U/Th-rich bitumen in Archean granites and Palaeoproterozoic metasediments, Rum Jungle Mineral Field, Australia: implications for mineralizing fluids

Uranium/thorium (U/Th)‐rich bitumen has been discovered within both Palaeoproterozoic black pelites and the Archean granitic basement of the Rum Jungle Mineral Field, Northern Territory, Australia. Granite‐hosted bitumen occurs as small (up to 400‐µm diameter) discrete individual nodules, which exhibit many morphological similarities to those observed in Phanerozoic siliciclastic rocks. Thorium, the dominant radioelement, occurs primarily as a hydrated Th–Y–Si–P phase. Uranium‐rich inclusions are rare, and correspond to a hydrated U–Th–Y–Si–P phase, identified as coffinite–thorogummite. Metasediment‐hosted bitumen is more variable in morphology, occurring as massive (<2 cm in width) veins that cross‐cut all foliations, as discrete individual nodules or as elongate seams (up to 500 µm in length), interpreted to represent a series of coalesced individual nodules. In all examples, uranium, the dominant radioelement in the metasediment‐hosted bitumen, is present as Th‐poor uraninite, with variable Y₂O₃ contents (up to 3.21 wt.%). Raman investigation of all types of bitumen indicates that it is a poorly organized carbonaceous matter, which has not been subjected to metamorphism. Consequently, a post‐metamorphic timing for hydrocarbon emplacement can be inferred and a magmatic origin can be precluded. Potential source rocks for the bitumen are black shales of the Whites Formation (up to 8 wt.% total organic carbon (TOC)) and the Koolpin Formation (approximately 13 wt.% TOC). Post‐metamorphic sericitization of rocks within the Whites Formation is accompanied by a near‐complete removal of organic matter. Alteration was possibly the catalyst for hydrocarbon generation. The Th–Y–Si–P phase within the granite‐hosted nodules is interpreted to be the result of the alteration of antecedent monazite. During this alteration, U, LREE and P were fractionated and removed, while Th, Y and Si remained immobile, and recombined to form a hydrated Th–Y–Si phase. This pervasive alteration within the basement U/Th‐rich granites is proposed as a genetic model for the formation of uranium deposits in the Rum Jungle Mineral Field and possibly unconformity associated uranium deposits on a global scale.     

基于旅游业发展变迁的旅游学科知识体系建设

本文通过对旅游服务起源的追溯,论证了旅游业是为人们出行提供服务的一种商业模式;通过对这种商业模式的解剖,总结了旅游学科赖以成立的理论基础,旅游学科知识体系与行业发展变化的关系,从而梳理出旅游课程建设的思路。     

被拐儿童生命历程变迁与原生家庭融入研究——基于寻亲成功案例的实证

被拐儿童的生命历程变迁与寻亲成功后的原生家庭融入境遇值得关注.本文通过实地调研访谈寻亲成功后的被拐儿童及其家乡社会网络成员,以生命历程理论为指导,揭示被拐儿童的生命历程变化,考察寻亲成功后的原生家庭融入情况.研究发现:被拐儿童的生命历程主要经历被拐、被收养、寻亲与寻亲成功4个重大生命事件.被拐儿童寻亲成功后的原生家庭融...     

An Acutely Embarrassing Affair: Whitehall and the Indian-South African Dispute at the United Nations (1946)

ABSTRACT

Before the Second World War it was a cardinal Commonwealth principle that intra-imperial disputes must be kept away from international fora. Yet in 1946 the not-yet-independent India complained to the United Nations about South African legislation discriminating against people of Indian origin. It did so without seeking Britain's approval, and went on to level fierce criticism at Britain's opposition to the UN General Assembly's discussion of the matter.

This article explains the circumstances which led to these events; uncovers the divergent responses of the relevant British government departments – the India Office, the Dominions Office, and the Foreign Office – and shows how they were resolved; depicts the way in which Britain's delegation to the General Assembly handled the matter; and discusses the significance and consequences of the dispute for South Africa and for Anglo-Indian relations.     

Transient Response of Concrete Gravity Dam Considering Dam-Reservoir-Foundation Interaction

This article deals with the finite element analysis of dam with and without fluid-structure, soil-structure and soil-structure-fluid interaction. A two-dimensional direct coupling methodology is proposed to obtain the response of dam-reservoir-foundation system considering fluid-structure and soil-structure interaction simultaneously. The displacement based finite element technique is used to formulate the dam and foundation. The reservoir is modeled by pressure based finite element to reduce the degree of freedoms and there by the computational cost. The responses of dam, reservoir, and foundation with and without fluid-structure, soil-structure and soil-structure-fluid interaction are compared to study the influence of reservoir and soil foundation on the behavior of these respective sub systems. The fundamental frequency of individual sub system decreases with the consideration of coupling effect among these sub systems. On the comparison of the responses of dam, it is observed that the displacement and principal stresses are increased if the effect of reservoir and foundation are considered and the worst responses were observed when both the fluid-structure and soil-structure interaction effects are considered simultaneously. The magnitude and distribution of stresses within the foundation change with the consideration of soil-structure-fluid interaction. Similar to wstresses in the foundation, the hydrodynamic pressure within the reservoir also gets magnified due to interaction effects. The velocity distribution within the reservoir becomes distorted when the fluid-structure and soil-structure-fluid interaction are considered.     

试析历史地理学在人地关系研究中的时间特征

人地关系是历史地理学研究的核心。本文以系统方法论为指导,对人地关系发展过程中所体现出来的宏观、中观和微观的时间特征进行了初步分析,认为历史地理学在探讨人地关系中,其所揭示的过程是完整性和阶段性、连续性与差异性的统一过程,因而是最富有揭示人地关系动态过程及其规律的学科之一。     

Evaluating sources of variation in the identification of linear hypoplastic defects of enamel: a new quantified method

Assessment and interpretation of the presence of developmental defects of enamel formation that result from childhood experiences of growth disruption, enamel hypoplasia, is a standard part of almost any systematic bioarchaeological assessment. However, different identification methods lead to different results. This study presents a new method of defect identification that offers a quantitative criterion for establishing defect presence rather than relying solely on observer judgement. It then compares this with a standard field approach to assessing enamel hypoplasia and a non-quantified microscopic approach in order to determine (a) if traditional methods of identifying enamel hypoplasia under little or no magnification offer the same information about the experience of childhood health as methods that examine dental enamel growth microscopically, and (b) the effect of using a quantified criterion to identify enamel hypoplasia. A case study using simultaneously developing teeth in one individual is presented where observations of defect presence are made both macroscopically and microscopically and with and without this novel metric method. The results demonstrate that the chosen scale of observation is a critical variable in identifying linear hypoplastic defects of enamel. Defects that occur in the more cervical regions of a tooth are ‘missed’ by methods that rely on macroscopic observation or the unaided visual judgement of the observer. This finding has considerable implications for the interpretation of reported enamel hypoplasia prevalence.     

Student Empowerment through 'Area Analysis'

As a result of the teaching quality assessment at the Faculty of Spatial Sciences in Groningen (Netherlands), the course 'Gebiedsanalyse' (Area Analysis) was set up in spring 1998. The aim was to provide an opportunity for the development of transferable and geographical skills in the context of a group-based research project at level II. In addition, an effort was made to move from tutor-led to student-led learning. Experiences from the past 3 years have shown that Area Analysis has been largely successful in providing an opportunity for the application of geographical and transferable skills but also for the 'deep empowerment' of undergraduate students.     

Surviving the First Time Through: A New Instructor's Views on Designing and Teaching Economic Geography and how Mentoring Early-Career Faculty Can Help

This article presents the reflections of a new instructor of economic geography in the USA. The author offers practical advice for designing and delivering a course for the first time. Suggestions are given in support of the view that sharing knowledge of effective teaching practices is an important component of mentoring early-career faculty. By producing and publishing practical examples of teaching materials, experienced faculty may assist novice instructors in balancing time spent on teaching and research. The author encourages economic geographers to contribute to the health of the sub-discipline by supporting new faculty in this manner.     

Evaluation of Strength Hierarchy of Beam-Column Joints of Existing RC Structures under Seismic Type Loading

To evaluate the strength hierarchy, three different types of exterior beam-column joint, i.e., gravity load designed, non ductile and ductile, following two different codes are considered. Strength of different components of beam-column joint, i.e., column, beam, and joint core, is individually calculated from different failure criteria. Shear strength of the joint is evaluated from softened strut and tie model. Strength hierarchy, ultimate strength, and critical failure modes of the specimens are analytically estimated and found to be well corroborated with the experimental results. The study will help in designing the earthquake resistant RC structures in a more rational way.