裂变径迹技术及其地质应用

裂变径迹技术以样品用量少、封闭温度低以及测年范围广等优势,被广泛应用于地质学研究中。完全退火或部分退火样品可有效记录岩体的冷却-剥露历史,限制构造活动起始时间,探讨上覆岩石的风化剥蚀历史与矿床保存变化之间的关系,定量化矿床隆升剥蚀量,实现找矿预测; 锆石裂变径迹封闭温度对应天然气生成温度区间,可运用于油气勘探研究计算中; 近年来结合元素含量分析的裂变径迹技术还可进行物源分析,LA-ICP-MS技术的引进为测量低U含量矿物的径迹带来了曙光。系统总结了磷灰石与锆石裂变径迹退火特性的研究成果,以及温度、化学成分、结晶各向异性及D_par值等因素对磷灰石径迹退火特性数据解释可能产生的影响,锆石径迹热稳定性的降低主要受制于辐射损伤效应。实验室退火特性研究为了解繁杂的径迹退火化学动力机制提供了重要的理论参考,但在实际的数据解释中需结合地质背景,以获得更为清晰的地质热事件演化研究时间格架。结合径迹测年在矿床、山体隆升剥蚀、盆地热史等研究的典型案例分析,以期为裂变径迹应用的相关研究提供参考。     

农商部地质调查局始末考

中国地质调查事业始于民国。1913年地质调查所正式成立,直至1950年裁撤,30余年间一直是中国地质学家的大本营。1916年初,地质调查所重新改组为地质调查局,并在行政上直接隶属农商部。同年夏天,地质研究所学生毕业后入地质调查局工作,成为地质调查局主要成员。1916年底,地质调查局被裁撤,又恢复地质调查所,但此后工作形式与机构管理均与调查局时期无太大变化。地质调查局因存在时间较短,加之史料不多,以往著述着墨不多。本文以《农商公报》、《政府公报》及地质调查局相关原始材料为基础,考察地质调查局成立始末、机构设置、人员组成及早期进行的地质调查工作。认为地质调查局的成立是中国地质学者建立独立地质调查专门机构的一次尝试。     

东北那丹哈达岭中—新生代构造-热演化史:来自(U-Th)/He和裂变径迹热年代学的证据

中国东北的那丹哈达岭地区位于中亚造山带最东部,它的中新生代热演化史是认识陆内造山活动的关键,但该地区相关研究比较薄弱,其中—新生代的热演化史缺乏有效的约束.因此本文应用磷灰石裂变径迹、锆石和磷灰石(U-Th)/He等多种低温热年代学方法,对东北那丹哈达岭地区的侵入岩开展构造热演化历史研究.热年代学数据和热史模拟结果表明,该地区存在早白垩世晚期—晚白垩世(110～80Ma)、古新世—始新世(60～40 Ma)两期快速冷却事件,其冷却速率分别为3.42～4.81℃/Ma和1.43～1.83℃/Ma.结合区域构造和应力分析,我们认为两期冷却事件均受构造活动控制.第一期快速冷却事件是古太平洋板块北西向俯冲引发的构造叠加到鄂霍特莫茨克地块并与东亚大陆边缘碰撞引起;而第二期快速冷却事件是古太平洋俯冲的板片后撤使东亚陆缘处于伸展环境,造成东北大面积的剥露作用引起.这次研究增强了对东亚陆缘中新生代构造-热演化历史的认识,对于理解大陆内部造山带的构造变形过程与机理具有重要意义.     

Comparative phylogeography and population genetic structure of three widespread mollusc species in the Mediterranean and near Atlantic

Although several studies have evaluated the genetic structure and phylogeographic patterns in many species of marine invertebrates, a general model that applies to all of them remains elusive. For example, some species present an admixture of populations with high gene flow, whereas others exhibit more complex patterns characterized by small‐scale unstructured genetic heterogeneity, even at a local scale. These differences are thought to be due to clear biological aspects such as direct versus indirect development, or the presence of lecithotrophic versus planktotrophic larvae, but few studies compare animals with similar distributions and life modes. Here, we explore the phylogeographic and genetic structure patterns in two chiton (Chiton olivaceus and Lepidopleurus cajetanus) and one abalone (Haliotis tuberculata) species co‐occurring in the same habitat. Samples were obtained from shallow rocky bottoms along the Iberian Peninsula (Atlantic and Mediterranean coasts), Italy, Croatia and Greece, and the mitochondrial markers COI and 16S rRNA gene were sequenced. Our data show evidence of admixture and population expansion in C. olivaceus and H. tuberculata, whereas L. cajetanus exhibited a ‘chaotic patchiness’ pattern defined by a high genetic variability with locality‐exclusive haplotypes, high genetic divergence, and a lack of geographic structure. Shared haplotypes were sampled in both coasts of Iberia (for H. tuberculata) and in the Western and Eastern Mediterranean (for C. olivaceus), potentially indicating high dispersal ability and a recent expansion. The processes underlying the fine‐scale structuring in L. cajetanus remain a mystery. These results are especially interesting because the reproductive mode of the two chitons is similar but differs from that of the abalone, with a veliger larva, while instead the genetic structure of C. olivaceus and H. tuberculata are similar, thus contrasting with predictions based on the life history of the three molluscs and showing that the genetic patterns of marine species may be shaped by many factors, including historical ones.     

“A red cross appeared in the sky” and other celestial signs: Presumable European aurorae in the mid AD 770s were halo displays

The interpretation of the strong ¹⁴C variation around AD 775 as one (or several) solar super‐flare(s) by, e.g., Usoskin et al. (2013) is based on alleged aurora sightings in the mid AD 770s in Europe: A red cross /crucifix in AD 773/4/6 from the Anglo‐Saxon Chronicle, inflamed shields in AD 776 (both listed in the aurora catalogue of Link 1962), and riders on white horses in AD 773 (newly proposed as aurora in Usoskin et al. 2013), the two latter from the Royal Frankish Annals. We discuss the reports about these three sightings in detail here. We can show that all three can be interpreted convincingly as halo displays: The red cross or crucifix is formed by the horizontal arc and a vertical pillar of light (either with the Sun during sunset or with the moon after sunset); the inflamed shields and the riders on white horses were both two mock suns, especially the latter narrated in form of a Christian adaptation of the antique dioscuri motive. While the latter event took place early in AD 774 (dated AD 773 in Usoskin et al. 2013), the two other sightings have tobe dated AD 776, i.e. anyway too late for being in connection with a ¹⁴C rise that started before AD 775. We also sketch the ideological background of those sightings and there were many similar reports throughout that time. In addition, we present a small drawing of a lunar halo display with horizontal arc and vertical pillar forming a cross for shortly later, namely AD 806 June 4, the night of full moon, also from the Anglo‐Saxon Chronicle; we also show historic observations of halo phenomena (mock suns and crosses) from G. Kirch and Hevelius – and a modern photograph. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

On the history of some explicit formulae for solving Kepler's equation

In this paper we examine, in their historical context, some approximate solutions for Kepler's equation. These explicit formulae, obtained by Trembley, Pacassi, Fergola, and Horrebow, had not a great diffusion and were thus often rediscovered by other astronomers. We will prove that the formulae are equivalent and, moreover, we will give an evaluation of the error. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

考虑上部结构影响的山区桥梁支座刚度设计方法研究

为了合理计算山区桥梁支座刚度,针对桥墩高度不相同的特点,考虑上部结构对桥墩顶部的转动约束作用,提出在横桥向可将墩顶视为自由约束,而在纵桥向将墩顶视为定向约束。分别按照地震作用下各墩底剪力和弯矩相等的原则,推导桥梁支座纵、横桥向的刚度设计公式,并给出各桥墩支座的设计方法。为验证方法的正确性,以墩底剪力相等的原则为例,利用OpenSees建立一座墩高不等的5跨连续梁桥模型,并依支座刚度取值不同分三种工况:工况一各桥墩支座刚度相同;工况二按墩顶自由计算各支座的纵、横桥向刚度;工况三按墩顶定向约束计算各支座的纵、横桥向刚度。分别对三种工况下的桥梁结构输入三条地震动记录进行时程分析,考察各桥墩的底部剪力。分析结果表明:工况一各桥墩纵、横桥向的底部剪力均不相同;工况二各桥墩横桥向的底部剪力相同而纵桥向的底部剪力不同;工况三各桥墩纵桥向的底部剪力相同而横桥向的底部剪力不同。上述结果表明在桥梁支座设计时,横桥向桥墩的抗推刚度应按墩顶自由计算,而纵桥向桥墩的抗推刚度应按墩顶为定向约束计算。     

Everyday Ecologies: Cities,Nature, and leaching Urban Ecology

Abstract

Conventional geographical approaches to the city tend to place the study of urban form and urban space squarely within the political-economic and cultural branches of geography. Geographic pedagogy has tended to assume, therefore, that nature is absent from the city or exists only as a backdrop or stage on which urban economic and cultural activities take place. In contrast, there has been a recent groundswell of interest—originating in places as diverse as environmental activism, environmental history, landscape architecture, and environmental education—in reinterpreting the city as a space intimately connected with nature. This article examines the possibilities for integrating this rethinking of the relationship between city and nature into undergraduate education. Specifically, it outlines the rationale, objectives, and design of a course on urban ecology and examines the benefits and challenges of doing urban ecology as part of geographic education.     

From Gauß to Biermann: Highlights from the first 117 years of publications in Astronomische Nachrichten/Astronomical Notes

We present facsimiles of some of the scientifically and historically most relevant papers published in Astronomische Nachrichten/Astronomical Notes (AN) between 1821 and 1938. Almost all of these papers were written and printed in German and it is sometimes not completely straightforward to find these original works and then to cite the historically correct version, e.g. in case of a series of articles or editorial letters. It was common during the early years that many contributions were made in form of letters to the editor. We present a summary for these original works with an English translation of their titles. Among the highlights are the originals of the discovery of stellar parallaxes by FriedrichWilhelm Bessel, the discovery of the solar cycle by Heinrich Schwabe, the discovery of the planet Neptune by Johann Gottfried Galle, the first ever measured stellar radial velocity by Hermann Vogel, the discovery of radio emission from the Sun by Wilsing and Scheiner, the first ever conducted photoelectric photometry of stars by Paul Guthnick and up to the pioneering work by Karl Schwarzschild, Ejnar Hertzsprung, Erwin Finlay Freundlich and others. As a particular gimmick we present the still world record holding shortest paper ever published; by Johannes Hartmann in AN 226, 63 (1926) on Nova Pictoris. Our focus is on contributions in the early years and published until 1938 near the verge of the second world war (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The Troughton & Simms transit circle of Coimbra Astronomical Observatory from the 1850s: An example of the dissemination of technological developments

Yesterday, as today, technological developments led by large and expensive instrumental projects are later on disseminated to smaller and more affordable devices. In 1847, Airy requested a new transit circle for the Greenwich Observatory. When the first observation was performed, on 4 January 1851, Airy's Greenwich Transit Circle (ATC) was the largest instrument of its class in the world. The construction of the ATC implied solving several technical difficulties, for example, the maintenance of the instrument rigidity and the illumination of the graduated circle and telescope field of view. After the ATC completion Troughton & Simms stand at the 1851 Great London Exhibition included two small transit instruments which were praised for their telescope field of view/eyepiece wires illumination. One of which, was based upon the design implemented beforehand on the ATC. In this paper we will discuss the field and eyepiece wire illumination innovations introduced on the ATC and the Simms transit instruments exhibited in 1851. We will also describe the small Troughton & Simms transit circle currently belonging to Coimbra Astronomical Observatory collection that is, we believe, one of the earliest implementation of this ATC lead development (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)