渤海湾西北岸中更新世中期以来的气候环境和沉积环境演变

渤海湾西北岸是渤海湾沿岸砂坝-澙湖沉积体系组成部分,其沉积物蕴含着丰富的地质环境演变信息,是认识该地区气候环境和新构造活动的关键.通过对渤海湾西北岸QEJ01孔80 m以上地层沉积环境、孢粉分析及微体古生物研究,结合测年数据,根据定量古气候重建数据,探讨了本区中更新世中期以来特征时期的植被演替及环境演变,并对MIS6～MIS1各阶段渤海湾西北岸的气候及环境变化进行了区域对比.QEJ01孔450.40～377.14 ka,植被类型以针阔混交林为主,气候温暖干燥,沉积环境由河床逐渐演变为滨海湖泊;377.14～113.96 ka,气候相对寒凉湿润,植被类型以针阔叶混交林-草原为主,沉积环境以湖泊为主,后期为洪泛平原;113.96～98.84 ka,该时期气候波动频繁,以稀树荒漠草原为主,气候温凉湿润,河床发育;98.84～74.33 ka,气候温暖湿润,植被景观为针阔混交林-草原,降水量增加,沉积环境以漫滩湖泊和河床相为主;74.33～48.09 ka,气候异常寒冷干旱,以针叶林为主的稀疏-荒漠草原较发育;48.09～25.72 ka,植被类型为针阔混交林-草原,气候温暖偏湿;25.72～22.52 ka,气候寒凉干旱,植被为稀树-荒漠草原;22.52～3.87 ka,植被类型由常绿落叶阔叶林演变为针阔混交林-草原,气候温暖湿润,沉积环境以三角洲平原为主;3.87～0.0 ka,气候凉爽干旱,植被类型以针阔混交林为主.渤海湾西北岸平原为构造活动的活跃地带,自MIS5阶段以来,沉降中心呈现自北西向南东迁移,以及海侵层的发育程度,均受区域构造运动和气候环境变化的影响控制.     

末次盛冰期以来青藏高原东北部共和盆地气候与环境变化研究进展

青藏高原东北部共和盆地气候与环境变化文献分析认为:末次盛冰期(14 C年龄14ka BP或16cal ka BP之前)地层沉积主要为风成砂和黄土,冰缘地貌发育,气候寒冷干燥,植被可能为干旱荒漠或荒漠草原;末次冰消期(14 C年龄14ka BP或16 cal ka BP-Younger Dryas,缩写YD事件)地层发育古土壤,湖泊水位明显上升,并显著的捕捉到冷暖事件(Blling-Allerd,缩写B/A、YD)的信息,气候趋于温暖湿润,对应植被为荒漠草原;全新世8.5ka BP(14 C年龄)之前区域温度和湿度不同程度增加,湖泊水位较高,地层发育古土壤,植被为荒漠草原或干草原;8.5～7.0ka BP(14 C年龄)风成砂出现,古土壤发育中断,气候寒冷干燥,为全新世新冰期第一期;7.0～3.0ka BP(14 C年龄)古土壤显著发育,高水位湖面出现,水热组合达到全新世最佳,植被向干草原方向演化,但期间也存在千–百年尺度的冷事件(全新世新冰期第二期);3.0ka BP(14 C年龄)以来气候向温凉(寒冷)干燥方向发展.太阳辐射等外部因素变化并触发地球系统内部各个圈层之间相互作用是区域气候、环境变化的主要驱动力.同时,对研究现状进一步剖析,阐明其存在的问题,并提出气候、环境变化研究的发展方向.     

阳原西堡剖面的孢粉分析

通过对阳原西堡剖面的孢粉分析,得到16000年以来该地区植被与环境发展的历史。约16000~11000aBP期间,植被是以蒿和藜为主的干旱草原景观,气候寒冷而干燥;约11000~9000aBP期间,植被有一定的增长,气候变得温凉稍湿;约9000~4800aBP期间,气温上升湿度下降,植被呈现疏林草原景观;距今4800aBP以来,植被虽然仍以草原为主,但低花粉浓度指示环境条件又趋于恶劣,气候进一步向暖干方向发展。      

内蒙古克什克腾旗地区距今16 000 a以来的孢粉组合特征与环境变迁

本文通过对三义黄土剖面孢粉资料的分析，初步重建了内蒙克旗地区16000a以来植被及环境的变迁过程。约16010～15380a B P，植被稀疏，气候寒冷而干燥；约15380～11270a B P，植被以草本植物为主，气候变得更加干旱；约11270～9940a B P，气候总体上由先前的冷干开始向暖湿方向发展，植被仍以草原为主；约9940～2320a B P，植被得到进一步发展，气候表现出温暖湿润的特征；约2320a B P至今，植被仍以草原为主，气候向温凉方向发展。     

辽宁北部至内蒙古东南部地区晚更新世风成砂与乌尔吉组的研究

根据最新的光释光测试结果及产出化石的年代,乌尔吉组的年代应为中更新世.乌尔吉组岩性以灰黄色砂、亚砂土为主,孔隙及柱状节理发育,夹不规则姜块状钙质结核,主要分布于内蒙古通辽白音花和辽宁阜新旧庙地区.上更新统风积物以土黄色细粉砂、深灰色粉砂为主,弱固结,柱状节理发育,不夹姜块状钙质结核,主要分布在内蒙古库伦旗以北、科尔沁左翼后旗等地区.     

孢粉记录的新疆地区新近纪植被格局与气候环境演化

新近纪是地球气候系统由古近纪温室气候向第四纪冰室气候转变的一个关键过渡阶段.本文综述了近30年来新疆地区新近纪孢粉资料,通过时空对比,认识了该地区新近纪植被与气候环境格局特征.中新世早期新疆地区总体气候温暖湿润,大部分地区发育森林植被,局部地区发育草原植被;晚期气候温暖干旱,准噶尔区的独山子、塔里木区的罗布泊和库车盆地开始出现草原植被,准噶尔区的金沟河出现荒漠植被,其他地区为森林植被或森林-草原植被.上新世时期,气候干旱化显著加剧,准噶尔区、塔里木区和昆仑区都出现草原和荒漠草原.晚新生代全球变冷和青藏高原、昆仑山山脉、天山山脉的加速抬升可能是导致新疆地区植被与气候环境格局形成和中亚地区干旱化的两个主要因素.而研究地点的地形地貌、雨影效应、迎风和背风等因素以及古特提斯海退却可能是其他应当考虑的次要因素.     

甘肃疏勒河冲积扇绿洲全新世孢粉组合和环境演化

通过甘肃疏勒河冲积扇九道沟下游剖面(JDG)沉积物系统的孢粉分析,探讨了这一极干旱区全新世植被和气候环境演化.约4.3 m厚沉积剖面的孢粉组合特征清楚地反映了研究区全新世植被经历了6个发展演替阶段,从老而新依次为:针叶林为主的针阔混交林-灌丛草原;灌丛草原;疏林灌木草原;针叶树为主的针阔混交林-灌丛草原;草原植被;针叶林-灌木草原.与植被发展演替相对应的气候环境经历了凉较湿→温干→暖湿→温较湿→温干→凉较湿的变化.这些结果对于了解该地区全新世气候演化以及中国西北干旱区未来环境预测方面都具有重要意义.     

新疆罗布泊地区32.0～9.1kaB.P.期间的孢粉记录及其古气候古环境演化

新疆罗布泊地区罗北洼地CK­2钻孔的孢粉记录揭示出： 32.0～9.1kaB.P. 植被演替明显,气候干湿波动显著; 晚冰期向全新世过渡期间,气候波动频繁且具突变性。31.98～19.26kaB.P.罗布泊地区处于末次冰期的盛冰期阶段,气候寒冷湿润,冷暖波动频繁,但幅度不大,研究区植被以草原－荒漠草原为主; 19.26～13.67kaB.P. 气候明显变为温暖干燥,植被以荒漠为主; 13.67～12.73kaB.P.气候冷湿偏干,植被以草原－荒漠草原为主; 12.73～9.14kaB.P.气候冷湿与暖干交替频繁,波动幅度较大,植被逐渐由荒漠向草原－荒漠草原过渡。其中, 16.45～15.39kaB.P.,14.27～13.67kaB.P.和 11.74～11.23kaB.P.之间的冷颤动分别相应于老仙女木、中仙女木和新仙女木事件; 15.39～14.27kaB.P.和 12.73～11.74kaB.P.之间的暖期则分别对应于欧洲博令和阿勒罗得暖期; 新仙女木事件后的气候具有突变性的特点,10.49kaB.P.前后的暖事件和9.14kaB.P.前后的冷事件,成为全新世早期气候变化的显著特征。孢粉浓度和花粉组合所反映的罗布泊地区晚冰期以来的气候演化同全球性的气候事件具有显著的可比性。     

天津北部4.00 Ma BP以来古植被与古气候

依据CQJ1孔275块孢粉样品分析结果,结合岩性特征和测年资料,建立了天津北部4.00 Ma BP以 来古植被与古气候变化序列。大约在3.60-4.00Ma BP, 天津北部植被以荒漠草原为主, 气候冷干;3.44- 3.60Ma BP植被为疏林草原, 气候温和湿润;3.18-3.44Ma BP植被为荒漠草原, 气候冷干;2.58-3.18Ma BP植被以针阔叶混交林草原为主,气候温暖湿润;1.90-2.58Ma BP植被以疏林草原为主,气候温凉偏干; 1.74-1.90Ma BP植被为荒漠草原,气候冷干;1.30-1.74Ma BP植被以针阔叶混交林为主,气候温暖潮湿; 0.78-1.30Ma BP植被为以针叶树种为主的针阔叶混交林草原,气候温和湿润;0.15-0.78Ma BP植被以针阔叶 混交林为主,气候温暖潮湿;0.15Ma BP以来,孢粉丰度呈现有规律的变化,3个高丰度层段分别相当于MIS（海洋氧同位素） １、３、５阶段,与河北平原东部具有可比性。     

内蒙古敖汉旗辉绿岩脉体LA-ICP-MS锆石U-Pb年代学——对赤峰-开原深断裂活动的指示

辉绿岩脉作为来源于地幔的脉体,可作为深断裂活动的标志.在赤峰敖汉旗1：5万区调工作中,在邢家窝铺古元古代宝音图群中识别出近东西向展布的辉绿岩脉.辉绿岩脉锆石U-Pb LA-ICP-MS年龄显示603~521 Ma、450 Ma、259~262 Ma、237 Ma、（167.4±3.0）Ma等5组年龄.其中最小年龄（167.4±3.0）Ma代表了辉绿岩脉体的形成年龄.反映了赤峰-开原深断裂在中侏罗世的活化;其余几组年龄也与赤峰地区不同期次的岩浆活动相对应.结合前人资料总结了赤峰-开原深断裂的形成与演化.     

内蒙古扎鲁特旗地区更新世地层划分

根据孢粉组合特征及光释光测年结果,对分布在内蒙古东南部的第四系更新统做了进一步的划分和研究。研究结果表明,主要分布在内蒙古东南部的中更新统风积物,岩性为黄色亚砂土,含钙质结核,发育柱状节理,区域上称乌尔吉组,含Artemisia-Ephedra-Pinus孢粉组合,光释光测年结果为(40.4±1.9)~(110.0±7.5)ka; 下更新统沉积物,岩性为红褐色亚砂土及亚黏土,含钙质结核、砂砾透镜体,区域上称为赤峰黄土,含Artemisia-Polygonum-Betula孢粉组合,光释光测年结果为（200.9±9.6）~（220.4±13.2）ka。上述2套地层在内蒙古东南部广泛分布,更新世地层的划分为内蒙古东南部地区的第四系地层划分对比研究提供了基础地质资料。     

汉江上游I级河流阶的形成及对东亚季风 变化的响应

对郧县—白河段汉江Ⅰ级河流阶地上风成黄土的沉积学、理化性质、地球化学和年代学进行了系统研究。结果表明,汉江Ⅰ河流阶的形成不晚于25 ka BP;黄土具有马兰黄土(L1)→过渡黄土(Lt)→古土壤(S0)→全新世黄土(L0)→表土(TS)的地层序列,与渭河谷地的黄土地层序列完全可比;25~11.5 ka BP,冬季风强盛,气候冷干,从11.5 ka BP开始,冬季风逐渐减弱,气候开始向暖湿方向逐步转化,从8.5 ka BP开始,夏季风达到了末次冰期结束后的鼎盛时期,3.1 ka BP前后,东亚季风格局发生变化,夏季风减弱,重新进入一个相对干冷的时期,而人类活动对地表的影响形成了表土;汉江上游谷地黄土记录的末次冰期后季风逐渐加强、中全新世季风强盛、随后季风衰退和气候变干的夏季风演变模式与渭河谷地黄土的记录高度一致,与邻区石笋和泥炭记录的季风变化趋势也有良好的可比性,但与石笋/泥炭记录的夏季风强盛期的起始时间(9.3~4.2 ka BP)并不完全一致。     

甘肃临夏盆地新近纪红粘土粒度组成的古环境意义①

临夏盆地十里墩剖面新近纪红粘土粒度组成特征、磁化率值分析表明:8.2Ma以来,临夏盆地经历了干旱化的逐级发展和东亚冬季风的逐渐加强过程。8.2～7.4Ma,东亚冬季风形成,干旱化已经发生,风成红粘土开始在盆地沉积;7.4～6.8Ma,亚洲冬季风逐渐加强,开始影响黄土高原地区,形成大面积的红粘土堆积,盆地为半干旱～半湿润的气候环境;6.8～6.0Ma气候与构造稳定,基本维持了前期的气候特点;5.9～5.3Ma,盆地冬季风强度略有增加,为干湿与干凉交替的气候环境;5.3～4.8Ma盆地冬季风盛行、干旱化程度强烈,气候特征为干凉;4.8～4.0Ma,夏季风开始盛行,气候变的湿润。4.0Ma后,青藏高原开始发生又一次强烈隆升。     

台湾头社盆地湖沼相沉积孢粉记录的6.2~1.3 cal ka BP以来气候研究

头社盆地位于中国台湾省中部,东亚季风区的最前沿,对东亚季风的响应十分敏感,研究其中晚全新世以来古植被、重建古气候序列,探讨其气候与东亚夏季风的关系具有重要的科学意义。文章对头社盆地泥炭—湖泊沉积的AMS14C测年、体积磁化率测试的基础上,基于孢粉记录,重建晚全新世来植被变化,恢复古气候。结果表明全新世中晚期以来分六个阶段：6.2~6.0 cal ka BP,气候凉干,植被类型是亚热带常绿阔叶林;6.0~4.0 cal ka BP,气候转暖湿,植被类型为含较多热带成分的亚热带常绿阔叶林;4.0~2.2 cal ka BP,气候相对凉干,植被类型转为亚热带常绿阔叶林;2.2~1.9 cal ka BP,气候又变暖湿;1.9~1.7 cal ka BP,气候快速冷干事件,森林退化;1.7~1.3 cal ka BP,气候重转温暖湿润,植被类型为接近现代的沼泽草原。整体上6.2~2.2 cal ka BP的气候变化是由温暖湿润向温凉干燥转变的趋势,这是全新世中晚期以来的太阳辐射量减少所导致的,太阳辐射量的减少导致热带辐合南移,进而导致东亚夏季风减弱,而2.2 cal ka BP之后气候波动较大,可能是在东亚夏季风减弱的背景下,ENSO活动加强与人类活动的干扰下耦合的结果。     

A 20‐ka climate record from Central Himalayan loess deposits

The southwest monsoon that dominated Central Himalaya has preserved loessic silt deposits preserved in patches that are proximal to periglacial areas. The occurrence of such silts suggests contemporary prevalence of cold and dry northwesterly winds. Field stratigraphy, geochemistry, mineral magnetism, infrared stimulated luminescence (IRSL) and radiocarbon dating has enabled reconstruction of an event chronology during the past 20 ka. Three events of loess accretion could be identified. The first two events of loess deposition occurred betweem 20 and 9 ka and were separated by a phase of moderate weathering. Pedogenesis at the end of this event gave rise to a well‐developed soil that was bracketed around 9 to > 4 ka. This was followed by the third phase of loess accretion that occurred around 4 to > 1 ka. Episodes of loess deposition and soil formation are interpreted in terms of changes in the strength of the Indian southwest monsoon. Copyright © 2005 John Wiley & Sons, Ltd.     

Late Weichselian fluvio‐aeolian sands and coversands of the type locality Grubbenvorst (southern Netherlands): sedimentary environments,climate record and age

The Weichselian Late Pleniglacial and Lateglacial aeolian stratigraphy (Older Coversand I, Beuningen Gravel Bed, Older Coversand II, Younger Coversand I, Usselo Soil, Younger Coversand II) in the southern Netherlands has been reinvestigated in its type locality (Grubbenvorst). Sedimentary environments have been reconstructed and related to their climatic evolution based on periglacial structures. In addition, 22 optically stimulated luminescence (OSL) ages have been determined that provide an absolute chronology for the climatic evolution and environmental changes of the coversand area. From this work it appears that, prior to 25 ka fluvial deposition by the Maas dominated. After 25 ka fluvial activity reduced and deposition occurred in a fluvio‐aeolian environment with continuous permafrost (Older Coversand I). This depositional phase was dated between 25.2 ± 2.0 and 17.2 ± 1.2 ka. The upward increase of aeolian activity and cryogenic structures in this unit is related to an increase of climatic aridity and a decrease in sedimentation rate during the Last Glacial Maximum (LGM). The Beuningen Gravel Bed, that results from deflation with polar desert conditions and that represents a stratigraphic marker in northwestern Europe, was bracketed between 17.2 ± 1.2 and 15.3 ± 1.0 ka. Based on this age result a correlation with Heinrich event H1 is suggested. Permafrost degradation occurred at the end of this period. Optical ages for the Older Coversand II unit directly overlying the Beuningen Gravel Bed range from 15.3 ± 1.0 ka at the base to 12.7 ± 0.9 ka at the top. Thus this regionally important Older Coversand II unit started at the end of the Late Pleniglacial and continued throughout the early Lateglacial. Its formation after the Late Pleniglacial (LP) maximum cold and its preservation are related to rapid climatic warming around 14.7 ka cal. BP. The Allerød age of the Usselo Soil was confirmed by the optical ages. Copyright © 2007 John Wiley & Sons, Ltd.     

陕西洛川黄土的粒度分维值及其意义

对陕西洛川剖面１５８０个黄土样品的粒度数据分析表明,黄土的基本粒级,即在２－５０μｍ的标度范围内,粒度分布具有分形特征。黄土的粒度分维值在２．１６－２．５１之间,平均值为２．３２;而古土壤的粒度分维值在２．２３－２．５１之间,平均值为２．４１;粒芳分维值对黄土与古土壤的形成环境的演变,有良好的指示意义。粒度分雏值显示,250万年以来,东亚季风不断增强,变化周期和变化幅度逐渐变大。在早更新世,季风较弱,变化周期短．变化幅度小,表现为2～4万年的周期;而在晚更新世,季风较强,冬季风和夏季风相互消长,变化周期长且明显,变化幅度大,表现出10万年的变化周期。     

Evolution of Quaternary alluvial fans and terraces in the intramontane Pinjaur Dun, Sub-Himalaya, NW India: interaction between tectonics and climate change

Quaternary alluvial fans in the tectonically active Pinjaur Dun, an intramontane valley in the Sub‐Himalaya, were deposited in front of the Nalagarh Thrust and were influenced both by tectonics and glacial climate fluctuations. The surface morphology indicates that an earlier set of first‐order fans (Qf1) became entrenched and onlapped by a series of second‐order fans (Qf2). The younger fan segments were then cut by a pair of terraces (T1 and T2). Quartz optically stimulated luminescence dating establishes that the Qf1 aggradational phase was initiated before 96·5 ± 25·3 ka and terminated after 83·7 ± 16·3 ka. This was followed by a period of incision, before Qf2 fan deposition started at 72·4 ± 13·4 ka and continued until 24·5 ± 4·9 ka. Sediment was deposited on the T1 (upper) and T2 (lower) terraces at 16·3 ± 2·1 and 4·5 ka, respectively, recording a return to overall degradation punctuated by minor deposition on terraces. The period of incision separating the younger and older fan deposits coincided with enhanced SW monsoon precipitation. The subsequent development of the Qf2 fans and their progradation until 20 ka suggest erosional unloading of the thrust hangingwall during a tectonically quiescent phase. Toe cutting, deposition of axial river and lacustrine facies, and retreat of Qf2 around 45 ka, indicate fanward shift of the axial river due to tilting of the valley towards the NE in response to reactivation of the Nalagarh Thrust. The cessation of Qf2 deposition around 20 ka and the onset of through‐fan entrenchment suggest reduced sediment supply but relatively high stream power during the last glacial maxima (LGM). The prolonged stream incision since the cessation of Qf2 deposition, with only minor depositional phases at 16·3 ± 2·1 and 4·5 ka, resulted from high water discharge and low sediment input during intensification of the SW monsoon and vegetation changes in the hinterland.     

黄土高原和南海陆架古季风演变的生物记录与Heinrich事件

宝鸡黄土中０．１５Ｍａ以来植物硅酸体研究表明,年均温度、１月份和年均降水量的变化与深海氧同位素变化有很好的一致性,而７月份降水量的变化与印度洋反映季风强弱的粒度变化相类似。南海陆架孢粉研究发现,１４７００—１３９００ａＢ．Ｐ．和２２９００一２０６００ａＢ．Ｐ．气候变冷期与北大西洋沉积物中Ｈ１、Ｈ２变冷事件存在成因上的联系。全球冰量通过冬季风等因素在“轨道尺度”上可能影响了夏季风对特定地区的控制时间,从而控制了黄土区气候的年均状况,但没有影响夏季风固有的变化周期和振幅。由低纬夏季太阳辐射控制的夏季风以其准２００００ａ周期叠加在冬季风所具有的准０．１Ｍａ周期上。冬、夏季风的演化行为具有较强的相对独立性,冬、夏季风同时减弱或增强的情况是存在的。Ｈｅｉｎｒｉｃｈ事件在东亚地区不仅影响了冬季风而且影响了夏季风。     

Late Quaternary landscapes in Central Australia: sedimentary history and palaeoecology of Puritjarra rock shelter

Puritjarra rock shelter provides a long record of late Quaternary vegetation in the Australian arid zone. Analysis of the sedimentary history of this rock shelter is combined with reanalysis of charcoal and phytolith records to provide a first‐order picture of changing landscapes in western Central Australia. These show a landscape responding to increasing aridity from 45 ka with deflation of clay‐rich red palaeosols (<45 ka) and sharp declines in grassland and other vegetation at 40–36 ka, and at the beginning of the Last Glacial Maximum (LGM) (24 ka). Vegetation in the catchment of the rock shelter recovered after 15 ka with expansion of both acacia woodland and spinifex grasslands, registering stronger summer rainfall in the interior of the continent. By 8.3 ka re‐vegetation of local palaeosols and dunes had choked off sediment supply to the rock shelter and the character of the sediments changed abruptly. Poaceae values peaked at 5.8 ka, suggesting the early–mid Holocene climatic optimum in Central Australia is bracketed between 8.3 and 5.8 ka. Local vegetation was disrupted in the late Holocene with a sharp decline in Poaceae at 3.8 ka, coinciding with an abrupt intensification of ENSO. Local grasslands recovered over the next two millennia and by 1.5 ka the modern vegetation appears to have become established. Copyright © 2009 John Wiley & Sons, Ltd.