广西大厂锡多金属矿田西矿带稀散元素铟的富集规律研究——来自矿石组构和闪锌矿地球化学的证据

广西大厂锡多金属矿田是世界最主要的铟产地之一,对其的富集机制还有很大争议。文章以大厂矿田西矿带高峰矿床和铜坑矿床中的闪锌矿为研究对象,在野外和室内矿相显微观察的基础上,应用高精度电子探针与等离子体质谱分析手段,研究稀散元素铟的空间分布规律、赋存状态及与主成矿元素的关系,揭示其在闪锌矿中的富集规律。实验结果表明,铜坑矿床中闪锌矿内稀散元素铟的含量随深度增加而减少,而高峰矿床中铟含量却保持稳定;铟主要以类质同象形式赋存,与铜以双替代锌的形式进入闪锌矿晶格中,也不排除铟以微细包体形式赋存的可能。结合前人研究,推断燕山晚期复式岩体岩浆演化末期花岗斑岩侵位冷却过程中,岩浆结晶产生的富铟、铜等流体对早期生成的闪锌矿进行交代并富集。这一研究结果为寻找稀散元素铟指示了方向。     

Thermal expansion of gehlenite, Ca2Al[AlSiO7], and the related aluminates LnCaAl[Al2O7] with Ln=Tb, Sm

The thermal expansion of gehlenite, Ca₂Al[AlSiO₇], (up to T=830 K), TbCaAl[Al₂O₇] (up to T=1,100 K) and SmCaAl[Al₂O₇] (up to T=1,024 K) has been determined. All compounds are of the melilite structure type with space group Thermal expansion data was obtained from in situ X-ray powder diffraction experiments in-house and at HASYLAB at the Deutsches Elektronen Synchrotron (DESY) in Hamburg (Germany). The thermal expansion coefficients for gehlenite were found to be: α₁=7.2(4)×10⁻⁶ K⁻¹+3.6(7)×10⁻⁹ΔT K⁻² and α₃=15.0(1)×10⁻⁶ K⁻¹. For TbCaAl[Al₂O₇] the respective values are: α₁=7.0(2)×10⁻⁶ K⁻¹+2.0(2)×10⁻⁹ΔT K⁻² and α₃=8.5(2)×10⁻⁶ K⁻¹+2.0(3)×10⁻⁹ΔT K⁻², and the thermal expansion coefficients for SmCaAl[Al₂O₇] are: α₁=6.9(2)× 10⁻⁶ K⁻¹+1.7(2)×10⁻⁹ΔT K⁻² and α₃=9.344(5)×10⁻⁶ K⁻¹. The expansion-mechanisms of the three compounds are explained in terms of structural trends obtained from Rietveld refinements of the crystal structures of the compounds against the powder diffraction patterns. No structural phase transitions have been observed. While gehlenite behaves like a ’proper’ layer structure, the aluminates show increased framework structure behaviour. This is most probably explained by stronger coulombic interactions between the tetrahedral conformation and the layer-bridging cations due to the coupled substitution (Ca²⁺+Si⁴⁺)-(Ln ³⁺+Al³⁺) in the melilite-type structure. Electronic Supplementary Material Supplementary material is available for this article at     

江西雅山花岗岩长石中磷的分布及意义

雅山富氟高磷花岗岩具较高的全岩磷含量（０．１５％～０．５５％）,长石是磷的主要赋存矿物,磷以ＰＡｌＳｉ－２替换方式进入长石结构中。各种结晶习性的长石的磷含量各不相同。早世代钠长石和雪球结构中钠长石包裹体的结晶较早,平均磷含量分别为０．１８％和０．１９％,而晚世代钠长石和环带钾长石中钠长石嵌晶的结晶稍晚,具较高的平均磷含量（分别为０．２５％和０．２３％）。钾长石的磷含量相对于钠长石总体上较低,早期结晶的雪球结构主晶钾长石和环带钾长石的磷含量最低,分别为０．０４％和０．０２％,晚期细粒钾长石的平均磷含量略高（０．１９％）。长石对全岩磷的贡献率还与磷锂铝石等磷酸盐副矿物是否达到饱和有关,当无磷锂铝石结晶时,长石磷的贡献率约为７６％,反之则约为３１％。     

The Role of Fluvial and Glacial Erosion in Landscape Evolution: The Ben Ohau Range,New Zealand

A morphometric comparison of valleys has been made for the Ben Ohau Range in the central Southern Alps of New Zealand. The range is undergoing rapid tectonic transport and uplift. The humid north of the range is a glacial trough-and-arête landscape, with a temperate glacial climate. The dry south has rounded divides and plateau remnants dissected by fluvial valleys. Assuming that space–time substitution allows today's spatial valley-form transition to represent evolutionary stages in valley development, the tectonic history allows time constraints to be placed on the rate of transition to an alpine glacial landscape. Morphometric change has been quantified using hypsometric curves, and distance–elevation plots of cirque and valley-floor altitudes. Ancestral fluvial valleys have less concave long profiles but are stepped at altitude owing to the presence of high-level cirques and remnant plateau surfaces, and possess a low proportion of land area at low elevation. Increasing glacial influence is manifest as smoother, more deeply concave long profiles and U-shaped cross-profiles associated with a higher proportion of the land area at lower elevation. The full morphological transition has involved up to 2.4 km of vertical denudation over the 4 Ma lifetime of the mountain range, of which 80 per cent would have occurred by preglacial fluvial erosion. Combining the trajectory of tectonic transport with reconstructed glaciation limits and climatic history, it is indicated that about 200 ka of temperate glacial erosion produces recognizable trough-and areête topography. Mean and modal relief increase where glacial activity is confined to cirques, but decrease when trough incision by ice becomes established as a dominant process in the landscape. © 1997 by John Wiley & Sons, Ltd.     

Effect of pore geometry on Gassmann fluid substitution

Although there is no assumption of pore geometry in derivation of Gassmann's equation, the pore geometry is in close relation with hygroscopic water content and pore fluid communication between the micropores and the macropores. The hygroscopic water content in common reservoir rocks is small, and its effect on elastic properties is ignored in the Gassmann theory. However, the volume of hygroscopic water can be significant in shaly rocks or rocks made of fine particles; therefore, its effect on the elastic properties may be important. If the pore fluids in microspores cannot reach pressure equilibrium with the macropore system, assumption of the Gassmann theory is violated. Therefore, due to pore structure complexity, there may be a significant part of the pore fluids that do not satisfy the assumption of the Gassmann theory. We recommend that this part of pore fluids be accounted for within the solid rock frame and effective porosity be used in Gassmann's equation for fluid substitution. Integrated study of ultrasonic laboratory measurement data, petrographic data, mercury injection capillary pressure data, and nuclear magnetic resonance T₂ data confirms rationality of using effective porosity for Gassmann fluid substitution. The effective porosity for Gassmann's equation should be frequency dependent. Knowing the pore geometry, if an empirical correlation between frequency and the threshold pore‐throat radius or nuclear magnetic resonance T₂ could be set up, Gassmann's equation can be applicable to data measured at different frequencies. Without information of the pore geometry, the irreducible water saturation can be used to estimate the effective porosity.     

土地利用空间格局的置换变化与代换变化分析

为揭示土地利用空间格局的动态变化,本文基于土地利用转移矩阵,从类型间的空间转移过程出发,构建了置换变化与代换变化的计算模型,并对其2种变化进行了分析。置换变化是2种类型之间以相同面积发生空间位置的置换过程,且各种类型的数量结构保持不变;代换变化则是所研究类型的数量结构保持不变,而与之转换的其他类型数量上的增加或减少;从而将单一类型的总变化进一步细分为置换变化、代换变化与净变化。以晋江流域1985年与2006年2期土地利用格局的变化为例进行分析,结果显示：在1985-2006年间,晋江流域的土地利用空间格局发生了显著变化;园地、建设用地、未利用地呈现扩张态势,草地与旱地呈现萎缩变化,水域变化不大;这6种地类的交换变化面积相对较少,以置换变化为主。水田与林地则主要表现为空间位置的交换变化,其中,水田呈现出与林地、旱地2种类型之间的置换变化,而林地则主要是园地-林地与林地-草地这2对类型间的代换变化。结果表明,通过置换变化与代换变化的分析,更细化了各种类型之间的动态变化过程。     

农村中小学选址的空间运筹

农村中小学的选址问题是当前地理学区位理论应用的一个热点,学校作为一个设施对学生上学安全和便捷程度有很大影响。许多学者研究了学校的区位问题,然而对农村地区来说,采用模型不够适合。本文学校选址研究充分考虑P-重心模型和P-中心模型的优缺点,在P-重心模型的基础上对模型进行改进,增加学生上学最大距离不超过某一阈值的约束,这样改进后的模型同时具有P-中心和P-重心模型的优点,既保证农村偏远地区的学生上学相对方便,又保证加权距离和相对最小。为了方便应用,应用地理信息科学方法,使用改进的节点交换搜索算法求解,然后通过Visual Studio 开发平台和ArcGIS Engine 二次开发组件库开发了农村中小学最优选址的决策支持系统。最后以山东省某镇为例,用该系统解决该镇的小学选址,结果发现改进后同时具有P-重心和P-中心特性的模型比传统的P-重心模型更能适合农村小学选址,能够作为小学学校规划选址的辅助决策依据。     

The Satisfaction of Human Needs in Physical and Virtual Spaces

This article attempts to explore the spatial dimension of Maslow's theory on the hierarchy of human needs, in light of the growing role of virtual space via the Internet in the contemporary information age. Generally speaking, virtual space constitutes a space for the gratification of human needs, side by side with physical space. Its role, as compared to physical space, grows along the hierarchy of human needs: physiology, safety, love and belonging, esteem, and self-actualization. Thus, its role for the gratification of physiological needs is complementary, whereas its role for self-actualization is significant. The growing role of virtual space has evolved into an equivalent hierarchical relationship with physical space: complementarity, competition, substitution, escape, and, potentially also exclusivity. Escape from physical to virtual space, as both need and relationship, has been brought about by social networking, being similar to the physical escape offered by tourism. It does not seem real to foresee that virtual space will offer exclusive fulfillment of as of yet unforeseen new human needs.     

基于岩石物理实验的时移地震研究

时移地震技术是油田开发阶段动态检测的一个重要手段.岩石物理实验室能实现模拟油气田在开采过程中其储层参数变化对岩石弹性参数的影响.本文基于岩石物理实验及地震正演模拟,分析了X气田在开采过程中其孔隙压力下降及水不断侵入情况下,进行时移地震监测的可行性及其主要影响因素.