若尔盖盆地兴措湖沉积记录揭示的近代气候与环境

依据湖泊沉积记录进行古气候环境要素定量的是过去全球变化研究的重要内容,本文通过若尔盖盆地兴措湖近代湖泊沉积特征、沉积物总有机碳及其同位素指标分析,并与器测气象资料进行比较,对兴措湖泊近代湖泊沉积物中有机碳及其同位素指标所代表的气候环境信息进行了定量研究,在此基础上,建立了兴措湖沉积物总有机碳及其同位素记录与对应的降水和气温间的函数关系,为定量恢复该区长尺度历史时期古气候环境特征提供了基础。     

若尔盖RM孔揭示的青藏高原900kaBP以来的隆升与环境变化

通过对青藏高原迄今为止最深的全取芯井,即若尔盖盆地RM孔湖泊沉积物环境多代用指标的综合判识,重建了900kaBP以来盆地的古气候古环境演化序列.根据该孔的沉积特征、沉积旋回的结构,以及沉积速率的变化,结合环境冷暖、干湿的组合特点,分辨出900kaBP以来高原东部3次明显的隆升加速时期,也即800,360及160kaBP.同时对青藏高原3次构造加速抬升在全球变化背景下的环境效应作了初步探讨.     

若尔盖盆地200 ka以来氧同位素记录的古温度定量研究

利用湖泊水体氧同位素的演化特征 ,建立了求解古温度的物理模型 ,并在若尔盖古湖研究中进行了具体应用 ,获得了近 2 0 0ka来的温度序列 .结果表明 ,相当于 7阶段 ,最高温度比现代高 2 .7℃ ;6阶段比今低 4.3℃ ;5阶段峰值温度比今高约5 .2℃ ;4阶段平均比现今低 2～ 3℃ ,而 3阶段曲线上表现为双峰一谷特征 ,内部温差在 4℃以上 .另外 ,通过比较模拟古温度值与碳酸盐氧同位素值两者间的关系 ,发现若尔盖地区 6阶段环境有其特殊性 ,并且是暖干冷湿型环境转向暖湿冷干型环境特征的过渡阶段 .     

近2600年来内蒙古居延海湖泊沉积记录的环境变迁

根据东居延海Ｓ１孔湖泊沉积柱状岩芯的多环境指标分析结果,将近２６００年来湖泊沉积物记录的环境演化过程分为十个阶段,湖泊沉积记录的气候组合特点具有冷湿→暖湿（冷干）→暖干→冷湿的过程,现阶段处于暖干阶段,预测未来气候向偏湿方向变化。近２６００年来自然的气候变化在居延海湖泊环境演化中居于主导地位,而人类活动只在特定时段对湖泊环境产生较大影响。     

云南鹤庆盆地30ka以来的古气候与环境变迁

通过云南鹤庆钻孔（ＨＱ孔）顶部８．１１ｍ岩芯剖面样品的多项环境指标的综合分析,重建了云南鹤庆盆地３０ｋａＢＰ以来的古气候环境演化历史。研究表明,该区气候在千年时间尺度上表现为冷湿与暖干组合交替的特点,未次冰盛期,为明显的冷湿环境,表现为最高湖面。盆地于晚冰期,约１４．２ｋａＢＰ始被切开,造成环境指标的大变化;进入全新世后,则以温干环境为主导,出现数次冷事件,手者是与东南季风区刊物比较研究的桥梁。     

青藏高原东北部30ka以来的古植被与古气候演变序列

利用孢粉分析并结合沉积学及~(14)C测年等资料,阐明青藏高原东北部若尔盖高原30ka来的古植被与古气候演变序列以及主要的气候事件。古植被经历了高寒荒漠-草原和亚高山草甸-高寒荒漠-草原、沼泽和亚高山草甸-岛状森林、沼泽和草甸-云杉、冷杉林及沼泽-岛状暗针叶林、沼泽和亚高山草甸7个阶段。气候与植被相应发生了多次变化,冰后期和全新世期间的气候事件在这里均有明显表现。     

13kaBP以来滇池地区古环境演

根据ＤＣ９３－１孔孢粉组合、总有机碳（ＴＯＣ）、总氮（ＴＮ）、碳氮比（Ｃ／Ｎ）、有机碳同位素δ＾１３Ｃｒｏｇ、磁化率（ｘ）、频率磁化率（ｘｆｄ）等资料,结合＾１４Ｃ、＾２１０Ｐｂ和＾１３７Ｃｓ测年,汗池地区１３ｋａ以来的古环境演化历史经历了以下几个阶段：１３－１０．２ｋａＢＰ,气候偏凉湿,湖水深度不大;１０．２－７．５ｋａＢＰ,气候向暖湿过渡,湖水渐深：７．５－４．０ｋａＢＰ,气候暖湿,水热条件达     

若尔盖盆地RH孔有机碳同位素序列指示的古气候事件诊断

定量化是过去全球气候变化研究的必然趋势,突变事件的诊断是古气候定量化研究中极其重要的过程。本文运用Ｍ－Ｋ法和ｔ检验法对ＲＨ孔有机碳同位素序列进行了气候突变诊断研究。结果发现,近８００ｋａＢＰ来该区气候存在明显的突变,且突变开始于４７０ｋａＢＰ。进一步的研究发现４７０ｋａＢＰ开始的这一气候突变事件与青藏高原的构造隆升有密切的关系。     

青海湖盆地35万年来的植被演化及环境变迁

本文依据青海湖南岸二郎剑阶地QH-86孔(深155m)中200余个孢粉样品的分析资料,将该孔深78m以上的孢粉图式,从下至上划分出七个区域性孢粉带,并结合铀系法测年数据,论述了350ka B.P.来的湖区植被和环境演变。其气候曲线与毗邻的柴达木盆地,甚至与深海钻孔及洛川黄土,具有可对比性。     

山西临汾盆地黄土及其形成古环境

叙述了临汾盆地黄土地层分布特征，并根据王绪典型黄土剖面孢子花粉、颗粒成分、古土壤特点以及磁化率变化，将王绪剖面划分为１８个气候组及１９个温暖期和２０个干冷期，每个干湿期构成一个气候旋回，这些旋回均可同深海沉积物所揭示的古气候旋回对比     

The uplifting and environmental change of Qinghai-Xizang (Tibetan) Plateau in the past 0.9 Ma inferred from core RM of Zoige Basin

According to the synthetic multi-disciplinary study on the lake sediments from core RM of Zoige Basin, i.e. the deepest wholly-collected core in Tibetan Plateau, the palaeoclimate and palaeoenvironment for the basin in the past 0.9 Ma have been reconstructed. The analytical results suggest that there distinctively exist 3 accelerated uplifting periods for the east Plateau in the past 0.9 Ma, i.e. 800, 360 and 160 kaB.P., with the study on the sedimentary characteristics, the texture of sedimentary cycles and variations of depositional rates, in conjunction with the environment features of cold/warm to dry/wet combination. The paper also probes into the environmental effect under the 3 accelerated tectonic-upliftings on the background of global change.     

Climatic variations in the past 140 ka recorded in core RM, east Qinghai-Xizang Plateau

The sequences of climatic evolution are reconstructed by the analyses of δ¹³C and δ¹⁸O of carbonate from core RM in the Zoige Basin since 140 kaB. P. During the Last Glaciation there existed at least seven warm climatic fluctuations and five cold events correlated with the records of ice core and deep sea, and during the preceding last interglacial period there were two cold climatic variations coinciding with the record of ice core GRIP. These results de-pict climatic instability in east Qinghai-Xizang Plateau over the last interglacial period. In addition, the environmental proxies of the carbonate content and pigments indicate the similar results to the stable isotope record from core RM. Project supported by the Chinese Climbing Project (85-029-02-01).     

Holocene peatland development and vegetation changes in the Zoige Basin,eastern Tibetan Plateau

Peat sediments and peatland evolution process offer abundant clues into the history of vegetation and climate changes.In order to reconstruct Holocene peatland, vegetation and climate changes on eastern Tibetan Plateau, we conducted analyses of fossil pollen, loss-on-ignition, and carbon accumulation rate on one peat core from Zoige Basin. Our results show local peatland initiated at 10.3 ka, thrived in the early-mid Holocene, and then began to degrade. Throughout the Holocene, Zoige Basin was dominated by alpine meadow. Coniferous forest on montane regions expanded for several times during 10.5–4.6ka, and then dramatically retreated. Results of peatland property, principal component analysis on fossil pollen suggested the climate maintained warm/wet during 10–5.5 ka, and became relatively cold/dry in the late Holocene. Rapid degradation of peatland, retreat of coniferous forest and climatic drought/cooling occurred at 10.2–10, 9.7–9.5, 8.7–8.5, 7.7–7.4, 6.4–6, 5.5–5.2,4.8–4.5, 4–3.6, 3.1–2.7, 1.4–1.2 and 0.8–0.6 ka. The long-term variations of Holocene climate and vegetation on eastern Tibetan Plateau could be attributed to changes in insolation-driven temperature and Asian Summer Monsoon intensity, while those rapid centennial changes were probably triggered by abrupt monsoon failures and temperature anomalies in the high northern latitudes.     

Cenozoic tectonic and sedimentary evolution of southern Qaidam Basin,NE Tibetan Plateau and its implication for the rejuvenation of Eastern Kunlun Mountains

The Eastern Kunlun Mountains play an important role in the growth and eastward extrusion of the Tibetan Plateau. Tectonic and sedimentary study of the Cenozoic Qaidam Basin, especially the southern part, provides key evidence for understanding their evolution. Here we present evidence including isopach maps, seismic sections and sedimentary analysis of single well to illustrate the sedimentary development of the basin and the structural features of its southern margin. The Qaidam Basin extended across Qiman Tagh-Eastern Kunlun Mountains in the early Cenozoic and withdrew northward at ca. 35.5 Ma, and then buckled as an EW striking elliptical depression since ca. 14.9 Ma, with the main depocenter migrating eastward. Our results support the view that the Kumukol and Hoh Xil basins joined the Qaidam Basin in the early Cenozoic time and we propose the Eastern Kunlun Mountains uplifted in the mid-Miocene.     

青藏高原冬春积雪对长江流域夏季降水的影响

本文根据青藏高原主体72个气象站日测资料建立的积雪序列分析了高原积雪对长江流域夏季降水的影响,高原冬春积雪异常与长江流域汛期特别是6、7月降水呈显著的正相关关系.青藏高原冬春多雪年,随后夏季多出现Ⅱ、Ⅲ类雨型,长江中游和下游鄱阳湖地区多偏涝;青藏高原冬春少雪年,随后夏季多出现Ⅰ、Ⅱ类雨型,长江下游鄱阳湖地区多偏旱,长江中游多正常偏旱.多(少)雪年东亚洲大陆上空的气温明显偏低(高),而大陆南部海洋上空的气温明显偏高(低),降低(增加)了陆海温差,延迟(促进)了东亚夏季风的到来,一定程度上减弱(加强)东亚季风的强度.多(少)雪随后夏季,由于南亚夏季风和东亚夏季风都明显减弱(增强),对流层中低层从孟加拉湾吹向中南半岛的西南风减弱(增强),我国大陆东部的南风也明显减弱(增强),西太副高偏南(北);青藏高原东南侧到中南半岛北部的上升运动较弱(强),长江中下游及其以东洋面上升运动较强(弱),长江中下游地区多(少)雨.     

Paleoclimatic indication of X-ray fluorescence core-scanned Rb/Sr ratios: A case study in the Zoige Basin in the eastern Tibetan Plateau

The X-ray fluorescence(XRF)core-scanned Rb/Sr ratios of lake sediments have been widely used as a proxy for chemical weathering intensity and past climate change.However,some factors could affect Rb/Sr ratios,causing misinterpretation and limiting its application.In this study,we present a high-resolution XRF core-scanned Rb/Sr record of core ZB13-C1 from the Zoige Basin in the eastern Tibetan Plateau.To validate its application,we correlated this record with the chemical index of alteration(CIA)and other paleoclimatic proxies.Our results showed that(1)the core-scanned Rb/Sr ratios and CIA were reliable proxies of chemical weathering intensity in fine-grained sedimentary sequences;(2)the low values of corescanned Rb/Sr ratios and CIA were significantly correlated with high total organic carbon content,arboreal pollen content,carbonate content,and C/N ratios,confirming its reliability as a proxy for the Asian summer monsoon intensity;(3)the corescanned Rb/Sr ratios at core depths of 25–0.3 and 56–47 m were unable to reliably reflect chemical weathering intensity due to both the grain-size effect and the low test accuracy.Our study highlights the need for mutual verification of multiple indicators before accurately applying Rb/Sr as a paleoclimatic proxy in other similar study areas.     

基于XRF岩芯扫描的Rb/Sr比值的古气候意义探讨——以青藏高原东部若尔盖盆地为例

XRF岩芯扫描技术是古气候研究中的重要工具,其中所获得的基于湖泊岩芯的Rb/Sr比值在古气候研究中被广泛用于表征流域化学风化的强度.然而在不同的地质背景下,影响Rb/Sr比值变化的因素不同,使得其古气候解释意义较为复杂.本研究选取青藏高原东部若尔盖盆地的湖泊沉积物岩芯,获取了高分辨率的XRF岩芯扫描Rb/Sr比值、传统...     

Late Quaternary terrace formation from knickpoint propagation in the headwaters of the Yellow River,NE Tibetan Plateau

Upstream knickpoint propagation is an essential mechanism for channel erosion, carrying changes in base level, tectonics and climate across the landscape. Generally, the terraces on cross-sections at steady-state conditions have been widely reported. However, many landscapes in the field appear to be in a transient state. Here, we explore the mechanism of knickpoint initiation and fluvial evolution in a transient setting in the northeastern Tibetan Plateau. Analysis of channel profiles and terrace correlation indicates that the Yellow River is adjusted to match the increase in differentiated fault activity and climate change in a regional setting of continuous uplift. Consequently, a series of terraces were formed, and the number of terrace steps increased downstream, in the headwaters of the Yellow River. All terraces were dated using the optically stimulated luminescence method. The top terrace, distributed continuously in the whole basin with a gradient, was deposited during a cold period and abandoned at the climatic transition from cold to warm state, at approximately 14.6–9.5 ka. After that, one terrace formed at around 4.2 ka in the upper reach. In correlation with the continuous topographic gradient surface of this terrace, three terrace steps were formed in the down reach during the period from 9.5 ka to 4.2 ka. This phenomenon might indicate multiple phases of continuous headward migration of fluvial knickpoint waves and terrace formation during the downcutting. It was caused by fault activity and tectonic uplift of the gorge at the outlet of the basin, under influence of the gradual integration of the Yellow River from downstream. This phenomenon shows that the fluvial incision in a transient state along the high relief margin of the orogenic plateau can be caused by fault activity, in addition to widespread surface uplift, climatically driven lake spillover and the establishment of external drainage.     

青藏高原东南部楚雄盆地构造-热演化史及其与油气关系

青藏高原东南部是构造最为活跃、变形最强烈的地区之一.楚雄盆地作为青藏高原东南部重要的中生代含油气叠合盆地,其演化历史复杂,后期改造强烈,热演化史研究薄弱.恢复楚雄盆地构造-热演化史对系统评价盆地油气资源和深入认识青藏高原东南部的构造变形过程有重要意义.本文研究在楚雄盆地全盆地系统采集了裂变径迹样品,分析确定了盆地的抬升过程,结合大量镜质体反射率（R_O）、包裹体测温等古温标,系统恢复了楚雄盆地构造-热演化史.裂变径迹研究结果表明楚雄断裂以西靠近哀牢山—红河断裂带地区的冷却年龄在41.9~72.7 Ma之间,主要为始新世41.9~55.5 Ma;楚雄断裂以东冷却年龄在20.0~38.4 Ma之间,主要为渐新世-早中新世.楚雄盆地抬升过程总体具有西早东晚的特征,主体部位20~38.4 Ma以来有一次快速抬升冷却过程.楚雄盆地三叠系热演化程度高,R_O异常高值与火成岩活动密切相关.热演化史研究表明三叠系最大古地温在上新世之前达到,最高古地温梯度可达30℃·km^-1.三叠系烃源岩在侏罗纪开始生烃,白垩纪为主要生烃期,古新世-始新世主要为过成熟生干气阶段.渐新世以来盆地整体抬升,地层温度降低,生烃作用减弱.楚雄盆地构造-热演化史除了受火成岩影响外,还与印度和欧亚板块的碰撞及哀牢山—红河断裂带的活动密切相关.