Permafrost mapping of Northeast European Russia based on the period of climatic warming 1970-1995

Verdenskrigen som efterhånden i do krigførende land tok alle hjelpemidler og all intelligens i sin tjeneste og innskrenket den frie samferdsel selv for de nøitrale stater, måtte selvfølgelig legge hindringer i veien for forskningsekspedisjoner til Asia. De stoppet velikke helt op. Som vi skal se blev der også under krigen foretatt og begynt undersøkelser av denne art; men først efter krigen utviklet de sig igjen i større stil. Det synes derfor å være naturlig å velge denne verdenskatastrofe som et skille, og jeg vil i det følgende mere utførlig omtale bare de ekspedisjoner og forskninger, som vesentlig er blitt utført efter denne tid.     

中蒙俄毗邻地区中蒙古—额尔古纳成矿带成矿地质条件与成矿特征

正介于蒙古—鄂霍次克断裂带和中蒙古—得尔布干断裂带之间的中蒙古—额尔古纳成矿带,西起蒙古杭爱山,经中戈壁省、乔巴山,向东延伸至我国大兴安岭北段满洲里—呼吗一带,封闭于俄罗斯阿穆尔州,中国境内部分包括了大兴安岭成矿省的上黑龙江(边缘海)Au(Cu-Mo)成矿带和额尔古纳Cu-Mo-Pb-Zn-Ag-Au—萤石成矿亚带(徐志刚等,2008;朱群等,2014)。     

斯特列利措夫矿田一个大型-超大型铀矿床群在苏联时期是怎样被发现和被勘探的

斯特列利措夫（简称Str）矿田是一个主要由大型-超大型钼铀矿床构成的矿床群,它位于南滨额尔古纳地区,铀的总储量在25万t以上,平均品位0.20%。该矿田在苏联解体以来的很长时间内几乎是俄罗斯唯一的天然铀来源。该区找铀的工作历程漫长而曲折,并颇具传奇色彩。早在1948年苏联地质部第一局松林大队在南滨额尔古纳地区开始了找铀工作。但因区内几乎所有矿床均属盲矿,而且多埋深较大,1962年之前找铀无果,1962年春已决定放弃在该区进行的找铀工作。1962年夏天高级地质师Л П伊舒科娃参观了哈萨克斯坦产在酸性火山岩中2个规模不大的铀矿床（波统-布鲁姆和克泽尔-萨伊）,注意到斯特列利措夫萤石脉围岩霏细岩的蚀变与哈萨克斯坦2个规模不大的铀矿床相似。归来之后,她上书领导力主恢复本区找矿工作并获得了再去做最后一试的机会。1963年5月,伊舒科娃所设计的钻孔一箭中的,发现了首个Str超大型铀矿床,整个局面立刻出现大转折,加速矿田开发成了所有工作的总方针。矿床的普查勘探工作和对矿床的地质研究工作平行加速进行,两者互相促进。不到10年,矿田的大部分矿床被一一发现;到1966年底,Str等矿床的初勘成果已经成为1970年代初组建全苏最大铀矿山的充分依据。到1980年底,矿田已有17个钼铀矿床完成勘探。1992年底19个矿床勘探完成。新一轮找矿采用的方略：首先合理综合运用地质、放射性及传统地球物理和地球化学方法,并合理综合使用深度普查自动装置射孔和钻探手段,进行不同比例尺的立体地质-构造填图;然后在其成果的基础上用钻孔去发现矿体。勘探工作所面对的基本事实：矿床构成的多重复杂性为Str矿田内所有矿床的共同特征;每个矿床的特点各异,其勘探过程不尽相同。初勘使用地表钻探进行,基本网度200 m×100 m~400 m×100 m。详勘使用坑探工程与钻探相结合的手段,采用水平与垂直断面联合的勘探系统,基本网度50 m×20 m~50 m×25 m。所有矿床的勘探成果完全被开采工程证实,并有10%的储量增长。Str铀矿床形成于晚中生代,为区域构造-岩浆活化作用晚阶段的陆相火山作用地区的岩浆热液矿床,受断裂构造控制是其基本特征之一。铀矿床在矿田内空间定位的重要规律：Str及其他绝大多数铀矿床均受控于南北向、北西向或东西向断裂与北东向额尔古纳隐伏深断裂带交汇。"斯特列利措夫效应"曾迅速地在我国铀矿地质勘查工作中传播,期待在我国,尤其在呼伦贝尔,乃至大兴安岭-燕山山脉中生代构造-岩浆带地区继续发酵,取得更多和更大的成果。     

A preliminary investigation of siliceous microfossil succession in late Quaternary sediments from Lake Baikal, Siberia

Siliceous microfossil assemblage succession was analyzed in a 100 m sediment core from Lake Baikal, Siberia. The core was recovered from the lake's central basin at a water depth of 365 m. Microfossil abundance varied greatly within the intervals sampled, ranging from samples devoid of siliceous microfossils to samples with up to 3.49 × 10¹¹ microfossils g^-1 sediment. Fluctuations in abundance appear to reflect trends in the marine ¹⁸O record, with peak microfossil levels generally representing climate optima. Microfossil taxa present in sampled intervals changed considerably with core depth. Within each sample a small number of endemic diatom species dominated the assemblage. Changes in dominant endemic taxa between sampled intervals ranged from extirpation of some taxa, to shifts in quantitative abundance. Differences in microfossil composition and the association of variations in abundance with climate fluctuations suggest rapid speciation in response to major climatic excursions.     

Extending the known distribution of the Younger Dryas Vedde Ash into northwestern Russia

The known distribution of wind‐blown Vedde Ash (ca. 10.3 ka BP) has been extended to the Karelian Isthmus in northwestern Russia. This has been possible as the result of a density separation technique that separates the rhyolitic Vedde Ash shards from the minerogenic host sediment. The Vedde Ash occurs in the middle of a pollen zone with high percentages of, for example, Artemisia and Chenopodiaceae, suggesting that the Younger Dryas (or GS‐I in the GRIP ice‐core event stratigraphy) was cold and dry throughout its duration. This is in agreement with sites in south Sweden where the Vedde Ash also occurs in the middle of a pollen zone dominated by Artemisia, Chenopodiaceae and Cyperaceae. Copyright © 2000 John Wiley & Sons, Ltd.     

2003年俄、中、蒙交界M7.9地震前地倾斜异常

简要归纳了M7．9地震前地倾斜记录的异常及其特征,认为M7．9地震前地倾斜存在明显的阶段性异常,趋势异常持续3年以上,中短期异常由近场向600km范围扩展,700-850km范围的多个台站记录到较明显的临震异常,富蕴台地倾斜的掉格图像是M7．9地震最突出的前兆异常。     

Spatial distribution of cyanotoxins and ratios of microcystin to biomass indicators in the reservoirs of the Volga,Kama and Don Rivers,the European part of Russia

We studied the distribution of cyanotoxins and potential producers, as well as the variability of microcystin to biomass parameters (chlorophyll-a; MC/Chl-a; and biovolume; MC/BV) in 12 drinking water reservoirs of the world’s largest reservoir system, the Volga-Kama-Don cascade (European part of Russia) during the summers of 2016 and 2018. MC concentrations varied from below 0.1 μg L⁻¹ in June up to 16.4 μg L⁻¹ in August and exceeded 1 μg L^-1 in 25 % of the samples. This MC variability was associated to changes in the abundance of widespread bloom formers such as Microcystis spp., Dolichospermum spp. and Planktothrix agardhii. Ratios of MC/Chl-a and MC/BV_cyano ranged up to 0.88 μg μg⁻¹ and 4.5 μg mm⁻³, respectively. Together with microcystin profiles MC/BV_cyano ratios characterized cyanobacterial populations along the reservoir cascade and they indicated a potential toxin hazard better than MC/Chl-a. The neurotoxin anatoxin-a was observed only in the most southern and hypereutrophic Tsimlyansk Reservoir (maximum 0.01 μg L⁻¹). Toxin gene analysis revealed that MC mostly originated from Microcystis and Dolichospermum. During their co-existence up to 14 MC congeners co-occurred. Cuspidothrix issatschenkoi cf. Raphidiopsis mediterranea was identified as possible neurotoxin producers.     

How charophytes (Streptophyta,Charales) survive in severe conditions of the permafrost area in Far North-East Asia

Eight species of charophytes have been found in the vast area of the ubiquitous permafrost in Far North-East Asia (i.e. the Republic of Sakha (Yakutia), the Magadan Region, and the Chukotka Autonomous Area, Russia): Chara contraria, C. globularis, C. strigosa, C. virgata, Nitella flexilis, N. opaca, N. wahlbergiana and Tolypella canadensis.Charophytes are found in a variety of water bodies and watercourses in areas with various thicknesses of permafrost, within the boreal and subarctic climate zones. Charophyte habitats are mostly associated with the distribution of carbonate rocks. The number of species and their records decrease towards north and east mainly due to shortening of the vegetation period. The highest density of records of charophytes and their most northern records are in river valleys, where the topography and heating effect of the river mitigate the influence of climate and permafrost. This association can be used to model and predict charophyte distribution in periglacial areas during glaciation.Widespread eurytopic species with a flexible life cycle, Chara contraria and C. globularis, are found in valley water bodies due to their ability to withstand environmental variation associated with marked changes in water temperature and flood disturbance. Rare perennial species such as C. strigosa and Tolypella canadensis are represented in deep lakes with less variation in environmental conditions.This paper discusses the distribution, habitat and life history strategies of charophytes that exist in the severe conditions of the permafrost area in Far North-East Asia based on previously published and new data.