2 兰州大学资源环境学院, 西部环境教育部重点实验室, 甘肃 兰州 730000;
3 中国科学院地球环境研究所, 黄土与第四纪地质国家重点实验室, 陕西 西安 710061)
末次冰期(约115~12 cal.ka B. P.)气候不稳定性的存在是近20年古气候研究的一个重要发现[1],Heinrich(H1~H5)突变事件发生在冰期气候波动(D-O循环)的极冷期[2~3],伴随着大量陆源冰筏沉积(Ice-Rafted Debris,简称IRD)的出现和大洋表层温度的降低[4~5],浮冰阻碍了北大西洋高纬深层滞水的形成并通过改变北大西洋经向翻转流(Atlantic Meridional Overturning Circulation, 简称AMOC)的强度对全球气候产生重要影响[6~9]。其中,H1 (17~15 cal.ka B. P.)发生在末次冰消期,是研究冰期气候向间冰期气候过渡的最佳时段。已有研究表明H1发生时,欧洲地中海区域海表温度大幅度降低[10~11]、区域温度的降低改变了山地雪线的高度[12]、植被出现明显的退化[13~15];同样,在东亚季风区,石笋氧同位素的证据也表明亚洲季风衰退、降水减少[16~19]。但是关于亚洲内陆干旱区H1的研究较少,尤其是缺乏对湖泊水文状况和区域植被响应过程的系统研究。其主要原因是在内陆干旱区很难得到理想的测年材料,加之碳库对14C测年的影响,使得对H1的精细研究相对匮乏。
近年来,不同研究者在干旱区开展了一些研究工作,促进了对H1突变事件的认识。比如,来自新疆科桑洞石笋同位素的证据表明在约16 ka B. P.区域气候干旱,降低的蒸散率通过改变洞穴上方土壤过程、表层岩溶带和岩溶含水层的性质使得石笋中富集较重的δ13C[20];青海湖的研究结果同样揭示了在H1时期区域气候冷干、西风环流增强,更多的粗颗粒物质被输送到湖泊中沉积下来[21]。但遗憾的是,更多早期开展的关于内陆干旱区H1气候变化特征的研究因为诸如沉积特征复杂、测年精度不够或者分辨率低等因素的影响,极大的限制了对该事件发生过程、影响以及机制的认识[22]。比如,伊犁黄土剖面在末次冰盛期到早全新世出现沉积间断,致使H1记录缺失[23]。早期发表湖泊研究结果(比如:玛纳斯湖[24])尽管覆盖了整个末次冰消期,但是因为分辨率太低而无法识别出H1事件。而且值得注意的是,目前针对H1时期内陆干旱区植被状况报道较少,已有的报道多集中的干旱区的东部边缘地区(比如:罗布泊[25]、乱海子[26]和青海湖[27]等),能否代表干旱区的整体状况还有待进一步确认。
本研究拟以亚洲内陆干旱区新疆巴里坤湖的钻孔沉积物为研究对象,前期已对沉积岩芯末次冰盛期以来的年龄-深度模式开展了一些研究工作[28~30],发现H1事件大致位于岩芯450~610 cm处,本研究对该部分开展了的详细的岩性、粒度、烧失量、X射线荧光光谱元素钛含量(XRF-Ti)和孢粉等代用指标的分析,重点关注H1时段流域沉积特征和植被状况。最后将巴里坤湖重建结果与内陆干旱区和其他区域的记录(欧洲和东亚季风区)进行对比分析,以期能够在大空间尺度上理解H1时期中纬度欧亚内陆的气候状况以及该时期内陆干旱区气候和植被变化的主控因素。
1 研究区概况巴里坤湖(43°36′~43°45′N,92°42′~92°54′E;1575 m a.s.l.)位于新疆天山东部的地堑式山间盆地(图 1),盆地除西北部为平缓低山丘陵外,其余三面为中高山,有现代冰川和古冰川分布。巴里坤湖形成于早更新世,通过对古湖岸堤的研究,研究者推测该湖在第四纪面积最大能够达到约850 km2[31],随着内陆干旱化,湖泊逐渐萎缩。现代的湖泊主体位于盆地的西部,面积仅有约10 km2,平均水深小于1 m。巴里坤湖补给类型为入湖径流和降水,冰川融水对入湖河流量的贡献达到约50%,径流在出山口处汇入主干,自西往东流经山前洪积平原和巴里坤草原,最终汇入巴里坤湖[32]。巴里坤流域以温带干旱气候为主导,年平均温度1.0 ℃,夏季(6~8月)平均温度16.6 ℃;年平均降水量231 mm,降水主要集中在5~9月,占全年降水的76%;年平均蒸发量1620 mm,蒸发量远远大于降水量。巴里坤湖季节性波动较大,存在5~6月和7~9月两次高湖面,分别对应冰雪融水和降水的高峰期[33]。区域植被地带性明显,盆地西部为蒿属(Atermisia)和苋科(Amaranthaceae)藜亚科为优势种的温带草原和荒漠植被,东部河流流经的区域分布以禾本科(Poaceae)为主的草甸植被,在海拔2100~2900 m的盆地南北两侧山地分布有西部利亚落叶松(Larix sibirica)和雪岭云杉(Picea schrenkiana)[29]。
研究组于2011年7月在湖泊中心位置钻取了长度为62.5 m的岩芯BLK11A(43°39′51″N,92°48′10″E),前期已经开展了部分实验分析工作,本文侧重对末次冰消期H1突变事件记录的讨论(对应于岩芯450~610 cm)。首先,依据已有的测年结果,利用Bacon模型[34]对研究时段岩芯的年代模式重新进行了矫正(表 1和图 2c)。在此基础上,对岩性、粒度和XRF-Ti进行分析,同时结合已经发表的数据(主要包括收集的区域降尘和河流沉积物的粒度数据,以及钻孔岩芯的烧失量和孢粉数据)[29],对H1时期区域环境和植被进行重建。最后,将研究结果进行区域对比,讨论整个内陆干旱区H1时期的气候状况以及可能的驱动机制。
本研究涉及的AMS 14C年代测试在美国Beta实验室完成;粒度测试采用英国Malven公司的Mastersizer 2000型激光粒度仪,测试流程依据Peng等[35]中的方法,用双氧水去除有机质、盐酸去除碳酸盐胶结,加六偏磷酸钠((NaPO3)6)分散剂超声震荡后上机测试,粒度按照1 cm取样,共计160个样品;XRF-Ti的含量采用Avaatech XRF岩芯扫描得到,在沉积物扫描前先覆盖一层薄的Ultralene膜在切开的剖面上,减小表面的粗糙度,同时防止分析过程样品对仪器棱镜的污染,扫描分辨率为1 mm。粒度和XRF-Ti的测试在兰州大学完成。
3 结果与讨论 3.1 岩性和粒度揭示的不同时期湖泊沉积动力的差异H1事件发生时(17~15 cal.ka B. P.),巴里坤湖沉积相发生了明显改变,从以粘土为主的湖相转变为以粉砂为主的浅湖相(图 2a和2b),指示湖泊水位下降。沉积物粒度分布频率曲线从准单峰(图 3f)分布转变为双峰分布(图 3e),该时期的沉积物粒度分布频率曲线与流域现代局地扬尘分布特征(图 3a,类型2)一致,最为突出的特点是分布曲线的两个峰值分布在粒径约10 μm和100 μm处,且较大峰值对应的粒径成分所占比例高,由此可以推断H1时期流域局地扬尘发生频率增加,对湖泊物质输入起主导作用。
随着H1事件的结束(BA开始,即Bølling/Allerød暖事件(14.7~12.9 cal. ka B.P.)[36]),砂质沉积取代粉砂质沉积。沉积物中值粒径达到100 μm以上(图 2),BA时期粗颗粒成分较H1进一步增加,指示沉积动力进一步增强。沉积物粒度分布频率曲线为典型的三峰分布(峰值分别出现在10 μm、100 μm和500 μm,见图 3d),粒径最大的峰值出现在约500 μm(且该组分所占比例较高),从沉积物搬运动力来讲已经超出了风的搬运以及湖泊的二次搬运能力。通过与流域河床沉积物粒度分布频率曲线的对比分析(图 3b),初步推断BA时期河流输入增加,携带了粒径更粗的成分沉积在湖泊中。
3.2 H1时期巴里坤区域气候特征为了更好的理解H1时期巴里坤湖区域气候变化特征,本文将之前已发表的该湖泊的记录进行了汇总(图 4),总体而言该区域以冷干的气候为主,伴随着风尘输入增加和植被退化。从中值粒径(图 4a)和粒度频率分布曲线(图 3e)分析的结果来看,该时段局地扬尘增加,进而导致了沉积物中Ti含量的显著增加(图 4b)。由此可以推断风力可能是H1巴里坤湖沉积物中外源Ti输入的主导动力,而河流的作用相对弱一些。后期BA时段由于河流搬运能力增加导致了沉积物中粗颗粒(中值粒径> 100 μm,见图 4a)含量大幅度增加,但是Ti含量并没有随之增加,也可以推断出河流搬运对沉积物中Ti含量贡献较低。湖泊沉积物550 ℃(950 ℃)烧失量可以分别用来估算总有机碳(碳酸盐)的含量,进而重建流域环境[37~43]。从550 ℃烧失的结果(图 4c)推断在H1时期流域生物量(包括流域陆生和湖泊内源)降低较为明显。湖泊中碳酸盐的环境指示意义较为复杂,主要原因是外源碎屑碳酸盐与湖泊自生碳酸盐的比例难以确认,再者湖泊不同发育阶段碳酸盐的指示意义也会有差异[44~45]。我们的前期野外调查结果发现在巴里坤盆地没有大量的石灰岩出露,也即是说外源碳酸盐碎屑输入湖泊的量有限;而且沉积物XRD结果表明巴里坤湖碳酸盐主要是由粗颗粒的方解石和少量的白云石组成。因此可以推断巴里坤湖碳酸盐主要是由化学沉积形成的。在H1时期沉积物碳酸盐含量表现为低值(图 4d),其中最主要的原因是H1时期的低温(图 4e)减少了蒸发量进而抑制了碳酸盐的形成。基于陆生孢粉浓度重建的植被盖度在H1也达到了最低值(图 4f)。
H1事件阻断/延缓了区域由冰期气候向间冰期气候的转型。从末次冰盛期(LGM)结束(约19 cal.ka B. P.)到H1开始,巴里坤区域气候发生第一次明显好转。温度的回升(图 4e)促进了流域生物量的增加(图 4d),温暖的气候条件促进了植物的生长(图 4f),但是此次升温幅度不大,所以造成的冰川融水的量有限。从中值粒径(图 4a)和粒度分布频率曲线(图 3f)来看,此时湖泊以细粒的准单峰分布为主,河流作用并不大;低的Ti含量(图 4b)也反映出风力较弱,较高的植被盖度对地表也起到了很好的保护作用,降低了地表物质被风携带输入湖泊的几率。同时,升高的温度促进了湖泊碳酸盐的累积(图 4d)。伴随着H1事件的结束(约15 cal.ka B. P.)区域气候发生第二次好转(进入BA时期),同样表现为流域生物量的增加(包括植被,图 4c和4f)和粉尘输入的降低(图 4b)。但是由于BA时期的升温幅度较前一次更大(图 4e),进而造成了冰川融水的大量增加,因此携带了更多的粗颗粒物质进入湖泊中(图 4a)。
3.3 H1时期中国西部干旱区环境状况以及与其他区域的对比 3.3.1 H1时期中国西部干旱区环境状况在西北干旱区很难得到理想的测年材料,加之碳库对14C测年的影响,对H1精细的研究并不多见,且已有研究以湖泊居多,也包括一些沙地和黄土的记录[46]。综合已发表的资料[21, 25~27, 47~52],西北干旱区H1时期基本呈现出与巴里坤湖记录相似的冷干的气候特征(图 5),具体表现为风力增强、湖泊萎缩。例如,青海湖粒度分析结果表明H1时期湖泊以西风环流携带的风尘输入为主(图 5a),高的Rb/Sr比值指示流域物理风化加强(图 5b),区域环境冷干[21, 47];同样,更尕海(距离青海湖约50 km)沉积岩芯在15.3 cal.ka B. P.之前以浅黄色松散的风成砂沉积为主(图 5c),是冷干环境下风力增强、风沙活动增多的表现[48];祁连山区乱海子在H1时期呈现出的是与干盐湖相似的低湖面情形,沉积物中高的C/N比值指示外源输入增加,流域生物量也明显降低,反映了H1时期区域环境的退化[26];哈拉湖在16.6~15.8 cal.ka B. P.期间相对较高的盐度也指示了相对干旱的环境[49];来自湖泊碳酸盐δ18O(图 5c)的证据表明更尕海在15.3~14.5 cal.ka B. P.期间降水减少、湖泊水位下降[50];冬给错那沉积物在H1时期异常偏负的δDnC29值同样反映了区域降水减少、干旱加剧的状况[51]。
H1时期冷干的气候条件对干旱区植被造成了显著的影响。一方面表现为植被类型的改变,一些耐寒耐旱的荒漠类型植物种属(蒿属、藜亚科、麻黄属和白刺属等)比例显著增加。例如,巴里坤湖泊孢粉结果表明H1时期蒿属和藜亚科的总和达到了75% (平均值),耐旱菊科(比如:胖姑娘(Karelinia caspica)、蓝刺头(Echinops sphaerocephalus)等)含量明显增加,草甸类型(禾本科、莎草科等)几近消失(图 5e、5f和5g)。冬给错那湖泊孢粉结果同样揭示了干冷气候造成了荒漠类型增加、木本和草甸类型降低的现象[52]。另一方面表现为植被盖度的降低,H1时期包括巴里坤湖(图 5h)在内的诸多湖泊记录(罗布泊[25]、乱海子[26]、青海湖[27])显示此时孢粉浓度降低,反映植被盖度的降低。
3.3.2 中纬度欧亚地区不同气候载体对H1的记录越来越多的证据表明H1事件在中纬度欧亚地区不同区域、不同气候载体记录中都有很好的体现[10~11, 13, 16~19, 53~66]。基于生物标志化合物的不同钻孔重建的H1地中海表层温度表现出一致性的降低(图 6a),均低于全新世10 ℃左右[10~11];地中海东部浮游有孔虫壳体δ18O值(图 6b)在H1时期偏正[43~56],指示区域降水减少进而引起水位下降[56]或盐度升高[55];邻近的Jeita洞石笋δ18O值在H1偏正(图 6c),一则反映水汽源区δ18O的变化特征,二则是区域降水整体减少的“雨量效应”的结果[57];来自该洞的δ13C结果则反映H1时期由于区域降水/蒸发比例的降低,区域植被退化、土壤微生物和入渗速率作用,最终导致了较重δ13C在石笋中富集(图 6c)[57]。冷干的气候效应造成了包括死海[58]、土耳其Van湖[59]和塔吉克斯坦Karakul湖[60]在内的东欧和中、西亚内陆湖泊在H1时期水位明显降低。中纬度欧洲地区干旱/半干旱草本类型(蒿属、藜亚科和麻黄属等)取代暖温带木本(栎属、水青冈属、椴树属、榆属、杜鹃花科和桦木科等)植被类型,组成H1时期的优势群落[13, 61~66](图 6d);同时期亚洲季风明显衰退[16~19](图 6e),其主控区域湖泊和植被也表现出与冷干气候相对应的变化特征[67~68]。
综上所述,包括巴里坤湖在内的中国西部干旱区以及中纬度欧洲区域在H1时期都呈现出冷干的气候特征。成因方面可以把H1时期亚欧内陆大范围出现干旱解释为:当H1发生时大量冰筏沉积注入北大西洋高纬地区,导致北大西洋深层水(NADW)减弱甚至停滞,同时北大西洋经向翻转流(AMOC)活动的减弱(图 6f)阻碍了跨赤道的南北半球海洋热量交换[9],进而加大了北大西洋北部地区(图 6g)以及表层海水温度降低的幅度[69],低温导致低的蒸发量,致使能够到达中纬度欧亚内陆的水汽大大降低,从而引起了内陆地区的湖泊水位下降、植被退化。对于西风环流主控的中国西部干旱区而言,一方面由于西风路径上水汽的减少使得能够到达该区域的降水减少[70~71],另一方面温度降低导致了冰雪融水补给的减少[29],两者共同导致了中国西部干旱区植被和水文的退化。
4 结论和展望本研究以亚洲内陆干旱区新疆巴里坤湖沉积物为研究载体,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。巴里坤湖在H1时期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。流域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。
从巴里坤的结果和区域对比分析来看H1在中纬度地区很多的记录中都有体现,而且以干冷的气候状况为主,伴随着湖泊水位下降、风力输入增加和植被退化等。该研究对认识H1气候突变事件,以及中纬度亚欧内陆生态水文对突变事件的响应有重要的作用。但是由于H1突变事件发生的时间短,再加上现有的测年误差范围较大,使得对其传播过程和途径的研究还不够深入,后续应加深年代学的精细化研究,并开展多指标综合对比,系统理解突变事件的发生传播过程和气候-水文-生态响应等。对巴里坤湖而言,后续的工作一方面是将对不同区域的H1气候代用资料进行集成分析,另一方面要增加模拟的研究工作,以便更好的理解H1时期内陆干旱化的机理。
致谢: 审稿专家和编辑部杨美芳老师提出了宝贵的修改意见,在此一并感谢!
[1] |
Grootes P, Stuiver M, White J, et al. Comparison of oxygen isotope records from the GISP2 and GRIP Greenlandice cores[J]. Nature, 1993, 366(6455): 552-554. DOI:10.1038/366552a0 |
[2] |
Heinrich H. Origin and consequences of cyclic ice rafting in the Northeast Atlantic Ocean during the past 130, 000 years[J]. Quaternary Research, 1988, 29(2): 142-152. DOI:10.1016/0033-5894(88)90057-9 |
[3] |
Hemming S R. Heinrich events:Massive Late Pleistocene detritus layers of the North Atlantic and their global climate imprint[J]. Reviews of Geophysics, 2004, 42(1). DOI:10.1029/2003RG000128 |
[4] |
Bond G, Broecker W, Johnsen S, et al. Correlations between climate records from North Atlantic sediments and Greenland ice[J]. Nature, 1993, 365(6442): 143-147. DOI:10.1038/365143a0 |
[5] |
Bond G, Heinrich H, Broecker W, et al. Evidence for massive discharges of icebergs into the North Atlantic ocean during the last glacial period[J]. Nature, 1992, 360(6401): 245-249. DOI:10.1038/360245a0 |
[6] |
Keigwin L D, Lehman S J. Deep circulation change linked to Heinrich event 1 and Younger Dryas in a middepth North Atlantic core[J]. Paleoceanography and Paleoclimatology, 1994, 9(2): 185-194. |
[7] |
Vidal L, Labeyrie L, Cortijo E, et al. Evidence for changes in the North Atlantic deep water linked to meltwater surges during the Heinrich events[J]. Earth and Planetary Science Letters, 1997, 146(1-2): 13-27. DOI:10.1016/S0012-821X(96)00192-6 |
[8] |
Broecker W S. Massive iceberg discharges as triggers for global climate change[J]. Nature, 1994, 372(6505): 421. DOI:10.1038/372421a0 |
[9] |
McManus J F, Francois R, Gherardi J M, et al. Collapse and rapid resumption of Atlantic meridional circulation linked to deglacial climate changes[J]. Nature, 2004, 428(6985): 834-837. DOI:10.1038/nature02494 |
[10] |
Cacho I, Grimalt J O, Canals M, et al. Variability of the western Mediterranean Sea surface temperature during the last 25, 000 years and its connection with the Northern Hemisphere climatic changes[J]. Paleoceanography, 2001, 16(1): 40-52. DOI:10.1029/2000PA000502 |
[11] |
Cacho I, Grimalt J O, Canals M. Response of the western Mediterranean Sea to rapid climatic variability during the last 50, 000 years:A molecular biomarker approach[J]. Journal of Marine Systems, 2002, 33-34: 253-272. DOI:10.1016/S0924-7963(02)00061-1 |
[12] |
Ivy-Ochs S, Kerschner H, Kubik P W, et al. Glacier response in the European Alps to Heinrich Event 1 cooling:The Gschnitz stadial[J]. Journal of Quaternary Science, 2006, 21(2): 115-130. DOI:10.1002/(ISSN)1099-1417 |
[13] |
Nebout N C, Turon J L, Zahn R, et al. Enhanced aridity and atmospheric high-pressure stability over the western Mediterranean during the North Atlantic cold events of the past 50 k.y[J]. Geology, 2002, 30(10): 863-866. DOI:10.1130/0091-7613(2002)030<0863:EAAAHP>2.0.CO;2 |
[14] |
Wohlfarth B, Veres D, Ampel L, et al. Rapid ecosystem response to abrupt climate changes during the last glacial period in Western Europe, 40-16 ka[J]. Geology, 2008, 36(5): 407-410. DOI:10.1130/G24600A.1 |
[15] |
Tzedakis P C, Frogley M R, Lawson I T, et al. Ecological thresholds and patterns of millennial-scale climate variability:The response of vegetation in Greece during the last glacial period[J]. Geology, 2004, 32(2): 109-112. DOI:10.1130/G20118.1 |
[16] |
Cai Y J, Tan L C, Cheng H, et al. The variation of summer monsoon precipitation in Central China since the last deglaciation[J]. Earth and Planetary Science Letters, 2010, 291(1-4): 21-31. DOI:10.1016/j.epsl.2009.12.039 |
[17] |
Wang Y, Cheng H, Edwards R L, et al. Millennial-and orbital-scale changes in the East Asian monsoon over the past 224, 000 years[J]. Nature, 2008, 451(7182): 1090-1093. DOI:10.1038/nature06692 |
[18] |
Wang Y J, Cheng H, Edwards R L, et al. A high-resolution absolute-dated Late Pleistocene monsoon record from Hulu Cave, China[J]. Science, 2001, 294(5550): 2345-2348. DOI:10.1126/science.1064618 |
[19] |
Yuan D, Cheng H, Edwards RL, et al. Timing, duration, and transitions of the last interglacial Asian monsoon[J]. Science, 2004, 304(5670): 575-578. DOI:10.1126/science.1091220 |
[20] |
Cheng H, Spötl C, Breitenbach SF, et al. Climate variations of Central Asia on orbital to millennial timescales[J]. Scientific Reports, 2016, 6: 36975. DOI:10.1038/srep36975 |
[21] |
An Z S, Colman S M, Zhou W J, et al. Interplay between the Westerlies and Asian monsoon recorded in Lake Qinghai sediments since 32 ka[J]. Scientific Reports, 2012, 2(8): 619-625. |
[22] |
汪品先, 翦知湣. 寻求高分辨率的古环境记录[J]. 第四纪研究, 1999(1): 1-17. Wang Pinxian, Jian Zhimin. Searching high-resolution paleoenvironmental records:A review[J]. Quaternary Sciences, 1999(1): 1-17. DOI:10.3321/j.issn:1001-7410.1999.01.001 |
[23] |
Zhao K, Li X, Dodson J, et al. Climate instability during the last deglaciation in Central Asia, reconstructed by pollen data from Yili Valley, NW China[J]. Review of Palaeobotany and Palynology, 2013, 189: 8-17. DOI:10.1016/j.revpalbo.2012.10.005 |
[24] |
Rhodes T E, Gasse F, Lin R, et al. A Late Pleistocene-Holocene lacustrine record from Lake Manas, Zunggar(Northern Xinjiang, Western China)[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 1996, 120(1-2): 105-121. DOI:10.1016/0031-0182(95)00037-2 |
[25] |
Yang D, Peng Z, Luo C, et al. High-resolution pollen sequence from Lop Nur, Xinjiang, China:Implications on environmental changes during the Late Pleistocene to the Early Holocene[J]. Review of Palaeobotany and Palynology, 2013, 192: 32-41. DOI:10.1016/j.revpalbo.2012.12.002 |
[26] |
Herzschuh U, Zhang C, Mischke S, et al. A Late Quaternary lake record from the Qilian Mountains(NW China):Evolution of the primary production and the water depth reconstructed from macrofossil, pollen, biomarker, and isotope data[J]. Global and Planetary Change, 2005, 46(1): 361-379. |
[27] |
Shen J, Liu X, Wang S, et al. Palaeoclimatic changes in the Qinghai Lake area during the last 18, 000 years[J]. Quaternary International, 2005, 136(1): 131-140. DOI:10.1016/j.quaint.2004.11.014 |
[28] |
Zhao J, An C B, Huang Y, et al. Contrasting Early Holocene temperature variations between monsoonal East Asia and Westerly dominated Central Asia[J]. Quaternary Science Reviews, 2017, 178: 14-23. DOI:10.1016/j.quascirev.2017.10.036 |
[29] |
Zhao Y, An C B, Mao L, et al. Vegetation and climate history in arid Western China during MIS 2:New insights from pollen and grain-size data of the Balikun Lake, eastern Tien Shan[J]. Quaternary Science Reviews, 2015, 126: 112-125. DOI:10.1016/j.quascirev.2015.08.027 |
[30] |
段阜涛, 安成邦, 赵永涛, 等. 新疆湖泊岩芯记录的末次间冰期以来气候变化初步研究[J]. 第四纪研究, 2018, 38(5): 1156-1165. Duan Futao, An Chengbang, Zhao Yongtao, et al. A preliminary study on the climate change since the last interglaciation based on lake sediments from Xinjiang, Northwest China[J]. Quaternary Sciences, 2018, 38(5): 1156-1165. |
[31] |
韩淑媞, 董光荣. 巴里坤湖全新世环境演变的初步研究[J]. 海洋地质与第四纪地质, 1990, 10(3): 91-98. Han Shuti, Dong Guangrong. Preliminary study of Holocene environmental evolution in the Balikun Lake[J]. Marine Geology & Quaternary Geology, 1990, 10(3): 91-98. |
[32] |
韩淑媞, 李志中. 论新疆巴里坤湖沉积地球化学指标的累积规律[J]. 海洋与湖沼, 1994, 25(4): 429-37. Han Shuti, and Li Zhizhong. The accumulating regulation of deposit geochemistry of Balikun Lake, Xinjing[J]. Oceanologia et Limnologia Sinica, 1994, 25(4): 429-437. DOI:10.3321/j.issn:0029-814X.1994.04.015 |
[33] |
邢文渊, 肖继东, 沙依然, 等. 基于MODIS影像的湖泊动态变化遥感监测——以巴里坤湖为例[J]. 草业科学, 2009, 26(7): 28-31. Xing Wenyuan, Xiao Jidong, Sha Yiran, et al. Remote sensed monitoring of lake dynamic change based on MODIS image[J]. Pratacultural Science, 2009, 26(7): 28-31. |
[34] |
Blaauw M, Christen J A. Flexible paleoclimate age-depth models using an autoregressive gamma process[J]. Bayesian Analysis, 2011, 6(3): 457-474. |
[35] |
Peng Y, Xiao J, Nakamura T, et al. Holocene East Asian monsoonal precipitation pattern revealed by grain-size distribution of core sediments of Daihai Lake in Inner Mongolia of north-Central China[J]. Earth and Planetary Science Letters, 2005, 233(3): 467-479. |
[36] |
Bond G, Showers W, Cheseby M, et al. A pervasive millennial-scale cycle in North Atlantic Holocene and glacial climates[J]. Science, 1997, 278(5341): 1257-1266. DOI:10.1126/science.278.5341.1257 |
[37] |
Brauer A, Mingram J, Frank U, et al. Abrupt environmental oscillations during the Early Weichselian recorded at Lago Grande di Monticchio, Southern Italy[J]. Quaternary International, 2000, 73-74: 79-90. DOI:10.1016/S1040-6182(00)00066-5 |
[38] |
Håkanson L, Jansson M. Lake Sedimentology[M]. Berlin: Springer-Verlag, 1983: 316-456.
|
[39] |
Zhang J, Kong Z, Du N. The respondence of loss-on-ignition range to past climate and environment in Beijing[J]. Acta Ecologica Sinica, 1998, 18(4): 343-347. |
[40] |
Cato I. Recent sedimentological and geochemical conditions and pollution problems in two marine areas in south-Western Sweden[J]. Striae, 1977, 6(1): 1-150. |
[41] |
韩鹏, 刘兴起. 内蒙古中东部查干淖尔湖流域7000年以来的气候演变[J]. 第四纪研究, 2017, 37(6): 1381-1390. Han Peng, Liu Xingqi. The climate evolution inferred from Chagan-Nuur in middle-east part of Inner Mongolia since the last 7000 years[J]. Quaternary Sciences, 2017, 37(6): 1381-1390. |
[42] |
牛蕊, 周立旻, 孟庆浩, 等. 贵州草海南屯泥炭记录的中全新世以来的气候变化[J]. 第四纪研究, 2017, 37(6): 1357-1369. Niu Rui, Zhou Limin, Meng Qinghao, et al. The paleoclimate variations of the Nantun peat in the Caohai area since the Middle Holocene[J]. Quaternary Sciences, 2017, 37(6): 1357-1369. |
[43] |
王庆锋, 金会军, 吴青柏, 等. 距今约6000年以来青藏高原东北部黄河源区冻结泥炭沉积记录的气候演化[J]. 第四纪研究, 2017, 37(2): 402-415. Wang Qingfeng, Jin Huijun, Wu Qingbai, et al. Climatic evolution since 6 cal.ka B. P. recorded by frozen peat deposits in the source area of the Yellow River, northeastern Qinghai-Tibet Plateau[J]. Quaternary Sciences, 2017, 37(2): 402-415. |
[44] |
王云飞. 青海湖、岱海的湖泊碳酸盐化学沉积与气候环境变化[J]. 海洋与湖沼, 1993, 24(1): 31-36. Wang Yunfei. Lacustrine carbonate chemical sedimentaion and climate-encironmental evolution-A case study of Qinghai Lake and Daihai Lake[J]. Oceanlogia et Limnologia Sinica, 1993, 24(1): 31-36. |
[45] |
郑绵平, 赵元艺, 刘俊英. 第四纪盐湖沉积与古气候[J]. 第四纪研究, 1998(4): 297-307. Zheng Mianping, Zhao Yuanyi, Liu Junying. Quaternary saline lake deposition and paleoclimate[J]. Quaternary Sciences, 1998(4): 297-307. DOI:10.3321/j.issn:1001-7410.1998.04.002 |
[46] |
鹿化煜, 周亚利, Mason J, 等. 中国北方晚第四纪气候变化的沙漠与黄土记录[J]. 第四纪研究, 2006, 26(6): 888-894. Lu Huayu, Zhou Yali, Mason J, et al. Late Quaternary climatic changes in Northern China-New evidences from sand dune and loess records based on optically stimulated luminescence dating[J]. Quaternary Sciences, 2006, 26(6): 888-894. DOI:10.3321/j.issn:1001-7410.2006.06.002 |
[47] |
Jin Z, An Z, Yu J, et al. Lake Qinghai sediment geochemistry linked to hydroclimate variability since the last glacial[J]. Quaternary Science Reviews, 2015, 122: 63-73. DOI:10.1016/j.quascirev.2015.05.015 |
[48] |
Qiang M, Jin Y, Liu X, et al. Late Pleistocene and Holocene aeolian sedimentation in Gonghe Basin, northeastern Qinghai-Tibetan Plateau:Variability, processes, and climatic implications[J]. Quaternary Science Reviews, 2016, 132: 57-73. DOI:10.1016/j.quascirev.2015.11.010 |
[49] |
Wünnemann B, Wagner J, Zhang Y, et al. Implications of diverse sedimentation patterns in Hala Lake, Qinghai Province, China for reconstructing Late Quaternary climate[J]. Journal of Paleolimnology, 2012, 48(4): 725-749. DOI:10.1007/s10933-012-9641-2 |
[50] |
Qiang M, Song L, Jin Y, et al. A 16-ka oxygen-isotope record from Genggahai Lake on the northeastern Qinghai-Tibetan Plateau:Hydroclimatic evolution and changes in atmospheric circulation[J]. Quaternary Science Reviews, 2017, 162: 72-87. DOI:10.1016/j.quascirev.2017.03.004 |
[51] |
Saini J, Günther F, Aichner B, et al. Climate variability in the past~19, 000 yr in NE Tibetan Plateau inferred from biomarker and stable isotope records of Lake Donggi Cona[J]. Quaternary Science Reviews, 2017, 157: 129-140. DOI:10.1016/j.quascirev.2016.12.023 |
[52] |
Wang Y, Herzschuh U, Shumilovskikh L S, et al. Quantitative reconstruction of precipitation changes on the NE Tibetan Plateau since the Last Glacial Maximum-Extending the concept of pollen source area to pollen-based climate reconstructions from large lakes[J]. Climate of the Past, 2014, 10: 21-39. DOI:10.5194/cp-10-21-2014 |
[53] |
Emeis K C, Schulz H, Struck U, et al. Eastern Mediterranean surface water temperatures and δ18O composition during deposition of sapropels in the Late Quaternary[J]. Paleoceanography and Paleoclimatology, 2003, 18(1): 1005. DOI:10.1029/2000PA000617 |
[54] |
Almogi-Labin A, Bar-Matthews M, Shriki D, et al. Climatic variability during the last~ 90 ka of the southern and northern Levantine Basin as evident from marine records and speleothems[J]. Quaternary Science Reviews, 2009, 28(25): 2882-2896. |
[55] |
Essallami L, Sicre M, Kallel N, et al. Hydrological changes in the Mediterranean Sea over the last 30, 000 years[J]. Geochemistry, Geophysics, Geosystems, 2007, 8(7): Q07002. DOI:10.1029/2007GC001587 |
[56] |
Grant K, Rohling E, Bar-Matthews M, et al. Rapid coupling between ice volume and polar temperature over the past 150, 000 years[J]. Nature, 2012, 491(7426): 744. DOI:10.1038/nature11593 |
[57] |
Cheng H, Sinha A, Verheyden S, et al. The climate variability in northern Levant over the past 20, 000 years[J]. Geophysical Research Letters, 2015, 42(20): 8641-8650. DOI:10.1002/2015GL065397 |
[58] |
Bartov Y, Goldstein SL, Stein M, et al. Catastrophic arid episodes in the Eastern Mediterranean linked with the North Atlantic Heinrich events[J]. Geology, 2003, 31(5): 439-442. DOI:10.1130/0091-7613(2003)031<0439:CAEITE>2.0.CO;2 |
[59] |
Çaǧatay M, Öǧretmen N, Damcı E, et al. Lake level and climate records of the last 90 ka from the Northern Basin of Lake Van, eastern Turkey[J]. Quaternary Science Reviews, 2014, 104: 97-116. DOI:10.1016/j.quascirev.2014.09.027 |
[60] |
Heinecke L, Mischke S, Adler K, et al. Climatic and limnological changes at Lake Karakul(Tajikistan)during the last~ 29 cal ka[J]. Journal of Paleolimnology, 2017, 58(3): 317-334. DOI:10.1007/s10933-017-9980-0 |
[61] |
Tarasov P E, Cheddadi R, Guiot J, et al. A method to determine warm and cool steppe biomes from pollen data; application to the Mediterranean and Kazakhstan regions[J]. Journal of Quaternary Science, 1998, 13(4): 335-344. DOI:10.1002/(ISSN)1099-1417 |
[62] |
Allen JR, Brandt U, Brauer A, et al. Rapid environmental changes in Southern Europe during the last glacial period[J]. Nature, 1999, 400(6746): 740. DOI:10.1038/23432 |
[63] |
Naughton F, Sanchez Goñi M F, Desprat S, et al. Present-day and past(last 25000 years)marine pollen signal off Western Iberia[J]. Marine Micropaleontology, 2007, 62(2): 91-114. DOI:10.1016/j.marmicro.2006.07.006 |
[64] |
Naughton F, Sánchez Goñi M F, Kageyama M, et al. Wet to dry climatic trend in north-Western Iberia within Heinrich events[J]. Earth and Planetary Science Letters, 2009, 284(3): 329-342. |
[65] |
Fletcher W J, Sánchez Goñi M F, Allen J R M, et al. Millennial-scale variability during the last glacial in vegetation records from Europe[J]. Quaternary Science Reviews, 2010, 29(21): 2839-2864. |
[66] |
Roucoux K H, de Abreu L, Shackleton N J, et al. The response of NW Iberian vegetation to North Atlantic climate oscillations during the last 65 kyr[J]. Quaternary Science Reviews, 2005, 24(14): 1637-1653. |
[67] |
张恩楼, 孙伟伟, 刘恩峰, 等. 末次冰盛期以来洱海沉积物元素碳同位素特征与区域植被组成变化[J]. 第四纪研究, 2017, 37(5): 1027-1036. Zhang Enlou, Sun Weiwei, Liu Enfeng, et al. Vegetation change reconstructed by a stable isotope record of elemental carbon from Lake Erhai, Southwest China since the Last Glacial Maximum[J]. Quaternary Sciences, 2017, 37(5): 1027-1036. |
[68] |
沈吉, 肖霞云. 2万年来南亚季风演化历史[J]. 第四纪研究, 2018, 38(4): 799-820. Shen Ji, Xiao Xiayun. Evolution of the South Asian monsoon during the last 20 ka recorded in lacustrine sediments from Southwestern China[J]. Quaternary Sciences, 2018, 38(4): 799-820. |
[69] |
North Greenland Ice Core Project Members. High-resolution record of Northern Hemisphere climate extending into the last interglacial period[J]. Nature, 2004, 431(7005): 147-151. DOI:10.1038/nature02805 |
[70] |
Tierney J E, Pausata F S R, deMenocal P. Deglacial Indian monsoon failure and North Atlantic stadials linked by Indian Ocean surface cooling[J]. Nature Geoscience, 2015, 9: 46. DOI:10.1038/ngeo2603 |
[71] |
Stager J C, Ryves D B, Chase B M, et al. Catastrophic drought in the Afro-Asian monsoon region during Heinrich event 1[J]. Science, 2011, 331(6022): 1299-1302. DOI:10.1126/science.1198322 |
2 Key Laboratory of Western China's Environmental Systems(Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, Gansu;
3 State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, Shanxi)
Abstract
Reconstructing the vegetation and climate in the arid inland areas during the Heinrich 1 (H1) event is beneficial for us understanding the relationship between arid ecosystem and abrupt climate change. We use multi-proxy analyses (e.g., lithology, gain size, LOI, XRF-Ti, pollen) of a sediment core BLK11A obtained from Balikun Lake, eastern Tienshan Mts. in Xinjiang, China, to elucidate variations in sedimentation, vegetation and climate during the postglacial, with emphasis on the H1 event. Balikun Lake (43°36'~43°45'N, 92°42'~92°54'E; 1575 m a.s.l.) is located in the west of the Balikun basin. The Balikun basin is a faulted plateau basin situated in the eastern part of Xinjiang. It lies between the Balikun Mountains to the south and the Moqinwula Mountains to the north Balikun Lake is a hydrologically closed inland lake with a peculiar wetland-arid ecosystem. A number of alluvial fans are distributed in the western basin, and the Dahe River originates on the northern slopes of the Balikun Mountains, runs along the Balikun steppe to the west and finally discharges into Balikun Lake. The BLK11A core (62.5 m; 43°39'51"N, 92°48'10"E) was taken from the centre of Balikun Lake in June 2011. In this study, we focus on a segment of the core between 450 cm and 610 cm to study climate change during H1 (17~15 cal.ka B. P.). The core was subsampled at 1-cm intervals in the laboratory and then freeze-dried. The chronology framework of the core was established by six accelerator mass spectrometry (AMS) 14C dates measured by Beta Analytic Inc., USA on various fractions. The results show that:(1) the H1 deposition was dominated by sandy silt or silty sand, along with the high value of XRF-Ti, both indicated a high frequency of dust storm around the Balikun Lake, which in turn brought more coarse material to the lake. Grain-size distribution of the H1 samples showed a similar mode to the modern aeolian dust collected from Balikun region. (2) Regional vegetation around Balikun Lake during the H1 was mainly dominated by desert and/or desert-steppe, with low vegetation cover reflected by the low pollen concentration, suggested a degraded environment, also the watershed bio-productivity showed a relatively low value. (3) A synchronous cold-dry climate prevailed over the mid-latitude inland areas of the Eurasia during the H1, and it caused a catastrophic drought condition along these areas with an increase in aeolian input, shrink in lake area, and degradation of vegetation. The general pattern of widespread aridity in the arid inland areas during the H1 was generally caused by decreased evaporated water vapor along the westerlies linked to the low temperature, together with limited meltwater contributions of the mountain glaciers.