共查询到20条相似文献，搜索用时 512 毫秒
1.
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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对南极普里兹湾ＮＰ９３－２和ＮＰ９５－１两柱样沉积硅藻进行了定量分析。两柱样分别可划分出３个和７个硅藻组合带。前者的优势种是Ｎｉｔｚｓｃｈｉａｃｕｒｔａ和Ｔｈａｌａｓｉｏｓｉｒａａｎｔａｒｃｔｉｃａ，次优势种是Ｎ．ｋｅｒｇｕｅｌｅｎｓｉｓ和Ｎ．ｒｉｔｓｃｈｅｒｉ；后者常见的优势种有Ｎ．ｋｅｒｇｕｅｌｅｎｓｉｓ，Ｎ．ｃｕｒｔａ，Ｄｅｎｔｉｃｕｌｏｐｓｉｓｓｐｐ．和Ｔ．ｌｅｎｔｉｇｉｎｏｓａ，常见的次优势种有Ｅｕｃａｍｐｉａｂａｂｌａｕｓｔｉｕｍ，Ｔ．ａｎｔａｒｃｔｉｃａ和Ｔ．ｇｒａｃｉｌｉｓ。利用Ｎ．ｃｕｒｔａ／Ｎ．ｋｅｒｇｕｅｌｅｎｓｉｓ比值并结合１４Ｃ测年数据，可将１５０００年以来南极气候的变化划分出８个古气候带，其中完好地记录了Ｈｅｉｎｒｉｃｈ１事件、波令－阿德罗暖期、新仙女木冰期、全新世低温期等重大的气候变化事件，而南极的全新世低温期是首次报道。 相似文献
3.
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
4.
南京江北地区晚更新世末期以来泥炭层δ13 C记录的古气候变化 总被引：14，自引：13，他引：1
对南京江北地区林峰桥剖面晚更新世末期以来的两个泥炭层有机碳同位素测定结果表明,上部泥炭层和下部泥炭层δ13C值皆较低(≤-23.79‰),部泥炭层的δ13C值明显高于下部泥炭层。结合其它研究可知,该区全新世大暖期稳定暖湿鼎盛阶段的校正年代约在8.2~7.0 ka B.P.,在此阶段前后,表现为持续时间相对较短的低温气候环境。12.8~12.1 cal.ka B.P. 该区气温高低波动频繁期。12.8~12.7 cal.ka B.P.和12.6~12.2 ka B.P.两时段气温较低;2.7~12.6 cal.ka B.P. 阶段气温较高。12.2~12.1 cal.ka B.P. 表现为Younger Dryas之后气候的迅速增暖,可视为该区全新世开始的标志。 相似文献
5.
Katharine Guiles Ellis Henry T. Mullins William P. Patterson 《Journal of Paleolimnology》2004,31(3):343-361
Climate change in the northeastern United States has been inferred for the last deglaciation to middle Holocene (∼16,600 to 6000 calendar years ago) using multi-proxy data (total organic matter, total carbonate content, δ18 O calcite and δ13 C calcite) from a 5 m long sediment core from Seneca Lake, New York. Much of the regional postglacial warming occurred during the well-known Bolling and Allerod warm periods (∼14.5 to 13.0 ka), but climate amelioration in the northeastern United States preceded that in Greenland by ∼2000 years. An Oldest Dryas climate event (∼15.1 to 14.7 ka) is recognized in Seneca Lake as is a brief Older Dryas (∼14.1 ka) cold event. This latter cold event correlates with the regional expansion of glacial Lake Iroquois and global meltwater pulse IA. An increase in winter precipitation and a shorter growing season likely characterized the northeastern United States at this time. The Intra-Allerod Cold Period (∼13.2 ka) is also evident supporting an “Amphi-Atlantic Oscillation” at this time. The well-known Younger Dryas cold interval occurred in the northeastern United States between 12.9 and 11.6 ka, consistent with ice core data from Greenland. In the Seneca Lake record, however, the Younger Dryas appears as an asymmetric event characterized by an abrupt, high-amplitude beginning followed by a more gradual recovery. Compared to European records, the Younger Dryas in the northeastern United States was a relatively low-amplitude event. The largest amplitude and longest duration anomaly in the Seneca Lake record occurs after the Younger Dryas, between ∼11.6 and 10.3 ka. This “post-Younger Dryas climate interval” represents the last deglacial climate event prior to the start of the Holocene in the northeastern United States, but has not been recognized in Greenland or Europe. The early to middle Holocene in the northeastern United States was characterized by low-amplitude climate variability. A general warming trend during the Holocene Hypsithermal peaked at ∼9 ka coincident with maximum summer insolation controlled by orbital parameters. Millennial- to century-scale variability is also evident in the Holocene Seneca Lake record, including the well-known 8.2 ka cold event (as well as events at ∼7.1 and 6.6 ka). Hemispherical cooling during the Holocene Neoglacial in the northeastern United States began ∼5.5 ka in response to decreasing summer insolation. 相似文献
6.
通过对江西沟风成沉积剖面的地球化学分析,并结合OSL年代、粒度和磁化率数据,探讨了末次冰消期以来青海湖南岸气候的演变。剖面常量元素氧化物含量呈SiO_2Al_2O_3CaOFe_2O_3MgOK_2ONa_2O变化特征,常量元素氧化物及化学元素综合参数与地层有较好的对应性。不同的环境指标对气候变化的敏感性不同,总体上看,地球化学元素的敏感性高,全新世以来粒度和磁化率的变幅较小,即使在全新世大暖期,其值变化都很小。地球化学元素记录所反映的气候变化过程如下。Ⅰ.末次冰消期~12 ka BP,13.2 ka BP前总体上呈相对温暖状态,可能受B/A暖期的影响,13.2~12 ka BP气候不断向干冷方向发展,寒冷程度不断加剧并在12 ka BP达到最强,可能反映出12 ka BP左右的新仙女木事件;Ⅱ.12~9 ka BP,气候呈波动回升状态,暖湿程度呈增加趋势,表现出温凉的气候变化特征;Ⅲ.9~4.5 ka BP,气候温暖湿润,与全新世大暖期相对应,该阶段水热组合达到最佳,但存在阶段性的变化;Ⅳ.4.5~2 ka BP,气候总体向冷干方向转变,3 ka BP前变化幅度较小,气候较温暖湿润,3~2 ka BP气候凉偏干。 相似文献
7.
末次盛冰期以来青藏高原东北部共和盆地冬夏季风演化记录 总被引：2，自引：0，他引：2
对青藏高原东北部共和盆地冬其剖面的化学元素与粒度分析表明,末次盛冰期以来区域冬夏季风总体上呈现此消彼长的关系,气候出现多次冷干-暖湿旋回。15.82 ka BP之前冬季风最强,夏季风最弱,为末次盛冰期时的冷干气候,但21 ka BP之前气候可能寒冷偏湿。15.82~9.5 ka BP夏季风明显增强,冬季风衰弱,气候明显转暖,其中老仙女木时期（14.7~13.7 a BP）和新仙女木时期（12.1~9.5 ka BP）气候相对冷干,而B-A时期（13.7~12.1 ka BP）气候相对暖湿。全新世以来冬夏季风出现多次波动,9.5~7.0 ka BP夏季风相对较强,气候相对暖湿;7.0~5.1 ka BP冬夏季风强弱交替频繁,气候出现冷干-暖湿旋回;5.1~2.7 ka BP夏季风总体较强,气候温暖湿润;2.7 ka BP 之后冬季风明显增强,气候趋于冷干。此外,区域冬夏季风演变过程与极地冰芯记录的冷暖事件大体一致,可以认为共和盆地气候变化是全球气候变化的区域响应。 相似文献
8.
Yuan Shang RuiJie Lu FeiFei Ji LiHui Tian QingLiang Tang Yuan Chen Chao Zhao WangYang Wu 《寒旱区科学》2013,5(3):0301-0308
As the largest inland lake of China, along with its unique landscape and geographical location, Qinghai Lake has got much attention of the scientists for a long time. The precursors have done substantive researches by using the lake sediment, which deepen our understanding of the climate changes in this region. Although sand dunes and loess sediment are widely distributed around the lake, so far the researches on geochemical elements from aeolian sediment have been less reported. In this paper, we selected a typical aeolian profile on the east of Qinghai Lake. Based on systematic sampling and analysis of seven major geochemical elements, combined with OSL dating and previous researches, this paper discusses climate changes in the Qinghai Lake area since 12.5 ka B.P.. Our conclusions are: (1) Before 12.5 ka B.P., the climate in this region was dry, cold, and accompanied by strong wind-sand activities. (2) During 12.5–11.9 ka B.P., the climate became warm and wet. However, there was an abrupt climate cooling event during 12.2–11.9 ka B.P., which likely corresponded to the Younger Dryas event. (3) During 11.9–8.0 ka B.P., the climate fluctuated greatly and frequently from warm to cold, and three cooling events occurred. (4) During 8.0–2.6 ka B.P., the climate was warm and humid. (5) Since 2.6 ka B.P., similar to the modern climate, the climate was mainly dry and cold. 相似文献
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11.
《Polar Science》2014,8(4):357-369
An analysis of remanent magnetism and radiocarbon ages in the dry lacustrine/sediment fills of the Schirmacher Oasis (SO) in East Antarctica was conducted to reconstruct past climatic condition. The statistically run mineral magnetic data on paleontological statistics software package (multivariate cluster analysis) placed on accelerator mass spectrometer radiocarbon chronology of the three sediment sections, trace 6 phases of climatic fluctuation between 13 and 3 ka, (Phases 1, 3 and 5 represent cold periods while Phases 2, 4, and 6 represent warm periods). One short warm period (Phase 2, ca. 12.5 ka) occurred in the late Pleistocene, and two marked warm periods (Phase 4, 11–8.7 ka; Phase 6, 4.4–3 ka) occurred in the Holocene. High magnetic susceptibility (χ), saturation isothermal remanent magnetism (SIRM), and soft isothermal remanent magnetism (soft IRM) values correspond to colder periods and low values reflect comparatively warmer lacustrine phases. Holocene Optima (Phase 4) and Mid Holocene Hypsithermal (Phase 6) are distinguished by decreased values of concentrations dependent parameters. Remanence is preserved in the low-coercive minerals. Heavy metals in the sediments include, Fe, Rb, Zn, Mo, Co, Pb, Mn, Cu, and As in order of decreasing abundance. 相似文献
12.
Wisconsinan and Holocene Climate History from an Ice Core at Taylor Dome, Western Ross Embayment, Antarctica 总被引：4，自引：0，他引：4
Eric J. Steig David L. Morse Edwin D. Waddington Minze Stuiver Pieter M. Grootes Paul A. Mayewski Mark S. Twickler & Sallie I. Whitlow 《Geografiska Annaler: Series A, Physical Geography》2000,82(2-3):213-235
Geochemical data and geophysical measurements from a 554-m ice-core from Taylor Dome, East Antarctica, provide the basis for climate reconstruction in the western Ross Embayment through the entire Wisconsinan and Holocene. In comparison with ice cores from central East and West Antarctica, Taylor Dome shows greater variance of temperature, snow accumulation, and aerosol concentrations, reflecting significant variability in atmospheric circulation and air mass moisture content. Extreme aridity during the last glacial maximum at Taylor Dome reflects both colder temperatures and a shift in atmospheric circulation patterns associated with the advance of the Ross Sea ice sheet and accounts for regional alpine glacier retreats and high lake levels in the Dry Valleys. Inferred relationships between spatial accumulation gradients and ice sheet configuration indicate that advance of the Ross Sea ice sheet began in late marine isotope stage 5 or early stage 4. Precise dating of the Taylor Dome core achieved by trace-gas correlation with central Greenland ice cores shows that abrupt deglacial warming at Taylor Dome was near-synchronous with the ∼14.6 ka warming in central Greenland and lags the general warming trend in other Antarctic ice cores by at least 3000 years. Deglacial warming was following by a warm interval and transient cooling between 14.6 and 11.7 ka, synchronous with the Bølling/Allerød warming and Younger Dryas cooling events in central Greenland, and out of phase with the Antarctic Cold Reversal recorded in the Byrd (West Antarctica) ice core. Rapid climate changes during marine isotope stages 4 and 3 at Taylor Dome are similar in character to, and may be in phase with, the Northern Hemisphere stadial–interstadial (Dansgaard–Oeschger) events. Results from Taylor Dome illustrate the importance of obtaining ice cores from multiple Antarctic sites, to provide wide spatial coverage of past climate and ice dynamics. 相似文献
13.
青海湖湖东风成剖面化学元素特征及其环境指示意义 总被引：2，自引：0，他引：2
通过对青海湖湖东沙地风成沉积剖面化学元素特征的分析,结合光释光测年结果,并和已有研究进行对比,探讨了青海湖区12.5 ka BP以来的气候环境变化过程,将其划分为5个阶段：12.5 ka BP前气候寒冷干燥,青海湖应处于冰川消退的寒冷期,风沙活动强烈;12.5~11.9 ka BP气候向暖湿转变,其中12.2~11.9 ka BP发生一次寒冷事件,对应于新仙女木事件;11.9~8.0 ka BP气候冷暖波动频繁,期间出现了3次寒冷事件;8.0~2.6 ka BP是一个持续时间较长的温暖湿润期;2.6 ka BP至今,气候以干冷为主,与现代气候相近。 相似文献
14.
16 ka以来黄土高原东亚夏季风变化的环境磁学记录 总被引：1，自引：1，他引：0
末次冰消期以来的气候变化是第四纪古气候研究的重要内容。本文对黄土高原西部和平镇剖面16 ka以来的黄土沉积序列（厚度为3.5 m）进行了高分辨率环境磁学研究。结果表明：该黄土序列的磁性颗粒主要由细颗粒磁铁矿主导。其磁化率和频率磁化率具有相同的变化特征,与黄土高原中部和东部的黄土磁化率变化机制一致,即黄土高原西部和平镇黄土的磁化率和频率磁化率仍然受成土作用形成的细颗粒磁铁矿控制,因此其磁化率和频率磁化率仍然可以反映季风降雨的变化特征,并且其反映的16 ka以来季风降雨变化与南方石笋氧同位素记录的季风变化特征一致。通过详细的海陆综合对比,本文认为16 ka至11 ka间东亚季风降雨的变化受到北半球太阳辐射和北半球区域温度的共同影响,而11 ka之后的夏季风降雨减少主要受太阳辐射降低的影响。 相似文献
15.
江汉平原9.0 ka B.P.以来的气候演化:来自江陵剖面沉积物记录 总被引：20，自引：19，他引：1
对2002年9月在荆州市江陵县发现的9 ka B.P.以来的江陵剖面进行14C测年、粒度、TOC、TN、δ13C、孢粉等综合分析,重建江汉平原江陵地区9 ka B.P.以来古气候古环境演化:9.0~6.07 ka B.P.为高温阶段,其间8.1 ka B.P.记录到一次较明显降温事件;6.07~4.60 ka B.P.为冷干期;4.60~3.44 ka B.P.间气候波动频繁,为全新世第二个暖湿期前期阶段;3.44~2.50 ka B.P.为高温期,湖沼泥炭发育,是全新世第二个暖湿期后期阶段,为稳定的暖湿阶段;2.50 ka B.P.以来温度相对较低,为冷期。江陵地区近9 ka B.P.以来气候变化不仅与国内大量研究资料相一致,且在许多较大气候事件上与世界许多研究结果一致,表明江陵气候变化具有全球性。 相似文献
16.
莱州湾南岸中全新世聚落遗址时空分布特征及其环境背景 总被引：2，自引：2，他引：0
基于ArcGIS10.3平台对莱州湾南岸中全新世聚落遗址的高程、坡度、坡向、濒河度等指标进行分析,得出该时期聚落遗址的时空分布及演变特征,并结合全新世莱州湾南岸的环境背景,探讨全新世环境演变对聚落遗址分布及演变的影响。研究表明：① 全新世莱州湾南岸的聚落遗址数量、出现频率及在总数中的比重基本呈现明显的先增后降的倒V型（非对称）变化趋势。② 遗址高程分布具有一定的规律性,几乎所有时期的遗址点均分布于高程范围在0~29 m的地区,而大汶口文化时期遗址高程分布范围为10~29 m。从坡度来看,聚落遗址主要分布于坡度范围在0~4°的平缓地区;从坡向来看,古人大多集中在南向、东南向和西南向的位置。后李文化至龙山文化时期,河流对聚落选址的影响程度逐渐降低。③ 8.5~6.9 ka B.P.气候总体进入温暖期,且冷暖波动,干湿交替,后李文化由此得到发展;6.9~4.5 ka B.P.出现了短暂的降温,但整体较温和,优越的自然条件促进了大汶口文化的发展;4.5~4.0 ka B.P.左右气候条件较大汶口文化时期略干,但在此基础上新石器文化仍得到进一步发展,并于龙山文化时期进入鼎盛阶段;4.0 ka B.P.左右气候突变,出现剧烈降温事件,变化幅度超出了人类的适应能力,岳石文化随之衰落。④ 海水入侵限制了人类活动,而古湖泊和古河道的形成为古人生活质量的提高创造了天然条件。 相似文献
17.
Stable isotopes and sediments from Pickerel Lake, South Dakota, USA: a 12ky record of environmental changes 总被引：2，自引：0，他引：2
Sedimentological parameters and stable O- and C-isotopic composition of marl and ostracode calcite selected from a 17.7-m-long core from the 8-m-deep center of Pickerel Lake, northeastern South Dakota, provide one of the longest (ca. 12ky) paleoenvironmental records from the northern Great Plains. The late Glacial to early Holocene climate in the northern Great Plains was characterized by changes from cold and wet to cold and dry, and back to cold and wet conditions. These climatic changes were controlled by fluctuations in the positions of the Laurentide ice sheet and the extent of glacial Lake Agassiz. We speculate that the cold and dry phase may correspond to the Younger Dryas event. A salinity maximum was reached between 10.3 and 9.5 ka, after which Pickerel Lake shifted from a system controlled by atmospheric changes to a system controlled by groundwater seepage that might have been initiated by the final withdrawal of Glacial Lake Agassiz. A prairie lake was established at approximately 8.7 ka, and lasted until about 2.2 ka. During this mid-Holocene prairie period, drier conditions than today prevailed, interrupted by periods of increased moisture at about 8, 4, and 2.2 ka. Prairie conditions were more likely dry and cool rather than dry and warm. The last 2.2 ka are characterized by higher climatic variability with 400-yr aridity cycles including the Medieval Warm Period and the Little Ice Age.Although the signal of changing atmospheric circulation is overprinted by fluctuations in the positions of the ice sheet and glacial Lake Agassiz during the late Glacial-Holocene transition, a combination of strong zonal circulation and strong monsoons induced by the presence of the ice sheet and high insolation may have provided mechanisms for increased precipitation. Zonal flow introducing dry Pacific air became more important during the prairie period but seems to have been interrupted by short periods of stronger meridional circulation with intrusions of moist air from the Gulf of Mexico. More frequent switching between periods of zonal and meridional circulation seem to be responsible for increased climatic variability during the last 2.2 ka. 相似文献
18.
Geochemical and grain size analysis on the DQ (Dongqi) profile from Gonghe Basin, northeastern Qinghai-Tibetan Plateau, indicates that regional climate has experienced several cold-dry and warm-wet cycles since the last glacial maximum (LGM). The cold and dry climate dominated the region before 15.82 cal. ka B.P. due to stronger winter monsoon and weaker summer monsoon, but the climate was relatively cold and wetter prior to 21 cal. ka B.P.. In 15.82–9.5 cal. ka B.P., summer monsoon strength increased and winter monsoon tended to be weaker, implying an obvious warm climate. Specifically, the relatively cold and dry condition appeared in 14.7–13.7 cal. ka B.P. and 12.1–9.5 cal. ka B.P., respectively, while relatively warm and wet in 13.7–12.1 cal. ka B.P.. The winter and summer monsoonal strength presents frequent fluctuations in the Holocene and relatively warm and wet conditions emerged in 9.5–7.0 cal. ka B.P. due to stronger summer monsoon. From 7.0 to 5.1 cal. ka B.P., the cycle of cold-dry and warm-wet climate corresponds to frequent fluctuations of winter and summer monsoons. The climate becomes warm and wet in 5.1–2.7 cal. ka B.P., accompanying increased summer monsoon, but it tends to be cold and dry since 2.7 cal. ka B.P. due to enhanced winter monsoonal strength. In addition, the evolution of regional winter and summer monsoons is coincident with warm and cold records from the polar ice core. In other words, climatic change in the Gonghe Basin can be considered as a regional response to global climate change. 相似文献
19.
通过对尕海DG03孔岩芯碳酸盐含量的测定,表明碳酸盐含量指标较好地记录了尕海湖地区自冰消期晚期以来的气候环境变化。对阿勒罗德暖期和新仙女木期都有较好的反映,并揭示出早全新世气候变暖且波动明显,中全新世早期暖湿,后期温凉偏干,晚全新世气候明显变干,早期较为寒冷,后期偏暖。碳酸盐含量的变化反映了湖水的浓缩程度,与湖泊所处的沉积阶段相联系,同时与岩性特征所反映的环境也有关。在风成作用堆积的粉砂至中砂层,碳酸盐含量降至很低;在滨湖相沉积的细砂层,碳酸盐含量也较低,因此,碳酸盐含量指示的气候环境意义应与岩性及其他指标相结合进行分析,方可得到可信的结论。 相似文献
20.
新仙女木期黄河晋陕峡谷古风成沙层年代及其物质来源 总被引：2，自引：2，他引：0
通过对黄河晋陕峡谷壶口至龙门段开展广泛细致的野外考察,发现了典型的晚更新世以来黄土—土壤层夹古风成沙层剖面—北桑峪剖面（BSY）。结合不同类型沉积物的野外宏观特征、磁化率、粒度成分、石英颗粒表面特征和地球化学元素的对比分析,确定黄河晋陕峡谷壶口至龙门段BSY剖面中所夹古风成沙层的性质为中沙质细沙,是在干旱多风环境下形成的沙质沉积物。基于光释光（OSL）测年数据,确定其沉积年代为12.5-11.6 ka,记录了黄河中游发生在末次冰消期的极端干旱事件,其与相邻区域沙漠/黄土过渡带中湖沼沉积和风成黄土—古土壤剖面记录的新仙女木事件相对应。该剖面中古风成沙沉积物的物质来源,主要来自黄河晋陕峡谷的古河床相沙层物质。这是因为该河段处于干旱半干旱季风气候区,在新仙女木时期,黄河晋陕峡谷处于极端干冷的环境之中,冬季风强盛、夏季风衰弱,黄河水位下降明显,河漫滩和江心洲将大面积出露,大量的沙物质在风力作用下向岸边输移,成为河谷两侧缓坡台地上古风成沙沉积层出现的主要沙源地。这个研究成果对于进一步揭示黄河中游流域极端干旱事件发生的时间性规律及其与季风气候变化的关系,具有重要的科学意义。 相似文献