Geochemical Process of Gas Hydrate Formation in the Nankai Trough Based on Chloride and Isotopic Anomalies in Interstitial Water   总被引：2，自引：0，他引：2  

Hitoshi Tomaru    Ryo Matsumoto    Hailong Lu  Takashi Uchida 《Resource Geology》2004,54(1):45-51

Abstract: Interstitial water expelled from gas hydrate-bearing and -free sediments in the Nankai Trough are analyzed in terms of Cl-, SO₄²-, δ¹⁸O and δD. The baselines for the Cl- concentration and δ¹⁸O value are close to seawater values (530 mM and 0%), indicating that the interstitial water is of seawater origin. The δD values decrease with depth, implying isotopic exchange of hydrogen between upwelling biogenic methane depleted in D and interstitial water. The Cl- concentrations in gas hydrate-bearing sediments are anomalously low, while the δ¹⁸O and δD values are both high, suggesting that the water forming these gas hydrates was poor in Cl- and enriched in ¹⁸O and D during gas hydrate formation. Calculation of the gas hydrate saturations using Cl "and δ¹⁸O anomalies gives results of up to 80 % in sand, and shows that the δ¹⁸O baseline is not consistent with the Cl" baseline. The δ¹⁸O baseline increases by +1% in gas hydrate-free clay and silt. This is considered to be caused by clustering of water molecules after gas hydrate dissociation in response to the upward migration of the base of gas hydrate stability, as indicated by the presence of a double bottom-simulating reflector at this site. The water clusters enriched in ¹⁸O are responsible for the increase in the δ¹⁸O baseline with normal Cl". The abrupt shallowing of the base of gas hydrate stability may induce the dissociation of gas hydrates and the accumulation of gases in the new stability zone, representing a geological process that increases gas hydrate saturation.  相似文献   

软钾镁矾溶解动力学Ⅰ:对K~ ,Mg~(2 )/SO_4~(2-)—H_2O三元体系的研究(50-75℃)     

宋粤华  夏树屏 《盐湖研究》1998,(1)

前言青藏高原的诸多盐湖中存在大量的钾、钠、镁复盐,如KCI和KSO。这两种钾肥可以由盐湖中所含的钾钱复盐光卤石和软钾镁矾（K。SO。·MgSO。·sH刀）在水中溶解制得,因此,有必要对复盐溶解过程进行系统的研究,夏树屏等人‘’,‘’已对复盐氯碳酸镁和氯柱硼镁石等的溶解转化机理和动力学进行了较为详细的研究,解决了不同类型复盐的研究方法和数据处理方法。德国和独联体两国的学者对钾光卤石固体盐矿的工艺及基础研究曾进行过不少的工作H．H．Emons和HVo…等‘”对钾光卤石的天然单晶和压块光卤石不同条件下的溶解速度常数及…  相似文献   

海盐氯循环对输送污染物致酸的缓冲作用   总被引：1，自引：0，他引：1  

姚小红  黄美元  高会旺  郝吉明 《大气科学》1998,22(6):913-918

着重研究海盐氯循环对输送污染物致酸的缓冲作用,通过对全球低污染点酸雨资料分析,初步结论是:海盐氯循环使经过海洋上空输送的致酸大气污染物转化为中性盐,这一机制缓冲了经过海洋上空输送的致酸前提物的酸性,使受体点降水中出现氯亏损、硫富集,并伴随有降水中氯亏损和H+离子浓度的负相关。在高氯亏损降水样品中,降水pH值一般大于5.0。硫同位素动力学分析表明,当降水pH值大于5.6氯亏损时,污染物在海洋上空输送过程中和海盐发生非均相反应的速率与其发生均相反应的速率接近。但这一机制仅适用沿海地区。  相似文献   

Geochemical Evolution of Hydrothermal Fluids at the Daejang Cu–Zn–Pb Vein Deposit, Korea     

Sang Hoon CHOI 《Resource Geology》1998,48(3):171-182

Abstract: The Daejang mine is located within the Cretaceous Gyeongsang basin. Mineral paragenesis can be divided into four stages (stages I, II, III and IV) by major tectonic fracturing. Stages I, III and IV are economically barren. Stage II, at which the precipitation of major ore minerals occurred, is further divided into three substages with paragenetic time based on minor fractures and discernible mineral assemblages: substage IIa, marked by deposition of quartz and Fe–sulfides; substage IIb, by introduction of base-metal sulfides within carbonates and some quartz; substage IIc, by quartz and carbonates with various sulfosalts. Fluid inclusion data indicate a complex geochemical evolution of hydrothermal fluids. Both CO₂–rich and H₂O–rich fluids were trapped in fluid inclusions at stage I and substage IIa. It is suggested that a compositionally heterogeneous fluid was formed by fluid boiling and CO₂ immiscibility at temperatures of about 400° to 300°C. Composite lodes of base-metal sul–fides, carbonates and quartz at substage IIb were deposited in open spaces created by fracturing. The fracturing event prompted rapid decreases in pressure and temperature of residual fluids and resulted in retrograde fluid boiling at about 200 bars and 300°–250°C during substage IIb. The progressive loss of CO₂ by CO₂ effervescence and retrograde boiling from substage IIa and IIb fluids resulted in pH increase and related increase in carbonate activity, causing deposition of abundant carbonates. The change in pH also caused the decrease of stability of hydrogen sulfide with Cu, Zn and Pb chloride complexes (as main transporting agents at Daejang) and resulted in the pricipitation of base-metal minerals. Deposition of Ag– and Sb-bearing sul–fides and sulfosalts of substage IIc occurred at temperatures of about 250° to 150°C from a dominantly aqueous fluid with low salinity (down to 3. 0 equiv. wt % NaCl). At this substage, aqueous fluid formed by mixing with cooler and less saline meteoric groundwater. There is a systematic decrease in caculated δ¹⁸O_water values with the mineralization stage (and decreasing temperature) in the Daejang hydrothermal system, from values of about 11% for stage I, through about 4% for stages II and III, to about –3 per mil for stage IV. The result of stable isotope and fluid inclusion studies are interpreted to indicate progressive less evolved and/or unexchanged meteoric water influx of an early hydrothermal system formed by highly evolved meteoric waters.  相似文献   

五硼酸钾水溶液的差示FT-IR和Raman光谱研究   总被引：2，自引：0，他引：2       下载免费PDF全文

王奖  朱黎霞  李淑妮  夏树屏  高世扬 《盐湖研究》2004,12(1):19-22

研究了KB5O8·4H2O水溶液20℃时的差示FT-IR光谱和Raman光谱,对振动频率进行了归属。探讨了KB5O8·4H2O水溶液中硼氧配阴离子的存在形式(主要是B(OH)3、[B3O3(OH)4]-和[B5O6(OH)4]-)和相互作用。  相似文献   

四川盆地下中三叠统异常水点水化学特征及探盐找钾预测研究   总被引：1，自引：0，他引：1       下载免费PDF全文

林耀庭  何金权 《盐湖研究》2004,12(4):1-8

四川盆地下中三叠统盐卤分布广泛,是四川探盐找钾的重要时代。通过区域地质背景条件分析,其盐类保存、水动力条件和水化学特征在不同水文地质区表现不一,反映在储层的水型也极不一致,按水中阴、阳离子优势组分异常水点分为SO4-Ca、SO4-Na和Cl-Na3种类型。利用异常水点离子的比例系数在海水浓缩曲线图上的落点位置,判别水点成因类型,从而发现盆地东北部宣汉、盆地西部平落和盆地东部万县向斜周边背斜水点具含钾溶滤水特征,值得重视和进一步开展找钾探索。  相似文献   

高铁酸钡的电化学合成研究          下载免费PDF全文

曹长年  任彦蓉 《盐湖研究》2004,12(4):49-52

以2Ba0·Fe2O3为正极材料、GP镍氢和镍铬二次商业电池的阴极材料为负极,13 5molKOH溶液为电解液,在隔膜电解池中电化学合成高铁酸钡。理想合成温度为20℃,电流密度约为为0 18mA cm2;高铁酸钡产率为52 1%。充电电压为1 45～1 58V。电化学合成时间约为50h。  相似文献   

无机晶须研究进展Ⅰ:钛酸钾晶须的制备及应用   总被引：15，自引：0，他引：15       下载免费PDF全文

魏明  王春波  乃学瑛  李中  李武 《盐湖研究》2004,12(4):58-62,48

钛酸钾晶须是一种高性能、多用途的合成纤维。综述了钛酸钾特性、制备方法及工艺,并且通过分类着重介绍了钛酸钾晶须的应用现状。  相似文献   

中国东部富钾埃达克岩成因的实验约束   总被引：27，自引：21，他引：27  

RobertP.PAPP  肖龙 《岩石学报》2002,18(3):293-302

Adakite在地球化学上具明显特征的火山岩和深成花岗岩类岩石，见于洋内岛孤环境和大陆孤，如安底斯孤。在洋内岛孤，由热的消减的大洋岩石圈熔融形成（叫做“板片熔融”），而在大陆孤，熔融曾发生在构造或岩浆加厚的下地壳底（叫做“下地壳熔融”）。在这两种产状环境中，adakite的鲜明地球化学特征被认为是起因子，一种不同程度含水的变质基性原岩在足够深度上的部分熔融，这里的足够深度是指可使石榴子石在残余结晶组合（即石榴角闪石和/或榴辉石的残余）中保持稳定的深度。“原始”或“母”adakite熔体一旦形成，便可能在其向上运移和侵位上地壳期间受到同化作用（或是地幔，或是大陆物质）和结晶分异作用的改造。中国东部晚中生代（早中白垩世，160-110Ma）的adakite,与见于同一地区和其它地方的钠质adakite相比，通常富含钾(K2O)和其它大离子亲石元素（如Ba,Th,U），有较低的Na2O/K2O比值（-1.0-1.1）,类似于玄武岩在石榴角闪岩-榴辉岩相含水熔融实验中所产生adakite熔体，要么是由洋壳板片熔融所形成，要么是由不同成分的玄武质下地壳原岩部分熔融所形成。尽管有些成分差异，它们的总体化学特征仍然可将中国东部的富钾花岗岩类岩石定均adakite。我们把这些富钾的adakite的独特化学行特征，归因于成分来源的特殊性，或adakite母岩浆遭受了同化混染和结晶分异(AFC)作用的改造。虽然中国东部与消减带环境明显不同这一点表明，那里的adakite可由板块底部侵位的（岩浆加厚的）镁铁质下地壳部分熔融所形成，但燕山运动期间中国东部存在“平坦”俯冲的地球动力学环境是可能被排除的。  相似文献   

论中国西部钾矿资源分布特征与开发前景   总被引：2，自引：0，他引：2       下载免费PDF全文

涂怀奎 《甘肃地质》2002,11(1):69-75

中国钾矿资源严重不足 ,寻找钾矿新类型和富钾 (岩石 )资源 ,应成为解决中国钾资源紧缺的重要任务。中国西部钾矿资源分布很不平衡。青海与新疆是远景最大、质量最佳的成矿区。鄂尔多斯盆地奥陶纪含盐建造具有含钾性是目前世界上已知的惟一特例。中国钾长石、绿豆岩、霞石等含钾岩石矿物资源非常丰富 ,开发利用前景乐观。在开发中一定注意 :(1)盐湖找钾与开发并举 ;(2 )寻找钾盐矿床与含钾岩石并行 ;(3)钾矿石的开发与工艺研究并重 ;(4)综合利用与评价并用 ;(5 )国内与国外钾矿资源统一利用。  相似文献