拉尔玛金矿矿源层──太阳顶群硅质岩的有机地球化学研究

拉尔玛金矿矿源层──太阳顶群硅质岩的有机地球化学研究林丽（成都理工学院，成都６１００５９）关键词有机地球化学，硅质岩，太阳顶群，拉尔玛金矿床拉尔玛金矿床赋存于寒武系太阳顶群中，该群的硅质岩是矿源层。本文探讨矿源层形成过程中与金关系密切的有机质的生物先...     

Temnospondyls from the Beaufort Group (Karoo Basin) of South Africa and Their Biostratigraphy

The Permo-Triassic Beaufort Group (Karoo Basin) of South Africa is biostratigraphically subdivided into eight, temporally successive assemblage zones based on therapsids (‘mammal-like reptiles’). The Temnospondyli, fossil tetrapods usually regarded as extinct amphibians, are second only to therapsids in terms of diversity and abundance in these strata, with nine higher-level taxa (‘families’) known. Temnospondyls are also playing an increasingly important role in biostratigraphy and correlation of the Beaufort strata. The lower Beaufort Group (Late Permian) contains six of the eight biozones, but only one temnospondyl ‘family’, the Rhinesuchidae, whose record in the Karoo is the richest in the world. However, rhinesuchid taxonomy remains in flux and the group is thus of limited biostratigraphic utility. The Early Triassic Lystrosaurus Assemblage Zone (middle Beaufort Group) contains the Rhinesuchidae, Amphibamidae, Lydekkerinidae, Tupilakosauridae, Rhytidosteidae, Mastodonsauridae and Trematosauridae, although the biostratigraphy of temnospondyls within this biozone is poorly constrained. The uppermost reaches of the Lystrosaurus biozone contain a paucity of fossils but includes ‘Kestrosaurus’ (Mastodonsauridae) and ?Trematosuchus (Trematosauridae), taxa previously thought to pertain to the lower part of the overlying Cynognathus biozone. The late Early to Middle Triassic Cynognathus Assemblage Zone (upper Beaufort Group) hosts the Mastodonsauridae, Trematosauridae, Brachyopidae, Laidleriidae and, possibly, the Rhytidosteidae. Based largely on the spatial and temporal distribution of mastodonsaurids, this biozone has been biostratigraphically subdivided into a lower A, middle B and upper C subzones, characterised by differing ages and faunas.     

甘肃北山红柳园地区泥盆系三个井组和墩墩山群LA-ICP-MS锆石U-Pb测年及其意义

对甘肃北山红柳园地区三个井组下部玄武岩和墩墩山群安山质火山岩进行了LA-ICP-MS锆石U-Pb年龄测定,三个井组火山岩形成于420Ma±15Ma,相当于晚志留世;墩墩山群火山岩形成于367Ma±10Ma,相当于晚泥盆世。测年结果表明,晚志留世北山古生代洋盆已经俯冲消亡,并开始碰撞造山,而晚泥盆世墩墩山群火山岩则是北山早古生代洋盆碰撞造山后裂谷拉伸作用的产物,标志北山及相邻地区晚泥盆世进入到新的构造演化阶段——晚古生代板内伸展阶段。     

西天山古元古代木札尔特岩群地质特征及时代厘定

西天山木札尔特岩群发育于塔里木原始古陆台内毗邻陆缘活动带,为一套角闪岩相中深变质岩系,主要岩石组合为变粒岩-浅粒岩-片麻岩-斜长角闪岩-大理岩等,局部受韧性变形改造形成各类糜棱岩系,原岩为中基性火山熔岩-火山碎屑岩-火山碎屑沉积岩夹碳酸盐岩建造.由于缺少古生物化石,其地层时代主要依据区域地层对比和同位素年代学数据进行确定.笔者应用钐钕全岩等时线定年法,在该岩群斜长角闪岩中获得(1966±93)Ma的同位素年龄,这是迄今为止,西天山范围内该岩群内获得的最古老同位素年龄,代表了其成岩年龄.据国际地层表(2000)关于古元古界造山系2 050~1 800 Ma的划分方案,笔者最终将西天山木札尔特岩群成岩时代厘定为古元古代造山纪.     

锦屏隆里地区剪切构造变形的初步研究

在隆里地区新元古界下江群中发育有剪切变形的构造，形成脆－韧性剪切带（过渡性剪切带）。按其产状可分为切层和顺层过渡性剪切带两类，具有较典型的脆性－韧性变形的宏观和微观特征。此类变形是地壳浅层次剪切构造作用产物，显示了江南造山带外带的特征     

Characteristics of paleoproterozoic Subduction System in Western Margin of Yangtze Plate

INTRODUCTIONDebate centered on Proterozoic tectonic style and crustalevolution has existed for a long time.The customary viewbelieved that the Proterozoic undeveloped solid plate could notput into effect on the subduction because of the high heat flowin the earth,and the continental crustal growth was dominatedby mafic magm a vertical underplating (Wyborn,1988;Etheridge etal.,1987) .However,many observations recentlyobtained from Proterozoic mobile zones in the world suggeststhat Proter…     

Fossil caddisflies (Insecta: Trichoptera) from the Early Cretaceous of southern England

The first fossil caddis cases from the Early Cretaceous (Wealden) of SE England are described and named Conchindusia rasnitsyni ichnosp. nov., Piscindusia sukachevae ichnogen. et isp. nov., ?Ostracindusia vyalovi ichnosp. nov. and Pelindusia percealleni ichnosp. nov. In addition, the necrotauliid caddisfly Paratrichopteridium purbeckianum (Handlirsch) comb. nov. from the earliest Cretaceous (Purbeck Group) of Dorset is redescribed.     

利马气候大会成果分析与展望

利马气候大会达成的《利马气候行动号令》明确了《联合国气候变化框架公约》所有原则,尤其是共同但有区别的责任原则适用于拟于2015年巴黎会议达成的新协议。会议还就“国家自主决定的贡献”等做出了决定。利马大会成果对2015年巴黎气候大会达成气候变化新协议具有重要推动作用。面对2020年后的新挑战,中国需尽快制定应对气候变化法,建立碳排放交易机制,促进对应对气候变化先进技术投资,以及加大参与治理国际气候变化事务力度。     

Group K-Nearest Neighbors queries in spatial network databases

This paper addresses the problem of Group K-Nearest Neighbors (GKNN) queries in spatial network databases, and suggests a novel approach based on real network distances. This approach essentially uses network Voronoi diagram properties together with a progressive incremental network expansion for determining the inner network distances that are needed to obtain GKNN queries.      

Global synchroneity of a positive carbon isotope excursion at the Cenomanian/Turonian boundary: Validation by calcareous microfossil biostratigraphy of the Yezo Group, Hokkaido, Japan

Abstract Isotopic analyses of organic carbon from the mid-Cretaceous sequence in Hokkaido, Japan, revealed a 2‰ positive excursion of δ¹³C values at the biostratigraphically defined Cenomanian/Turonian (C/T) boundary recognized in the Yezo Group. The planktonic foraminiferal Whiteinella archaeocretacea Zone, which is known to bracket the Cenomanian/Turonian boundary elsewhere in the world, was recognized in the Oyubari area of central Hokkaido based on the distribution of commonly occurring planktonic foraminifera. In the Tappu area of northwestern Hokkaido, where diagnostic planktonic foraminifera are rare but calcareous nannoplankton occur commonly, the interval coeval with the W. archaeocretacea Zone can also be established by recognizing the conjoined last appearance levels of Corollithion kennedyi and Axopodorhabdus albianus, both calcareous nannoplankton species. Carbon isotope profiles exhibit a similar pattern with comparable peaks and troughs occurring in the same stratigraphic position in the sequences. A prominent, positive 2‰ shift of δ¹³C values, here called ‘δ¹³C spike’ occurs in the middle of the W. archaeocretacea Zone in the Oyubari area and just above the conjoined last appearances of the two above-mentioned nannoplankton taxa in the Tappu area. The Cenomanian/Turonian boundary can be drawn just above the peak position of the spike in both sections. The Rock Eval analyses and biomarker analyses of organic carbon indicate that organic carbon subjected to our isotope analyses is of terrestrial origin. Therefore, the observed 2%o shift should reflect changes in the isotopic composition of the atmospheric CO₂. A unique layer composed predominantly of sand-grain sized spumellarian Radiolaria is present immediately above the δ¹³C spike both in the Oyubari and Tappu areas, suggesting an increasing availability of both nutrients and silica in surface waters.