排序方式： 共有68条查询结果，搜索用时 15 毫秒
11.
Solubility of Anhydrite, CaSO4, in NaCl-H2O Solutions at High Pressures and Temperatures: Applications to Fluid-Rock Interaction 总被引：1，自引：0，他引：1
Anhydrite solubility in H2O–NaCl solutions was measuredat 6–14 kbar, 600–800°C and NaCl mole fractions(XNaCl) of 0–0·3 in piston–cylinder apparatus.Solubilities were determined by weight changes of natural anhydritein perforated Pt envelopes confined with fluid in larger Ptcapsules. In initially pure H2O at 10 kbar and 800°C, CaSO4concentration is low (0·03 molal), though much largerthan at the same temperature and 1 kbar. Hematite-buffered experimentsshowed slightly lower solubilities than unbuffered runs. CaSO4solubility increases enormously with NaCl activity: at 800°Cand 10 kbar and XNaCl of 0·3, CaSO4 molality is 200 timeshigher than with pure H2O. Whereas CaSO4 solubility in pureH2O decreases with rising T at low T and P, the high-P resultsshow that anhydrite solubility increases with T at constantP at all XNaCl investigated. The effects of salinity and temperatureare so great at 10 kbar that critical mixing between sulfate-richhydrosaline melts and aqueous salt solutions is probable at900°C at XNaCl 0·3. Recent experimental evidencethat volatile-laden magmas crystallizing in the deep crust mayevolve concentrated salt solutions could, in light of the presentwork, have important implications regarding such diverse processesas Mount Pinatubo-type S-rich volcanism, high-f O2 regionalmetamorphism, and emplacement of porphyry Cu–Mo ore bodies,where anhydrite–hematite alteration and fluid inclusionsreveal the action of very oxidized saline solutions rich insulfur. KEY WORDS: anhydrite; sulfur; solubility; metamorphic brines; granulites 相似文献
12.
KONZETT JURGEN; MILLER CHRISTINE; ARMSTRONG RICHARD; THONI MARTIN 《Journal of Petrology》2005,46(4):717-747
Olivine-rich rocks containing olivine + orthopyroxene + spinel+ Ca-amphibole ± clinopyroxene ± garnet are presentin the central Ötztal–Stubai crystalline basementassociated with eclogites of tholeiitic affinity. These rockscontain centimetre-sized garnet layers and lenses with garnet+ clinopyroxene ± corundum. Protoliths of the olivine-richrocks are thought to be olivine + orthopyroxene + spinel dominatedcumulates generated from an already differentiated Fe-rich () tholeiitic magma that was emplaced into shallowcontinental crust. Protoliths of the garnet-rich rocks are interpretedas layers enriched in plagioclase and spinel intercalated ina cumulate rock sequence that is devoid of, or poor in, plagioclase.U–Pb sensitive high-resolution ion microprobe dating ofzircons from a garnet layer indicates that emplacement of thecumulates took place no later than 517 ± 7 Myr ago. Aftertheir emplacement, the cumulates were subjected to progressivemetamorphism, reaching eclogite-facies conditions around 800°Cand >2 GPa during a Variscan metamorphic event between 350and 360 Ma. Progressive high-P metamorphism induced breakdownof spinel to form garnet in the olivine-rich rocks and of plagioclase+ spinel to form garnet + clinopyroxene ± corundum inthe garnet layers. Retrogressive metamorphism at T 650–680°Cled to the formation of Ca-amphibole, chlorite and talc in theolivine-rich rocks. In the garnet layers, högbomite formedfrom corundum + spinel along with Al-rich spinel, Ca-amphibole,chlorite, aspidolite–preiswerkite, magnetite, ilmeniteand apatite at the interface between olivine-rich rocks andgarnet layers at P < 0·8 GPa. Progressive desiccationof retrogade fluids through crystallization of hydrous phasesled to a local formation of saline brines in the garnet layers.The presence of these brines resulted in a late-stage formationof Fe- and K-rich Ca-amphibole and Sr-rich apatite, both characterizedby extremely high Cl contents of up to 3·5 and 6·5wt % Cl, respectively. KEY WORDS: cumulates; Variscan metamorphism; SHRIMP dating; högbomite; saline brines 相似文献
13.
《International Geology Review》2012,54(4):501-524
The alkaline El Chichón and calc-alkaline Tacaná volcanoes, located in southern Mexico, form parts of the Chiapanecan Volcanic Belt and Central American Volcanic Arc, respectively. El Chichón has emitted potassium-, sulphur-, and phosphorus-rich trachyandesites and trachybasalts (as mafic enclaves), whereas Tacaná has erupted basalts to dacites with moderate potassium contents, and minor high-Ti magmas (1.5–1.8 wt.% TiO2). The magmatic evolution in the two volcanoes has involved similar fractionating assemblages: Fe-Ti oxides, olivine, plagioclase, pyroxenes, amphibole, and apatite. K2O/P2O5 ratios and isotopic signatures indicate that magmas from both El Chichón and Tacaná have undergone significant crustal contamination. The volcanism at both Tacaná and El Chichón was previously related to northeastward subduction of the Cocos Plate, representing the main arc and the backarc, respectively. Although such an origin is in accord with Tacaná occurring 100 km above the Cocos Benioff Zone, it is inconsistent with: (a) the absence of a calc-alkaline belt between El Chichón and the Middle America Trench; and (b) truncation of the subducted Cocos Plate by the southwesterly dipping Yucatan slab near the Middle America Trench (i.e. the Cocos Plate does not presently underlie El Chichón). On the other hand, El Chichón and the Chiapanecan Volcanic Belt are located on the sinistral Veracruz fault zone that forms the northern boundary of the Southern Mexico block, which has been migrating relatively to the east since ca. 5 Ma. In this context, the anomalous high potassium, sulphur, and phosphorus levels in the El Chichón magmas are explicable in terms of rifting in a pull-apart system with the weak subduction fingerprint inherited from the Yucatan slab. 相似文献
14.
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
15.
16.
Growth rates of two halophilic phytoflagellates, Dunaliella euchlora Lerche and D. salina Teodoresco, were studied in mixed batch cultures grown in filtered, axenic brines from Lake Grassmere, New Zealand. Forty‐five combinations of temperature, salinity, and light intensity were used. A maximum growth rate of 1.50 doublings day‐1 was attained by D. salina at 26°C, 190 × 10‐3S at a light intensity of 126 μE m‐2 s‐1. D. euchlora showed maximum growth rate of 1.16 doublings day‐1 at 20°C, 120 × 10‐3S at a light intensity of 180 μE m‐2s‐1. Predicted maximum values of 1.41 and 1.14 doublings day‐1 respectively were obtained from regression models based on 45 replicate treatment combinations. In decreasing order of importance, temperature, salinity, and light intensity influence growth rates of brine algae. The optimum temperature for growth of both species increased as the salt concentration increased but decreased with increasing light intensity. 相似文献
17.
塔里木盆地西部古盐矿点卤水水化学特征与找钾研究 总被引：12，自引：0，他引：12
在塔里木盆地发展地史上,白垩纪—第三纪时曾有过多次大的海浸,带来了丰富的盐类物质成分,又由于干旱封闭的气候环境,其西部沉积了广阔而厚层的盐岩,因此一直被列为我国有利的找钾远景区。在对塔里木盆地西部晚白垩—第三纪地层出露盐矿点实地考察的过程中,采集、分析了一些卤水样品的水化学组成,通过K+含量及一些水化学系数变化特征的研究,查明了卤水的成因类型属石盐岩淋滤水,K+含量较低,没有出现显著水化学系数异常;但相比之下,塔里木盆地西南喀什坳陷构造区Br含量值明显高于库车坳陷,Br×103/Cl值等具找钾意义的水化学系数比其他地区高1～2个数量级,推测淋滤的盐层当时的成盐古卤水浓缩程度较高,Br出现相对的富积,有一定的找钾远景;另外,对比海水蒸发实验结果,发现卤水的化学成分明显不同于经典的海相成盐淋滤卤水,指示海相标志的Br、B等含量较低,反映了该区成盐环境是在海陆相互作用的复杂条件下形成的,今后的找钾工作不能局限于经典的海相成盐理论,应该结合岩盐及含盐系地层地球化学、盆地构造变形历史及构造分异特征的综合分析研究,寻找新的找钾指标,以期在喀什坳陷等更深一级次级盆地发现可能的钾盐矿床。 相似文献
18.
青海盐湖锂资源开发现状及对提锂产业发展建议 总被引：4，自引：4，他引：0
中国正处在环境污染治理和产业结构调整的关键时期,发展新能源产业是应对能源和环境危机的必然选择;同时,锂资源储备和提锂技术直接影响到国家能源战略安全。中国科学院青海盐湖所经过二十年开发,目前已形成一套成熟的选择性离子迁移分离提锂技术,并经过了产业化和工业应用验证,核心技术达到国际领先水平。该产业化具有绿色、高效、低能耗、低物耗、低产品成本、高纯度等特点,技术通用性好,可推广应用到青海、西藏高海拔生态脆弱地区以及南美玻利维亚、阿根廷、智利等高镁锂比盐湖中锂的分离提取,在高钙镁地热水、油(气)田水提锂方面也有一定的应用潜力。 相似文献
19.
Field observations indicate that tectonic compression, anticline formation and concomitant uplift events of marine Paleogene carbonates in eastern United Arab Emirates, which are related to the Zagros Orogeny, have induced brecciation, karstification, and carbonate cementation in vugs and along faults and fractures. Structural analysis, stable isotopes and fluid inclusion microthermometry are used to constrain the origin and geochemical evolution of the fluids. Fluid flow was related to two tectonic deformation phases. Initially, the flux of moderately 87Sr-rich basinal NaCl–MgCl2–H2O brines along reactivated deep-seated strike-slip faults have resulted in the precipitation of saddle dolomite in fractures and vugs and in dolomitization of host Eocene limestones (δ18OV-PDB −15.8‰ to −6.2‰; homogenization temperatures of 80–115 °C and salinity of 18–25 wt.% eq. NaCl). Subsequently, compression and uplift of the anticline was associated with incursion of meteoric waters and mixing with the basinal brines, which resulted in the precipitation of blocky calcite cement (δ18OV-PDB −22‰ to −12‰; homogenization temperatures of 60–90 °C and salinity of 4.5–9 wt.% eq. NaCl). Saddle dolomite and surrounding blocky calcite have precipitated along the pre- and syn-folding E–W fracture system and its conjugate fracture sets. The stable isotopes coupled with fluid-inclusion micro-thermometry (homogenization temperatures of ≤50 °C and salinity of <1.5 wt.% eq. NaCl) of later prismatic/dogtooth and fibrous calcites, which occurred primarily along the post-folding NNE–SSW fracture system and its conjugate fracture sets, suggest cementation by descending moderately 87Sr-rich, cool meteoric waters. This carbonate cementation history explains the presence of two correlation trends between the δ18OV-PDB and δ13CV-PDB values: (i) a negative temperature-dependent oxygen isotope fractionation trend related to burial diagenesis and to the flux of basinal brines, and (ii) positive brine-meteoric mixing trend. This integrated study approach allows better understanding of changes in fluid composition and circulation pattern during evolution of foreland basins. 相似文献
20.
The variable salinity of fluid venting from mid-ocean ridges is indicative of mixing between hydrothermal seawater and fluids that have undergone supercritical phase separation. In order to study the stability of a brine-saturated layer that may form in the lowermost part of the hydrothermal system, we have performed numerical simulations of a system that has returned into the subcritical regime. For typical geological parameters, it is shown that the interface between the brine layer and the overlying fluids is not very stable, but vanishes by one of two dynamical mechanisms: convective breakdown or vertical migration. This contradicts the conventional picture of a steady, layered convective system in which the brine is depleted only by dispersion and diffusion across the interface. The depletion mechanism depends on the fluid-dynamical stability of the brine layer. Convection within the brine layer results either in the convective breakdown (for low excess salinity of the brine, as compared to seawater) or the upward migration of the interface (for higher excess salinities). Consequently, the depletion times are much shorter than for models with pure dispersion/diffusion across the interface. If the brine layer is static, high-chlorinity liquid is entrained slowly by the convecting overlying fluids, leading to downward migration of the interface. This gradual depletion of the brine layer results in almost constant vent salinities, in agreement with measured salinities of chronic high-chlorinity vents. 相似文献