首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 125 毫秒
1.
东南极拉斯曼丘陵区的冰川作用   总被引:5,自引:0,他引:5  
拉斯曼丘陵在渐新世已被冰盖覆没,晚渐新世冰盖厚度最大,自中新世开始,冰盖逐渐减薄后退,但该丘陵仍为冰盖占据。更新世冰川作用规模不及第三纪。18kaB.P.该丘陵区覆冰厚度超过170m,冰盖前缘仅厚30m左右。冰盖后退出露其岩约在10.0kaB.P前后,自9.41-6.5kaB.P,冰川以2-3m/a的速率后退,岛屿区人武部出露,自6.5-5.0kaB.P,冰川后退速率砬为1.0-1.5m/a,丘陵  相似文献   

2.
南极15ka以来海洋沉积物的环境磁学研究   总被引:4,自引:2,他引:4       下载免费PDF全文
通过对东南极普里兹湾陆坡区NP95-1及西南极长城湾NG93-1两柱样系统的环境磁学研究,获得了南极地区15.0~5.5kaB.P.以来的古气候变化序列。结果表明,磁学参数较好地记录了古气候变化及沉积环境变化的信息。NP95-1柱样较好地记录了Heinrich1事件、新仙女木事件以及波令-阿罗德暖期,其中Heinrich1事件发生于14.3kaB.P.,新仙女木冷期为11.7~10.3kaB.P.,10.3kaB.P.以后,南极地区进入全新世。在全新世,两柱样记录了在10.0kaB.P.及6.0kaB.P.前后两个暖期,其间夹有小幅气温下调的时段;6.0kaB.P.后,两柱样均有气候颤动变冷的记录。  相似文献   

3.
祁连山东段北麓近10ka来的气候变化初步研究   总被引:14,自引:4,他引:10  
邬光剑  潘保田 《中国沙漠》1998,18(3):193-200
磁化率、碳酸钙含量和有机碳含量可用作良好的气候指标,主要是反映了降水量的变化。祁连山东段北麓哈溪剖面研究表明,9560aB.P.时本区已进入全新世。大暖期是对温度而言,与气候适宜期是不同的概念,二者在时间上也不一定是同时的。本区的气候适宜期为6.8~3.6kaB.P.,气候最宜期为5.0~3.6kaB.P.,与其它记录有不同之处。在7.8~7.2kaB.P.和1.5~0.8kaB.P.间出现了“冷湿”的气候组合,这与传统的气候组合不同,但后一阶段的“冷湿”是有大量证据的。9.0~8.7kaB.P.间是全新世最干旱的时段,堆积了砂黄土。  相似文献   

4.
祁连山东段全新世与现代水热组合特征研究   总被引:6,自引:3,他引:6  
位于祁连山北麓的扁都口和哈溪记录了该地区的全新世气候变化。采用磁化率、有机碳含量和碳酸钙含量作为降水指标,其记录的水分变化与冰芯及其他记录的对比,显示了地区全新世水热组合变化的特征。传统的大暖期鼎盛阶段并非本研究的气候最宜期。5.2~4.0kaB.P。.本区的环境相当优越,是气候最宜期。4.0kaB.P.存在一次比3.0kaB.P.明显的气候恶化,地层和剖面记录突出。2.0~1.0kaB.P.是低  相似文献   

5.
毛乌素沙地全新世地层化学元素特点及其古气候意义   总被引:13,自引:6,他引:13  
系统采集毛乌素沙地东、西部各一个全新世地层剖面样品作全量化学分析。根据景观地球化学特征的变化,推论一万年以来气候的变化过程:10.5—10ka,B.P.、6—50ka,B.P.、3.5ka,B.P.、2.5ka,B.P.和1.5—1ka,B.P.期间分别为化学风化较强,钠、钾淋失较多,而钙、镁、铝、铁、钛相对富集的相对湿润时期;夹于其间的则是化学风化较弱,钠钾相对富集,相对干燥的风化活动时期。  相似文献   

6.
南极普里兹湾NP951柱样元素地层与古环境初步研究   总被引:3,自引:0,他引:3       下载免费PDF全文
古森昌  颜文 《极地研究》1997,9(2):33-39
对南极普里兹湾NP951柱样的元素地球化学特征及其古环境意义进行了研究。结果表明,本区沉积物在沉积过程中受冰盖消融、淡水涌入和陆源物质的影响较大;沉积物中SiO2、Al2O3、Fe2O3、CaO、MgO、P、S、Corg等元素组分较好地记录了由古气候变化而引起的物源改变,这些元素组分在地层中的分布规律与古海洋沉积环境及古气候变迁相一致;自晚更新世末期以来的气候大致可分为温暖期、寒冷期、高温期、转冷期和转暖期五个区段;在柱样的145cm(14.4kaB.P.)、85cm(10.3kaB.P.)和25cm(6.3kaB.P.)处出现了古气温的高值点,指示了气候的变化;85cm处元素含量的突变指示了异常事件的发生,该层位正好对应于哥德堡地球磁场漂移,全球气温突然变暖,标志着10.3kaB.P.以后南极地区进入了全新世。  相似文献   

7.
晚冰期以来毛乌素沙漠环境特征的湖沼相沉积记录   总被引:24,自引:8,他引:16  
苏志珠  李小强 《中国沙漠》1999,19(2):104-109
毛乌素沙漠南缘靖边海则滩湖沼相沉积剖面,真实地记录了晚冰期以来东亚季风气候和沙漠演化历史。在地层沉积相划分和测年基础上,据地球化学元素和孢粉等气候指标分析表明,该区古气候变迁序列为:12kaBP前干燥寒冷;12~10kaBP气候转暖湿;10~8.5kaBP以温湿为主,在10~9.5kaBP出现YoungerDryas冷干事件;8.5~3.0kaBP温暖湿润;3.0kaBP后气候趋于半干旱与现代气候较接近。这种气候演化规律是受地球轨道因素影响,通过东亚冬夏季风的强弱变化来实现的  相似文献   

8.
贡嘎山区在全新世初期(10000-7500aBP),气候渐暖,冰川后退,泥石流发生频次剧增;中期(7500-4000aBP),出现高温气候,冰川强烈后退,沉积物则以冰水河流相为主;晚期(<4000aBP),气候转冷,出现新冰期。嗣后,气候转暖,但有三次明显的冰进过程;400aBP前,气候再度转冷,出现小冰期。大量的泥石流点是出现在气候转暖、冰川退缩的初始阶段。  相似文献   

9.
自1988年11月至1989年3月,对南极长城湾(62°13′S,58°57′W)中5个站位的水温、pH值、海水透明度、水下照度、水中和海冰中叶绿素含量、磷酸盐含量、亚硝酸盐和硝酸盐含量等理化要素,每月进行1至2次不定期的常规测定。在整个调查期间,海水温度变化范围在-1.6~2.2°C之间,pH值变化范围在8.0~9.1之间,海水中叶绿素a的变化范围在0.30~1.48mg/m3之间,叶绿素a的最大值出现在11月26日5号站的表层水中,海冰中叶绿素a的含量远远高于海水中的含量,海冰中叶绿素a的变化范围在2.55~56.84mg/m3之间。磷酸盐含量变化范围在1.023~2.187μgP/L,亚硝酸盐含量变化范围在0.093~0.186μgN/L之间,硝酸盐含量变化范围在13.308~26.584μgN/L之间。本文对以上结果作了初步探讨  相似文献   

10.
柯林斯冰帽两支冰芯层位记录证实了该冰帽主冰穹顶部(海拔约700m)属暖渗浸带,小冰穹顶部(海拔约250m)属渗浸带。雪、冰的层位分布和密度变化包含了一定的测年信息。主冰穹顶冰芯密度-深度曲线在表层呈现韵律性变化,与层位记录中的融化冻结现象相对应,据此粗略划分年层,断定当地年积累雪层厚度为3-3.5m,折合水当量1650-1925kg/m2a,年平均积累速率约为2.0m/a(冰当量)。主冰穹顶成冰深度为38-39m,此深度以上密度自上而下缓慢增加,但以下由于含水层的出现,密度迅速升高,在5-6m区间达到900kg/m3。小冰穹冰芯除表层外,密度基本在800-900kg/m3之间,冰芯中雪冰互层,存在污化面,40m以下发现很厚的火山灰沉积物。小冰穹平均年积累率约为0.7m/a(冰当量),成冰深度7-8m,成冰年限为10年左右  相似文献   

11.
本文首次报道东南极中山站沿岸潮间带冰融期砂和砾质砂中微小型硅藻的分布、种类组成及各站位间种类组成的相似性。中山站潮间带微小型硅藻主要分布在中山湾B站,1989年1月和1990年2月每克砾砂细胞丰度分别在0.8×103~3651×103个和4.5×103~2618×103个,并具有细胞个体小、丰度大等特点,其优势种为冰川舟形藻Naviculaglaciei。  相似文献   

12.
王自磐 《极地研究》2000,11(2):147-160
Coastal region on the Antarctic continent, where it is under the influences both of ocean and ice sheet, as well as frequent human activities, could be considered as a fragile zone in Antarctic ecological environment. There are many lakes in coastal region, showing much differences from each other in physical-chemical features because of individual evolutionary history in their geographical environments, and suffering from different outside factors, such as climate changes and precipitation. Thus, it results in respective biological distribution and ecological structure in lakes. The present paper reports the results from the studies of chemical components, species distributions and community structures, which mainly consisted of planktons in lakes in the Vestfold Hills (68°38′S, 78°06′E), and the Larsemann Hills (69°30′S, 76°20′E), East Antarctica. It also treats the biological diversities and nutrient relationships of these different types of lakes. So as to provide more scientific basis for monitoring of climate changes and environmental protection in Antarctica.  相似文献   

13.
南极大陆冰缘环境变迁与沿海盐湖生态特征   总被引:1,自引:3,他引:1       下载免费PDF全文
王自磐 《极地研究》1998,10(1):20-28
现代南极大陆冰缘地理地貌,形成于18000年以来全球气候变化,南极大陆冰盖的退缩,以及随后的大陆均衡抬升和海平面变化等过程。研究表明,在维斯德福尔特丘陵地,这一过程仍在继续,并导致该区许多海生盐湖自然环境和理化因子的改变,以及湖中生物的种群结构的变化和群落演替。本文通过对这些现象的剖析,阐明了南极大陆冰缘环境变迁的客观存在,为进一步研究南极乃至全球气候变化提供生态学佐证。  相似文献   

14.
Astudyonnano-andmicrodiatomsintheintertidalzonesofZhongshanStation,AntarcticaZhuGenhai(朱根海);LuDouding(陆斗定)andWangZipan(王自磐)(S...  相似文献   

15.
王自磐 《极地研究》1998,9(2):55-62
1IntroductionTheAntarcticcoastlineisafectedbytheretreatoftheiceshetwhichbeganaround18000aB.P..Icefreareas,suchastheBungerHils...  相似文献   

16.
对中山站附近2个大地电磁测深点的数据处理结果表明,拉斯曼丘陵地区的岩石圈厚度为140km,在地壳内22km处有一高导层  相似文献   

17.
李栓科 《极地研究》1996,8(3):39-48
分析制图说和综合制图说是目前国内外占主导地位的两种地貌制图体系。本文阐述了这两种体系的优劣。并设计出适合拉斯曼丘陵区的地貌制图系统,分步骤对地貌形态的五大要素进行分析取舍。并辅以营力分区图、古剥蚀面图等图件,使综合地貌图信息更丰富,同时清晰度和直观性亦得到保证。  相似文献   

18.
The Bunger Hills in East Antarctica occupy a land area of approximately 400 km2. They have been exposed by Holocene retreat of the Antarctic ice sheet and its outlet glaciers. The accompanying sea level rise flooded the marine inlets that now separate the northern islands and peninsulas from the major part of the hills. During deglaciation the continental ice sheet margin retreated south‐eastwards with several temporary halts, during which ice‐dammed lakes were formed in some valleys. These lakes were maintained long enough to permit formation of beaches of sand and gravel, and for the erosion of shore platforms and low cliffs in bedrock. Around the western end of Fish Tail Bay impressive shoreline features 20 m above sea level define a former ice‐dammed lake that was 5.5 km long. A similar 7 km long former ice‐dammed lake was formed at Lake Dolgoe. The more extensive and deeper glacial lake is revealed by well‐developed and preserved shoreline features cut at 29 m which is 16 m above present lake level. In addition, several small ice‐dammed lakes existed temporarily near Lake Shchel and in the valley to the west. Lake Fish Tail existed more than 6,900 14C years ago and Lake Shchel probably more than 6,680 14C years ago. It is inferred that the shore platforms and beaches were formed by lake ice and wave action over considerable periods when the lakes were impounded by steep cold ice margins. There appears to have been a balance between meltwater input and evaporative loss from the lakes in the cold dry continental climate. There is no evidence for rapid lake level fluctuations, and there was very little input of clastic sediment. This resulted in poor development of deltaic and rhythmically laminated lake floor deposits. It is suggested that such deposits are more characteristic of ice‐dammed lakes formed in association with wet‐based temperate ice than those associated with dry‐based polar ice.  相似文献   

19.
《极地研究》1992,3(2):56-68
The extension of ice sheet on King George Island during the last glaciation was an environment event since the last glaciation. At that time South Shedlands Islands were a large unified island and the ice mass on King George Island might come from the Antarctic Peninsula. The model of ice retreat and ice advance events in the Holocene show that the ice sheet was separated into three small ice caps and then dispeared gradually. At present the retreating velocity of glacier is about 1.3m each year. After the retreat of ice sheet the isostatic compensation appeared in the crust there, and then 5-6 steps of the uplifted marine terraces have been developed along the coast. The uplift rate of the crust may be 6-10mm/a.  相似文献   

20.
The fabrics and crystals of Bohai one year ice show that the noncontinuous ice growth rate enables the level ice layers with different amount of air bubbles to be formed in lower part of an ice sheet which was clearly seen from CT technology; typical grain ice and columnar ice occur in the grey ice which grows in stable water; thaw refrozen ice and rafted ice have their specific crystal characters. On the Arctic sea ice, the ice core located at 72°24.037′N, 153°33.994′W and 2.2 m in length was a 3 year ice floe and a new sort of crystal was found, which is defined as refrozen clastic pieces. The crystal profile of the ice core 4.86 m in length located at 74°58.614′N, 160°31.830′W shows the evidence that ice ridge changed into hummock.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号