共查询到19条相似文献，搜索用时 578 毫秒
1.
通过高温熔融，对同结线附近一系列硅酸盐熔体进行淬冷或不同速度冷却，实验获得的样品经过显微拉曼光谱分析，对比研究了AbxAnxDiy系列熔体在不同结线附近熔体结构跨相区变化情况，以及析出晶体对相应熔体结构的继承特点，熔体结构单元相对含量，在相界线两侧有某种程度的突变，熔体结构的变化对熔体的粘度，密度影响不同，拉曼光谱检测显示，硅酸盐玻璃的结构对降温速度变化不敏感，晶体对其相应熔体结构的部分继承作用，可能意味着晶体生长单元与熔体结构单元密切相关。 相似文献
2.
本研究报道的Ｆ对密度的影响，对Ｆ２Ｏ－１在明显加速重力驱动富Ｆ岩浆体系中的晶体－熔体分异过程中对花岗质熔体粘度降低的影响是一个补充。 相似文献
3.
吉伯特铁矿是新疆阿勒泰地区产于泥盆纪海相火山岩中的小型矿床。本文对吉伯特铁矿床的包裹体开展了研究,识别了熔体包裹体、熔体-流体包裹体以及富晶体的流体包裹体,并对其进行了初步的显微测温、激光拉曼光谱和电子探针等研究。熔体包裹体中含有富Si玻璃质、贫Si富Fe熔体、石英、萤石、方解石、磁铁矿等多种成分,它们分别组成不同的包裹体组合。熔体包裹体、熔体-流体包裹体和流体包裹体的存在表明它们被捕获时是一种熔体与流体共存的不混溶状态,这充分说明了吉伯特铁矿床的形成与岩浆熔体、岩浆-热液过渡性流体有直接的成因联系。吉伯特铁矿床中Fe的矿化是一个熔体相逐渐减少,流体相逐渐增加的连续演化过程,它受岩浆作用、岩浆-热液过渡性流体以及矽卡岩作用的共同制约。 相似文献
4.
本文讨论了MO-SiO_2二元熔体的结构与熔体热力学性质的相互关系。在低x_(sio_2)(X_(sio_2)<0.5)的这类熔体中,SiO_4~(4-)、Si_2O_7~(6-)、Si_3O_(10)~(8-)……及链状聚合物是熔体中的主要阴离子。聚合作用是决定熔体结构的主要机制。高x_(sio_2)(x_(sio_2)≥0.5)的二元熔体中出现环状及三维架状的阴离子聚合物。熔体不混溶性是这类熔体的普遍特征。在聚合模型的基础上,本文讨论了x_(sio_2)>0.5的二元熔体中的桥氧、非桥氧及自由氧离子在熔体中的分配及其与x_(sio_2)的关系。在动力学过程基础上推导出在熔体中服从Poission分布。最后对聚合反应平衡常数与聚合物链长及x_(sio_2)的关系进行了讨论。 相似文献
5.
6.
李迪恩 《矿物岩石地球化学通报》1997,(2)
硅酸盐玻璃和熔体中硅和铝的配位与局部结构：Ｋ边Ｘ射线吸收光谱研究＊李迪恩（中山大学地质系，广州５１０２７５）关键词硅酸盐玻璃和熔体硅和铝的配位Ｘ射线吸光谱高压下硅酸盐矿物和玻璃中的硅可以形成八面体配位［１］，但在通常的低压硅酸盐玻璃中，硅和铝为四面体... 相似文献
7.
水作为深熔熔体中最常见的一种挥发分,是影响熔体的物理和化学性质的主要因素.由于现有的测试技术以及熔体包裹体自身的局限性,很难定量确定熔体包裹体中水的含量和种型,导致对俯冲带熔体产生机制和演化过程的认识也极为有限.共聚焦显微激光拉曼光谱仪具有高的空间分辨率、快速、无损分析、样品制备简单等优点,且可分析暴露于表面或包裹于内部的样品,因此对探测微小熔体包裹体具有极大的优势.该方法的原理是基于拉曼谱峰高度/强度与其对应基团含量具有良好的线性关系,以人工合成硅酸盐玻璃为标准样品,用于硅酸盐熔体包裹体中水的含量和种型的定量限定.作为新发展起来的技术和方法,越来越多地引起地质学家的关注,但是目前大量的研究还集中于该分析方法自身的推演和校正,对天然样品的研究还相对缺乏.目前有限的研究表明,该方法可被广泛应用于岩浆岩和高级变质岩体系中,不仅可定量限定岩浆岩基质或斑晶中硅酸盐熔体包裹体水含量,有效示踪岩浆侵入或喷发过程中岩浆的流变学行为;而且可定量限定俯冲带内经历过部分熔融的高级变质岩中代表初始熔体的多晶矿物包裹体中水的含量和种型,示踪俯冲带熔体组成和演化,进而为研究深俯冲地壳分异、板片-地幔楔界面的熔体交代作用等重要问题提供新的制约. 相似文献
8.
硅酸盐熔体结构及水—熔体反应机理 总被引：4，自引：0，他引：4
本文对铝硅酸盐熔体结构这一领域的研究成果从以下三个方面作了总结：（１）熔体结构及其物理性质；（２）水－熔体反应机理；（３）熔体结构与压力的关系。熔体结构的变化是熔体粘度、密度、热膨胀性变化乃至粘流发生的根本原因，水与熔体的反应促使熔体粘度降低，不同的水溶解模式的建立是熔体结构研究深入的标志；压力对熔体结构的影响与温度和挥发份对它的影响大致相反，压力的增高使熔体结构产生加密效应，而温度的升高和挥发份 相似文献
9.
近年来研究表明岩浆的物理及化学性质与其熔体结构密切相关，因此熔体结构的研究对于理解岩浆的性质及岩动力学等与岩浆作用相关的地质问题是非常重要的。本文概括介绍了熔体结构的研究进展，着重讨论了熔体中熔体组分、温度及压力对熔体结构的影响。此外，并对硅酸盐熔体结构的研究意义进行了论述。 相似文献
10.
硅酸盐熔体中的（ＳｉＯ４）四面体借助于共同氧连接形成结构基团，使产生这种基团的作用称为聚合作用，聚合作用程度的差异是硅酸盐熔体结构多样性的主要原因，聚合作用随温度降低而增强。熔体结构在局部与其相应的晶体结构很相似，但在整体上，不象晶体那样，其原子在三维空间内连续有规则的排列且只含一种结构简单，而是多种结构单元可以共同存在于同一熔体中，且其位置和排列方式随原子不规则的热运动而不断地改变，在一定的温度 相似文献
11.
吉林蛟河地幔岩碎块是被碱性橄榄玄武岩岩浆喷发携带至地壳浅部或地表的。碱性橄榄玄武岩中地幔岩碎块含量40%~55%,局部达60%以上;碎块大小不等,一般直径以5~10 cm居多,大者达20~35 cm,故定名为地幔岩集块熔岩(岩流)。地幔岩碎块以尖晶石二辉橄榄岩和尖晶石斜辉橄榄岩碎块为主,纯橄榄岩次之,未发现石榴石橄榄岩;胶结物为碱性橄榄玄武岩岩浆。本次研究发现地幔岩内存在丰富的、不同成分和形态的熔融微区。熔融微区类型以其形状可分为滴状、扇状、球状、不规则状、短脉状和环边状,以其特征新生矿物分为OL型、K型、Na+Chl型、PL型、OL+SP型、C+SP型和SP+Chl+Ser型。熔融微区结构为玻基间隐结构或放射状结构;矿物呈骸晶状、中空为玻璃质;残余玻璃脱玻化,产生少量针状和不透明黑色雏晶。熔融微区的形状、结构、物质组成及矿物结晶等特征具有标型性,表征这些熔融体是在上地幔深度保存的幔源岩熔融交代的产物,幔源结晶岩是固相残留。该幔源岩经历强火山喷发使其发生爆炸的地质事件,导致K、Na、Al、Ca易熔组分和H2O、CO2等挥发分开始熔融和气体释放,营造快速固化结晶和淬火的环境。这些少量的熔融物择优占据矿物间隙、裂隙、位错或晶体缺陷处汇聚并熔融交代相邻矿物,不断扩展空间,遂形成滴状等特征形状的“微区”。由于熔融程度不同,产生的熔融物的化学成分和结晶程度也有差异,所代表的初始岩浆性质也不一样,可以是超基性或碱性橄榄玄武质,抑或碧玄岩质岩浆。从检测出的这些信息证实,蛟河地幔岩是被不一致熔融抽取后的地幔残留,即岩石圈地幔。 相似文献
12.
Cordierite–quartz and plagioclase–quartz intergrowths in a paragneiss from northern Labrador (the Tasiuyak Gneiss) were studied using SEM, STEM and TEM. The gneiss experienced granulite facies conditions and partial melting during both regional and, subsequently, during contact metamorphism. The microstructures examined all results from the contact metamorphism. Cordierite–quartz intergrowths occur on coarse and fine scales. The former sometimes exist as a ‘geometric’ intergrowth in which the interface between cordierite and quartz appears planar at the resolution of the optical microscope and SEM. The latter exists in several microstructural variants. Plagioclase is present as a minor component of the intergrowth in some examples of both the coarse and fine intergrowth. Grain boundaries in cordierite–quartz intergrowths are occupied by amorphous material or a mixture of amorphous material and chlorite. Cordierite and quartz are terminated by crystal faces in contact with amorphous material. Chlorite is sometimes found on cordierite surfaces and penetrating into cordierite grains along defects. Quartz contains (former) fluid inclusions 10–20 nm in maximum dimension. The presence of planar interfaces between cordierite and the amorphous phase is reminiscent of those between crystals and glass in volcanic rocks, but in the absence of compelling evidence that the amorphous material represents former melt, it is interpreted as a reaction product of cordierite. Plagioclase–quartz intergrowths occur in a number of microstructural variants and are commonly associated with cordierite–quartz intergrowths. The plagioclase–quartz intergrowths display simple, non‐planar interfaces between plagioclase and quartz. Quartz contains (former) fluid inclusions of dimensions similar to those observed in cordierite–quartz intergrowths. The boundary between quartz and enclosing K‐feldspar is cuspate, with quartz cusps penetrating a few tens of nanometres into K‐feldspar, commonly along defects in K‐feldspar and sometimes with very low dihedral angles at their tips. This cuspate microstructure is interpreted as melt pseudomorphs. The plagioclase–quartz intergrowths share some features with myrmekite, but differ in some respects: the composition of the plagioclase (An37Ab62Or1–An38Ab61Or1); the association with cordierite–quartz intergrowths; and microstructures that are atypical of myrmekite (e.g. quartz vermicules shared with cordierite–quartz intergrowths). It is inferred that the plagioclase–quartz intergrowths may have formed from, or in the presence of, melt. Inferred melt‐related microstructures preserved on the nanometre scale suggest that melt on grain boundaries was more pervasive than is evident from light optical and SEM observations. 相似文献
13.
Phase equilibria modelling of residual migmatites and granulites: An evaluation of the melt‐reintegration approach 
下载免费PDF全文
下载免费PDF全文 Omar Bartoli 《Journal of Metamorphic Geology》2017,35(8):919-942
Suprasolidus continental crust is prone to loss and redistribution of anatectic melt to shallow crustal levels. These processes ultimately lead to differentiation of the continental crust. The majority of granulite facies rocks worldwide has experienced melt loss and the reintegration of melt is becoming an increasingly popular approach to reconstruct the prograde history of melt‐depleted rocks by means of phase equilibria modelling. It involves the stepwise down‐temperature reintegration of a certain amount of melt into the residual bulk composition along an inferred P–T path, and various ways of calculating and reintegrating melt compositions have been developed and applied. Here different melt‐reintegration approaches are tested using El Hoyazo granulitic enclaves (SE Spain), and Mt. Stafford residual migmatites (central Australia). Various sets of P–T pseudosections were constructed progressing step by step, to lower temperatures along the inferred P–T paths. Melt‐reintegration was done following one‐step and multi‐step procedures proposed in the literature. For El Hoyazo granulites, modelling was also performed reintegrating the measured melt inclusions and matrix glass compositions and considering the melt amounts inferred by mass–balance calculations. The overall topology of phase diagrams is pretty similar, suggesting that, in spite of the different methods adopted, reintegrating a certain amount of melt can be sufficient to reconstruct a plausible prograde history (i.e. melting conditions and reactions, and melt productivity) of residual migmatites and granulites. However, significant underestimations of melt productivity may occur and have to be taken into account when a melt‐reintegration approach is applied to highly residual (SiO2 <55 wt%) rocks, or to rocks for which H2O retention from subsolidus conditions is high (such as in the case of rapid crustal melting triggered by mafic magma underplating). 相似文献
14.
本文根据核爆炸岩石熔融玻璃的地球化学研究结果,与超速陨石撞击坑的熔岩进行比较,获得在远离热力学平衡条件下,各种玻璃和熔岩在化学成分上分布十分均匀的重要结论。岩石玻璃和熔岩是由基岩各组成岩石按一定比例混合熔融形成的。它们的主量元素和痕量元素丰度受基岩元素背景值制约。文中根据熔体和靶岩的化学成分,计算了熔岩各组成岩石的百分比。玻璃陨石是地壳岩石受撞击熔融形成的。同一撒布区的玻璃陨石化学成分相近,说明起源于同一源坑;而玻璃陨石化学成分的不同,则说明母岩组成分量的差异。因此,文中通过模拟计算,得出各玻璃陨石的组成源岩。澳大利亚撒布区的玻璃陨石,Al2O3,K2O 和Na2O 与 SiO2及 K2O/Na2O 比值不完全相同,说明澳大利亚撒布区存在着几个不同的源岩和源坑,至少有印支、爪哇、菲律宾和澳大利亚四个相应撞击坑。 相似文献
15.
Compositional variations are documented in friction melts along the Hari Hari section of the Alpine Fault, New Zealand, with multiple stages of melt injection into quartzo-feldspathic schists. Intermediate to felsic melts were heterogeneous in composition, but all fractions show a common trend, with a tendency for the younger melt layers and glasses to be more alkali − (Na + K) and Si-enriched, while being depleted in mafic (Fe + Mg + Mn) components. These changes are attributed primarily to crystal fractionation of the melt during transport. Farther traveled molten layers were on the whole less viscous, mostly due to a higher melt-to-clast ratio; however, compositional change, together with a decrease in volatile content, produced a progressively more viscous liquid melt with time. The glass phase is interpreted as a remnant of this high viscosity felsic residual melt that was preserved during final quenching. Following initial failure, the formation of largely phyllosilicate-derived, volatile-rich, lower viscosity melt corresponds with a phase of fault weakening. Subsequent rapid crystal fractionation during melt transport, the loss of volatiles and freezing of residual melt contributed to the strengthening of the fault during seismic slip. 相似文献
16.
以合成花岗岩、水、不同浓度的盐酸溶液、氢氟酸溶液作为反应初始物,在850℃,100 MPa,接近于NNO的条件下开展了金在不同花岗质熔体中溶解度的实验研究,实验固液相产物中的金含量使用石墨炉原子吸收法测定。实验结果显示,金在花岗质熔体中的溶解度变化范围为1.87～156.62μg/g,流体相中金的溶解度为0.31～6.92μg/g;金在熔体相中的溶解度较其在共存液相中的高。花岗质熔体相中金的溶解度明显受熔体化学组成的影响,过碱性富钠花岗质熔体中金的溶解度明显高些;金在花岗质熔体中的溶解度随着熔体中Na2O/K2O摩尔比增大而增大;在氟氯共存岩浆体系中,氟含量变化对金在熔体相中的溶解度影响不明显,而液相中氯含量增大有利于提高金在流体相中的含量。 相似文献
17.
Physical properties and the crystallization behavior of natural diaplectic labradorite glass of the shocked anorthosite from the Manicouagan impact crater have been studied. Glasses prepared by laboratory fusion of this anorthosite and a synthetic An55 plagioclase composition were used for comparison. The close similarities in the mid-and far-infrared spectra of the diaplectic and fused glasses indicate a comparable degree of short-range order and lack of long-range order in their structures. They also show an identical viscosity-temperature relation, reflecting a similar and probably high degree of coherence of the (Si,Al)O4 tetrahedra in the network. However, striking differences exist in the crystallization characteristics. Diffusion-controlled crystallization takes place in the fused glass between about 900 and 1,400° C and proceeds generally by the advance of dendritic crystal layers from the surface into the interior of the samples. By contrast, diffusion plays a minor, if any, role in the crystallization of the diaplectic glass, which, on annealing between 800 and 1,000° C reverts to the original plagioclase structure and the primary mineral grains are restored. From the present experimental results it is suggested that high shock-induced temperatures cause onset of the melting process in the compressed crystalline labradorite. However, due to the extremely short duration of the transient high-temperature excursions, the crystal-melt transition does not come to completion. Instead, a disordered transitional state of the compressed material is frozen-in which is recovered after pressure release as diaplectic glass. Its structure thus represents a frozen-in disordered state intermediate between the structures of the crystalline labradorite and its melt. It appears that the diaplectic glass structure is rather inhomogeneous, thereby reflecting the heterogeneous deformational and thermal conditions associated with shock compression. 相似文献
18.
岩浆作用的物理过程研究进展 总被引：8，自引：0，他引：8
概略地介绍了８０年代以来硅酸盐熔体及硅酸盐晶－液悬浮体的密度、粘度、熔体结构、流全动力学等方面的研究动向,及其对岩浆作用、岩浆运移、岩浆侵位机制的动力学约束条件,硅酸盐熔体的结构是制约熔粘度的主导因素,化学成分对熔体匠控制是通过改变熔体结构而实现的,粘度在一定程度上决定着岩浆的迁移、侵痊和喷发方式。密度和浮力是岩浆上升侵位的重要约束,地壳是岩交涉升的一个密度过滤器岩浆最终由于浮和的消失而停止上升。 相似文献
19.
S. FERRERO O. BARTOLI B. CESARE E. SALVIOLI‐MARIANI A. ACOSTA‐VIGIL A. CAVALLO C. GROPPO S. BATTISTON 《Journal of Metamorphic Geology》2012,30(3):303-322
The occurrence of crystallized and glassy melt inclusions (MI) in high‐grade, partially melted metapelites and metagraywackes has opened up new possibilities to investigate anatectic processes. The present study focuses on three case studies: khondalites from the Kerala Khondalite Belt (India), the Ronda migmatites (Spain), and the Barun Gneiss (Nepal Himalaya). The results of a detailed microstructural investigation are reported, along with some new microchemical data on the bulk composition of MI. These inclusions were trapped within peritectic garnet and ilmenite during crystal growth and are therefore primary inclusions. They are generally isometric and very small in size, mostly ≤15 μm, and only rarely reaching 30 μm; they occur in clusters. In most cases inclusions are crystallized (‘nanogranites’) and contain a granitic phase assemblage with quartz, feldspar and one or two mica depending on the particular case study, commonly with accessory phases (mainly zircon, apatite, rutile). In many cases the polycrystalline aggregates that make up the nanogranites show igneous microstructures, e.g. granophyric intergrowths, micrographic quartz in K‐feldspar and cuneiform rods of quartz in plagioclase. Further evidence for the former presence of melt within the investigated inclusions consists of melt pseudomorphs, similar to those recognized at larger scale in the host migmatites. Moreover, partially crystallized inclusions are locally abundant and together with very small (≤8 μm) glassy inclusions may occur in the same clusters. Both crystallized and partially crystallized inclusions often display a diffuse nanoporosity, which may contain fluids, depending on the case study. After entrapment, inclusions underwent limited microstructural modifications, such as shape maturation, local necking down processes, and decrepitation (mainly in the Barun Gneiss), which did not influence their bulk composition. Re‐homogenized nanogranites and glassy inclusions show a leucogranitic and peraluminous composition, consistent with the results of partial melting experiments on metapelites and metagraywackes. Anatectic MI should therefore be considered as a new and important opportunity to understand the partial melting processes. 相似文献