Valley glaciers persisted in the Lake District,north‐west England,until ∼16–15 ka as revealed by terrestrial cosmogenic nuclide (10Be) dating: a response to Heinrich event 1?          下载免费PDF全文

Peter Wilson  Ángel Rodés  Alan Smith 《第四纪科学杂志》2018,33(5):518-526

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福建第四纪不可能有冰川活动     

王绍鸿 《福建地理》2008,(1):83-88

根据已有研究的文献资料,对福建第四纪冰期时没有冰川活动进行论证．首先从早、中、晚更新世的化石研究资料,阐明福建地层古生物资料不支持“冰川说”;然后根据福建从北到南各地大量现存的第三纪以至古生代的喜暖孑遗植物,说明第四纪福建南北都没有冰川活动;再从福建的纬度和海拔2方面,证明福建第四纪不具备形成冰川的温度条件;最后指出所谓的冰臼,实为河水冲刷侵蚀而成的壶穴．  相似文献   

Glacier retreat and climatic variability in the eastern Terskey–Alatoo, inner Tien Shan between the middle of the 19th century and beginning of the 21st century     

Stanislav Kutuzov  Maria Shahgedanova   《Global and Planetary Change》2009,69(1-2):59-70

Changes in the extent of glaciers and rates of glacier termini retreat in the eastern Terskey–Alatoo Range, the Tien Shan Mountains, Central Asia have been evaluated using the remote sensing techniques. Changes in the extent of 335 glaciers between the end of the Little Ice Age (LIA; mid-19th century), 1990 and 2003 have been estimated through the delineation of glacier outlines and the LIA moraine positions on the Landsat TM and ASTER imagery for 1990 and 2003 respectively. By 2003, the glacier surface area had decreased by 19% of the LIA value, which constitutes a 76 km² reduction in glacier surface area. Mapping of 109 glaciers using the 1965 1:25,000 maps revealed that glacier surface area decreased by 12.6% of the 1965 value between 1965 and 2003. Detailed mapping of 10 glaciers using historical maps and aerial photographs from the 1943–1977 period, has enabled glacier extent variations over the 20th century to be identified with a higher temporal resolution. Glacial retreat was slow in the early 20th century but increased considerably between 1943 and 1956 and then again after 1977. The post-1990 period has been marked by the most rapid glacier retreat since the end of the LIA. The observed changes in the extent of glaciers are in line with the observed climatic warming. The regional weather stations have revealed a strong climatic warming during the ablation season since the 1950s at a rate of 0.02–0.03 °C a^− 1. At the higher elevations in the study area represented by the Tien Shan meteorological station, the summer warming was accompanied by negative anomalies in annual precipitation in the 1990s enhancing glacier retreat. However, trends in precipitation in the post-1997 period cannot be evaluated due to the change in observational practices at this station. Neither station in the study area exhibits significant long-term trends in precipitation.  相似文献   

天山乌源1号冰川表面冰尘及底部沉积层真菌群落结构比较及其系统发育分析     

王叙贤  顾燕玲  倪雪姣  关波  倪永清 《冰川冻土》2017,39(4)

对天山乌源1号冰川表面冰尘(Fz)及底部沉积层(Dz)的理化性质及真菌的多样性、群落结构、OTU的系统发育进行了比较分析。ITS克隆文库分析显示,依据99%相似性共得到26个真菌OTU,表面冰尘和底部沉积层分别为21和22个,其中17个为共有OTU。天山1号冰川中真菌以担子菌门(Basidiomycota)、子囊菌门(Ascomycota)占绝对优势,子囊菌门的真菌在Fz、Dz文库中的比例分别约为27%、57%。系统发育分析显示子囊菌门的真菌有14个OUT,8个属,其中Cladosporium仅分布在冰川表面(6.25%),而Aureobasidium仅出现冰川底部沉积层(8.93%)。另外6个属Tetracladium、Pseudeurotium、Fusarium、Penicillium、Simplicillium、Aspergillus在冰川底部和表面均有分布,但丰度明显不同,尤其是Aspergillus、Simplicillium在冰川底部沉积物中占优势(分别为17.86%、12.50%)。担子菌门的克隆主要来自Rhodotorula、Leucosporidium属,前者主要在分布冰川表面(12%),底部沉积层很少,后者在冰川表面及底部均有分布,分别占文库的比例为8.69%、12.50%。冰川表面和底部沉积层生态条件迥异,对其中的微生物系统发育类群具有明显的选择性。  相似文献   

Halokinetics and other features of GLORIA long-range sidescan sonar data from the Red Sea     

《Marine and Petroleum Geology》2017

The Red Sea is an unusual example of a rift basin that transitioned from its evaporitic stage to fully open-ocean conditions at the end of the Miocene (∼5.3 Ma), much more recently than older Mesozoic margins around the Atlantic and Gulf of Mexico. The patterns of halokinetic deformation occurring in the Red Sea are potentially of interest for understanding more generally how evaporite deposits deform during this early stage. Relevant to this issue, a line of reconnaissance sidescan sonar data (GLORIA) collected along the Red Sea in 1979 is re-evaluated here. We first interpret the data with the aid of newly compiled bathymetry from multibeam sonars in the central and southern Red Sea. Features in the acoustic backscatter data are associated with ridges, valleys and rounded flow fronts produced by halokinetic deformation. Some areas of higher acoustic backscattering from the evaporites are suggested to relate to roughness produced by deformation of the evaporite surface. Within the volcanic (oceanic) axial valleys, areas of differing high and low backscattering suggest varied sediment cover and/or carbonate encrustations. With the benefit of the above experience, we then interpreted data from the northern Red Sea, where there are fewer multibeam data available. Rounded fronts of halokinetic deformation are present in the Zabargad Fracture Zone, a broad, shallow valley crossing the Red Sea obliquely. The presence of halokinetic deformation here is evidence that subsidence has occurred along the fracture zone. Elsewhere in the northern Red Sea, the GLORIA data reveal folds in the evaporite surface, suggesting local areas of convergence, like those implied by multibeam data from inter-trough zones further south. Some linear features are observed, many of which are likely to be ridges overlying salt walls. Interestingly, several such features are oriented along an accommodation zone that is oriented parallel to the plate spreading direction. Several rounded, corrugated features are interpreted as possible evaporite flow fronts. Overall, the impression from the data is of a strongly mobile seabed in the Red Sea because of halokinetic deformation, involving both vertical and horizontal movements. However, salt walls appear more common than in the central and southern axial Red Sea, where horizontal movements instead tend to dominate.  相似文献   

基于KH-9数据对青藏高原山地冰川DEM提取及精度评价——以普若岗日冰川和雅弄冰川为例     

张鑫  周建民  刘志平 《冰川冻土》2019,41(1):27-35

针对青藏高原山地冰川区早期DEM数据缺乏、精度低、覆盖范围小等问题,以普若岗日冰川和雅弄冰川为例,利用解密的早期高分辨率间谍卫星KH-9立体像对,建立了基于KH-9数据的山地冰川DEM提取技术流程,并以ICESat GLAS高程数据为基准对提取的DEM进行了精度评价和精度影响分析。结果表明：无论是在普若岗日冰川区还是雅弄冰川区,所获取的DEM精度均完全满足估算山地冰川长时间尺度物质平衡的精度要求。KH-9数据具有空间分辨率高,地面覆盖范围广,成像时间较早（1971-1980年）等特点,可为山地冰川物质平衡研究提供很好的基础数据源。  相似文献   

Can Lichenometry be Used to Date the "Little Ice Age" Glacial Maximum in Iceland?     

Martin P. Kirkbride  Andrew J. Dugmore 《Climatic change》2001,48(1):151-167

In Iceland, there are numerous examples of glacier advances dated to the latter half of the last century. However, in marked contrast to the Alps and northern Europe, the record of historical-age moraines before ca. 1850 is rather sparse. This paper examines to what extent this pattern reflects the actual history of glacier fluctuations, and to what extent it could be a function of preservation and dating of the geomorphological record. Measurements of Rhizocarpon geographicum sp. lichen thalli on ice-marginal moraines and sandur form the basis for the late "Little Ice Age" glacial chronology in south Iceland. Recent studies have converged on the view of a maximum glacier extent in the late nineteenth century, and not during earlier and possibly colder parts of the "Little Ice Age". Here, results of independent dating of moraine ridges and a jökulhlaup deposit demonstrate that conventional lichenometric techniques tend to cluster dates of these landforms to the 1860s-1880s, underestimating tephrochronological dates on the same landforms by >100 yr in some cases. A mid-eighteenth century glacial maximum may be better represented in the landform record than hitherto thought, with implications for reconstruction of North Atlantic circulation patterns.  相似文献   

雪冰中生物有机酸的测试分析方法研究   总被引：4，自引：2，他引：4  

李心清  秦大河  周会 《冰川冻土》2001,23(1):85-91

生物有机酸是构成酸雨的组分类别，对地表环境有着重要影响，由于其来源与生物界关系密切，因此，对其在雪冰中记录的研究是从历史的角度认识C，H，O等生源元素生物地球化学循环，认识过去生态和环境变化的途径之一，但是，由于其含量较低，易遭受污染等原因，雪冰中有机酸含量的定量测定一直是困扰研究人员的一个问题，在对目前有机酸测试分析现状，测试分析的难点和问题调研的基础上，文章提出了一种利用DX－300离子色谱测试山地冰川雪冰中生物有机酸含量的方法，该方法利用AS4A分析柱，AG4A保护柱，TAC－2样品富集柱和ATC－1阴离子捕集柱，以梯度淋洗方式，在14min内可分离检测出甲酸，乙酸，丙酮酸，甲烷磺酸，草酸等有机酸根离子及氟，氯，亚硝酸，硝酸，溴，磷酸和硫酸等常见无机阴离子，上述有机，无机离子的测试分析相对标准误差分别为：氟（2．0％），乙酸（4．5％），甲酸（2．0％），甲烷磺酸（16．9％），氯（3．1％），亚硝酸（3．9％），硝酸（2．2％），溴（4．9％）和硫酸（2．4％）。  相似文献   

贡嘎山东麓第四纪冰川作用与磨西台地成因探讨   总被引：8，自引：0，他引：8  

郑本兴 《冰川冻土》2001,23(3):283-291

青藏高原东部的最高峰贡嘎山（海拔7556m)东麓磨西河流域发育了三次更新世冰期，分别为雅家埂、南门关、贡嘎冰期，其中燕子沟的倒数第二次冰期（南门关冰期）的冰川一直伸到磨西镇下街磨西饭店北，古冰川阻塞主谷，在新兴与南门关沟之间的堡子坝区形成冰川阻塞湖，在磨西镇上街东，该期古冰川覆盖在谢家河坝东面山坡上，融水切形成峡谷，冰退过程中又在峡谷西基岩丘社形成该期古冰川覆盖在谢家河坝东面山坡上，融水深切形成峡谷，冰退过程中又在峡谷西基岩丘陵旁形成冰水湖，南门关冰期后的间冰期时，小湖变干发育了红色古土壤层，该期的红色古土壤层在磨用镇下街南的古冰川与冰川泥石流沉积层顶面也有保存。证明磨西台地的主体为倒数第二次冰期的冰川堆积物，其中也包括有冰水砂砾层透镜体和冰湖相等沉积，磨西台地出露地表的巨大砾石，直径在10－20m之间，多数为冰川表面的消融碛，也可能有冰川泥充夹带的大岩块，磨西台地两侧断续分布有4级冰水阶地以及磨西饭店以下的磨西台地尾部均为末次期后期至全新世的冰水沉积，其中也含有泥石流堆积物。  相似文献   

藏东南冰川地区250 m空间分辨率全天候地表温度生成     

黄志明  周纪  丁利荣  张入财  张晓东  马晋 《遥感学报》2021,25(8):1873-1888

遥感全天候地表温度产品在多云雾地区意义重大,对冰川泥石流多发的藏东南地区极具应用价值,但遥感全天候地表温度空间分辨率不足限制了其在精细化灾害监测中的应用。以藏东南冰川地区为研究区,采用高程、坡度、坡向、地表覆盖类型、植被指数、地表反射率、积雪指数作为全天候地表温度的影响因子,结合移动窗口,进行多种地表温度降尺度方法的对比,进而使用最优的降尺度方法将现有的遥感全天候地表温度产品（TRIMS LST）的空间分辨率从1 km提升至250 m。利用地面站点实测数据的评价结果表明,基于梯度提升决策树（LightGBM）的降尺度方法得到的250 m空间分辨率全天候地表温度的均方根误差在白天/夜间为2.25 K/2.15 K,优于基于多元线性回归和随机森林的降尺度方法,且比原始1 km分辨率全天候地表温度的精度高0.25 K左右。基于Q指数与SIFI指数的图像质量评价结果表明,降尺度得到的250 m地表温度不仅在空间格局和幅值上与原始1 km遥感全天候地表温度一致,而且补充了大量的地表温度空间细节信息。生成得到的250 m分辨率的地表温度对于藏东南冰川地区的灾害分析具有积极的意义。  相似文献