The onset of post-collisional magmatism in the Macururé Domain,Sergipano Orogenic System: The Glória Norte Stock

In the northern-central portion of the Sergipano Orogenic System there is an expressive Neoproterozoic granitic magmatism with high-K calc-alkaline and shoshonitic affinities. The Glória Norte Stock (GNS, 45 km²) is the most important representative of the shoshonitic magmatism in one the domains of the Sergipano System, the Macururé. The contacts of the stock with the host metasedimentary rocks are discordant and steep, with generation of amphibolite facies hornfels. The GNS is made up of predominantly porphyritic quartz-monzonite and monzogranite. It shows a magmatic flow foliation defined by oriented mafic enclaves and feldspar phenocrysts, without evidence for solid state regional deformation. Mafic microgranular enclaves (MME) are abundant and present different sizes and shapes. Minette and biotite diopside cumulate enclaves are also present. Coexistence between two different magmas is indicated by crystal corrosion and dissolution textures, compositional zoning of feldspar and presence of clusters of mafic minerals. Grain size decrease towards the rims of the MME indicates fast cooling of small drops of mafic magma, due to temperature contrast with the felsic magma. The monzonites and granites of the GNS have shoshonitic affinity, and the enclaves are related to ultrapotassic suites (MgO > 3%, K₂O > 3%). LREE are enriched as compared to HREE, and there are remarkable negative anomalies of Ta, Nb, Ti, P, Sr and Eu, mostly in the enclaves. The MME have been probably formed from a mantellic magma with shoshonitic affinity. The observed evolution from MME to quartz-monzonites and monzogranites is essentially linked to a process of fractional crystallization. The relations between Ta/Yb and Th/Yb ratios suggest enriched mantle as a possible source of this magmatism. The relative enrichment in Rb, Th, Ce and Sm indicates that magma was generated in post-collisional events. The U-Pb_SHRIMP age of 588 ± 5 Ma in zircon crystals indicates that the emplacement of the GNS represents a post-collisional magmatism, marking the end of collisional processes in the Macururé Domain.     

Random domain decomposition for flow in heterogeneous stratified aquifers

We study two-dimensional flow in a layered heterogeneous medium composed of two materials whose hydraulic properties and spatial distribution are known statistically but are otherwise uncertain. Our analysis relies on the composite media theory, which employs random domain decomposition in the context of groundwater flow moment equations to explicitly account for the separate effects of material and geometric uncertainty on ensemble moments of head and flux. Flow parallel and perpendicular to the layering in a two-material composite layered medium is considered. The hydraulic conductivity of each material is log-normally distributed with a much higher mean in one material than in the other. The hydraulic conductivities of points within different materials are uncorrelated. The location of the internal boundary between the two contrasting materials is random and normally distributed with given mean and variance. We solve the equations for (ensemble) moments of hydraulic head and flux and analyze the impact of unknown geometry of materials on statistical moments of head and flux. We compare the composite media approach to approximations that replace statistically inhomogeneous conductivity fields with pseudo-homogeneous random fields. This work was performed under the auspices of the US Department of Energy (DOE): DOE/BES (Bureau of Energy Sciences) Program in the Applied Mathematical Sciences contract KC-07–01–01 and Los Alamos National Laboratory under LDRD 98604. This work made use of STC shared experimental facilities supported by the National Science Foundation under Agreement No. EAR-9876800. This work was supported in part by the European Commission under Contract No. EVK1-CT-1999–00041 (W-SAHaRA).     

哀牢山-红河左旋走滑剪切带中新世抬升的时间序列

在哀牢山－红河剪切带的元阳到者龙的６个不同地点，对１８个变质岩样品进行系统分析钾长石的＾４０Ａｒ－＾３９Ａｒ年龄。发现用ＭＤＤ模式得到的１８条冷却曲线均存在一次快速冷却过程，这种快速冷却过程不仅反映了该剪切带在大约２５－１７Ｍａ时，韧性走滑作用结束和正断作用的开始，而且它的起始时间还有自东南向西北逐渐变新的趋势。     

Gauss-Helmert模型及其在测量平差中的应用

对于Gauss-Helmert模型,本文直接从广义逆阵的性质而不必通过Lagrange乘子方法简洁地给出参数向量的最佳线性无偏估计(BLUE),然后将所得结果用于求解测量平差中的拟合推估问题,以及广义的含未知量的带权条件平差问题。     

Genetic implications of pyrite chemistry from the Palaeoproterozoic Olary Domain and overlying Neoproterozoic Adelaidean sequences, northeastern South Australia

Sulphide mineralisation associated with rocks from the Palaeoproterozoic Olary Domain (OD) and overlying Neoproterozoic Adelaidean sequences has undergone a complex history of metamorphism and remobilisation. In this study, new trace element and sulphur isotopic analyses of pyrites from a large number of deposits and paragenetic generations are combined with an existing data set to build up a sequence of mineralising events linked to the tectonometamorphic evolution of the region. The typically high Co/Ni ratios (>10) indicate that early strata-bound pyrite precipitated from a volcanic-related fluid, which had fluctuating activities of the two metals during the early stages of the evolution of the Willyama basin. This period of mineralisation was followed by a diagenetic concentration of sulphide mineralisation at the horizon known as the Bimba Formation, which occurred as a result of the differing redox conditions between the upper and lower sequences in the Willyama Supergroup. During the Mesoproterozoic (1600 to 1500 Ma) Olarian Orogeny, metamorphic remobilisation of strata-bound pyrite resulted in an epigenetic signature; the trace element concentrations of this generation were controlled primarily by the proximity of mineralisation to the mafic intrusive bodies found throughout the terrane. Further reworking of existing sulphides during the Delamerian Orogeny and associated granitoid-intrusive rocks led to the formation of a new generation of epigenetic pyrite that occurs in quartz veins in the Adelaidean sequences and veins that crosscut Olarian fabrics in the Olary Domain. δ³⁴S results range from 16‰ to 11‰, but most data fall between 2‰ and 4‰. This association is suggestive of an initial uniform deep-seated crustal reservoir of sulphur, which has been repeatedly tapped throughout the metallogenic history of the region. The isotopic outliers can be explained by the input of biogenic sulphur or sulphur derived from oxidised, possibly evaporitic, sediments, respectively. Previous workers have invoked the Kupferschiefer and the Zambian Copperbelt as analogues to mineralisation processes in the Olary Domain. This study shows that δ³⁴S and trace element data are suggestive of some affinities with the aforementioned analogues, but a more likely link can be made between epigenetic remobilisation in the Olary region and the iron oxide copper gold (IOCG) style of mineralisation found at the nearby Olympic Dam deposit.     

东坪金矿地球物理和地球化学找矿模式

东坪金矿产于华力西期偏碱性杂岩体内接触带中，成矿与地层、构造、岩浆演化密切相关，为石英脉（网脉）、钾长石化蚀变岩型金矿床。通过大量的物化探资料分析研究，建立了物化探综合找矿模式。     

滑坡系统静动态规律及斜坡不稳定性空时定量预测

文章基于近数年来室内外测绘试验分析研究工作,论述了滑坡静、动态规律。针对其群体“静态” 规律,论证了斜坡不稳定性空间定量预测的某些基本原理方法;针对其群、单体动态规律讨论了滑坡灾害暴发时间的预测预报基础技术。从系统论观点出发,概括了滑坡系统空时定量预测的三类数学模型——确定性、随机性及灰色系统模型的基本分工和联合模式的勾通特点与功能。文章以陕西东南部变质岩滑坡和长江中上游中生界砂泥岩地层滑坡为实例,讨论了斜坡不稳定性空、时定量预测的重点研究成果。文末概括了几点重要结论。     

陕西双王大型金矿床成矿模式成矿规律与找矿前景探讨

本文在《陕西汉王金矿床地质特征及其成因》科研专著的基础上，结合近几年来各大专院校、科研单位针对双王金矿床所发表的论文资料，经过二轮区划工作认真分析研立后认为双王金矿床的成矿具备多成因、多来源、多期多阶段的特征。它的成因类型成矿模式可以概括为：“层控—构造改造—碳酸岩岩浆热液叠加复成金矿床”。并结合成矿理论和初步掌握的成矿规律研究预测整个双王金矿床的规模有向超大型发展的远景。     

Contextualising gender empowerment at the grassroots: a tale of two policy initiatives

The policy environment on gender is fraught with contradictions and contestation of varying degrees in India that does not disappear even as recent transformative mode of participatory initiatives seem to place women’s agency at the core of empowerment agenda. Drawing from two collaborative projects at the grassroots, the paper argues that even well conceptualised projects miss the cutting edge distinction between women and gender and continue to engage with an instrumental logic of women’s development and empowerment at the expense of issues of gender equality and equity in translating the intention into action. It is also observed, however, that spatially embedded social and cultural specificities impact policy discourse resulting in very different outcomes of conceptually comparable policy formulations. According to the author acknowledging spatiality of experiences provides a vantage point to critically engage with context-specific strategies to resolve gendered conflicts and tensions resulting from confining social relations and normative gender codes.     

Lagrange multiplier-based domain decomposition methods for a non-linear sedimentary basin problem

We present two Lagrange multiplier-based domain decomposition methods for solving iteratively a non-linear sedimentary basin problem. Both methods are Uzawa-type algorithms derived from saddle point equations of Lagrangian and augmented Lagrangian functionals. Numerical experiments show that both methods are scalable with respect to the mesh size.