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1.
长江口氧化还原敏感元素的早期成岩过程 总被引：2，自引：0，他引：2
通过测试长江口沉积物及间隙水中Fe、Mn、U及Mo的含量,结合早期成岩模型及地球化学热力学分析,探讨了在河口环境中影响间隙水氧化还原敏感元素(Fe、Mn、U及Mo)分布的主要因素.根据Fick第一定律,估算了Fe、Mn、U及Mo在沉积物-水界面的扩散通量.结果表明,间隙水Fe、Mn、U及Mo的含量分别介于0.8~106μmol/L、14.8~258μmol/L、1.9~14.4nmol/L及60~546nmol/L之间.在垂直剖面上,间隙水Fe、Mn峰值分别出现在约5cm或10cm的深度.早期成岩过程是影响长江口沉积物间隙水Fe、Mn分布的主要因素.吸附系数对间隙水Fe、Mn的分布也有重要的影响.吸附系数越高,间隙水Fe、Mn浓度越低.影响间隙水U分布的主要因素为Fe,而Mo与Fe、Mn之间不存在相关性.通量计算结果显示Fe、Mn、U及Mo的扩散通量分别介于3.0~10.5μmol·(m2·d)-1、35.7~439.5μmol·(m2·d)-1、-2.3~0.2nmol·(m2·d)-1及-36.0~94.6nmol·(m2·d)-1之间.沉积物中自生铀组分约占总铀的6%~67%. 相似文献
2.
高铁高砷地下水严重威胁饮水质量,曝气-砂滤法因处理效果好且成本低在农村地区得到广泛应用。砂滤过程石英砂表面富集铁和砷后需定期更换,然而废弃石英砂堆置具有砷释放风险。本文以江汉平原某水厂砂滤池废弃石英砂为研究对象,采用激光剥蚀-等离子体质谱(LA-ICP-MS)、拉曼光谱(Raman)、X射线衍射(XRD)和分步化学提取等手段,研究了砂样中的Fe和As含量及形态分布。结果表明,砂粒表面形成了一层厚度为20100 μm的高铁砷薄层,薄层内部Fe和As含量显著高于两侧,Fe和As分布高度相关(R2=0.985)。砂样表面铁矿物以无定型/弱结晶型为主,同时检出赤铁矿和臭葱石等矿物。砂样中Fe和As总含量分别为20.1 mg/g和53.4 μg/g。砂样表面铁主要以易溶解态、碳酸盐结合态和易还原态为主,As主要吸附在铁矿物上。研究区降雨充沛,当废弃石英砂遭遇雨水冲刷或淹没时,可能导致铁砷薄层中As解吸或随Fe矿物还原溶解而释放。 相似文献
3.
季风性波动引起的降雨、径流和排泄过程会引发浅层地下水系统周期性氧化还原动态变化,从而对地下水系统中有害组分的迁移转化产生影响。为探讨氧化还原动态过程对沉积物中砷(As)和氟(F)释放的影响,本研究选择河北白洋淀地区沉积物样品,利用发酵罐作为反应器,建立氧化还原动态实验体系,并监测动态变化过程中实验体系各组分含量的变化。结果表明,碱性和还原环境均有利于地下水中As、F的富集。还原阶段较高的pH条件有利于溶液中F-的解吸,且体系中有机物降解会产生大量HC03-和C032-,与F-发生竞争吸附而有利于F-的富集。对于溶液中As的富集,一方面是由于还原条件下体系中的As以As(III)为主,受沉积物的吸附作用较弱,从而有利于As被释放到溶液中;另一方面是因为还原阶段较高的pH也会使反应体系中As和沉积物间的吸附作用被减弱,造成As的解吸附。由于实验所用沉积物砷含量较低,不同S042-浓度条件对氧化还原动态过程中As、F迁移的影响不明显。总之,氧化还原动态变化过程会强烈影响地下水系统中砷、氟的富集。 相似文献
4.
碳酸盐岩的Fe/Mn元素比值,作为一项新的地球化学指标,可以用于恢复海洋的氧化还原状态.在氧化条件下,Fe3+和Mn4+均不可溶,因此氧化海水中的溶解Fe和Mn的含量均很低.Fe3+和Mn4+在还原条件下可以被细菌还原为可溶的Fe2+和Mn2+,而氧化还原电位的计算表明,Mn4+的还原要早于Fe3+的还原,因此细菌的Mn还原过程发生在沉积物的更浅层.可溶的Fe2+和Mn2+向上扩散到海水中,替代碳酸盐岩晶格里的Ca2+,因此碳酸盐岩晶格中的Fe2+和Mn2+的含量受控于来自沉积物孔隙水的扩散,而后者又与水岩界面的氧化还原状态相关.因此可以预测,随着海水变得逐渐缺氧,碳酸盐岩中的Fe/Mn比值会逐渐增高.为了验证这一假说,我们分析了中元古代高于庄组白云岩的Fe/Mn比值.研究发现,几乎所有的样品的Fe/Mn比值介于20～30之间,显著高于泥盆纪末期深水碳酸盐岩和浅水台地碳酸盐岩的Fe/Mn比值.高于庄组碳酸盐岩高的Fe/Mn比值一方面可能指示了中元古代低的大气氧气浓度和海洋的广泛缺氧,也可能反映了白云岩形成于缺氧的沉积物空隙水里. 相似文献
5.
随着经济的快速发展,城镇化和工业化成为影响地下水环境的重要因素。沿海城市化地区地下水中砷来源复杂,不仅有各种人为来源,天然沉积环境更是造成高砷地下水的主要成因。本文通过对比珠江三角洲地区不同历史时期水化学组分变化,采用离子比和主成分分析技术,研究了城镇化背景下研究区不同类型含水层地下水中砷的分布特征及成因。结果表明,研究区浅层地下水砷浓度介于未检出至420 μg·L-1之间,主要以As(Ⅲ)的形态存在,孔隙含水层的砷浓度普遍高于裂隙和岩溶含水层。取自研究区的1 567组地下水化学样品测试结果显示,ρ(As)>10 μg·L-1的高砷地下水样品检出89组,占比5.7%。其中,孔隙、裂隙和岩溶含水层高砷地下水分别检出82组、4组和3组,占比分别为7.8%、0.8%和9.7%。高砷地下水主要分布在城镇化地区,其比例为非城市化地区的5倍以上。对比历史水化学数据,近10年新增城镇建设用地浅层高砷地下水中砷浓度平均值增加了30%。高砷地下水通常具有pH值较高、氧化-还原电位(Eh)较低等特性。地下水中砷浓度与 、Fe、Mn浓度及耗氧量呈正相关。三角洲平原区第四系基底富含有机质的淤泥质沉积地层,在微生物降解和有机质矿化作用下,固着砷的铁(氧)氢氧化物被还原溶解促使砷释放富集。城镇化过程中含砷工业废水的泄漏入渗是佛山市南部顺德区地下水中砷的另一重要来源。受原生沉积环境和人为输入双重作用,三角洲平原区所形成的中性至弱碱性还原环境是高砷地下水赋存的主要成因。 相似文献
6.
岩溶地下河中砷迁移过程及其影响因素分析——以广西南丹县里湖地下河为例 总被引：2，自引：1，他引：1
以广西南丹县里湖地下河作为研究区,对砷在地下河中的存在形态,迁移过程及其影响因素进行了分析。结果发现,里湖地下河中砷浓度较高且与人类活动密切相关;由于地下河中相对较低的氧化还原环境,使毒性更强的 As（Ⅲ）含量超过 As（V）,占总无机砷的53%,增加了该地区发生砷中毒的风险;总 As、As （III）和 As（V）在地下河中衰减了51%、36%、59%。相关性分析结果表明,沉积物中的 Fe、Ca、Mn、有机质及水体中的 Ca2＋与沉积物中的砷呈现显著正相关关系,有助于水体中砷的吸收;而水体中的 Cl-、SO 2-4、HCO -3与沉积物中的砷呈现负相关关系,不利于砷的吸附,其中 HCO -3的抑制作用最为明显。与非岩溶区水体相比,Ca 和 HCO -3成为影响砷迁移转化的主要因素,因此在岩溶地下河砷污染治理中应考虑岩溶区的水文地质特点,提高砷的污染治理效率。 相似文献
7.
为了研究厌氧微生物作用下沉积物中砷的形态转化及固液界面的分配过程对砷的环境行为与归趋的影响,通过采集锦州湾清洁沉积物进行负载砷,利用微生物培养与非生物培养实验,对比研究厌氧微生物作用下砷铁硫共还原条件下污染体系中砷的环境行为与归趋。实验结果表明在培养的42 d周期内,液相的总砷量首先砷浓度保持降低趋势,而后再次升高。在培养第3~7 d时液相的As5+迅速被还原,约26%的溶解态砷从液相移除,97%以上的As5+被还原为As3+。同时微生物作用下固相中90%以上铁氧化物矿物逐渐转化为次生的亚铁矿物,固相中结晶态铁氧化物发生明显活化,而硫酸盐还原产物硫离子综合调控体系中游离的亚铁离子和As3+。因此,厌氧微生物还原条件下,砷,铁,硫同步发生还原,硫离子调控体系中砷和铁环境行为,硫化亚铁成为亚铁矿物的主要形态,硫化砷是砷的主要归趋。 相似文献
8.
硫酸盐还原菌是厌氧环境中参与砷形态转化的重要微生物种群,其介导的生物地球化学循环过程对铁氧化物表面吸附态砷迁移转化的影响亟待深入研究.选取江汉平原典型高砷含水层原位沉积物分离纯化出一株严格厌氧硫酸盐还原菌Desulfovibrio JH-S1,对其进行砷和铁还原能力鉴定,并通过模拟培养实验探究硫酸盐还原菌参与下的铁矿物相转化对吸附态砷迁移的影响.Desulfovibrio JH-S1具有Fe(III)还原能力,无硫和有硫体系中Fe(III)均能被还原,但在硫酸盐充足条件下铁还原量显著增加;该菌株不具备As(V)还原能力,但添加硫酸盐的培养体系中As(V)去除率可达96%以上.Desulfovibrio JH-S1能够还原硫酸盐从而促进载砷的水铁矿还原转化为纤铁矿,并导致吸附的砷释放.江汉平原高砷含水层土著硫酸盐还原菌兼具硫酸盐/铁还原功能,参与了高砷含水层系统中砷-铁-硫耦合循环,对高砷地下水的形成具有重要作用. 相似文献
9.
通过在滇池开展原位实验,研究探讨了湖泊沉积物中磷灰石制约水铁矿分解和转化的机制,以及二者共存时的环境效应。结果表明:将水铁矿放置到沉积物中1个月,矿物保持稳定;放置时间达到3个月时,添加磷灰石实验中水铁矿发生了显著物相转变。冬天(12—2月)实验中,转化产物随深度的变化趋势为针铁矿+磁(赤)铁矿→针铁矿+纤铁矿→针铁矿;夏天(6—9月)实验中,转化产物随深度的变化趋势为针铁矿+纤铁矿+磁(赤)铁矿→针铁矿+纤铁矿→未转化。透射电镜分析结果显示冬天实验中生成的磁性铁氧化物为纳米磁铁矿和磁赤铁矿,夏天实验中产生的则主要为纳米磁铁矿。X射线光电子能谱分析结果显示冬天表层实验样品具有较高P含量。分析表明的湖泊沉积物中磷灰石促进水铁矿转化的过程为:(1)微生物促进磷灰石溶解;(2)磷灰石溶解释放的P促进铁还原菌生长;(3)铁还原菌促进水铁矿还原;(4)水铁矿还原产生的溶解态Fe2+催化水铁矿向针铁矿、纤铁矿和磁铁矿转化。冬天及沉积氧化-还原界面最适宜磷灰石分解菌和铁还原菌生长,水铁矿的转化和P释放能力也更强,相应地内源磷释放的风险也更大。 相似文献
10.
11.
Arsenic species including arsenite, arsenate, and organic arsenic were measured in the porewaters collected from Poyang Lake, the largest freshwater lake of China. The vertical distributions of dissolved arsenic species and some diagenetic constituents [Fe(II), Mn(II), S(−II)] were also obtained in the same porewater samples in summer and winter. In sediments the concentration profiles of total As and As species bound to Fe–Mn oxyhydroxides and to organic matter were also determined along with the concentrations of Fe, Mn and S in different extractable fractions. Results indicate that, in the summer season, the concentrations of total dissolved As varying from 3.9 to 55.8 μg/L in sediments were higher than those (5.3–15.7 μg/L) measured in the winter season, while the concentrations of total As species in the solid phase varied between 10.97 and 25.32 mg/kg and between 7.84 and 30.52 mg/kg on a dry weight basis in summer and winter, respectively. Seasonal profiles of dissolved As suggest downward and upward diffusion, and the flux of dissolved As across the sediment–water interface (SWI) in summer and winter were estimated at 3.88 mg/m2 a and 0.79 mg/m2 a, respectively. Based on porewater profiles and sediment phase data, the main geochemical behavior of As was controlled by adsorption/desorption, precipitation and molecular diffusion. The solubility and migration of inorganic As are controlled by Fe–Mn oxyhydroxides in summer whereas they appear to be more likely controlled by both amorphous Fe–Mn oxyhydroxides and sulfides in winter. A better knowledge of the cycle of As in Poyang Lake is essential to a better management of its hydrology and for the environmental protection of biota in the lake. 相似文献
12.
Distribution of colloidal trace metals in the San Francisco Bay estuary 总被引：11，自引：0，他引：11
Sergio A. Sañudo-Wilhelmy Ignacio Rivera-Duarte A. Russell Flegal 《Geochimica et cosmochimica acta》1996,60(24):4933-4944
The size distribution of trace metals (Al, Ag, Cd, Cu, Fe, Mn, Ni, Sr, and Zn) was examined in surface waters of the San Francisco Bay estuary. Water samples were collected in January 1994 across the whole salinity gradient and fractionated into total dissolved (<0.2 μm colloidal (10 KDa–0.2 μm) and < 10 kDa molecular weight phases. In the low salinity region of the estuary, concentrations of colloidal A1, Ag, and Fe accounted for ≥84% of the total dissolved fraction, and colloidal Cu and Mn accounted for 16–20% of the total. At high salinities, while colloidal Fe was still relatively high (40% of the dissolved), very little colloidal Al, Mn, and Cu (<10%) and no colloidal Ag was detectable. Colloidal Zn accounted for <3% of the total dissolved along the estuary, and colloidal Ni was only detectable (<2%) at the river endmember. All of the total dissolved Cd and Sr throughout the estuary consisted of relatively low molecular weight (<10 kDa) species. The relative affinity of metals for humic substances and their reactivity with particle surfaces appear to determine the amounts of metal associated with colloids. The mixing behavior of metals along the estuary appears to be determined by the relative contribution of the colloidal phase to the total dissolved pool. Metals with a small or undetectable colloidal fraction showed a nonconservative excess (Cd, Cu, Ni, and Mn) or conservative mixing (Sr) in the total dissolved fraction, relative to ideal dilution of river water and seawater along the estuary.
The salt-induced coagulation of colloidal A1, Fe, and Cu is indicated by their highly nonconservative removal along the salinity gradient. However, colloidal metals with low affinity for humic substances (Mn and Zn) showed conservative mixing behavior, indicating that some riverine colloids are not effectively aggregated during their transport to the sea. While colloidal metal concentrations correlated with dissolved organic carbon, they also covaried with colloidal Al, suggesting that colloids are a mixture of organic and inorganic components. Furthermore, the similarity between the colloidal metal:A1 ratios with the crustal ratios indicated that colloids could be the product of weathering processes or particle resuspension. Distribution coefficients for colloidal particles (Kc) and for large, filter-retained particles (Kd) were of the same magnitude, suggesting similar binding strength for the two types of particles. Also, the dependence of the distribution coefficients on the amount of suspended particulate matter (the so-called particle concentration effect) was still evident for the colloids-corrected distribution coefficient (Kp+c) and for metals (e.g., Ni) without affinity for colloidal particles. 相似文献
13.
The vertical distributions of dissolved Se species [Se(IV), Se(VI) and organic Se] and diagenetic constituents [Fe(II) and Mn(II)] were obtained in porewater samples of two Sudbury area lakes (Clearwater and McFarlane). The sedimentary concentration profiles of total Se, Se species bound to Fe–Mn oxyhydroxides and to organic matter, and of elemental Se were also determined along with the concentrations of Fe, Mn and S in different extractable fractions. Results indicated that the concentrations of total dissolved Se in porewater samples were very low, varying from around 2.0 nM to a maximum level of 6.5 nM, while the concentrations of total Se species in the solid phase varied between 2 and 150 nmol/g on a dry weight basis. The two lakes showed striking differences in the presence of Se(IV) and Se(VI) at the sediment–water interface (SWI). In Clearwater Lake, Se(VI) was present at this interface and Se(IV) was not detectable, whereas the opposite was found in McFarlane Lake. This suggests that reducing conditions might have existed near the SWI of McFarlane Lake at the sampling time; this hypothesis was confirmed by several other measured chemical parameters. The profiles of total dissolved Se of both lakes suggest upward and downward diffusion of dissolved Se species along the concentration gradients. Assuming that no precipitation occurred at the SWI, the fluxes of dissolved Se species across the SWI in Clearwater and McFarlane lakes were estimated to be 0.108 and 0.034 nmol cm−2 a−1, respectively. These values do not include the possible losses of volatile Se species due to microbial methylation. In the reducing sediments of both lakes, the formation of elemental Se and pyritic Se were found to be important mechanisms for controlling the solubility of Se in this environment. The main geochemical processes involving Se identified in this study are: the adsorption of Se onto Fe–Mn oxyhydroxides at or near the SWI, the release of adsorbed Se by the reduction of the same oxyhydroxides and the mineralization of organic matter, and the removal of Se from porewaters to form elemental Se and a S mineral phase such as Se–pyrite or pure ferroselite. 相似文献
14.
科洛金矿床位于黑龙江省嫩江—黑河构造混杂岩带中,为一正在勘查的中型金矿床。前人研究认为该矿床为一中温、富水、低盐度的韧性剪切带型金矿床。但随着勘查工作的持续开展,新发现了大量含多金属硫化物的石英脉型矿石。为进一步明确该矿床成因,对科洛金矿床内韧性变形和浸染状-团块状两种不同产状黄铁矿进行了系统的成分标型及稳定同位素特征研究。结果表明:韧性变形黄铁矿较浸染-团块状黄铁矿的S/Fe值低,Au、Ag、Co含量高,As含量低,总体显示韧性变形黄铁矿相对贫硫;黄铁矿微量元素显示两类黄铁矿REE具有相似的地球化学特征,整体呈轻稀土富集、重稀土亏损的“右倾”式稀土配分模式。稀土元素总量为17.00×10-6~66.95×10-6,韧性变形黄铁矿含量明显偏低,LREE/HREE值为5.25~12.50,相对较稳定。Y/Ho值与地幔和地壳重合范围较多,Zr/Hf值、Nb/Ta值变化范围较大,显示成矿环境不稳定;黄铁矿3He含量为2.405×10-13~10.811×10-13,4He含量为3.35×10-7~4.99×10-7,3He-4He图和R/Ra-40Ar/36Ar图显示成矿流体有以地幔为主的壳幔混源特征,成矿过程应有大气降水的参与;黄铁矿δ34S变化范围小,集中在+2.3‰~+7.6‰(韧性变形黄铁矿δ34S平均值偏低),稍正向偏离陨石硫特征;黄铁矿的206Pb/204Pb=18.157~18.211;207Pb/204Pb=15.542~15.594;208Pb/204Pb=38.032~38.218(韧性变形黄铁矿的206Pb/204Pb、207Pb/204Pb、208Pb/204Pb平均值偏低),均显示与造山作用关系密切。利用黄铁矿化学成分特征元素Co/Ni值及Co-Ni成因判别图解认为科洛金矿有热液成因矿床特征;利用w(Fe+S)-w(As)图解和Co-Ni-As含量图解显示石英脉型矿石反映浅成低温热液型金矿特征。综合区域变质变形事件、典型矿床特征及矿区内已取得的年龄、流体包裹体等相关数据认为,科洛金矿床应存在两期矿化:三叠纪形成的韧性剪切带型金矿床和白垩纪形成的浅成低温热液型金矿床。建议在今后的矿产勘查中注意寻找真正的韧性剪切带型金矿。 相似文献
15.
Jitka &#x;pi
kov Irena Dobe&#x;ov Marek Vach Petr Sk&#x;ivan Martin Mihaljevi
Milo&#x; Burian 《Chemie der Erde / Geochemistry》2008,68(1):105-115
Atmospheric precipitation samples were collected in the Bohemian Karst (30 km SW from Prague, Czech Republic) at six localities in the vicinity of the limestone-quarry Čertovy schody during years 1996–2003. Samples were analyzed for major components (Na+, K+, Mg2+, Ca2+, F−, Cl−, NO3−, HCO3−, SO42−) and trace metals (Cu, Mn, Fe, Zn, Pb, Be, As, Sr, Cd, Al, Cr). Deposition fluxes were calculated from more than 10 000 elemental analyses of samples collected monthly. The fluxes of monitored substances show temporal and spatial variability. The most marked attribute is the strong affection by local emission sources confirmed by the investigation of seasonal variability, temporal trend and correlation analysis. 相似文献
16.
Environmental geochemistry of high arsenic groundwater at Hetao plain was studied on the basis of geochemical survey of the
groundwater and a core sediment. Arsenic concentration in groundwater samples varies from 76 to 1093 μg/L. The high arsenic
groundwater mostly appears to be weakly alkaline. The concentrations of NO3− and SO42− are relatively low, while the concentrations of DOC, NH4+, dissolved Fe and sulfide are relatively great. Analysis of arsenic speciation in 21 samples shows that arsenic is present
in the solution predominantly as As(III), while particulate arsenic constitutes about 10% of the total arsenic. Methane is
detected in five samples with the greatest content being 5107 μg/L. The shallow aquifer in Hangjinhouqi of western Hetao plain
is of strongly reducing condition. The arsenic content in 23 core sediment samples varies from 7.7 to 34.6 mg/kg, with great
value in clay and mild clay layer. The obvious positive relationship in content between Fe2O3, Mn, Sb, B, V and As indicates that the distribution of arsenic in the sediments may be related to Fe and Mn oxides, and
the mobilization of Sb, B and V may be affected by similar geochemical processes as that of As. 相似文献
17.
北方典型内陆盆地高砷地下水的水化学特征及处理技术 总被引：1，自引：0，他引：1
我国高砷地下水分布广泛,是受砷污染最严重的地区之一,严重危害居民身体健康,开发经济、高效、环境友好的高砷地下水修复治理技术极具必要性。以大同盆地、呼包平原、河套平原和银川平原为代表性研究区域,归纳总结了北方干旱、半干旱地区典型高砷地下水区水化学特征。通常情况下,高砷地下水的pH值较高,共存阴离子(HCO-3、SO2-4和Cl-)浓度较大,溶解性有机碳含量较高,并且As(Ⅲ)为主要砷形态。开展了针对北方典型高砷地下水特定水化学环境特点(如pH值、共存阴阳离子以及溶解性有机物等)的改性天然菱铁矿除砷性能研究。结果表明,改性天然菱铁矿对溶液pH值具有良好的缓冲能力,其除砷性能基本不受pH值、共存阴离子、Ca/Mg阳离子及以腐殖酸为代表的溶解性有机物等典型高砷地下水水化学特征因素的影响,表明吸附剂对砷具有良好的吸附选择性。另外,改性天然菱铁矿对As(Ⅲ)的去除效果优于对As(V)的去除效果,因此,利用改性天然菱铁矿作为反应介质材料,将其应用于处理主要以As(Ⅲ)形式存在的高砷地下水具备良好的发展前景。 相似文献
18.
花岗伟晶岩型矿床是稀有金属矿床重要的类型之一。在花岗伟晶岩中,稀有金属元素Li、Be、Nb和Ta主要以独立矿物的形式存在,前人对稀有金属独立矿物在硅酸盐熔体中的溶解度及其影响因素展开了系统研究。本文综合分析了已有的实验数据,其结果表明,影响稀有金属独立矿物溶解度最为重要的2个参数是温度(T)和铝饱和指数(ASI)。因此本文建立了稀有金属独立矿物,尤其是铌锰矿和钽锰矿溶解度,与温度(T)和铝饱和指数(ASI)之间的定量关系: lg [w(Li)/10-6]=-0.37×[1 000/(T/K)]+4.56,R2=0.44 lg [w(BeO)/10-6]=-4.21×[1 000/(T/K)]+6.86,R2=0.91 lg [Ksp(Nb)/(mg2·kg-2)]=-(2.86±0.14)×ASI(Mn+Li)-(4.95±0.31)×[1 000/(T/K)]+(4.20+0.28),R2=0.86 lg [Ksp(Ta)/(mg2·kg-2)]=-(2.46±0.11)×ASI(Mn+Li)-(4.86±0.30)×[1 000/(T/K)]+(4.00+0.30),R2=0.80 式中,温度T为热力学温度,ASI(Mn+Li)(ASI=Al2O3/(CaO+Na2O+K2O+Li2O+MnO),摩尔分数比)和T的适用范围分别为0.6~1.2和1 073~1 373 K的范围内。上述公式为估算硅酸盐熔体中稀有金属含量提供了便利,为量化花岗伟晶岩成矿模型提供了基础。 稀有金属独立矿物溶解度随温度降低和铝饱和指数的增加而急剧降低,因此,在岩浆演化过程中,由岩浆侵位、分离结晶以及流体作用等因素引起的岩浆温度降低和铝饱和指数的增加,是导致稀有金属独立矿物结晶的主要机制。 相似文献