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对亚洲内陆干旱区Heinrich (H)事件发生时的气候状况和植被响应过程的研究有利于加深对内陆干旱生态系统与气候突变事件关系的理解.本研究以新疆巴里坤湖BLK11A岩芯450~610 cm段的沉积物为研究载体,基于AMS 14C年代控制,通过岩性、粒度、 X射线荧光光谱元素钛含量( XRF-Ti)和孢粉变化特征等对H1突变事件(17~15 cal. ka B. P.)发生时流域的气候特征和植被分布状况进行了重建.研究结果表明: 1)H1时期湖泊岩性以砂质或者粉砂质的浅湖相为主,湖泊水位较低.沉积物粒度分布频率曲线表现出与流域现代扬尘一致的双峰分布特征,同时XRF-Ti含量增加,两者共同指示了流域局地扬尘发生频率增加,且对湖泊物质输入起主导作用;2)该时期耐旱的荒漠植被比例显著增加,植被覆盖度降低,流域生物量也相应降低,代表了流域植被显著退化;3)结合中纬度欧亚内陆干旱区其他地质记录,发现这一区域H1时期整体以冷干气候为主,风沙活动加强,湖泊萎缩,植被退化.主要原因为西风携带水汽的减少,使得能够到达该内陆区域的降水减少,另一方面温度降低导致了冰雪融水补给的减少,两者共同导致了内陆干旱区植被和环境的退化. 相似文献
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腾格里沙漠西北缘青土湖中更新世晚期以来沉积环境变迁 总被引：1，自引：0，他引：1
以腾格里沙漠西北缘青土湖钻孔ZK1为研究对象,通过对钻孔沉积物的光释光年代、粒度、磁化率等研究,揭示了该湖泊自中更新世晚期以来的环境变迁。研究结果表明：该地区中更新世晚期经历了干冷→暖湿两个阶段,晚更新世经历了湿暖→干冷两个阶段,与深海氧同位素的末次间冰期、末次冰期气候旋回特征吻合,全新世主要经历了干冷→暖湿的气候波动。反映了腾格里沙漠西北缘晚第四纪的气候波动变化特征,特别是为本区中更新世晚期以来的气候环境变化的研究提供了依据。 相似文献
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Lake Bonneville was a climatically sensitive, closed-basin lake that occupied the eastern Great Basin during the late Pleistocene. Ongoing efforts to refine the record of lake level history are important for deciphering climate conditions in the Bonneville basin and for facilitating correlations with regional and global records of climate change. Radiocarbon data from this and other studies suggest that the lake oscillated at or near the Provo level much longer than depicted by current models of lake level change. Radiocarbon data also suggest that the lake dropped from threshold control much more rapidly than previously supposed. These revisions to the Lake Bonneville hydrograph, coupled with independent evidence of climate change from vegetation and glacial records, have important implications for conditions in the Bonneville basin and during the Pleistocene to Holocene transition. 相似文献
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Late Pleistocene lake and glaciation evolution on the northeastern Qinghai–Tibetan Plateau: a review
Late Pleistocene paleoclimatic history on northeastern Qinghai–Tibetan Plateau (QTP) has been reconstructed mainly from lake
sediments; however, data regarding dry–wet climate changes reported in this region are still not clear and controversial.
Based on shoreline features and highstand lacustrine sediments around lakes on the QTP, high lake level histories in this
paper were summarized and compared with paleoclimatic records from lake sediments, ice core and glaciation evolution surrounding
mountains on the NE QTP during late Pleistocene. The results indicate that periods of high lake level occurred at MIS 5, MIS
3 and early-middle Holocene and most likely corresponding to warm and wet climate periods, while periods of low lake level
existed in intervening intervals, corresponding to cold and dry climate periods, which most likely coincide with glacial advances
surrounding high mountains. With an exception, no wide glacial advance in study area was found during MIS 3, possibly suggesting
that effective moisture is lower than that in the other region of NE QTP in this period. 相似文献
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流域生物、化学风化对小冰期气候变化的响应 总被引：2，自引：3，他引：2
岱海近500年沉积物的孢粉，介形类和地球化学记录表现了流域生物，化学风化对全球性小冰期气候波动明显而快速的响应，孢粉量的下降，化学风化强度的减弱（高Rb/Sr比值）以及意外湖花介（Limnocythere inopinata)的繁盛反映了小冰期最盛期岱海地区以干旱为特征的气候环境及其造成的高矿化度湖水，其中，介形类丰度及种类对环境变化的反应最迅速，植被生长的调节则要缓慢一些，内陆湖泊流域植被的衰弱与干旱环境下化学风化强度的减弱以及风尘作用的加强是相辅相成的。 相似文献
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Hydrogeochemical and isotopic study of groundwater in the Habor Lake Basin of the Ordos Plateau,NW China 总被引：2，自引：2，他引：0
Lihe Yin Guangcai Hou Yan Dou Zhengping Tao Ying Li 《Environmental Earth Sciences》2011,64(6):1575-1584
Hydrogeochemistry and isotopes were used to understand the origin and geochemical evolution in the Habor Lake Basin, northwestern
China. Groundwater samples were taken, and the isotopic compositions δD, δ18O and major ions were analyzed. The groundwater can be divided into three types: the Quaternary groundwater, the shallow Cretaceous
groundwater and the deep Cretaceous groundwater. The groundwater chemistry is mainly controlled by the feldspar weathering
and dolomite weathering, the dissolution of Glauber’s salt, and cation exchange. Chemistry of lake water is mainly controlled
by evaporation and precipitation. The stable isotopes of oxygen and hydrogen in groundwater cluster along the local meteoric
water line, indicating that groundwater is of meteoric origin. Comparing with shallow groundwater, deep groundwater is depleted
in heavy isotopes indicating that deep groundwater was recharged during late Pleistocene and Holocene, during which the climate
was more wetter and colder than today. 相似文献
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黄河源地区晚更新世湖泛事件及其意义 总被引：1，自引：1，他引：0
通过青海玛多湖相地层剖面沉积特征,结合ESR样品年代测试结果,分析认为黄河源地区在13万年左右的晚更新世时期发生过湖泛事件。湖泛时期,玛多"四姐妹湖"相互连通,形成一个面积巨大的湖泊,约是现今"四姐妹湖"总面积的4.1倍。玛多地区此次湖泛事件与深海氧同位素MIS 6（Marine isotope stages 6）向MIS 5（Marine isotope stages 5）转变时期相对应,显示出青藏高原气候变化与全球气候变化密切相关,然而黄河源地区湖相地层对全球气候变化反应更敏感,记录的气候转换时间早于其他地区。玛多剖面湖相地层剖面沉积物的粒度、碳酸盐、磁化率分析表明,在132±10~128±12 ka年间,黄河源地区湖相沉积可分为9个阶段,表明青藏高原在MIS 6向MIS 5转变时期的气候变化是一个波动上升过程。13万年左右,黄河源地区大面积的湖相地层结束沉积,认为由于青藏高原共和运动,下游的多石峡被切开,湖水突然外泄所形成。 相似文献
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内蒙古河套盆地为受断裂控制形成的新生代断陷盆地,盆地中积水成湖,称河套古湖。晚更新世时期,河套古湖为继承性闭塞型断陷湖。上更新统主要为湖泊沉积体系,地层划分建组为上部东河村组、中部万水泉组、下部达拉特组。达拉特组在湖盆连续沉降条件及半深湖深湖中硫酸盐型、碳酸盐型湖水交替环境下沉积形成。万水泉组在湖盆沉降速率与沉积速率大体平衡条件及浅湖半深湖中半咸水湖环境下沉积形成。东河村组在湖盆沉降速率小于沉积速率条件下以及半咸水湖、局部时期为碳酸盐湖环境下的滨浅湖中沉积形成。晚更新世末期,河套古湖处于大湖水期,晋陕内蒙古交界处河流袭夺、河套盆地北侧山前断裂强烈活动和超强地震导致河套古湖湖水快速外泄,银川盆地、河套盆地、晋陕峡谷贯通而形成今日黄河河道。 相似文献
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Fan Yuxin Li Zhenjun Yang Guangliang Yi Shuangwen Zhang Qingsong Liu Wenhao Mou Xuesong 《第四纪科学杂志》2020,35(8):994-1006
The timing of high lake-level stands during the Late Pleistocene in western China remains controversial. Here we report new results from Megalake Tengger based on a study of palaeo-shorelines and a drill core from Baijian Lake in the northwestern Tengger Desert. Multiple dating methods, based on luminescence signals (quartz optically stimulated luminescence, K-feldspar post infrared-infrared stimulated luminescence) and electron spin resonance signals of quartz, were used to date beach sands from palaeo-shoreline profiles at altitudes of ~1310 m (+20 m above lake level), ~1320 m (+30 m) and ~1350 m (+60 m), and from the top 20 m of sandy sediments from the drill core obtained from the modern beach of Baijian Lake. The dating results show that high lake-level stands associated with the previously reported Megalake Tengger (~1310–1320 m) occurred during the late Early to Middle Pleistocene, which is much earlier than previously reported. In addition, no geomorphological evidence of shorelines and sedimentary evidence from the drill core profile were found to support the previously reported Late Pleistocene lake levels. Our results indicate that the exact age of the previously reported ‘high lake level event’ in a large part of northwestern China during the Late Pleistocene needs to be re-evaluated. 相似文献
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罗布泊东部阿奇克谷地第四纪古地理 总被引：5，自引：0，他引：5
通过对罗布泊东部阿奇克谷地中部AK1孔及露头剖面第四纪沉积特征的综合研究,初步分析了阿奇克谷地第四纪以来的沉积环境与古地理演化。结果表明,阿奇克谷地第四纪古地理受上新世以来区域构造控制,谷地两侧北山及阿尔金山的隆升,一方面为其提供了丰富的物质来源,同时也控制了其沉积环境的演化。其中第四纪以来阿奇克谷地沉积环境有两次明显变化,早更新世中期谷地中开始出现湖相沉积;中更新世晚期湖相沉积范围扩大,为罗布泊湖的大发展期。晚更新世谷地两侧普遍出现砾石层,与中更新世呈不整合接触,表明构造抬升造成湖泊退缩。晚更新世以来湖泊沉积环境波动变化加快。 相似文献
13.
青海巴颜喀拉山北麓古高位湖相沉积的分布与特征 总被引：3，自引：0，他引：3
巴颜喀拉山北麓地区古湖岸线分布广泛,湖相沉积与湖成地貌发育。目前,在扎陵湖和鄂陵湖沿岸可清晰地划分出4级湖岸阶地、多级湖相沉积和古高位湖相沉积。古高位湖相沉积出露的最高海拔为4615m,分别高出现代扎陵湖水面328m、鄂陵湖水面346m;在扎陵湖和鄂陵湖谷地分布着多级湖岸堆积阶地或基座阶地、多级湖相沉积和古高位湖相沉积;在小野马岭、大野马岭、扎陵湖北等地的基岩山丘上,也发育有多级湖相沉积和古高位湖相沉积,其古高位湖相沉积高出现代扎陵湖和鄂陵湖湖面50～350m。巴颜喀拉山北麓古高位湖相沉积的形成时代可能为中更新世。 相似文献
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Flavio S. Anselmetti Ruth Drescher-Schneider Heinz Furrer Hans Rudolf Graf Sally E. Lowick Frank Preusser Marc A. Riedi 《Swiss Journal of Geoscience》2010,103(3):345-361
A 30 m-deep drill core from a glacially overdeepened trough in Northern Switzerland recovered a ~180 ka old sedimentary succession that provides new insights into the timing and nature of erosion–sedimentation processes in the Swiss lowlands. The luminescence-dated stratigraphic succession starts at the bottom of the core with laminated carbonate-rich lake sediments reflecting deposition in a proglacial lake between ~180 and 130 ka ago (Marine Isotope Stage MIS 6). Anomalies in geotechnical properties and the occurrence of deformation structures suggest temporary ice contact around 140 ka. Up-core, organic content increases in the lake deposits indicating a warming of climate. These sediments are overlain by a peat deposit characterised by pollen assemblages typical of the late Eemian (MIS 5e). An abrupt transition following this interglacial encompasses a likely hiatus and probably marks a sudden lowering of the water level. The peat unit is overlain by deposits of a cold unproductive lake dated to late MIS 5 and MIS 4, which do not show any direct influence from glaciers. An upper peat unit, the so-called «Mammoth peat», previously encountered in construction pits, interrupts this cold lacustrine phase and marks more temperate climatic conditions between 60 and 45 ka (MIS 3). In the upper part of the core, a succession of fluvial and alluvial deposits documents the Late Glacial and Holocene sedimentation in the basin. The sedimentary succession at Wehntal confirms that the glaciation during MIS 6 did not apparently cause the overdeepening of the valley, as the lacustrine basin fill covering most of MIS 6 is still preserved. Consequently, erosion of the basin is most likely linked to an older glaciation. This study shows that new dating techniques combined with palaeoenvironmental interpretations of sediments from such overdeepened troughs provide valuable insights into the past glacial history. 相似文献
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对山西娘子关绵河不同阶地上沉积的泉钙华进行了高精度的230Th定年和碳氧稳定同位素组成测定。结果发现,绵河II级阶地沉积的娘子关泉钙华的最老年龄在407～466ka,远老于早前通过钙华中的石英砂热发光法(TL)获得的年龄,即绵河II级阶地上的娘子关泉钙华是在中更新世MIS12/11阶段形成的,而非原来认为的是晚更新世的产物。由此推测,绵河III级阶地娘子关泉钙华形成的年代更早,可能是中更新世的MIS14/13阶段。230Th测年获得的绵河I级阶地顶部的钙华形成于5ka前,即是在全新世中期以前形成的。结合钙华规模及其碳氧稳定同位素组成分析进一步发现,上述绵河三级阶地上的娘子关泉钙华均主要是湿热气候下的产物。然而,自II级阶地钙华形成至今,气候总体上在向干冷方向发展,泉域植被则呈现退化的趋势。 相似文献
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东湖位于湖北省武汉市中心城区,是中国乃至亚洲最大的城中湖之一.她是首批国家重点风景名胜区和国家5A级旅游景区.武汉市正在打造东湖城市生态绿心.东湖对于武汉在资源、环境、生态、人文各方面均具有重要意义.关于东湖的成因长期众说纷纭.研究首次从地质、地貌、沉积等方面对东湖的成因进行了分析,并对东湖与长江的关系进行了讨论.（1）东湖位于中-晚更新世形成的岗地区.湖汊发育,岸线蜿蜒,岬湾交错,是东湖最大的特点.（2）东湖的湖相沉积厚度各处不一,总体呈现南薄北厚、边缘薄中间厚的特点.下伏主要地层为晚更新世下蜀黄土,在靠近基岩残丘的南部边缘局部为晚更新世坡积层,两者之间为明显的侵蚀接触关系.（3）东湖的湖盆形成于距今2万年左右的末次冰期盛期.东海海平面的大幅度下降,长江河床深切.发育于长江南岸珞珈山、南望山、喻家山一带的地表径流,在汇入长江时因江水水位较低而发生侵蚀,形成多条冲沟组合而成的侵蚀洼地.之后,随着冰后期的全球变暖,长江水位快速上升,两岸天然堤发育、壮大,使侵蚀洼地的出口被淤塞,逐渐积水成湖,即东湖为沟谷壅塞湖.（4）根据湖泊地质地貌特征,东湖与沙湖是两个不同成因且相对独立的湖泊;长江并未经东湖流过.但东湖的形成与长江有关,乃是全球气候变化驱动下海、江、湖相互作用的产物.（5）东湖之美,美于自然.保护其自然特质,顺应其自然规律,是东湖保护与利用必须坚持的原则.将湖域、湖岸、岸上作为一个整体,将水域和流域作为一个系统,按照山水林田湖草生命共同体的科学理念,对东湖进行整体性和系统性的保护与治理是十分必要的. 相似文献
17.
《Boreas: An International Journal of Quaternary Research》2018,47(3):754-767
The Fehmarn Belt is a key area for the Late Pleistocene and Holocene development of the Baltic Sea as it was a passage for marine and fresh water during its different stages. The pre‐Holocene geological development of this area is presented based on the analysis of seismic profiles and sedimentary gravity cores. Late Pleistocene varve sediments of the initial Baltic Ice Lake were identified. An exceptionally thick varve layer, overlain by a section of thinner varves with convolute bedding in turn covered by undisturbed varves with decreasing thicknesses is found in the Fehmarn Belt. This succession, along with a change in varve geochemistry, represents a rapid ice‐sheet withdrawal and increasingly distal sedimentation in front of the ice margin. Two erosional unconformities are observed in the eastern Mecklenburg Bight, one marking the top of the initial Baltic Ice Lake deposits and the second one indicating the end of the final Baltic Ice Lake. These unconformities join in Fehmarn Belt, where deposits of the final Baltic Ice Lake are missing due to an erosional hiatus related to a lake‐level drop during its final drainage. After this lake‐level drop, a lowstand environment represented by river deposits developed. These deposits are covered by lake marls of Yoldia age. Tilting of the early glacial lake sediments indicates a period of vertical movements prior to the onset of the Holocene. Deposits of the earliest stages of the Baltic Sea have been exposed by ongoing erosion in the Fehmarn Belt at the transition to the Mecklenburg Bight. 相似文献
18.
新疆赛里木湖的湖滩岩特征、时代及其对 MIS3阶段湖面变化的指示意义 总被引：3，自引：0，他引：3
在对西天山赛里木湖盆地进行第四纪地质调查与5万填图基础上,发现沿该湖泊的不同湖岸阶地上都不同程度地发育了可指示湖面变化的湖滩岩。水准测量结果表明,典型的湖滩岩最常见于高出现今湖面7.1~9.4 m和33.4~39.4 m的低、高两级湖积台地上。对湖滩岩样品进行岩石学和矿物学研究进一步揭示,湖滩岩主要由内碎屑、藻团块、陆源碎屑、胶结物和填隙物等构成,胶结物主要为亮晶方解石,夹少量文石,表明赛里木湖周边的湖滩岩为典型的方解石胶结砂屑砾屑岩。湖滩岩样品的U系年代测试结果表明,低、高两级台地上的湖滩岩主要形成于距今24.8±1.5 ka至27.6±1.5 ka和55.4±3.8 ka的晚更新世晚期,大致对应末次冰期间冰阶MIS3阶段早期和末期的相对暖湿气候阶段。湖滩岩及其测年结果指示,赛里木湖最近一期最高湖面出现在距今55.4 ka左右末次间冰阶早期,其后由于气候的干旱化,湖面整体处于逐步下降过程,在相对暖湿期间经历了多次湖面相对稳定期并形成湖滩岩。 相似文献
19.
南黄海北部晚更新世以来常量元素记录的化学风化作用 总被引：1，自引：0，他引：1
以南黄海北部高沉积速率柱状样DLC70-3孔作为研究对象,对沉积物的黏土矿物和常量元素地球化学组成进行了综合分析。结果显示,DLC70-3孔沉积物中黏土矿物组合以伊利石为主,其次为蒙皂石,绿泥石和高岭石含量较低;绝大部分样品中伊利石与蒙皂石含量的比值<6,表明沉积物主要来源于黄河物质的输送。研究认为DLC70-3孔沉积物的化学风化指标CIA值受到海平面变化和源区气候变化共同控制,其中源区的气候变化为主要控制因素,而海平面变化造成的机械沉积分异作用主要影响27.80~38.00 m（MIS 4）层位沉积物的CIA值。CIA值显示在MIS 5和MIS 3期大陆化学风化作用较强,与内陆黄土高原地区夏季风和化学风化指标的变化趋势一致,尤其是在MIS 3早期（40~60 ka）记录的化学风化作用非常强,反映了黄河流域地区出现强夏季风降雨过程。 相似文献
20.
Abandoned shorelines are an important archive used to constrain past fluctuations in the hydrological balance of lakes around the globe. Within Australia, the shorelines preserved at Lake George, NSW, form one of the few shoreline archives in the south-east of the continent that record palaeoenvironmental conditions throughout the late Quaternary. Here, we examined and tested the lake-level record for Lake George constructed in the 1970s by dating a well-preserved shoreline sequence at Luckdale, on the lake's eastern shore, using single-grain optically stimulated luminescence (OSL) dating. Ten stratigraphic units were identified, and these suggest a late Quaternary highstand for Lake George in MIS 3, with fluctuations superimposed upon an overall drying trend throughout MIS 2 and into the present. At Luckdale, the highest four shoreline-associated units were deposited ~13 to 19 m above lake base and date to between 39 ± 2 and 29 ± 1 ka ago. Our study pushes back the timing of maximum lake depth at Lake George to at least MIS 3, rather than MIS 2. The overall drying trend is supported by similar reductions in both Riverine Plain fluvial activity and other associated lake-level records from within the Murray basin. 相似文献