西南极乔治王岛长城站区晚第四纪燕窝湖岩芯元素地球化学特征

本文阐述了乔治王岛长城站区燕窝湖沉积物中微量元素及某些常量元素的含量、分布、富集系数和相关系数的变化规律 ,探讨了该湖岩芯物质来源及气候环境的阶段性变迁 ,认为一方面燕窝湖周围碎屑沉积岩 (包括火山沉积岩 )是进入沉积体系的主要物源 ;另一方面 ,地幔物质也是其物源之一 ;同时 ,并不排除南极大陆冰进期搬运来的陆源物质进入沉积体系。     

乔治王岛地区原始土壤与母岩间化学组成的相互关系

与内生过程相比,表生过程具有显著的区域性特征。本文根据原始土壤与成土母岩间化学组成的相互关系,研究了极地条件下的风化成土过程。分析了乔治王岛土壤中化学元素的原始来源、生物作用及人为影响,推断了原始环境中元素的迁移特征,讨论了极地条件下成土母岩与原始土壤间化学元素丰度的相互关系。     

A Street Fit for a King: Naming Places and Commemoration in the American South

The naming of streets after Martin Luther King, Jr. (MLK) is an importantarena for African Americans as they rewrite the landscape of southern identity and commemoration. While less ornate and ostentatious than museums and monuments, MLK streets are powerful and highly contested cultural geographies because of their potential to connect disparate communities and incorporate a vision of the past into the spatial practices of everyday life. They reveal the importance of location, particularly intra‐urban location, to public memorialization. Naming streets for King is a significant part of the nonmetropolitan South as well as larger cities and dependent upon the relative size of a city's African‐American population. When estimating the intra‐urban character of MLK streets within several southern states, findings suggest that they are located in census areas that are generally poorer and with more African Americans than citywide averages. Analysis reveals a geographic unevenness in the frequency of businesses having an address identified with King. When compared with the stereotypical American thoroughfare of “Main” Street, the address composition of MLK streets appears to be more residential in nature, although there is significant state by state variation.     

西南极乔治王岛冰芯研究——冰雪层定年、微粒记录及离子迁移

在分析南极乔治王岛冰帽大冰穹顶部降水和成冰条件的基础上,利用冰芯上部层物理特征参数确定的5个年层及其附近气象站相应的降水记录,结合多年降水资料将大冰穹45m冰芯划分为15个年层.应用此年层剖面,证实了微粒含量的两个异常峰值分别对应于1987年Deception岛和1980年的SealNunataks两次火山喷发.乔治王岛冰帽属于温性冰帽,大、小冰穹冰芯阴阳离子受沉积后融水渗浸淋溶作用的影响.对冰芯阴阳离子的淋溶次序分析显示,大冰穹为SO₄^2->Mg²⁺>Ca²⁺>K⁺>Cl^->Na⁺>NO₃^->Br^-,而小冰穹为Mg²⁺>Ca²⁺>SO₄^2->K⁺>Cl^->Br^->Na⁺.     

南极乔治王岛第三纪火山岩中斜长石成分特征及成因意义

乔治王岛第三纪火山岩含大量斜长石斑晶。斜长石的主元素、稀土和微量元素分析表明,它们主要为中长石－钙长石。斜长石种类与寄主岩之间有较好对应关系,即玄武安山岩和安山岩中以中长石和拉长石为主,而高铝玄武岩中为倍长石和钙长石;它们的ΣＲＥＥ、Ｌａ／Ｙｂ和δＥｕ等之间也有明显对应关系。但不同种类的斜长石之过渡金属元素特征相近,反映了过渡金属元素在斜长石中的含量和分异趋势主要受制于斜长石的晶体结构。综合研究表,斜长石成分取决于其母岩浆成分,并反映了区域岩浆演化的趋势．     

Proterozoic – Early Palaeozoic rocks and the Tyennan Orogeny in central Victoria: The Selwyn Block and its tectonic implications

Aeromagnetic and field data suggest that meta‐igneous rocks exposed on the south coast of central Victoria at Waratah Bay, Phillip Island, Barrabool Hills and inland near Licola, are continuous—beneath Bass Strait—with Proterozoic/Cambrian igneous rocks in King Island and Tasmania. This correlation is supported by a pre‐Early Ordovician unconformity above gabbro protomylonite at Waratah Bay, age equivalent to the Tasmanian Tyennan unconformity. Cambrian volcanics at Licola and unusual features of the Melbourne Zone sequence indicate that Tyennan continental crust extends north as basement to the central Victorian portion of the Lachlan Fold Belt. In contrast, adjacent parts of the Lachlan Fold Belt in Victoria contain conformable sea‐floor sequences that span the Early Cambrian to Late Ordovician, with no evidence of either Cambrian deformation or underlying continental basement. The block of Tyennan continental crust beneath central Victoria—the Selwyn Block—is fundamentally different, and has influenced temporal and spatial patterns of sedimentation, deformation, metamorphism and plutonism. Palaeogeographical reconstructions suggest that the block was a submarine plateau that lay outboard of the Australian craton, upon which a condensed Ordovician sequence was deposited. The sequence above the Selwyn Block unconformity at Waratah Bay is similar to widespread post‐Tyennan sediments in western Tasmania. During Late Ordovician and Early Silurian deformation, the Selwyn Block protected much of the overlying sedimentary sequence. Instead, shortening was focused into the Stawell and Bendigo Zones to the west. These zones were sandwiched between the Selwyn Block and the Australian craton in a ‘vice’ scenario reminiscent of some Appalachian orogenic events. The region above the Selwyn Block was downwarped adjacent to the overthrust Bendigo Zone as a foreland deep, into which a conformable clastic wedge of sediment was deposited in Late Ordovician to Devonian time, prior to final Middle Devonian deformation. The Selwyn Block includes the Cambrian calc‐alkaline Licola and Jamieson Volcanics that are correlated with the Tasmanian Mt Read Volcanics. In Victoria, these form a basement high controlling the unusual down‐cutting thrusts in the overlying Melbourne Zone and explaining the major structural vergence reversal between the Melbourne and Tabberabbera Zones. The Selwyn Block has exerted some control on the timing, chemistry and distribution of post‐orogenic granites, and on central Victorian gold mineralisation. Reactivated faults in the block influenced deposition, and continue to control the deformation of the portions of the Otway and Gippsland Basins that lie above it.     

Photometric study of distant open clusters in the second quadrant: NGC 7245, King 9, King 13 and IC 166

We present a UBV CCD photometric study of four open clusters, NGC 7245, King 9, IC 166 and King 13, located between   l = 90°  and 135°. All are embedded in a rich Galactic field. NGC 7245 and King 9 are close together in the sky and have similar reddenings. The distances and ages are: NGC 7245, 3.8 ± 0.35 kpc and 400 Myr; King 9 (the most distant cluster in this quadrant), 7.9 ± 1.1 kpc and 3.0 Gyr. King 13 is 3.1 ± 0.3 kpc distant and 300 Myr old. King 9 and IC 166 (4.8 ± 0.5 kpc distant and 1 Gyr old) may be metal-poor clusters  ( Z = 0.008)  , as estimated from isochrone fitting. The average value of the distance of young clusters from the Galactic plane in the above longitude range and beyond 2 kpc (−47 ± 16 pc, for 64 clusters) indicates that the young disc bends towards the southern latitudes.     

西南极乔治王岛北海岸火山岩的~（40）Ar／~（39）Ar和K-Ar年龄测定

本文采用４０Ａｒ／３９Ａｒ、Ｋ－Ａｒ和激光微区等时线方法，对乔治王岛北海岸的火山岩进行了系统的年龄测定。实验结果表明，该区的火山活动从晚白垩世延续到始新世末期，主要喷发时代为始新世。岩石的年龄由南西向北东依次变新，表明乔治王岛的火山活动中心在不断迁移，与整个南设得兰群岛火山岩的时、空分布规律相符。侵入岩比火山岩生成晚而岩石化学成分更偏酸性，说明侵入岩可能是火山岩同源岩浆分异演化的产物。这批高质量数据的获得，将为区域火山岩地层时代的厘定和构造岩浆演化过程的研究提供有力的依据。