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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
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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
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
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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
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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
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塔里木盆地南缘4 ka B.P.以来气候环境演化与古城镇废弃事件关系研究 总被引：11，自引：6，他引：5
策勒绿洲沉积地层及地球化学元素的研究表明,虽然近４ ｋａ Ｂ．Ｐ．来本地区气候环境的干旱状况持续未变,但期间仍有若干次相对湿润与干旱化加剧时期的波动。结合年代学的研究,以约２ ０００ ａＢ．Ｐ．为界,其以前气候以相对湿润为主,而此以后,则以持续干旱为主要特征,且揭示出４ 次具有突变性质的气候转干时期,即自约１ ５００ａ Ｂ．Ｐ．开始,类似本地区现今气候环境特征已经出现,自约１ ２００ ａ Ｂ．Ｐ．至１ ０００ ａ Ｂ．Ｐ．、１ ０００ ａ Ｂ．Ｐ．至６３０ ａＢ．Ｐ．期间和２００ ａ Ｂ．Ｐ．以后,策勒地区沙漠化进程急剧加强。本研究揭示了４ ｋａ Ｂ．Ｐ．来本地区持续干旱化的特征,并有后期加剧的趋势,而上述气候的转干事件与塔里木盆地古城废弃事件之间具有良好的吻合关系,表明气候环境的自然演化是影响人地关系的重要因素之一。 相似文献
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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
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
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晚新生代青藏高原的隆升与东亚环境变化 总被引：171，自引：4，他引：167
青藏地区在第三纪青藏地区经过二次隆升与夷平的旋回,在２５ＭａＢＰ￣１７Ｍａ ＢＰ高原面隆升达到２００００ｍ左右高度,和当时大陆与海洋环境耦合,激发了亚洲季风,替代了先前的行星风系,导致第三纪中期我国环境大变化。此后高原面夷平降低,夏季风减弱,３．４Ｍａ以来高原整体快速隆起,２．５ＭａＢＰ开始中国北部黄土堆积。０．８ＭａＢＰ￣０．５ＭａＢＰ高原面上升至３０００ｍ￣３５００ｍ左右,与地球轨道转型导致的 相似文献
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可可西里地区湖泊资源调查研究 总被引：17，自引：0，他引：17
1989—1990年,国家可可西里综合考察填补了青藏高原腹地最后一块空白区。通过24个专业学科历时两年的奋战,取得了大量珍贵的第一性科学资料,基本查清了可可西里地区湖泊资源及其展布规律,湖泊度达0.047—0.053;并发现了本区特有的湖泊奇特景观。为可可西里地区自然环境演变过程中湖泊时空位置的揭示,湖泊的保护利用、开发管理以及国土整治等提供了科学依据。 相似文献
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西藏喜马拉雅山区危险冰湖及其溃决特征 总被引：28，自引：1，他引：28
喜马拉雅山区的冰湖溃决主要属终碛湖溃决。野外考察和编目研究的结果表明，终碛湖占各类高山冰湖总数的1/2和总水体的3/4。鉴别出34个危险终碛湖，其水体容量在10×10~6—30×10~6m~3之间，平均水深31m，实测最大水深在70m左右。危险终碛湖绝大多数形成于小冰期最后一次冰退阶段，由于其形态特征和现代冰川的直接影响而具有潜在的溃决危险；讨论了终碛湖溃决的特征，主要因素及其周期性。 相似文献
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David Fortin Darrell S. Kaufman Megan Arnold Erik Schiefer Nathan Hawley 《Geografiska Annaler: Series A, Physical Geography》2015,97(4):709-719
The timing of clastic sedimentation in two glacial‐fed lakes with contrasting watersheds was monitored using sequencing sediment traps for two consecutive years at Allison Lake (Chugach Range, Alaska) and four months at Shainin Lake (Brooks Range, Alaska). Shainin Lake is a weakly stratified lake fed by distant glaciers, whereas Allison Lake is more strongly stratified and fed predominantly by proximal glaciers. At Shainin Lake, sediment accumulation started in late June and reached its maximum in mid‐August, just before lake mixing and during a period of low river discharge. The grain size of the sediment reaching the sediment trap in Shainin Lake was homogenous throughout the summer. At Allison Lake, pulsed sedimentation of coarse particles during late summer and early fall storms were superimposed on the fine‐grained sedimentation pattern similar to that observed at Shainin Lake. These storms triggered underflows that were observed in the thermal structure of the lake and deposited abundant sediment. The sequencing sediment traps reveal a lag between fluvial discharge and sediment deposition at both lakes, implying limitations to interpreting intra‐annual sedimentary features in terms of inflow discharge. 相似文献
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盐湖沉积记录了区域的气候和水文变化,是重要的古气候研究对象。年代学是盐湖古气候研究最重要的一项内容,是后续几乎所有工作的基础。盐湖沉积最常用的定年方法有14C定年、铀系定年、光释光(OSL)定年、古地磁定年。受各种定年方法自身的局限性以及盐湖沉积特有的沉积特征,存在不同方法测出的年龄差异较大的现象。准确测定盐湖沉积的年代还较为困难,一定程度制约了盐湖古气候研究的发展。由于盐湖沉积有机质含量低,易受现代碳的污染,其14C年代老于30 cal ka BP时,测出的年龄可能已饱和,需要谨慎对待。未来需要加强铀系定年和光释光定年等方法在盐湖沉积中的基础研究,并开发新的更好的测年方法,提高盐湖沉积测年的准确度,为深入开展盐湖古气候变化及成盐成矿规律研究提供坚实基础。 相似文献
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Ronald B. Davis 《Journal of Paleolimnology》1989,2(4):263-283
I describe Quaternary paleolimnology on the basis of a review of abstracts published for meetings of: (1) American Society of Limnology and Oceanography (ASLO), 10 meetings since 1980; (2) International Association of Theoretical and Applied Limnology (SIL), 4 since 1977, (3) International Symposia on Paleolimnology (ISP), 4 since 1967, and (4) International Union for Quaternary Research (INQUA), 5 since 1969. A total of 9538 abstracts were scanned to find 678 with paleolimnological content. A data base constructed from the 678 contains frequencies of coverage of techniques, parameters, themes, interpretive aspects, and character and geography of study sites. These data indicate that Quaternary paleolimnology has been a diverse science dealing with many of the same aspects of lakes as neolimnology but with a longer time perspective. Most frequently studied paleolimnological characteristics were trophic state, water chemistry (particularly salinity, pH, alkalinity (ANC), micronutrients and oxygen), water levels, lake morphology, and mixis and other hydrology. Lake biological parameters that received greatest attention were diatoms, pigments, Cladocera, Mallomonadaceae, non-siliceous algae, Ostracoda, and Mollusca. Most often considered to influence these characteristics and parameters were climate; catchment vegetation, soil, geology, land use and erosion; water chemistry; aerial and non aerial pollutants; sedimentation; and tectonism. Most frequent chronologic sequences were (1) late-glacial to present, and (2) modern (ca. 0.3 ka to present). Lakes in moist temperate and boreal regions were most heavily studied.Of the four series, INQUA covered the longest time scales (to late Tertiary), but emphasized the last 100 ka. INQUA stressed outside-lake geomorphology (as it relates to lake) and lake morphology, physical forcing functions (e.g., climate and tectonism), hydrologic factors including water levels, paleosalinities, and reconstruction of paleoclimates. In contrast, SIL and ASLO rarely covered pre-15 ka. Most SIL and ASLO abstracts dealt with only the most recent 0.3 ka. Of strong interest to SIL and ASLO were the effects of catchment vegetation and soils, land uses, and pollutants (e.g., acid deposition) on past lake chemistry, biology, and trophic conditions. To infer these conditions from sediment contents, frequent use was made of modern analogues and, starting in the 1970's of microfossil (mostly diatoms) transfer functions based on calibration data sets. In several respects, ISP subject coverage and approaches were intermediate between those of INQUA and SIL/ASLO.Major improvements in paleolimnology have occurred since the 1960's, particularly in the areas of chronology and use of multivariate statistical techniques for paleoenvironmental inference based on microfossils. I conclude this paper with several suggestions for further advancement of the science.Over the last several issues, the Journal of Paleolimnology has published 13 papers that were presented in the paleolimnology sessions organized by R.B. Davis and H. Löffler for the XIIth Congress of the International Union for Quaternary Research (INQUA), which took place in Ottawa, Canada in August 1987. Dr. Davis served as guest editor for this series. This present review paper is an abridged version of the introductory chapter of a book containing these INQUA paper, entitled Paleolimnology and the Reconstruction of Ancient Environments, to be published by Kluwer Academic Publishers. 相似文献
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通过对盐湖地区岩土类型复杂性及特性的叙述,分析了盐湖矿产开发中不良地质现象产生的原因和岩土条件对开发规模、工程布局、工程安全、经济效益等方面产生的影响。论述岩土工程勘察在盐湖矿产开发中的特殊地位和重要价值,总结出岩土勘察与盐湖卤水矿产开发的关系,提出盐湖岩土勘察方案的相关建议。 相似文献
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盐湖卤水蒸发是提取盐湖资源的主要途径之一,当前盐湖卤水的蒸发实验主要集中在矿化程度较高的盐湖和咸水湖中,蒸出矿物以硫酸盐和氯化物为主。为了获得湖水蒸发过程中从低矿化度到高矿化度全阶段的析盐和pH值变化规律,本文用托素湖微咸水在恒温室内开展28±2℃蒸发实验。托素湖为硫酸镁亚型微咸水湖(矿化度27.8 g/L),整个蒸发过程中pH值由8.92持续降低到6.108;矿物析出顺序为三水菱镁矿-文石-石盐-六水泻盐-白钠镁矾-五水泻盐-四水泻盐,共有七组盐类析出。卤水pH值的变化主要受矿物相变化控制,在碳酸盐析出过程中pH由8.529迅速降低到7.205,而后以析出矿物石盐为主的石盐-硫酸盐析出阶段pH降低到6.887,之后在白钠镁为主硫酸盐-石盐阶段pH缓慢降低到6.29。同时分析了石膏、芒硝、泻利盐等矿物未析出的原因。通过托素湖湖水蒸发实验,可以更全面的认识硫酸镁亚型盐湖演化全过程中的矿物沉积规律及物理化学性质变化。 相似文献
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概要：本文通过对盐湖地区岩土类型复杂性及特性的叙述,分析了盐湖矿产开发中不良地质现象产生的原因和岩土条件对开发规模、工程布局、工程安全、经济效益等方面产生的影响。论述岩土工程勘察在盐湖矿产开发中的特殊地位和重要价值,总结出岩土勘察与盐湖卤水矿产开发的关系并提出盐湖岩土勘察方案的简单建议。 相似文献