A high-resolution climatic chanse since Holocene inferred from multi-proxy of lake sediment in westerly area of China

Multi-proxy data are presented and a discuss is made of paleoclimatic and paleoenvironmental changes during Holocene from a 225-cm-long sediment core from Wulungu Lake, located in westerly area of China. The chronology is constructed from six AMS radiocarbon dates on the bulk organic matter. Analyses of pollen, TOC, TN, δ^13Corg, ostracod assemblages and the shell stable isotopes, suggest Holocene climate pattern as follows： temperate and dry （10.0-7.6 cal. ka BP） -warm and wet （7.6-5.3 cal. ka BP） -warm and moist （5.3-3.6 cal. ka BP） -temperate and dry （3.6-2.1 cal. ka BP）-temperate and moist （2.1-1.3 cal. ka BP） -cool and dry （1.3 cal. ka BP-present）. With the climatic change, Wulungu Lake experienced two large-scale retreat （5.3-3.6 cal. ka BP and 1.3 cal. ka BP-present） and an obvious transgression （7.6-5.3 cal. ka BP）. The records of climatic and environmental evolution of Wulungu Lake were in good accordance with those of adjacent areas. It responded to regional environmental change, global abrupt climate events and followed the westerly climate change mode.     

A high-resolution environmental change record since 19 cal ka BP in Pumoyum Co,southern Tibet

A 380-cm-long sediment core was acquired from the deep water area of Pumoyum Co, southern Tibet. Twenty-five plant residue samples were selected, and organic carbon stable isotopes were obtained using the AMS ¹⁴C chronological method. The ¹⁴C age and carbon reservoir effect were calibrated with surface sedimentation rate measurements using ²¹⁰Pb dating. Results showed that the core sediment deposited over 19 cal ka BP. Based on a multi-proxy analysis of TOC and IC contents, grain size and pollen assemblage data, the palaeoclimatic evolution of Pumoyum Co was reconstructed since the last glacial. Pumoyum Co was a shallow lake prior to 16.2 cal ka BP; although the glacier around the lake began to melt due to increasing temperatures, climate was still cold and dry. In the interval of 16.2–11.8 cal ka BP, the sedimentary environment fluctuated drastically and frequently. Two cold-events occurred at 14.2 and 11.8 cal ka BP, and these may correspond to the Older Dryas and the Younger Dryas events, respectively. After 11.8 cal ka BP, Pumoyun Co developed into the deep lake as it is now. The lake water temperature was relatively lower at that time because of influx of cold water from glacial meltwater entering the lake. As a result, the multi-proxy indicators showed no sign of warm conditions. Comparisons between the sedimentary record of Pumoyum Co with that of other lakes of the same age in southern Tibet indicate a warmer climate following the last deglaciation influenced the southeastern Tibetan Plateau. These results imply that the southwest Asian monsoon gradually became stronger since the deglaciation during its expansion to the inner plateau. The glacial-supplied water of the lake responded sensitively to cold-events. The entire southern Tibet region was dominantly influenced climatically by the southwest Asian monsoon during the Holocene.     

Water balance estimates of ten greatest lakes in China using ICESat and Landsat data

Lake level and area variations are sensitive to regional climate changes and can be used to indirectly estimate water balances of lakes. In this study, 10 of the largest lakes in China, ～1000 km² or larger, are examined to determine changes in lake level and area derived respectively from ICESat and Landsat data recorded between 2003 and 2009. The time series of lake level and area of Selin Co, Nam Co, and Qinghai Lake in the Tibetan Plateau (TP) and Xingkai Lake in northeastern China exhibit an increasing trend, with Selin Co showing the fastest rise in lake level (0.69 m/a), area (32.59 km²/a), and volume (1.25 km³/a) among the 10 examined lakes. Bosten and Hulun lakes in the arid and semiarid region of northern China show a decline in both lake level and area, with Bosten Lake showing the largest decrease in lake level (?0.43 m/a) and Hulun Lake showing the largest area shrinkage (?35.56 km²/a). However, Dongting, Poyang, Taihu, and Hongze lakes in the mid-lower reaches of the Yangtze River basin present seasonal variability without any apparent tendencies. The lake level and area show strong correlations for Selin Co, Nam Co, Qinghai, Poyang, Hulun, and Bosten lakes (R ² >0.80) and for Taihu, Hongze, and Xingkai lakes (～0.70) and weak correlation for East Dongting Lake (0.37). The lake level changes and water volume changes are in very good agreement for all lakes (R ² > 0.98). Water balances of the 10 lakes are derived on the basis of both lake level and area changes, with Selin Co, Nam Co, Qinghai, and Xingkai lakes showing positive water budgets of 9.08, 4.07, 2.88, and 1.09 km³, respectively. Bosten and Hulun lakes show negative budgets of ?3.01 and ?4.73 km³, respectively, and the four lakes along the Yangtze River show no obvious variations. Possible explanations for the lake level and area changes in these four lakes are also discussed. This study suggests that satellite remote sensing could serve as a fast and effective tool for estimating lake water balance.     

Hydrologic and climatic implications of a multi－disciplinary study of the mid to late Holocene Lake Eastern Juyanze

A mid to late Holocene exposure in a recently desiccated lake basin in western Inner Mongolia was inves-tigated with regard to palaeoenvir onmental changes and theoverall climatic conditions in NW China between 2.7 and 5.4 cal. ka BP. High lake levels of Lake Eastern Juyanze were recorded by ostracod assemblages, shell geochemistry and sedimentology between 5.1 and 4.1 cal. ka BP. Relatively bumid conditions and a relatively strong influence of the Asian monsoon are indicated by palynological data for the corresponding period. Lake levels decreased afterwards and short-term regressive events occurred at about 4.1, 3.8 and 3.4 cal. ka BP. The overall trend towards lower lake levels culminated in repeated episodes of desiccation of Lake East-ern Juyanze between 3.2 and 2.9 cal. ka BP, in phase with very arid conditions inferred from the palynological record.Individual regressive events as well as the rapid environ-mental fluctuations of Lake Eastern Juyanze at about 3.0 cal.ka BP were regarded as driven by mid to late Holocene summer monsoon fluctuations, supported by the Dunde ice core record.     

Changes in palaeoproductivity of Genggahai Lake over the past 16 ka in the Gonghe Basin, northeastern Qinghai-Tibetan Plateau

Sequential samples of a 7.82-m sediment core from Genggahai Lake in the central Gonghe Basin,controlled with 12 accelerator mass spectrometry (AMS) 14 C dates,have been analysed for total organic carbon (TOC) and total nitrogen (TN) contents,carbon isotope of bulk organic matter (δ 13 C org),and carbonate content.Plant macrofossils and stem encrustations,derived mainly from the species of P.pectinatus,M.spicatum and Chara spp.,were identified,and they dominated the aquatic plant community of the lake.Alternations of plant macrofossils of Chara spp.and the vascular species reflect the changing productivity of the lake over time.In such a shallow lake,the carbonate content is highly related to photosynthesis of aquatic macrophytes and thus indirectly indicates variations in productivity,consistent with a quantitative estimate of palaeoproductivity.Based on these results,the palaeoproductivity history was reconstructed over the past ca.16 ka.The lake was formed or recharged at 15.3 cal ka BP,as indicated by aeolian sand deposits at the core base.A marked increase in palaeoproductivity occurred from 15.3 to 11.6 cal ka BP.Between 11.6 and 9.2 cal ka BP,a sharply increased water-level,modulated probably by the enhanced Asian summer monsoon,might have exceeded the optimum water depth for macrophyte vegetation,causing a marked decline in coverage of aquatic macrophytes and low palaeoproductivity.The palaeoproductivity appeared to be high in the early stage of the period from 9.2 to 7.4 cal ka BP,and then decreased at approximately 8.6 cal ka BP.The palaeoproductivity sustained an overall high level between 7.4 and 2.1 cal ka BP,and decreased gradually since 2.1 cal ka BP.Our results suggest that the variability of Genggahai Lake palaeoproductivity may be associated with fluctuations of the lake level controlled by the strength of the Asian summer monsoon,probably indicating changes in the Asian summer monsoon.     

Pollen-inferred vegetation and environmental changes since 16.7 ka BP at Balikun Lake,Xinjiang

A high-resolution fossil pollen record from the sedimentary cores of Balikun Lake, northwestern China, combined with modern surface pollen data, is used to reconstruct the history of vegetation and climatic change since 16.7 cal. ka BP. Fossil pollen assem-blages and lithology indicate that the study area was dominated by desert. The desert had extremely arid climate and lower effective moisture during 16.7–7.9 cal. ka BP, especially from 16.7 to 8.9 cal. ka BP when the lake maybe dried up. During 8.9–7.9 cal. ka BP, the environment gradually recovered in this area. It was then followed by the optimum period from 7.9 to 4.3 cal. Ka BP, when the effective moisture obviously increased. It was characterized by the typical desert-steppe/steppe vegetation and was accompanied with several patch-birch woodlands around the lake. After that, a short but extremely arid climatic event occurred during 4.3–3.8 cal. ka BP, and the vegetation quickly changed from desert-steppe/steppe to desert. It was a relatively optimum period from 3.8 to 0.53 cal. ka BP showing typical desert-steppe/meadow-steppe landscape. Since 0.53 cal. ka BP, the climate has shown signs of deteriorating again. Furthermore, regional comparison shows that the characteristics of climatic and environmental evolution in this area were clearly different from East Asia monsoonal area during the last 16.7 cal. ka BP. It was characterized by the arid climate during the late-glacial and early Holocene, and relatively wet during the mid-late Holocene.     

青藏高原中部色林错SL-1孔粒度参数指示的5.33 ka BP以来的水位变化

 对取自青藏高原中部色林错深水区的SL-1 孔开展年代学和粒度参数研究,以此重建了该湖5.33 ka BP 以来的水位变化.结果表明,5.33~4.25 ka BP 是一期较为稳定的高湖面期,湖面波动较小,始终维持在高湖面,后期(4.30～4.25 ka BP)湖面开始下降;4.25~2.20 ka BP,风力加强,湖面较上一期有所降低,属湖面降低期,风力作用的影响增加;2.20~1.90 ka BP,稳定的低湖面期;1.90 ka BP 至今,高湖面期.但有几期短暂而快速的湖面降低,湖面降低的持续时间一般为20~50 a,具有约0.10 ka和0.20 ka 的周期性,约0.20 ka 的准周期基本贯穿了色林错自5.33 ka BP 以来的湖面变化.这种周期在青藏高原冰芯氧同位素恢复的温度序列中也存在,说明在百年尺度上,温度对色林错的湖面变化有一定影响.     

Southwest monsoon changes indicated by oxygen isotope of ostracode shells from sediments in Qinghai Lake since the late Glacial

The δ 18O records of ostracode shells in sediments of core QH-2000 from Qinghai Lake can be used as a better proxy to reflect monsoon changes. Low monsoon precipitation between 17.5 and 11 cal. ka BP is indicated by positive δ 18O values averaging 2.37‰. A fast shift in δ 18O from positive at 11 cal. ka BP to negative at 10 cal. ka BP indicates sharp increase of monsoon precipitation. An interval of generally high monsoon precipitation is observed between 10 and 6 cal. ka BP with δ 18O values averaging -2.15‰. Decrease of monsoon precipitation between 6 and 2.5 cal. ka BP is indicated by positive δ 18O values. δ 18O keeps positive values averaging 3.0‰ between 2.5 and 0 cal. ka BP suggesting low high monsoon precipitation. The climatic changes indicated by δ 18O records of ostracode shells in sedi- ments of core QH-2000 from Qinghai Lake and our broader regional comparison show that the climate in Qinghai Lake since the late Glacial is probably controlled by southwest monsoon other than southeast monsoon.     

A carbon－and oxygen－isotoperecord of recent environ－mental change from Qinghai Lake, NE Tibetan Plateau

A c. 300-year oxygen and carbon isotope record derived from fine-grained and ostracod carbonate from Qinghai Lake testifies to dramatic interannual to illterde-cadal linmologicai change. Fine-grained carbonates, whichare mainly authigenic, are likely to have formed in the epillmnion of the lake and their isotopic composition reflects the summer temperature and, more importantly, the isotopic composition of the near-surface waters, which is mainly afunction of evapor ative concentration. Ostracod shells aresecreted in the benthos of the lake, and their isotopic compo-sition reflects summer bottom-water conditions, together with fractionation effects, which may differ between species.Differences between contemporaneous values from authi-genic carbonates and ostracod shells may provide an indica-tion of stratification within the lake and variations in effec-tive precip itation over the northeast part of the Tibetan Pla-tcau over the past 300 years. A period of moderate evapora-tive concentration, from about 300 to 100 yr BP, was inter-rupted by a marked wet phase from-100 to 40 vr BP. which was in turn followed by a return to drier conditions in the most recent part of the record. The increase in δ^18O values in the latter part of the record accords well with instrumental records of lake-level lowering and salinity increase since about 1955 AD.     

Holocene climatic and environmental changes recorded in Baahar Nuur Lake core in the Ordos Plateau, Inner Mongolia of China

A 5.3 m lake core was drilled in Baahar Nuur Lake in the Ordos Plateau, and measurements of meangrain size, organic δ 13C (δ 13Corg), organic carbon content (TOC), C/N, carbonate content, carbonate δ 13C(δ 13Ccar) and δ 18O (δ 18Ocar) were conducted for retrieving the Holocene chronosequence of climaticchanges based on 15 AMS 14C dates. The record documented four major stages of climate change inthe Ordos Plateau: (IV) a cold and dry condition before ～7.65 14C ka BP; (III) a warm and humid stagebetween ～7.65 and ～5.40 ka BP; (II) a generally drier and cooler climate since ～5.40 ka BP with twohumid events occurring from ～4.70 to ～4.60 ka BP and from ～4.20 to ～3.70 ka BP, and (I) a dry climatecharacterized by complete desiccation of the lake after 3.70 ka BP. Stage III can be further divided intothree sub-stages: (IIIa) a warm and humid episode from ～7.65 to ～6.70 ka BP, (IIIb) a warm and relativelydry episode from ～6.70 to ～6.20 ka BP, and (IIIc) the magthermal and maghumid episode of the Holo-cene from ～6.20 to ～5.40 ka BP.     

Mechanism of variations in environmental magnetic proxies of lake sediments from Nam Co, Tibet during the Holocene

High-resolution environmental records from the Tibetan Plateau are essential to understand past global climatic and environmental changes. Magnetic minerals in lake sediments are important proxies to reconstruct environmental and climatic changes. Nam Co (lake) is a typical great lake in the transitional region of southwest monsoon in the Tibetan Plateau. Previous studies have extensively focused on geochemistry, microfossils, sedimentology and biochemistry analysis of Nam Co, which provides sound interpretation of paleoclimatic and paleoenvironmental changes. However, up to now, no systematic environmental magnetic studies have been carried out. Therefore, high-resolution and systematic magnetic studies combined with geochemical parameters were carried on lake sediments of core NC 08/01 from Nam Co for the Holocene period (11.3 cal ka BP) in order to explore how magnetic properties of the sediments respond to climatic changes. Based on variations of magnetic proxies, the sequence can be separated into 3 units. Unit 1 (236-199 cm, 11.3-7.8 cal ka BP) contains dominantly coarse-grained magnetite with homogeneous grain size. A positive correlation between magnetite and Ti strongly suggests that these coarse-grained detrital magnetites reflect detrital input signals due to insignificant effects of postdepositional dissolution processes on these coarse-grained magnetite particles. For Unit 2 (198-102 cm, 7.8-2.1 cal ka BP), magnetic grain size is finer and the corresponding concentration of magnetite is also reduced. This is mainly due to significant dissolution of these fine-grained detrital magnetite particles, which were transported under reduced water flow conditions during this period. For Unit 3 (101-0 cm, 2.1-0 cal ka BP), the bulk magnetic properties are dominated by a mixture of single domain biogenic magnetite and detrital magnetite. The concentration of magnetic minerals is not correlated with the Ti content. In conclusion, the preservation of magnetic minerals in the lake sediment and thus the corresponding magnetic properties are related to the initial grain size. Combination of magnetic properties (including variation of grain size and concentration) and other proxies of detrital inputs (e.g. Ti) can be used to infer the variation of redox conditions in Nam Co. These results provide a viable framework for reconstructing the paleoenvironmental changes of this lake.     

A mid－Holocene drought interval as evidenced by lake desiccation in the Alashan Plateau,Inner Mongolia,China

The mid-Holocene in China is traditionally thought to be a warm and humid period with a strong sum-mer monsoon, and is often termed the Holocene Climatic Optimum or Megathermal Period. Here we present lakegeomorphologic and lithologicai evidence from the Alashan Plateau, part of the Mongolian Plateau, that indicates stronglake desiccation during the mid-Holocene. High resolution pollen data from Zhuyeze Lake, at the present summermonsoon margin, is also presented. These data show that present lakes and wetlands in the Juyanze Lake basin west of the Badain Jaran desert, in the Zhuyeze Lake basin between the Badain Jaran and Tengger deserts, and in lakes in the eastern Tengger desert, dried or experienced low lake levelsin the mid-Holocene around 5000-7000 cal yr BP. Pollen data further indicate that the vegetation cover declined in both the local areas and in the Qilian Mountains, suggesting the climate was drier than that associated with the presentAsian summer monsoon. This mid-Holocene drought interval was present throughout a quite large region of the south In-ner Mongolian Plateau. The period was also probably colder,at least in the high Asian plateaus and mountains.     

Monitoring the frozen duration of Qinghai Lake using satellite passive microwave remote sensing low frequency data

The Qinghai Lake is the largest inland lake in China. The significant difference of dielectric properties between water and ice suggests that a simple method of monitoring the Qinghai lake freeze-up and break-up dates using satellite passive microwave remote sensing data could be used. The freeze-up and break-up dates from the Qinghai Lake hydrological station and the MODIS LIB reflectance data were used to validate the passive microwave remote sensing results. The validation shows that passive microwave remote sensing data can accurately monitor the lake ice. Some uncertainty comes mainly from the revisit frequency of satellite overpass. The data from 1978 to 2006 show that lake ice duration is reduced by about 14--15 days. The freeze-up dates are about 4 days later and break-up dates about 10 days earlier. The regression analyses show that, at the 0.05 significance level, the correlations are 0.83, 0.66 and 0.89 between monthly mean air temperature （MMAT） and lake ice duration days, freeze-up dates, break-up dates, respectively. Therefore, inter-annual variations of the Qinghai Lake ice duration days can significantly reflect the regional climate variation.     

新疆博斯腾湖环境变化及其初步评价

本文简要地回顾了新疆焉耆盆地近四十年来主要的水事活动及其对博斯腾湖湖区的环境影响。在此基础上,对该区的环境变化作了初步评价并提出了一些继续改善环境的建议。     

Environmental changes during early-middle Holocene from the sediment record of the Chaohu Lake,Anhui Province

A typical lake sediment core is obtained from the Chaohu Lake in the lower reaches of the Yangtze River,Anhui Province,China.The timing scale is constrained by AMS 14 C dating method.Climate proxies such as pollen and grain size in the core are analyzed to reconstruct the environment changes at this site approximately between 9870 and 2170 cal.a BP.The results indicate that at the research area, the climate in the early-middle Holocene had evolved through 3 stages.From 9870 to 6040 cal.a BP, proxy records show a warm and dry climate with low water levels after the late-glacial period.During this stage,cool and dry events occurred at about 8910 and 6060-6030 cal.a BP.Then,between 6040 and 4860 cal.a BP,the climate was humid and vegetation was more flourishing in the Chaohu Lake Valley.The Holocene Optimum occurred at 5840-5500 cal.a BP in the Chaohu Lake,showing the best condition of water and heat.Elm Decline occurred at the period of 5380-4930 cal.a BP.Since 4860 cal.a BP,the climate was warm and dry through 2170 cal.a BP as shown in both pollen spectrum and grain-size histories.Two obvious dry events occurred in 3760 and 2170 cal.a BP,respectively.At 2170 cal.a BP,the water level of the Chaohu Lake reached the lowest as the lakebed possibly exposed. Such lake sediment observations are consistent with the historical records in this area.     

Late Glacial and Holocene vegetation history and paleoclimate of the Tengger Desert,northwestern China

With a total area of 36000 km2, the Tengger Desert is the fourth largest desert in China. The Qilian Mountains demarcate the southwestern boundary of the desert andthe Helan Mountain on the east separates the desert from the Mo Us Desert. The Yabulai Mountain on thenorthwest borders the Tengger Desert and the BadainJaran Desert and the Loess Plateau touch its southern tip (Fig. 1). Climatically, the area is situated at the junction of the hyper-arid northwest, the arid to semi-arid sou…     

Climatic changes documented by stable isotopes of sedimentary carbonate in Lake Sugan, northeastern Tibetan Plateau of China, since 2 kaBP

Lake Sugan at the northern edge of the Qaidam Basin was selected as the research object. The temporal sequence of sedimentary cores retrieved from Lake Sugan since 2 kaBP was reconstructed using the ^210Pb, AMS 14C and conventional 14C dating methods. Carbon and oxygen isotopes of carbonate in the fine-grained lake sediments were analysed. Combined with the changes of 8180 values of surface water and air temperature observation data in the study area, it might be thought that the δ^18O value of the carbonate indicates effective moisture, and the changes in δ^13C values are related to annual freeze-up duration of the lake and indirectly indicate air temperature changes in winter half year. From the above, the sequence of climatic changes in the region since 2 kaBP was established. The climatic changes experienced five stages： Warm-dry climate during 0-190 AD： cold-dry climate during 190-580 AD; warm-dry climate during 580-1200 AD （MWP）; cold-wet climate during 1200-1880 AD （LIA）; cold-dry climate during 1880-1950 AD： and climate warming since 1950s. The air temperature changes in winter half year reflected by carbon isotope since 2 kaBP are in good agreement with the historical literature records and other geologic records, which shows that the climate changes recorded by the stable isotopes from Lake Sugan since 2 kaBP are of universal significance.     

Oxygen isotope variation in the water cycle of the Yamzho lake Basin in southern Tibetan Plateau

Given the potential use of stable isotope in the paleoclimate reconstruction from lacustrine records as well as in the local hydrology cycle, it is crucial to understand the processes of stable isotope evolution in catchment in the Tibetan Plateau region. Here we present a detailed study on the water oxygen isotope based on 2 years observation including precipitation, river water and lake water in the Yamzho Lake, south of the Tibetan Plateau. Temporal variation of local precipitation 5180 shows an apparent ＂monsoon cycle＂. In monsoon season, 5180 in waters is lower. In non-monsoon season, δ^18O in precipitation and lake water is higher and higher river δ^18O exists in spring, probably reflecting the effect of land surface evaporation, together with the higher δ^18O values in spring precipitation. It is also found that the surface lake water δ^18O varies seasonally and annually. The lower lake water δ^18O in the late summer is apparently related to the summer monsoon precipitation. The mean δ^18O value of lake water in 2007 is 1.2‰ higher than that in 2004, probably due to the less monsoon precipitation in summer of 2007, as can be confirmed from the precipitation data at the Langkazi meteorological data. It is also found that an obvious shift of vertical lake water δ^18O reflects the fast mixture of lake water. δ^18O values of lake water are over 10‰ higher than those of precipitation and river water in this region due to the evaporation fractionation. The modeled results show that the evaporation process of the lake water is sensitive to relative humidity, and the present lake water δ^18O reflects a relative humidity of 51% in the Yamzho Lake. It shows that the lake will take 30.5 years to reach present lake water δ^18O given a large shift in the input water δ^18O. The modeled results also reveal that surface lake water temperature and inflow δ^18O have slight effect on the isotopic balance process of lake water in the Yamzho Lake.     

新疆巴里坤湖9.0 cal ka BP以来沉积物地球化学元素分布特征与古气候环境演化

根据中国西北干旱区巴里坤湖BLK-1剖面沉积物的地化元素分析,采用SPSS因子分析法提取了对沉积环境变化敏感的地化元素和氧化物组分.在R、Q型因子分析的基础上,结合沉积物的硅铁铝率(SiO2/(Al2O3+Fe2O3))、淋失系数(SiO2/(MgO+K2O))、CaO/MgO以及腐殖化度等指标,提取出古气候环境信息.初步研究结果表明:近9.0 cal ka BP以来,巴里坤湖地区气候环境仍以干旱化为主,全新世期间出现过多次不同程度的干湿变化,经历了5个气候阶段:9.0—7.5 cal ka BP期间,气候干旱;7.5—5.8 cal ka BP期间,气候温暖湿润,为研究区全新世最佳适宜期;5.8—3.0 cal ka BP期间,气候干旱;3.0—1.0 cal ka BP期间,气候湿润;1.0—0 cal ka BP期间,气候干旱.     

Study of the varve record from Erlongwan maar lake, NE China, over the last 13 ka BP

In a sediment sequence from Erlongwan maar lake that spans the last 13 ka BP, two main varve types can be recognized： biogenic varves （from the present to -11.2 ka BP, 0-632 cm） and clastic varves （from -11.2 to -12.7 ka BP, 632-700 cm）. Based on the dominant types of algae contained in the sediment, the biogenic varves can be classified into dinocyst-biogenic varves （0-63 cm） and mixed （dinocyst and diatom）-biogenic varves （214-632 cm）. In this paper, the formation process and components of the varve are described, the possible reason for the types of varve changing throughout the record is discussed and a high-resolution varve chronology is established spanning the last 13 ka BP. Although further varve counting and error assessment are needed, the results presented here represent a solid foundation for studying the palaeoclimate record of Erlongwan maar lake.