一种可能的棕闪煌斑岩变异新种—棕闪钠煌岩

浏阳县蕉溪岭岩体中发现富钠煌斑岩,Na_2O为4.05％,主要矿物钠长石为32—51％,棕闪石为25—37％,其他矿物钾长石2—8％,单斜辉石1—10％,黑云母0.5—10％,钛铁矿1—5％,可能是已知棕闪煌斑岩的一个变异新种棕闪钠煌岩。它与花岗岩体有空间上的共生关系,可能属蕉溪岭花岗岩熔离分异或结晶分异演化过程的产物。     

Ultraviolet-blue ionic luminescence of alkali feldspars from bulk and interfaces

Laboratory driven ionic thermal exchange of alkali feldspars from K to Na produces samples which are strongly luminescent in the ultraviolet region near 320 nm. The sites providing this luminescence are suggested as being correlated with the motion of Na atoms along interface-interphases of the material (i.e. with Na-O bond fracture). The thermoluminescence peaks show multi-order kinetics. Thermal preheatings of low albite sensitize the feldspar lattice with respect to thermoluminescence generated by exposure to UV irradiation and heating produces a strong blue luminescence spread over the range 350 nm to 500 nm band in feldspars. The upper temperature for thermoluminescence in feldspars is ∼300 °C, which is also the point where ionic conductivity of albite (010) begins, but the 300 °C region is also the starting point of a large second glow peak in adularia. Whilst it seems appropriate to link the Na motion to the 350–500 nm emission, it is unclear whether these changes are the result of the large anisotropic thermal vibration of Na atoms or the massive Na jumps that occur when the lattice reaches 300 °C. A speculative model is considered in which the UV TL emissions of natural minerals are linked to different interface-interphases (grain boundaries, exsolution limits, twinning planes, antiphase domains). Increased interface coherency energies are related to the kinetic order and the spectral position of luminescence emission peaks. Received: 3 December 1998 / Revised, accepted: 17 April 1999     

Grands gisements d'albite dans le massif métamorphique de Menderes (Turquie occidentale)

Albite deposits of western Turkey occur within gneiss in the basal part of the Menderes Metamorphic Massif. The most important deposits are located along the Karadere mineralization zone, within an anticlinorium of 15-km length with a direction of N10–30E. Detailed study of the four deposits forming the northern part of this zone has allowed us to discover large reserves of 100.65 million tons, of which 78% is composed of high-grade ore with a content of 10.27% Na₂O. The remainder is formed by low-grade ore with 8.37% Na₂O and 1.11% K₂O and mixed ore with 4.61% Na₂O and 4.05% K₂O, with reserves of 14.4 and 8.2 million tons, respectively. To cite this article: U. Çak?r, C. R. Geoscience 337 (2005).     

衡山县马迹钠长石矿床地质特征及成矿规律

马迹钠长石矿床产于衡山县白石峰花岗岩岩体西侧的混合岩带中,矿带走向北东—南西向,全长28km,其中马迹一带最为集中,矿床规模巨大。矿体呈透镜状、巨厚的板状及复杂的树枝状。矿石含Na_2O平均在9％以上。矿床与区内岩浆活动有密切关系,并且受控于北东向及北西向断裂中。岩浆期后的热液活动促使构造带附近围岩广泛钠化,形成良好的钠长石矿,钠质岩石在后期的风化作用下形成规模巨大的高岭土矿床。     

Geology,geochemistry and genesis of the Makou magnetite-apatite deposit in the Luzong volcanic basin,Middle-Lower Yangtze River Valley Metallogenic Belt,Eastern China

The Middle-Lower Yangtze River Valley Metallogenic Belt (MLYB) is located on the northern margin of the Yangtze Plate (Eastern China). Ore deposits in the belt are mainly clustered in seven ore districts, and are closely associated with Mesozoic intermediate-felsic magmatic rock. Among the seven ore districts, the Luzong and Ningwu districts host large-scale iron resources in volcanic basins. The Makou magnetite-apatite deposit in the southern Luzong Basin was previously interpreted to be related to a quartz syenite porphyry. In this study, we conducted field geological studies and determined the age and geochemistry of the Makou intrusive rocks. Petrography and electron probe micro analysis (EPMA) indicated that the Makou ore-hosting rocks have intense albite alteration. The wallrock alteration is spatially restricted, and comprises albite alteration (Stage I), magnetite mineralization (Stage II), quartz-sulfide alteration (Stage III) and carbonate alteration (Stage IV) stages. Fluid inclusions in syn-mineralization apatite homogenized at 252.2–322.6 °C, which slightly lower than is typical for magnetite-apatite deposits in the region. Field study revealed that the quartz syenite porphyry at Makou disrupted the orebodies along clear-cut intrusive contacts, and that the quartz syenite porphyry does not contain iron mineralization, suggesting it has no direct genetic relationship with the iron mineralization. The ore-hosting albitite and ore-forming biotite diorite have LA-ICP-MS zircon U-Pb ages of 129.6 ± 1.2 Ma and 131.2 ± 3.3 Ma, respectively, and the iron mineralization was dated by mass spectrometer phlogopite ⁴⁰Ar-³⁹Ar at 130.76 ± 0.77 Ma. We propose that the Makou magnetite-apatite deposit is genetically related to the biotite diorite, rather than to the quartz syenite porphyry in the mine pit. The biotite diorite closely resembles intrusions related to magnetite-apatite deposits elsewhere in the region.     

Transport properties of high albite crystals,near-endmember feldspar and pyroxene glasses,and their melts to high temperature

Thermal diffusivity (D) was measured using laser-flash analysis (LFA) from oriented single-crystal albite and glasses near LiAlSi₃O₈, NaAlSi₃O₈, CaAl₂Si₂O₈, LiAlSi₂O₆ and CaMgSi₂O₆ compositions. Viscosity measurements of the supercooled liquids, over 2.6 × 10⁸ to 8.9 × 10¹² Pa s, confirm strongly non-Arrhenian behavior for CaAl₂Si₂O₈, and CaMgSi₂O₆, and near-Arrhenian behavior for the others. As T increases, D _glass decreases, approaching a constant near 1,000 K. Upon crossing the glass transition, D decreases rapidly. For feldspars, D for the melt is ~15% below D of the bulk crystal, whereas for pyroxenes, this difference is ~40%. Thermal conductivity (k _lat = ρC _P D) of crystals decreases with increasing T, but k _lat of glasses increases with T because heat capacity (C _P ) increases with T more strongly than density (ρ) and D decrease. For feldspars, k _lat for the melt is ~10% below that of the bulk crystal or glass, whereas this decrease for pyroxene is ~50%. Therefore, melting substantially impedes heat transport, providing positive thermal feedback that could promote further melting.     

川西甲基卡花岗伟晶岩的锂铍成矿作用过程——来自308号脉流体包裹体的约束

甲基卡位于松潘-甘孜造山带内,为特大型花岗伟晶岩型锂-铍矿床。前人以锂辉石中发育的富子晶包裹体为研究对象,着重剖析了甲基卡锂成矿的物理化学条件。然而,就伟晶岩熔（流）体的演化过程,特别是稀有金属成矿的富集机制和物理化学条件,仍缺乏有效制约。308号脉作为甲基卡出露最大的钠长石型锂-铍伟晶岩脉,具有良好的内部分带,较完整地记录了甲基卡伟晶岩结晶演化过程。本文以308号伟晶岩脉为研究对象,开展了系统的流体包裹体研究工作。308号脉较早阶段的结晶介质以外带绿柱石中富子晶流体包裹体为代表,为高温（492~592℃）、低盐度（0.8%~8.5% NaCleqv）、弱碱性（CO₃^2-和HCO₃^-）、富挥发分（F、P、B、Li）的硅酸盐水体系,估算成矿压力平均值为400MPa。308脉较晚阶段的结晶介质以内带锂辉石中富子晶流体包裹体为代表,为高温（482~565℃）、低盐度（1.6%~8.5% NaCleqv）、弱碱性、富挥发分（P、Li）的硅酸盐水体系。晚期热液阶段以石英的富CO₂流体包裹体为代表,为中高温（291~365℃）、中低盐度（3.9%~13.2% NaCleqv）、弱酸性、富氯的盐水体系。308号脉由铍矿化至锂矿化、最终至热液阶段,是伟晶岩熔（流）体持续分异演化的结果,晚期热液为伟晶岩熔（流）体自身分异形成的。相对封闭的成矿体系、多种挥发组分（F、Li、P、B）的大量聚集和弱碱性的pH环境,是308号脉锂-铍矿化富集与沉淀的主要控制因素。晚期贫F富Cl、弱酸性特征的热液流体有利于锂辉石的保存。

     

Experimental deformation of sintered albite above and below the order-disorder transition

Abstract

Purified albite powder (44-53 μm) has been sintered to form an albite polycrystal suitable for deformation studies close to the melting temperature. Experiments have been carried out in Griggs solid medium deformation apparatus at 800, 1020 °C and 700 MPa pressure in a dehydrating pyrophyllite confining medium at constant strain rates of 10^?4, 10^?5, 10^?6 and 10^?7/s. At 800 °C the samples were brittle-ductile whereas at 1020 °C they were ductile with a rheology well described by a power law with a stress exponent of 3. The transition from brittle-ductile to ductile also coincided with the order-disorder or low-high albite transition, as indicated by the marked increase in mechanical twinning on the albite law at high temperature. At 1020 °C high dislocation densities (10^?10 - 10^?11/cm² and mechanical twinning characterised the original high albite grains, whereas fine recrystallised grains ( < 5 цm) had low dislocation densities (10⁷ - 10⁸/cm²) and often contained polysynthetic albite and pericline (M-type) twins. It is suggested that the recrystallized grains were monalbite (monoclinic) under test conditions which have inverted to high albite (triclinic) and in so doing produced M-twins, and that the recrystallization mechanism involved grain-boundary bulging to nucleate new high angle boundaries. The implications of the order-disorder transition for twinning and grain boundary migration are discussed and it is suggested that the data cannot be simply extrapolated to natural deformation in the low albite field.     

与翡翠伴生的含钠长石质玉石的鉴别及定名探讨

与翡翠伴生的含钠长石质玉石的外观与传统翡翠非常相似,但成分比较复杂,宝石学参数不再典型,性质常介于钠长石玉和翡翠之间。通过对标本的观察、常规宝石学测试和红外光谱测试,对该过渡类型玉石进行仔细区域调查,总结特征,建议国家标准应加强对翡翠与岩石过渡类型具体的成分标准和物理性质的归钠总结,对相应的类型划分与种类界定提出规范性和统一的标准。     

苏州善安浜钽铌矿床矿石特征

苏州善安浜钽铌矿床产于苏州花岗岩向北延伸呈局部隆起的钠长石花岗岩中,上钽下铌特征十分明显,由上而下分为3个矿体。其中Ⅰ矿体是主矿体,为钽矿体,伴生铌;Ⅱ矿体为铌矿体,伴生钽;Ⅲ矿体为铌矿体。主要有用矿物为铌钽铁矿,呈粒间嵌存于钠长石花岗岩基质中,占总量的95.04%。铌钽铁矿的嵌存关系与云母、长石最为密切,占93.99%,极少数与锆石连生。