以合成雪硅钙石为晶种回收废水中的磷

以合成雪硅钙石为晶种,探索了用结晶法以磷酸钙形式回收废水中磷的适宜条件。结果表明,在实验水质条件下,模拟废水pH=8、n(Ca)/n(P)=2、晶种用量大于1.6g/L、振荡24h后溶液中残留磷可达到国家污水综合排放标准一级(0.5mg/L)以下;在优化条件下证实了合成雪硅钙石的供碱能力,循环利用18次,回收磷的效果仍然很好。运用XRD、FTIR、SEM和EDS等测试手段对在实验条件下重复使用18次的雪硅钙石进行了表征,证明回收的磷主要以结晶度不高的羟基磷灰石形态存在。     

峨眉山大火成岩省晚期酸性火山岩的岩石地球化学特征

峨眉山大火成岩省出露有少量酸性火山岩,它们与基性火山岩共生,表现出双峰式的特征,为研究峨眉山地幔柱晚期岩浆活动提供了重要的窗口。本文通过对双峰式火山岩主、微量元素和斑晶电子探针分析研究表明,基性火山岩属于碱性玄武岩,酸性火山岩主要由粗面岩组成;相对玄武岩,粗面岩中MgO、Fe2O3、P2O5、TiO2、CaO含量明显降低;粗面岩与玄武岩具有相互平行的REE配分模式,但粗面岩出现明显的Eu负异常,以及Sr、Ti等元素的强烈亏损;粗面岩与玄武岩具有同源的特征,通过稀土元素模拟计算表明粗面岩可以由玄武质岩浆经过80%分离结晶作用(辉石、斜长石和Fe-Ti氧化物)而形成。在峨眉山大火成岩省晚期出现双峰式火山岩,可能与地幔柱活动晚期岩浆供给少,在地壳岩浆房中停留时间长,岩浆发生强烈分离结晶作用有关。     

岩石学混合计算在岩浆结晶分异作用研究中的应用——以云南白马寨镍矿区煌斑岩为例

公式CLi=F为岩浆结晶分异过程中的微量元素地球化学模型,但如何确定式中残余熔体的重量百分比(F)和熔体中分离出来的矿物相的总分配系数(Di)一直是个难题。本文介绍了一种直接计算出残余熔体比例(F)和岩浆结晶矿物比例(以此计算出Di)的方法———岩石学混合计算法的基本原理,以云南白马寨镍矿区煌斑岩为例,介绍了该方法在岩浆结晶分异作用研究中的应用。(Di-1)iC0,L     

滦平球状闪长岩岩相学特征和球状构造成因探讨

文章对滦平球状闪长岩作了详细的岩相学研究，并据此提出岩体中球状构造的形成机理。根据球核的不同，可将球分为三种类型，包括以同源岩浆组分为核的球、以异源捕虏体为核的球和没有明显壳层结构的球。球中壳层一方面表现为基本不含角闪石的浅色层和含有一定角闪石的暗色层交替发育的矿物组成韵律，另一方面表现为斑状半自形一它形斜长石梳状层与细粒半自形一自形斜长石层互层的矿物结构韵律。球中斑状斜长石显示清晰的格子双晶，而主岩和基质中的斜长石则为聚片双晶。研究表明，所描述的球状构造是通过岩浆同化捕虏体和岩浆结晶综合作用形成的。球壳的矿物组成韵律和矿物结构韵律受岩浆中水含量变化的控制。     

Cumulate and Cumulative Granites and Associated Rocks

Abstract. Processes that move crystals relative to melt, that is crystal fractionation, are of major importance in producing variations that are observed within cogenetic suites of granites. In low‐temperature granite suites, crystal fractionation initially involves the progressive separation of crystals residual from partial melting from that partial melt. Once separation of those crystals, or restite, has been completed, further fractionation may occur through the separation of crystals that had precipitated from the melt, the process known as fractional crystallization. High‐temperature granite magmas are largely or completely molten and elements such as Ca, Mg and Fe, and their associated minor elements, are in that case dissolved in the melt. Such magmas, particularly those that are more potassic and hence contain a higher fraction of low temperature melt, may evolve compositionally through fractional crystallization. Cumulate rocks result, comprising a framework of cumulus minerals with interstitial melt. In this process some of the melt is also displaced to form more felsic rocks. Such cumulate rocks may have distinctive chemical compositions, but that is often not the case. Distinctive features include SiC>2 contents near or below 50 % in rocks that are transitional in the field to more felsic granites, very high Cr and Ni, very low K, P, Ba, Rb and Zr, and anomalous abundances of the anorthite components Ca and Al. These rocks may also have positive Eu anomalies. Cumulate rocks do not necessarily have distinctive textures, at least as such features are understood at this time. Fractional crystallization can also involve the movement of precipitated crystals relative to melt. We refer to rocks as cumulative when formed from the fractions in which the abundance of crystals has increased. The production of cumulative granites typically occurs at more felsic melt compositions than is the case for cumulate granites, and this process may have its greatest significance in the fractional crystallization of the felsic haplogranites. Relative to felsic granites of broadly similar compositions lying on a liquid line of descent, cumulative granites contain more Ca, reflecting the addition from elsewhere of plagioclase crystals with solidus compositions. The abundances of Sr and Ba may be high to very high, and sometimes there are positive Eu anomalies. Cumulative I‐type granites may have low abundances of Y and the heavy REE, while the S‐type granites can be very distinctive with anomalously high abundances of Th and the heavy REE resulting from the concentrating of monazite. Generally, but not always, those who propose fractional crystallization as a mechanism for producing compositional variation within a suite of granites do not state whether the rocks in that particular case are thought to lie on a liquid line of descent or are cumulates/cumulative, although it is generally presumed that they were melts. Our experiences in eastern Australia have shown that the mechanism of fractional crystallization was quantitatively not as important during granite evolution as many workers would expect. However, there are some excellent examples of that process, most notably the Boggy Plain Supersuite. Overall in eastern Australia, varying degrees of separation of restite is a much more common mode of crystal fractionation, and that may also be seen to be the case for some other granite provinces if they are examined with that possibility in mind.     

Intensive Variables in Kimberlite Magmas, Lac de Gras, Canada and Implications for Diamond Survival

Crystallization temperatures (T) and oxygen fugacities (fO₂)of kimberlite magma are estimated from oxides included in olivinephenocrysts from the Leslie, Aaron, Grizzly and Torrie kimberlitepipes in the central Slave Province, Canada. Crystallizationtemperatures recorded by olivine–chromite pairs at anassumed pressure of 1·0 GPa are 1030–1170°C± 50°C, with a mean of     

岩浆岩中的熔体包裹体

熔体包裹体是岩浆岩矿物生长过程中捕获的天然岩浆珠滴 ,它们有效地保存了大量有关其主矿物形成时周围岩浆介质的物理化学信息 ,所以它们是其主矿物结晶演化史的忠实记录员 ,它们能够提供岩浆系统成分和演化的重要信息。文中对熔体包裹体研究的若干基本原理进行了讨论 ,它们涉及 :(1)熔体包裹体的一般特征 ;(2 )熔体包裹体封闭过程中和封闭后的演化 ;(3)熔体包裹体的均一化研究 ;(4 )熔体包裹体化学成分和挥发组分研究。熔体包裹体研究可以对岩浆岩石学中的一些重要问题进行更为深入的探索 :(1)重建天然岩浆结晶演化的热历史 ;(2 )提供有关岩浆沿下降液相线的成分数据 ;(3)查明天然岩浆结晶演化过程中化学成分的变迁规律 ;(4 )解决岩浆岩石学中的一些疑难问题 ,如岩浆不混溶作用、岩浆混合作用、岩浆混染作用、岩浆中硫的性状、地幔部分熔融和地幔交代作用等方面的问题。将熔体包裹体数据和常规的岩石学、地球化学和实验岩石学信息综合一体 ,可以提高我们模拟岩浆作用过程的能力。熔体包裹体研究已经成为现代岩浆岩石学的一个独立的分支 ,其前景十分广阔。     

Crystal fractionation in the petrogenesis of an alkali monzodiorite–syenite series: the Oshurkovo plutonic sheeted complex, Transbaikalia, Russia

The Oshurkovo Complex is a plutonic sheeted complex which represents numerous successive magmatic injections into an expanding system of subparallel and subvertical fractures. It comprises a wide range of rock types including alkali monzodiorite, monzonite, plagioclase-bearing and alkali-feldspar syenites, in the proportion of about 70% mafic rocks to 30% syenite. We suggest that the variation within the complex originated mainly by fractional crystallization of a tephrite magma.

The mafic rocks are considered as plutonic equivalents of lamprophyres. They exhibit a high abundance of ternary feldspar and apatite, the latter may attain 7–8 vol.% in monzodiorite. Ternary feldspar is also abundant in the syenites. The entire rock series is characterized by high Ba and Sr concentrations in the bulk rock samples (3000–7000 ppm) and in feldspars (up to 1 wt.%). The mafic magma had amphibole at the liquidus at 1010–1030 °C based on amphibole geothermometer. Temperatures as low as this were due to high H₂O and P₂O₅ contents in the melt (up to 4–6 and 2 wt.%, respectively). Crystallization of the syenitic magmas began at about 850 °C (based on ternary feldspar thermometry). The series was formed at an oxygen fugacity from the NNO to HM buffer, or even higher.

The evolution of the alkali monzodiorite–syenite series by fractional crystallization of a tephritic magma is established on the basis of geological, mineralogical, geochemical and Sm–Nd and Rb–Sr isotope data. The geochemical modeling suggests that fractionation of amphibole with subordinate apatite from the tephrite magma leaves about 73 wt.% of the residual monzonite melt. Further extraction of amphibole and plagioclase with minor apatite and Fe–Ti oxides could bring to formation of a syenite residuum. Rb–Sr isotopic analyses of biotite, apatite and whole-rock samples constrain the minimum age of basic intrusions at ca. 130 Ma and that of cross-cutting granite pegmatites at ca. 120 Ma. Hence the entire evolution took place in an interval of ≤10 My. Initial ⁸⁷Sr/⁸⁶Sr ratios for the mafic rocks range from 0.70511 to 0.70514, and for syenites from 0.70525 to 0.70542. Initial _Nd (130 Ma) values for mafic rocks vary from −1.9 to −2.4, and for syenites from −2.9 to −3.5. In a _Nd(T) vs. (⁸⁷Sr/⁸⁶Sr)_i diagram, all rock types of the complex fall in the enriched portion of the Mantle Array, suggesting their derivation from a metasomatized mantle source. However, the small but distinguishable difference in Sr and Nd isotopic compositions between mafic rocks and syenites probably resulted from mild (10–20%) crustal contamination during differentiation. Large negative Nb anomalies are interpreted as a characteristic feature of the source region produced by Precambrian fluid metasomatism above a subduction zone rather than by crustal contamination.     

富锂氟含稀有矿化花岗质岩石的对比和成因思考

Li-F花岗质岩石以超酸性、过铝、富含H2O、F、B、P等挥发性组分和富含Li、Rb、Cs、Be、Ta、Nb、Sn、W等亲石稀有金属元素为主要特征，以黄玉－锂云母－钠长石花岗岩为典型代表。从该类岩石地质产状的多样性和可对比性、空间分布的规律性、矿物岩石的结构构造、硅酸盐－熔体包裹体特征以及实验岩石学的研究成果等方面，综合论证该类岩石主要是从经过分异演化而形成的残余熔浆中直接结晶而在的；充分的分离结晶作用，是产生这种残余熔浆的主要机制；岩体的空间分带特征和各带之间的渐变过渡关系，为分离结晶作用的途径和演化方向提供了重要信息；熔体中挥发性组分的大量存在，是分离结晶作用能充分进行的关键因素；亲石稀有金属元素在流／熔配分中倾向于进入熔体相，是残余熔体中逐步富集这些稀有金属元素的主要原因；岩浆－热液过渡阶段出溶的流体相与已晶出的共存固相之间的相互作用，造成了广泛的交代蚀变现象；残余熔浆在不同地质和物理化学环境中的侵位、结晶和演化，造成了Li-F花岗质岩石在产状、结构构造和矿物组合等方面的多样性。     

Mechanisms of magmatic gas loss along the Southeast Indian Ridge and the Amsterdam -St. Paul Plateau

New analyses of He, Ne, Ar and CO₂ trapped in basaltic glasses from the Southeast Indian Ridge (Amsterdam-St. Paul (ASP) region) show that ridge magmas degas by a Rayleigh distillation process. As a result, the absolute and relative noble gas abundances are highly fractionated with ⁴He/⁴⁰Ar* ratios as high as 620 compared to a production ratio of ∼3 (where ⁴⁰Ar* is ⁴⁰Ar corrected for atmospheric contamination). There is a good correlation between ⁴He/⁴⁰Ar* and the MgO content of the basalt, suggesting that the amount of gas lost from a particular magma is related to the degree of crystallization. Fractional crystallization forces oversaturation of CO₂ because CO₂ is an incompatible element. Therefore, crystallization will increase the fraction of gas lost from the magma. The He-Ar-CO₂-MgO-TiO₂ compositions of the ASP basalts are modeled as a combined fractional crystallization-fractional degassing process using experimentally determined noble gas and CO₂ solubilities and partition coefficients at reasonable magmatic pressures (2-4 kbar). The combined fractional crystallization-degassing model reproduces the basalt compositions well, although it is not possible to rule out depth of eruption as a potential additional control on the extent of degassing. The extent of degassing determines the relative noble gas abundances (⁴He/⁴⁰Ar*) and the ⁴⁰Ar*/CO₂ ratio but it cannot account for large (>factor 50) variations in He/CO₂, due to the similar solubilities of He and CO₂ in basaltic magmas. Instead, variations in CO₂/³He (≡C/³He) trapped in the vesicles must reflect similar variations in the primary magma. The controls on C/³He in mid-ocean ridge basalts (MORBs) are not known. There are no obvious correlated variations between C/³He and tracers of mantle heterogeneity (³He/⁴He, K/Ti etc.), implying that the variations in C/³He are not likely to be a feature of the mantle source to these basalts. Mixing between MORB-like sources and more enriched, high ³He/⁴He sources occurs on and near the ASP plateau, resulting in variable ³He/⁴He and K/Ti compositions (and many other tracers). Using ⁴He/⁴⁰Ar* to track degassing, we demonstrate that mixing systematics involving He isotopes are determined in large part by the extent of degassing. Relatively undegassed lavas (with low ⁴He/⁴⁰Ar*) are characterized by steep ³He/⁴He-K/Ti mixing curves, with high He/Ti ratios in the enriched magma (relative to He/Ti in the MORB magma). Degassed samples (high ⁴He/⁴⁰Ar*) on the other hand have roughly equal He/Ti ratios in both end-members, resulting in linear mixing trajectories involving He isotopes. Some degassing of ASP magmas must occur at depth, prior to magma mixing. As a result of degassing prior to mixing, mixing systematics of oceanic basalts that involve noble gas-lithophile pairs (e.g. ³He/⁴He vs. ⁸⁷Sr/⁸⁶Sr or ⁴⁰Ar/³⁶Ar vs. ²⁰⁶Pb/²⁰⁴Pb) are unlikely to reflect the noble gas composition of the mantle source to the basalts. Instead, the mixing curve will reflect the extent of gas loss from the magmas, which is in turn buffered by the pressure of combined crystallization-degassing and the initial CO₂ content.