与实验值的相对偏差在±0.25%以内,计算的结果整体上要优于文献值,文献在计算中均未考虑Pitzer混合参数项。结果表明,K、Ca、Cl离子间的相互作用对于Na-K-Ca-Mg-Cl-H2O溶液的密度有显著的影响,本文获得的Pitzer参数反映了这些离子间的相互作用,可用于计算含有K、Ca、Cl离子的复杂卤水密度的预测。 相似文献