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Daniel E.Harlov 《地学前缘(英文版)》2012,3(6):813-827
High-grade dehydration of amphibolite-facies rocks to granulite-facies is a process that can involve partial melting,fluid-aided solid-state dehydration,or varying degrees of both.On the localized meter scale,solid-state dehydration,due to CO2-rich fluids traveling along some fissure or crack and subsequently outwards along the mineral grain boundaries of the surrounding rock,normally is the means by which the breakdown of biotite and amphibole to orthopyroxene and clinopyroxene occur.Various mineral textures and changes in mineral chemistry seen in these rocks are also seen in more regional orthopyroxene-clinopyroxene-bearing rocks which,along with accompanying amphibolite-facies rocks, form traverses of lower crust.This suggests that solid-state dehydration during high-grade metamorphism could occur on a more regional scale.The more prominent of these fluid-induced textures in the granulitefacies portion of the traverse take the form of micro-veins of K-feldspar along quartz grain boundaries and the formation of monazite inclusions in fluorapatite.The fluids believed responsible take the form of concentrated NaCl- and KC1- brines from a basement ultramafic magma heat source traveling upwards along grain boundaries.Additional experimental work involving CaSO4 dissolution in NaCl-brines. coupled with natural observation of oxide and sulfide mineral associations in granulite-facies rocks,have demonstrated the possibility that NaCl-brines,with a CaSO4 component,could impose the oxygen fugacity on these rocks as opposed to the oxygen fugacity being inherent in their protoliths.These results, taken together,lend credence to the idea that regional chemical modification of the lower crust is an evolutionary process controlled by fluids migrating upwards from the lithospheric mantle along grain boundaries into and through the lower crust where they both modify the rock and are modified by it. Their presence allows for rapid mass and heat transport and subsequent mineral genesis and mineral reequilibration in the rocks through which they pass. 相似文献
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库车盆地内古近系—新近系发育巨厚的蒸发岩沉积, 尤其是盆地的中部和西部盐层发育好, 厚度大, 局部盐层己暴露地表, 是找寻各种盐类矿床及钾盐的有利地区。DZK01孔是近年来在库车盆地实施的一口以找钾为目的的科研探井。本文主要通过对钻孔古近系蒸发岩岩芯样品进行岩石学及矿物学特征研究, 进而对盆地成钾环境进行分析。DZK01孔古近系蒸发岩以含泥砾石盐岩为主, 含泥砾石盐岩为构造成因, 是古盐湖高度浓缩的产物。盆地古近系蒸发岩以沉积石盐为主, 钻孔中含钾矿物为钾石膏, 钾石盐和光卤石, 同时含钾矿物的发现证明了库车盆地古盐湖可能达到钾盐析出阶段。通过样品分析可知, 库车盆地古近纪时期古盐湖沉积环境为封闭的浅湖沉积环境, 盐湖发育过程中有五次较大规模的淡化事件, 盐类物质得到很好的聚集, 具有良好的成钾环境。 相似文献
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莱州湾南岸地下卤水高浓度溶解铀及其成因研究 总被引：1，自引：0，他引：1
用α能谱法对莱州湾南岸地下卤水中的铀进行分析,发现卤水中溶解铀的浓度范围为3.4～96.0μg/L,80%以上站位卤水铀浓度超过了30μg/L,高于某些铀矿区地下水中铀的浓度。从卤水的形成过程及环境、含水层沉积物的铀含量及地下卤水对沉积物的淋溶作用、地表水下渗等几个方面对高浓度铀的成因进行了分析,发现卤水形成时海水的蒸发浓缩和锰氧化物还原可能是主要成因,藻类的矿化分解使其吸附的大量铀解吸进入地下水也可能是1个重要影响因素。 相似文献
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Depositional System and Seismic Response of Subsurface Brines Reservoirs in?Western Qaidam Basin, China 总被引：1，自引：0，他引：1
正It is a major continuous depocenter in Dalangtan area,western Qaidam basin since Early Cenozoic,which is most important Neogene salt deposits center in Qaidam basin.The Miocene Saline lake was developed firstly in 相似文献
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Interaction of metalliferous continental brines with biogenic sulphide is the basis of some syngenetic and early diagenetic models for the formation of Cu‐(Pb‐Zn) sulphides during a depositional cycle of carbonates in restricted marine environments. A variation of these models (an ‘evaporative concentration‐lateral groundwater flow’ model) is proposed, using hydrological, geochemical and biological data from low metal, but otherwise pertinent redbed‐associated, sabkha, tidal flat and subtidal environments at Nilemah Embayment, in Hamelin Pool (Shark Bay, Western Australia). The model is constrained by: (i) the short time available for ore accumulation during a single depositional cycle; (ii) limitation of adequate rates of bacterial sulphate reduction for the formation of an ore deposit to near‐surface sediments; (iii) restriction of the most favourable ore‐forming sites to the intertidal zone and the littoral shelf; (iv) coincidence in these sites of laterally‐flowing marine/meteoric groundwater brine, and mosaics of in situ cyanobacterial mats and shallow erosional depressions containing detrital organic matter eroded from the mats. Under these conditions the metalliferous fluid would have to contain about 1000 ppm Cu and flow for 1000 years at a rate of 5 m/a through the intertidal/littoral shelf environment to produce an ore deposit. Critical features of a model that could generate this combination of very high metal concentrations and flow rates are: (i) a highly permeable unconfined aquifer system comprising alluvial fans at the base of basaltic mountain ranges and continental redbeds beneath a broad coastal plain; (ii) mobilization, concentration and transport of the metals in this aquifer to intertidal/littoral shelf sites of ore deposition; (iii) effective concentration processes in the aquifer, involving evaporation and reflux of brines in groundwater discharge areas on the coastal plain and evaporation in marine‐continental and marine sabkhas bordering the sites of deposition; (iv) rapid lateral groundwater flow of the concentrated metalliferous brines under a strong seawards‐directed hydraulic gradient; and (v) discharge of the metalliferous brines into or through topographic depressions generated by erosion and shoaling in the peritidal and littoral shelf environments. The model hydrodynamic processes and their magnitude are within the range observed in modern environments but they are most likely to be effective in coarse‐grained, topographically irregular carbonate sabkhas and tidal flats, which usually form under high‐energy conditions. Even under these conditions, the individual ore‐forming processes must combine in an optimum manner before the highly demanding metal concentrations and flow rates required for ore formation in a single marine depositional cycle can be met. 相似文献
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D.?AvisarEmail author E.?Rosenthal H.?Shulman M.?Zilberbrand A.?Flexer J.?Kronfeld Z.?Ben?Avraham L.?Fleischer 《Hydrogeology Journal》2004,12(3):291-304
For several decades the “Saqiye beds” (later renamed Yafo Formation) underlying the Coastal Plain aquifer (Kurkar Group) aquifer of Israel, were regarded as an extremely thick, tectonically undisturbed, and absolutely impervious aquiclude. Following intensive groundwater exploitation from the overlying Kurkar Group aquifer, brackish and saline waters were locally encountered in the lower parts of this aquifer and always at the contact with the underlying Yafo Formation aquiclude. The present study revealed that this aquiclude is not a uniform and impervious rock unit, but rather an alternation of pervious and impervious strata within the Yafo Formation containing highly pressured fluids of different — mostly high — salinities. The permeable beds are at an angular unconformity and in direct contact with the overlying Kurkar Group aquifer. The Yafo Formation and the underlying and overlying rock units are dislocated by numerous fault systems, which facilitate accessibility of brines into the Kurkar Group aquifer. The mobilization of the saline fluids and their injection into the Kurkar Group aquifer could be due either to diffusion of saline fluids occurring in the permeable horizons of the Petah Tiqva Member through the clays of the Yafo Formation or to their upconing following intensive pumping in the Coastal Plain aquifer. It could have also been caused by up-dip movement of saline water as the result of overpressure generated by major accumulation of gas in the permeable horizons. Another possible mechanism could be hydraulic contact with pressurized brines up-flowing along fault zones from deep-seated Jurassic or Cretaceous reservoirs. The squeezing of saline interstitial water from the clays of the Yafo Formation into the overlying Kurkar Group aquifer, is of secondary importance for groundwater salinization (its input is comparable with salt input from rain). 相似文献
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C. V. Chrysikopoulos 《Environmental Geology》1993,22(1):60-70
Safe disposal of thermally spent geothermal brines that contain environmentally hazardous constituents is commonly obtained by reinjection. The reinjection process also serves to maintain reservoir pressure, enhance thermal recovery, and eliminate possible compactional subsidence. To avoid premature thermal breakthrough of reinjected fluids, tracer tests are employed for detection and evaluation of preferential path networks. In this paper some promising tracers that have not received much attention in geothermal reservoir studies are discussed, and a comprehensive tabulation of field sites of artificial tracer utilization is presented. Chemical and transport processes responsible for tracer retention by the formation of reservoir solids, as well as available tracer detection techniques, are emphasized. 相似文献
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Gian-Maria Zuppi Jean-Paul Novel Martial Dray Xavier Darmendrail Serge Fudral Claude Jusserand Gérard Nicoud 《Comptes Rendus Geoscience》2004,336(15):1371-1378
The presence in the French–Italian Alps of several springs characterized by a high sodium–chloride content, depleted in oxygen-18, tritium free and with low carbon-14 activity, is well known. The geological, hydrological, and geochemical studies in progress for the new high-speed railway tunnel crossing the French–Italian Alps, show, in the drilled boreholes at a mean elevation of 700 masl, the presence of brines. Brines appear to be the basis of the geological, structural, and hydrodynamic systems, and fill the largest faults and the main tectonic contacts. The brines squeezed by tectonic activity, are mobilised at depth by freshwaters from the surface. To cite this article: G.-M. Zuppi et al., C. R. Geoscience 336 (2004). 相似文献
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东台吉乃尔湖晶间卤水综合利用途径研究 总被引：5，自引：0，他引：5
本文简述了东台吉乃尔湖晶间卤水蒸发试验，研究了卤水蒸发过程盐析路线及各种盐类析出规律，确定了钠、钾、硼、锂、镁、硫酸根的富集行为，提出了该晶间卤水钾、硼、锂、硫酸根综合利用工艺路线。 相似文献